Materiały źródłowe

• #1 Subarachnoid hemorrhage – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/subarachnoid-hemorrhage/diagnosis-treatment/drc-20361014

  To diagnose a subarachnoid hemorrhage, you may need the following tests: […] CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram. […] MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram. […] Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

• #2 Subarachnoid Hemorrhage (SAH): Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/17871-subarachnoid-hemorrhage-sah

  Subarachnoid hemorrhage (SAH) is a medical emergency that requires immediate treatment. […] The main sign of SAH is a thunderclap headache, which is an extremely painful headache that comes on suddenly, like a clap of thunder. […] If your healthcare provider suspects you have a subarachnoid hemorrhage based on your symptoms and a physical exam, they’ll immediately order a CT (computerized tomography) scan. […] A CT scan of your brain is an effective way for your provider to see a subarachnoid hemorrhage. […] Sometimes, a CT scan may miss a very small subarachnoid hemorrhage or one that occurred a week or two ago. Your provider will likely order other tests to detect a subarachnoid hemorrhage if a CT scan is negative. […] The hospital care following the diagnosis of subarachnoid hemorrhage focuses on both discovering and treating the cause of the SAH, as well as managing its complications.

• #3 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  Headache is one of the most common reasons for presentation to the emergency department (ED), seen in up to 2% of patients. Most are benign, but it is imperative to understand and discern the life-threatening causes of headache when they present. Headache caused by a subarachnoid hemorrhage (SAH) from a ruptured aneurysm is one of the most deadly, with a median case-fatality of 27-44%. Fortunately, it is also rare, comprising only 1% of all headaches presenting to the ED. On initial presentation, the one-year mortality of untreated SAH is up to 65%. With appropriate diagnosis and treatment, mortality can be reduced to 18%. The implications are profound: Our careful assessment leading to the detection of a SAH as the cause of headache can significantly decrease our patients’ mortality. If this were an easy task, the 12% reported rate of missed diagnosis would not exist. We have multiple tools and strategies to evaluate the patient with severe headache and must understand the strengths and limitations of each tool.

• #4 Subarachnoid Hemorrhage (SAH): Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/17871-subarachnoid-hemorrhage-sah

  As subarachnoid hemorrhage (SAH) is a life-threatening, emergency condition, it’s typically treated in the intensive care unit (ICU) in a hospital with neurological expertise. […] The goals of treatment are to save your life, repair the cause of the bleeding, relieve symptoms, and prevent complications. […] The length of stay in the hospital varies based on your health status. […] The prognosis (outlook) for subarachnoid hemorrhage depends on its cause, severity and the presence of other complications or injuries. […] The one-year mortality rate of untreated SAH is up to 65%, meaning up to 65% of people who had an SAH that wasn’t treated died within one year of the episode. […] With appropriate diagnosis and treatment, the one-year mortality rate is around 18%.

• #5 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  Headache is one of the most common reasons for presentation to the emergency department (ED), seen in up to 2% of patients. Most are benign, but it is imperative to understand and discern the life-threatening causes of headache when they present. Headache caused by a subarachnoid hemorrhage (SAH) from a ruptured aneurysm is one of the most deadly, with a median case-fatality of 27-44%. Fortunately, it is also rare, comprising only 1% of all headaches presenting to the ED. On initial presentation, the one-year mortality of untreated SAH is up to 65%. With appropriate diagnosis and treatment, mortality can be reduced to 18%. The implications are profound: Our careful assessment leading to the detection of a SAH as the cause of headache can significantly decrease our patients’ mortality. If this were an easy task, the 12% reported rate of missed diagnosis would not exist. We have multiple tools and strategies to evaluate the patient with severe headache and must understand the strengths and limitations of each tool.

• #6 Subarachnoid Hemorrhage (SAH): Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/17871-subarachnoid-hemorrhage-sah

  Subarachnoid hemorrhage (SAH) is a medical emergency that requires immediate treatment. […] The main sign of SAH is a thunderclap headache, which is an extremely painful headache that comes on suddenly, like a clap of thunder. […] If your healthcare provider suspects you have a subarachnoid hemorrhage based on your symptoms and a physical exam, they’ll immediately order a CT (computerized tomography) scan. […] A CT scan of your brain is an effective way for your provider to see a subarachnoid hemorrhage. […] Sometimes, a CT scan may miss a very small subarachnoid hemorrhage or one that occurred a week or two ago. Your provider will likely order other tests to detect a subarachnoid hemorrhage if a CT scan is negative. […] The hospital care following the diagnosis of subarachnoid hemorrhage focuses on both discovering and treating the cause of the SAH, as well as managing its complications.

• #7 Subarachnoid haemorrhage – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/3000106

  Subarachnoid haemorrhage (SAH) presents as a sudden, severe headache that peaks within 1 to 5 minutes (thunderclap headache) and lasts more than an hour; typically alongside vomiting, photophobia, and non-focal neurological signs. […] Order an urgent non-contrast computed tomography (CT) head scan for all patients with suspected SAH. The CT scan should ideally be within 6 hours of symptom onset. SAH is confirmed by the hyperdense appearance of blood in the subarachnoid space/basal cisterns. […] As soon as the diagnosis of SAH is confirmed, urgently discuss with a specialist neurosurgical centre the need for transfer of care of the patient to the specialist centre. […] An interventional neuroradiologist and a neurosurgeon should decide the best mode of intervention to manage the culprit aneurysm, taking into account the patient’s clinical condition, the characteristics of the aneurysm, and the amount and location of subarachnoid blood.

• #8 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  The diagnosis of SAH should be considered in any patient with a severe and sudden onset or rapidly escalating headache. With such a large number of patients presenting to the ED with a chief complaint of headache, differentiating those with a benign cause from those with an emergent etiology such as SAH can be difficult. Deciding which patients require a workup for SAH is often the most challenging part of the emergency physician’s care, in part due to the low frequency and high acuity of the illness. […] Classic teaching characterizes the headache of SAH as a thunderclap headache, which is defined as a sudden, severe headache often described as the worst of the patient’s life. The headache is typically a sudden onset, which is commonly characterized as occurring within a few minutes, although research parameters include headache that reaches maximum intensity within one hour. Symptoms that increase the likelihood of a subarachnoid bleed as the cause of headache include exertional onset, syncope, vomiting, neck pain, and seizures. Focal neurologic deficits, meningismus, and/or retinal hemorrhage may be present, but up to 50% of SAH patients have a normal neurologic exam. Recent research has attempted to shed light on which elements of the history and physical exam are correlated with and discriminating for the diagnosis of SAH.

• #9 Subarachnoid Haemorrhage (SAH) • LITFL • CCC Neurosurgery

  https://litfl.com/subarachnoid-haemorrhage-sah/

  Subarachnoid Haemorrhage (SAH) potentially fatal bleeding into the subarachnoid space, usually due to a ruptured cerebral aneurysm […] LP: most sensitive at 12 hours for xanthochromia […] DSA: gold standard for diagnosis, allows intervention […] predictors of poor prognosis:- high grade- old age- co-morbidities- blood 1mm thick on CT- seizures- cerebral oedema- basilar artery aneurysm- symptomatic vasospasm- complications.

• #10

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  You’ll need to have some tests done in a hospital to confirm if you have a subarachnoid haemorrhage. […] A CT scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image. […] You may also have a test called a lumbar puncture. A needle is inserted into the lower part of the spine so that a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid) can be removed. It will then be analysed for signs of bleeding. […] If the results of a CT scan or lumbar puncture confirm you’ve had a subarachnoid haemorrhage, you’ll be referred to a specialist neuroscience unit. […] Further tests are usually needed to help plan treatment, which may include either: computed tomography angiography (CTA) using a CT scan or magnetic resonance angiography (MRA) using an MRI scan.

• #11 Subarachnoid hemorrhage – Knowledge @ AMBOSS

  https://www.amboss.com/us/knowledge/subarachnoid-hemorrhage/

  Subarachnoid hemorrhage (SAH) refers to bleeding into the subarachnoid space. The best initial diagnostic test is a head CT without contrast, in which acute subarachnoid bleeding can be seen as hyperdensities in the subarachnoid space. If a head CT is negative for SAH, this diagnosis can be ruled out in many patients. However, if clinical suspicion remains high, it may be necessary to perform a lumbar puncture or CT angiography. Once SAH is confirmed, angiography is always necessary in order to identify the source of bleeding (e.g., aneurysms or other vascular abnormalities) and plan definitive treatment. […] Since a missed diagnosis of SAH can have devastating consequences, clinicians should maintain a high index of suspicion when deciding whether to pursue testing. […] Best initial test: immediate head CT without contrast.

• #12 Subarachnoid hemorrhage – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/subarachnoid-hemorrhage/diagnosis-treatment/drc-20361014

  To diagnose a subarachnoid hemorrhage, you may need the following tests: […] CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram. […] MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram. […] Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

• #13

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  You’ll need to have some tests done in a hospital to confirm if you have a subarachnoid haemorrhage. […] A CT scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image. […] You may also have a test called a lumbar puncture. A needle is inserted into the lower part of the spine so that a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid) can be removed. It will then be analysed for signs of bleeding. […] If the results of a CT scan or lumbar puncture confirm you’ve had a subarachnoid haemorrhage, you’ll be referred to a specialist neuroscience unit. […] Further tests are usually needed to help plan treatment, which may include either: computed tomography angiography (CTA) using a CT scan or magnetic resonance angiography (MRA) using an MRI scan.

• #14 Subarachnoid Hemorrhage (SAH) – EMCrit Project

  https://emcrit.org/ibcc/sah/

  Noncontrast CT is the standard initial test for possible subarachnoid hemorrhage. […] The sensitivity is nearly 100% within six hours of headache onset, after which time blood starts looking a bit more grey, so the sensitivity may decrease slightly. […] CT angiography (CTA) is highly sensitive and specific (~95%) for aneurysm detection, but may miss very small aneurysms. […] For patients with thunderclap headache, a reasonable diagnostic strategy might be to perform a STAT noncontrast CT scan followed immediately by a CTA of the head and neck. CT/CTA is fast, noninvasive, and safe. […] If CT/CTA leaves remaining confusion about the possibility of SAH, then lumbar puncture and/or MRI/MRA may be considered. […] MRI can be useful to detect subtle underlying pathology (e.g., arteriovenous malformations, infections, malignancy, or inflammatory disorders).

• #15 Subarachnoid hemorrhage – Wikipedia

  https://en.wikipedia.org/wiki/Subarachnoid_hemorrhage

  Bleeding into the brain’s subarachnoid space […] Generally, the diagnosis can be determined by a CT scan of the head if done within six hours of symptom onset. […] Occasionally, a lumbar puncture is also required. […] The initial steps for evaluating a person with a suspected subarachnoid hemorrhage are obtaining a medical history and performing a physical examination. The diagnosis cannot be made on clinical grounds alone and in general medical imaging and possibly a lumbar puncture is required to confirm or exclude bleeding. […] The modality of choice is computed tomography (CT scan), without contrast, of the brain. This has a high sensitivity and will correctly identify 98.7% of cases within six hours of the onset of symptoms. […] A CT scan can rule out the diagnosis in someone with a normal neurological exam if done within six hours.

• #16 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  subarachnoid hemorrhage (SAH) should be considered in any patient presenting with a severe, sudden-onset, or rapidly worsening headache […] deciding which patients require evaluation for SAH is often challenging in emergency care; the Ottawa SAH Rule can help identify patients needing urgent imaging in the emergency setting (Perry, 2017) […] initial diagnosis is usually made with non-contrast CT (NCCT), which is 95% sensitive within 6 hours of onset […] if NCCT confirms SAH, CT angiography (CTA) is performed to identify the bleeding source (e.g., aneurysm) […] if NCCT is negative but SAH is strongly suspected, lumbar puncture (LP) with CSF analysis should be performed […] CT scan sensitivity for SAH is 90-98% within the first 24 hours, depending on SAH volume and location (Gee, 2012)

• #17 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  CT scan sensitivity decreases over time ~ 98% in the first 6 hours, to 70% by day 3, and to 50% a week later […] most SAH blood clears within ~7-10 days, so persistent or increasing blood suggests rebleeding […] MRI is sensitive to subarachnoid blood and can visualize it within the first 12 hours […] MRI can also detect thrombosed aneurysms (T1/2), sometimes not visible on CTA or DSA […] MR angiography can detect aneurysms (3mm) or other sources of bleeding […] it is recommended to wait 9-12 hours from the onset of presenting symptoms before performing lumbar puncture (LP) to allow for the breakdown of RBCs […] rapid analysis of collected CSF is required […] bedside multiple-tube test is useful to exclude traumatic tap […] xanthochromia typically appears 9-12 hours after bleeding and can persist for up to 2-4 weeks

• #18 Subarachnoid hemorrhage | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/subarachnoid-haemorrhage?lang=us

  Subarachnoid hemorrhage (SAH) is a type of extra-axial intracranial hemorrhage and denotes the presence of blood within the subarachnoid space. […] Patients typically present with a thunderclap headache, described as a sudden-onset headache that is the worst headache of their life. It is often associated with photophobia and meningism. Focal neurological deficits often present either at the same time as a headache or soon thereafter. […] The diagnosis is suspected when a hyperdense material is seen filling the subarachnoid space. Most commonly, this is apparent around the circle of Willis, on account of the majority of berry aneurysms occurring in this region (~65%), or in the Sylvian fissure (~30%). […] The sensitivity of non-contrast CT to the presence of subarachnoid blood is strongly influenced by both the amount of blood and the time since the hemorrhage.

• #19 Diagnosis of a subarachnoid hemorrhage with only mild symptoms using computed tomography in Japan | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-016-0726-9

  The first diagnostic study in these patients should be a non-contrast CT. […] The sensitivity of CT for SAH ranges from 90 to 95 %, implying that CT has a high sensitivity but should not be applied as a sole diagnostic modality for SAH diagnosis. […] The key CT finding of SAH is blood in the basilar cistern at the base of the brain where the Circle of Willis is located. […] If there is only a small quantity of blood which is mixed with CSF, it can appear isoattenuating (gray, similar to brain tissue) in these regions. […] CT is therefore less sensitive at detecting SAH after 24 h. […] However, if Sylvian fissures are not clearly visualized bilaterally, as in the case of our patient, and the difference between left and right visualization of Sylvian fissures are recognized, we should pay attention to minute details with suspicion of SAH.

• #20 Subarachnoid hemorrhage – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/subarachnoid-hemorrhage/diagnosis-treatment/drc-20361014

  To diagnose a subarachnoid hemorrhage, you may need the following tests: […] CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram. […] MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram. […] Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

• #21 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]). […] Given the sensitivity of the CT discussed above, shared decision-making should be conducted with regard to LP. In particular, with sensitivity of near 99% for an adequate study if completed within six hours, and meeting the criteria outlined above, patients should be made aware of the low diagnostic utility of LP if completed after a CT. In this setting, risks (adverse events and false positives) generally outweigh benefits and LP is advised against.

• #22 Subarachnoid Hemorrhage (SAH) – Neurologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/neurologic-disorders/stroke/subarachnoid-hemorrhage-sah

  Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space. […] Diagnosis is by CT or MRI; if neuroimaging is normal, diagnosis is by cerebrospinal fluid analysis to look for xanthochromia and red blood cells. […] Diagnosis of subarachnoid hemorrhage is suggested by characteristic symptoms. Testing should proceed as rapidly as possible, before damage becomes irreversible. […] Noncontrast CT is done within 6 hours of symptom onset. When done within this time frame, this test has very high sensitivity. Therefore, if this test does not detect a subarachnoid hemorrhage, no other testing is needed as long as patients have a normal physical examination, no meningeal signs, and no anemia, MRI is comparably sensitive but less likely to be immediately available. […] If subarachnoid hemorrhage is suspected clinically but not identified by neuroimaging or if neuroimaging is not immediately available, lumbar puncture is done.

• #23 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage – The Western Journal of Emergency Medicine

  https://westjem.com/articles/approach-to-the-diagnosis-and-management-of-subarachnoid-hemorrhage.html

  When a clinical suspicion for SAH exists based on history and physical exam, non-contrast computed tomography (CT) is the first diagnostic tool. It is also valuable in excluding other pathologies such as intracranial hemorrhage, malignancy, or abscess. […] A meta-analysis published in 2016 attempted to answer the question of CT sensitivity with relation to time from symptom onset.18 The analysis, which included five studies, assessed patients with a thunderclap headache and normal neurologic exam. While the results carry many of the limitations of a meta-analysis, a conservative statistical analysis showed that a non-contrast CT completed within six hours of headache onset had a sensitivity of 98.7% with confidence intervals 97.1%99.4%. […] If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]).

• #24 Subarachnoid Hemorrhage (SAH) – Neurologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/neurologic-disorders/stroke/subarachnoid-hemorrhage-sah

  Suspect subarachnoid hemorrhage if headache reaches peak, severe intensity within seconds of onset or causes loss of consciousness. […] Do lumbar puncture if subarachnoid hemorrhage is suspected clinically but CT shows no hemorrhage or is not available; however, lumbar puncture is contraindicated if increased intracranial pressure is suspected. […] CSF findings suggesting subarachnoid hemorrhage include numerous red blood cells (RBCs), xanthochromia, and increased pressure. […] In patients with subarachnoid hemorrhage, conventional cerebral angiography is done as soon as possible after the initial bleeding episode; alternatives include magnetic resonance angiography and CT angiography.

• #25 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]). […] Given the sensitivity of the CT discussed above, shared decision-making should be conducted with regard to LP. In particular, with sensitivity of near 99% for an adequate study if completed within six hours, and meeting the criteria outlined above, patients should be made aware of the low diagnostic utility of LP if completed after a CT. In this setting, risks (adverse events and false positives) generally outweigh benefits and LP is advised against.

• #26 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage – The Western Journal of Emergency Medicine

  https://westjem.com/articles/approach-to-the-diagnosis-and-management-of-subarachnoid-hemorrhage.html

  When a clinical suspicion for SAH exists based on history and physical exam, non-contrast computed tomography (CT) is the first diagnostic tool. It is also valuable in excluding other pathologies such as intracranial hemorrhage, malignancy, or abscess. […] A meta-analysis published in 2016 attempted to answer the question of CT sensitivity with relation to time from symptom onset.18 The analysis, which included five studies, assessed patients with a thunderclap headache and normal neurologic exam. While the results carry many of the limitations of a meta-analysis, a conservative statistical analysis showed that a non-contrast CT completed within six hours of headache onset had a sensitivity of 98.7% with confidence intervals 97.1%99.4%. […] If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]).

• #27 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  When scanned within 6h of headache onset, modern third generation CT scans are 100% sensitive (95% CI, 97.0%-100.0%) for the detection of SAH when interpreted by a radiologist. […] If the CT is negative no other investigations are required. […] After 6h from headache onset, CT scanning is only 85.7% sensitive. Therefore, patients with delayed imaging and a negative scan require further investigations (LP). […] If a detailed neurologic examination is normal, there are no signs of papilledema on examination, there is no bleeding disorder or use of anticoagulants, and there is no history of intracranial pathology, it is reasonable to perform a lumbar puncture to rule out SAH. […] All aneurysmal SAHs were identified by the presence of xanthochromia on visual inspection of the cerebrospinal fluid or the presence of >2000 x 10^6 red blood cells/L in the cerebrospinal fluid (sensitivity 100%; 95% CI 74.7%-100.0%). […] If the LP is positive or if clinical suspicion is high, the next diagnostic step is cerebral angiography to identify cerebral aneurysms. […] All patients with an SAH diagnosed with CT or positive LP will need angiography.

• #28 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage – The Western Journal of Emergency Medicine

  https://westjem.com/articles/approach-to-the-diagnosis-and-management-of-subarachnoid-hemorrhage.html

  True xanthochromia is pathognomonic for SAH. This is valuable when there is high clinical suspicion and RBC count is not sufficiently elevated to differentiate from a traumatic tap diagnostic. […] Over the last decade, CTA of the brain has become part of the discussion in ruling out SAH. As a non-invasive means of highlighting vascular anatomy and detecting aneurysms, CTA has many advantages. […] Many tools are available to assess for SAH including non-contrast CT, LP, CTA, and MRI. Understanding the potentially high mortality in the case of a missed SAH should mandate a diagnostic strategy with the highest sensitivity possible, which is currently accepted to be non-contrast CT followed, if negative, by LP.

• #29 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  CT scan sensitivity decreases over time ~ 98% in the first 6 hours, to 70% by day 3, and to 50% a week later […] most SAH blood clears within ~7-10 days, so persistent or increasing blood suggests rebleeding […] MRI is sensitive to subarachnoid blood and can visualize it within the first 12 hours […] MRI can also detect thrombosed aneurysms (T1/2), sometimes not visible on CTA or DSA […] MR angiography can detect aneurysms (3mm) or other sources of bleeding […] it is recommended to wait 9-12 hours from the onset of presenting symptoms before performing lumbar puncture (LP) to allow for the breakdown of RBCs […] rapid analysis of collected CSF is required […] bedside multiple-tube test is useful to exclude traumatic tap […] xanthochromia typically appears 9-12 hours after bleeding and can persist for up to 2-4 weeks

• #30 Subarachnoid Hemorrhage Workup: Approach Considerations, Computed Tomography, Lumbar Puncture

  https://emedicine.medscape.com/article/1164341-workup

  An LP is performed to evaluate the cerebrospinal fluid for the presence of red blood cells (RBCs) and xanthochromia. […] Xanthochromia typically will not appear until 2-4 hours after the ictus. In nearly 100% of patients with an SAH, xanthochromia is present 12 hours after the bleed and remains for approximately 2 weeks. […] Digital-subtraction cerebral angiography has been the criterion standard for the detection of cerebral aneurysms. […] Negative angiographic findings do not rule out aneurysm. Approximately 10-20% of patients with clinically diagnosed SAH have negative angiographic findings. […] Although digital-subtraction cerebral angiography has been the criterion standard for the detection of cerebral aneurysms, multidetector CT angiography (MD-CTA) of the intracranial vessels is now routinely performed, and it is becoming fully integrated into the imaging and treatment algorithm of patients presenting with acute subarachnoid hemorrhage in many centers in the United Kingdom and Europe.

• #31 Laboratory Diagnosis of Subarachnoid Haemorrhage | SpringerLink

  https://link.springer.com/chapter/10.1007/978-3-319-01225-4_22

  The diagnosis of CT-negative subarachnoid haemorrhage (SAH) is an important clinical challenge in clinical neurology. Cerebrospinal fluid (CSF) analysis via lumbar puncture is the method of first choice. The diagnosis of SAH in CSF is based on a bloody or xanthochromic discoloration of the CSF as well as on findings in nonautomated CSF cytology including the detection of erythrophages and siderophages. […] The automated determination of CSF ferritin concentrations or spectrophotometric detection of xanthochromia may contribute to the diagnosis but are only useful with regard to the overall clinical picture. Generally, the knowledge of the time flow of the CSF changes associated with SAH (812 h after onset of headache) is essential for a correct interpretation of CSF findings.

• #32 Subarachnoid Haemorrhage (SAH)

  https://emed.ie/Neurological/Headache/SAH.php

  The Ottawa SAH rule is 98% sensitive but has low specificity (good at ruling OUT but poor at ruling IN a SAH). If a patient does not have any of the following – you can safely exclude SAH. […] Any patient with a suspected SAH and negative CT scan should have a lumbar puncture. This is the definitive test for excluding a subarachnoid haemorrhage. […] Early diagnosis of subarachnoid haemorrhage is important for two reasons. […] CT brain (within 24 hrs of onset) should detect over 95% of sub-arachnoid haemorrhages (though less sensitive in people with lower initial coma grades). […] The presence of Bilirubin is strongly supportive of SAH. […] A traumatic tap will be positive for oxyhaemoglobin but not bilirubin.

• #33 Cerebrospinal fluid analyses for the diagnosis of subarachnoid haemorrhage and experience from a Swedish study. What method is preferable when diagnosing a subarachnoid haemorrhage?

  https://www.degruyter.com/document/doi/10.1515/cclm-2012-0783/html?lang=en

  Subarachnoid haemorrhage (SAH) has a high mortality and morbidity rate. Early SAH diagnosis allows the early treatment of a ruptured cerebral aneurysm, which improves the prognosis. Diagnostic cerebrospinal fluid (CSF) analyses may be performed after a negative computed tomography scan, but the precise analytical methods to be used have been debated. Here, we summarize the scientific evidence for different CSF methods for SAH diagnosis and describe their implementation in different countries. CSF analyses for SAH include visual examination, red blood cell counts, spectrophotometry for oxyhaemoglobin or bilirubin determination, CSF cytology, and ferritin measurement. The methods vary in availability and performance. There is a consensus that spectrophotometry has the highest diagnostic performance, but both oxyhaemoglobin and bilirubin determinations are susceptible to important confounding factors. Visual inspection of CSF for xanthochromia is still frequently used for diagnosis of SAH, but it is advised against because spectrophotometry has a superior diagnostic accuracy. A positive finding of CSF bilirubin is a strong indicator of an intracranial bleeding, whereas a positive finding of CSF oxyhaemoglobin may indicate an intracranial bleeding or a traumatic tap. Where spectrophotometry is not available, the combination of CSF cytology for erythrophages or siderophages and ferritin is a promising alternative.

• #34 Subarachnoid hemorrhage – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/subarachnoid-hemorrhage/diagnosis-treatment/drc-20361014

  To diagnose a subarachnoid hemorrhage, you may need the following tests: […] CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram. […] MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram. […] Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

• #35

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  You’ll need to have some tests done in a hospital to confirm if you have a subarachnoid haemorrhage. […] A CT scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image. […] You may also have a test called a lumbar puncture. A needle is inserted into the lower part of the spine so that a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid) can be removed. It will then be analysed for signs of bleeding. […] If the results of a CT scan or lumbar puncture confirm you’ve had a subarachnoid haemorrhage, you’ll be referred to a specialist neuroscience unit. […] Further tests are usually needed to help plan treatment, which may include either: computed tomography angiography (CTA) using a CT scan or magnetic resonance angiography (MRA) using an MRI scan.

• #36

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  Both of these tests are carried out in the same way as a CT scan. But a special dye is injected into a vein (usually in your arm or hand) to highlight your blood vessels and tissues. […] Occasionally, an angiogram may be needed. This involves inserting a thin tube called a catheter into one of your blood vessels (usually in the groin). […] Using a series of X-rays displayed on a monitor, the catheter is guided into the blood vessels in the neck that supply blood to the brain. […] Once in place, the dye is injected through the catheter and into the arteries of the brain. The dye casts a shadow on an X-ray, so the outline of the blood vessels can be seen and the exact position of the aneurysm identified.

• #37

  https://www.aurorahealthcare.org/services/neuroscience/brain-skull-base-care/brain-hemorrhage/subarachnoid-hemorrhage

  A subarachnoid hemorrhage is a potentially life-threatening brain bleed that requires immediate medical attention. The hallmark of a subarachnoid hemorrhage is a headache that feels like the worst headache of your life. […] To make a subarachnoid hemorrhage diagnosis, your doctor will first ask about your symptoms and review your medical history. […] Next, your doctor will work to locate the source of the bleeding by using imaging testing such as a CT scan or an MRI. They may also order one of the following advanced diagnostic tests for a subarachnoid hemorrhage: […] A lumbar puncture: Also known as a spinal tap, a lumbar puncture is another way to make a brain bleed diagnosis. […] Computed tomography angiography (CTA): During a CTA test, dye is injected directly into the bloodstream. This dye makes it easy to see the arteries in your brain on a CT scan. […] Angiogram: During an angiogram, a catheter is inserted into an artery and threaded through the circulatory system up to the brain. A dye is then injected through the catheter. This dye makes blood flow easier to see on X-rays.

• #38 Subarachnoid Hemorrhage (SAH) – EMCrit Project

  https://emcrit.org/ibcc/sah/

  Noncontrast CT is the standard initial test for possible subarachnoid hemorrhage. […] The sensitivity is nearly 100% within six hours of headache onset, after which time blood starts looking a bit more grey, so the sensitivity may decrease slightly. […] CT angiography (CTA) is highly sensitive and specific (~95%) for aneurysm detection, but may miss very small aneurysms. […] For patients with thunderclap headache, a reasonable diagnostic strategy might be to perform a STAT noncontrast CT scan followed immediately by a CTA of the head and neck. CT/CTA is fast, noninvasive, and safe. […] If CT/CTA leaves remaining confusion about the possibility of SAH, then lumbar puncture and/or MRI/MRA may be considered. […] MRI can be useful to detect subtle underlying pathology (e.g., arteriovenous malformations, infections, malignancy, or inflammatory disorders).

• #39 Diagnosis and management of subarachnoid haemorrhage | Nature Communications

  https://www.nature.com/articles/s41467-024-46015-2

  Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. […] Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. […] SAH should be considered in all patients presenting with sudden-onset severe headaches. […] A non-contrast CT scan of the head (CTH), usually modern third-generation CTH, is 100% specific and highly sensitive for aSAH if scanned in the first 6h of headache onset, the sensitivity decreases to 97% in the first 72h and further decreases by 50% in 5 days. […] For handling aSAH, computed tomographic and digital subtraction angiography play significant roles. […] However, in inconclusive CTA results, Digital Subtraction Angiography (DSA), the gold standard in angiography, is recommended.

• #40 Diagnosis and management of subarachnoid haemorrhage | Nature Communications

  https://www.nature.com/articles/s41467-024-46015-2

  Magnetic resonance angiography (MRA) is an alternative to CTA or DSA for aneurysm detection, especially in patients allergic to iodine. […] Among patients presenting with an acute nontraumatic headache that has reached maximal intensity within one hour and intact neurology, the Ottawa rules are very sensitive for identifying an SAH but with low specificity. […] If CTH performed 6h after the ictus is equivocal or negative, a lumbar puncture performed within 612h of symptom onset typically shows xanthochromia. […] DSA has the added benefit of offering an endovascular treatment and minimal complication rates of 1%. […] Studies comparing CTA and DSA indicate strong agreement, suggesting they both provide high sensitivity and specificity in diagnosing vasospasm.

• #41 Subarachnoid Haemorrhage (SAH) • LITFL • CCC Neurosurgery

  https://litfl.com/subarachnoid-haemorrhage-sah/

  Subarachnoid Haemorrhage (SAH) potentially fatal bleeding into the subarachnoid space, usually due to a ruptured cerebral aneurysm […] LP: most sensitive at 12 hours for xanthochromia […] DSA: gold standard for diagnosis, allows intervention […] predictors of poor prognosis:- high grade- old age- co-morbidities- blood 1mm thick on CT- seizures- cerebral oedema- basilar artery aneurysm- symptomatic vasospasm- complications.

• #42

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  Both of these tests are carried out in the same way as a CT scan. But a special dye is injected into a vein (usually in your arm or hand) to highlight your blood vessels and tissues. […] Occasionally, an angiogram may be needed. This involves inserting a thin tube called a catheter into one of your blood vessels (usually in the groin). […] Using a series of X-rays displayed on a monitor, the catheter is guided into the blood vessels in the neck that supply blood to the brain. […] Once in place, the dye is injected through the catheter and into the arteries of the brain. The dye casts a shadow on an X-ray, so the outline of the blood vessels can be seen and the exact position of the aneurysm identified.

• #43

  https://www.nhs.uk/conditions/subarachnoid-haemorrhage/diagnosis/

  Both of these tests are carried out in the same way as a CT scan. But a special dye is injected into a vein (usually in your arm or hand) to highlight your blood vessels and tissues. […] Occasionally, an angiogram may be needed. This involves inserting a thin tube called a catheter into one of your blood vessels (usually in the groin). […] Using a series of X-rays displayed on a monitor, the catheter is guided into the blood vessels in the neck that supply blood to the brain. […] Once in place, the dye is injected through the catheter and into the arteries of the brain. The dye casts a shadow on an X-ray, so the outline of the blood vessels can be seen and the exact position of the aneurysm identified.

• #44 Diagnosis and management of subarachnoid haemorrhage | Nature Communications

  https://www.nature.com/articles/s41467-024-46015-2

  Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. […] Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. […] SAH should be considered in all patients presenting with sudden-onset severe headaches. […] A non-contrast CT scan of the head (CTH), usually modern third-generation CTH, is 100% specific and highly sensitive for aSAH if scanned in the first 6h of headache onset, the sensitivity decreases to 97% in the first 72h and further decreases by 50% in 5 days. […] For handling aSAH, computed tomographic and digital subtraction angiography play significant roles. […] However, in inconclusive CTA results, Digital Subtraction Angiography (DSA), the gold standard in angiography, is recommended.

• #45 Subarachnoid Hemorrhage (SAH) – EMCrit Project

  https://emcrit.org/ibcc/sah/

  Following initial SAH diagnosis, angiography may allow for interventional embolization of aneurysms, to prevent rebleeding. […] For patients with a SAH and no evidence of an aneurysm on CT angiography, an invasive angiogram may be performed to further exclude the presence of aneurysms or other vascular causes of bleeding. […] New onset of focal neurological findings that correlates with vasospasm in the suspected vascular territory is the hallmark of diagnosing delayed cerebral ischemia. […] CT angiography can be performed rapidly and noninvasively, with high sensitivity and specificity.

• #46 Diagnosis and management of subarachnoid haemorrhage | Nature Communications

  https://www.nature.com/articles/s41467-024-46015-2

  Magnetic resonance angiography (MRA) is an alternative to CTA or DSA for aneurysm detection, especially in patients allergic to iodine. […] Among patients presenting with an acute nontraumatic headache that has reached maximal intensity within one hour and intact neurology, the Ottawa rules are very sensitive for identifying an SAH but with low specificity. […] If CTH performed 6h after the ictus is equivocal or negative, a lumbar puncture performed within 612h of symptom onset typically shows xanthochromia. […] DSA has the added benefit of offering an endovascular treatment and minimal complication rates of 1%. […] Studies comparing CTA and DSA indicate strong agreement, suggesting they both provide high sensitivity and specificity in diagnosing vasospasm.

• #47 Subarachnoid hemorrhage – Diagnosis and treatment – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/subarachnoid-hemorrhage/diagnosis-treatment/drc-20361014

  To diagnose a subarachnoid hemorrhage, you may need the following tests: […] CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram. […] MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram. […] Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

• #48 Subarachnoid hemorrhage – Wikipedia

  https://en.wikipedia.org/wiki/Subarachnoid_hemorrhage

  Its efficacy declines thereafter, and magnetic resonance imaging (MRI) is more sensitive than CT after several days. […] After a subarachnoid hemorrhage is confirmed, its origin needs to be determined. If the bleeding is likely to have originated from an aneurysm (as determined by the CT scan appearance), the choice is between cerebral angiography (injecting radiocontrast through a catheter to the brain arteries) and CT angiography (visualizing blood vessels with radiocontrast on a CT scan) to identify aneurysms. […] In emergency department patients complaining of acute-onset headache without significant risk factors for SAH, evidence suggests that CT scanning of the head followed by CT angiography can reliably exclude SAH without the need for a lumbar puncture. […] A lumbar puncture or CT scan with contrast is therefore regarded as mandatory in people with suspected SAH when imaging is delayed to after six hours from the onset of symptoms and is negative.

• #49 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  the diagnosis usually involves a CT scan of the head, which is effective in detecting blood in the subarachnoid space […] if the CT scan is inconclusive, a lumbar puncture (spinal tap) may be performed to look for blood in the cerebrospinal fluid […] a CT scan should be performed as soon as possible, ideally within the first few hours after symptom onset, for the highest sensitivity in detecting a subarachnoid hemorrhage […] MRI, particularly fluid-attenuated inversion recovery (FLAIR) and gradient echo (GRE) sequences, can be used to diagnose SAH […] MRI is typically more sensitive than CT for subacute or chronic hemorrhage […] a lumbar puncture is particularly useful when the CT scan is negative but clinical suspicion remains high. It can detect blood in the cerebrospinal fluid that might not be visible on a CT scan, especially in cases of minor hemorrhages […] yes, SAH can be misdiagnosed, especially if symptoms are mild or atypical. Misdiagnosis can occur in emergency settings if the symptoms are attributed to less serious conditions like migraine or tension headache.

• #50 Subarachnoid hemorrhage – Wikipedia

  https://en.wikipedia.org/wiki/Subarachnoid_hemorrhage

  Its efficacy declines thereafter, and magnetic resonance imaging (MRI) is more sensitive than CT after several days. […] After a subarachnoid hemorrhage is confirmed, its origin needs to be determined. If the bleeding is likely to have originated from an aneurysm (as determined by the CT scan appearance), the choice is between cerebral angiography (injecting radiocontrast through a catheter to the brain arteries) and CT angiography (visualizing blood vessels with radiocontrast on a CT scan) to identify aneurysms. […] In emergency department patients complaining of acute-onset headache without significant risk factors for SAH, evidence suggests that CT scanning of the head followed by CT angiography can reliably exclude SAH without the need for a lumbar puncture. […] A lumbar puncture or CT scan with contrast is therefore regarded as mandatory in people with suspected SAH when imaging is delayed to after six hours from the onset of symptoms and is negative.

• #51 Subarachnoid Hemorrhage (SAH) – Neurologic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/neurologic-disorders/stroke/subarachnoid-hemorrhage-sah

  Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space. […] Diagnosis is by CT or MRI; if neuroimaging is normal, diagnosis is by cerebrospinal fluid analysis to look for xanthochromia and red blood cells. […] Diagnosis of subarachnoid hemorrhage is suggested by characteristic symptoms. Testing should proceed as rapidly as possible, before damage becomes irreversible. […] Noncontrast CT is done within 6 hours of symptom onset. When done within this time frame, this test has very high sensitivity. Therefore, if this test does not detect a subarachnoid hemorrhage, no other testing is needed as long as patients have a normal physical examination, no meningeal signs, and no anemia, MRI is comparably sensitive but less likely to be immediately available. […] If subarachnoid hemorrhage is suspected clinically but not identified by neuroimaging or if neuroimaging is not immediately available, lumbar puncture is done.

• #52 Subarachnoid hemorrhage | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/subarachnoid-haemorrhage?lang=us

  MRI is sensitive to subarachnoid blood and is able to visualize it well in the first 12 hours, typically as a hyperintensity in the subarachnoid space on FLAIR. […] Digital subtraction catheter angiography remains the gold standard for diagnosis and characterization of vascular abnormalities, and in many centers, even if the causative lesion is identified on MRA or CTA and it is thought to require surgical management, a catheter study is carried out.

• #53 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  the diagnosis usually involves a CT scan of the head, which is effective in detecting blood in the subarachnoid space […] if the CT scan is inconclusive, a lumbar puncture (spinal tap) may be performed to look for blood in the cerebrospinal fluid […] a CT scan should be performed as soon as possible, ideally within the first few hours after symptom onset, for the highest sensitivity in detecting a subarachnoid hemorrhage […] MRI, particularly fluid-attenuated inversion recovery (FLAIR) and gradient echo (GRE) sequences, can be used to diagnose SAH […] MRI is typically more sensitive than CT for subacute or chronic hemorrhage […] a lumbar puncture is particularly useful when the CT scan is negative but clinical suspicion remains high. It can detect blood in the cerebrospinal fluid that might not be visible on a CT scan, especially in cases of minor hemorrhages […] yes, SAH can be misdiagnosed, especially if symptoms are mild or atypical. Misdiagnosis can occur in emergency settings if the symptoms are attributed to less serious conditions like migraine or tension headache.

• #54 Subarachnoid hemorrhage | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/subarachnoid-haemorrhage?lang=us

  MRI is sensitive to subarachnoid blood and is able to visualize it well in the first 12 hours, typically as a hyperintensity in the subarachnoid space on FLAIR. […] Digital subtraction catheter angiography remains the gold standard for diagnosis and characterization of vascular abnormalities, and in many centers, even if the causative lesion is identified on MRA or CTA and it is thought to require surgical management, a catheter study is carried out.

• #55 Diagnosis and management of subarachnoid haemorrhage | Nature Communications

  https://www.nature.com/articles/s41467-024-46015-2

  Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. […] Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. […] SAH should be considered in all patients presenting with sudden-onset severe headaches. […] A non-contrast CT scan of the head (CTH), usually modern third-generation CTH, is 100% specific and highly sensitive for aSAH if scanned in the first 6h of headache onset, the sensitivity decreases to 97% in the first 72h and further decreases by 50% in 5 days. […] For handling aSAH, computed tomographic and digital subtraction angiography play significant roles. […] However, in inconclusive CTA results, Digital Subtraction Angiography (DSA), the gold standard in angiography, is recommended.

• #56 Subarachnoid Hemorrhage, Vasospasm, and Delayed Cerebral Ischemia

  https://practicalneurology.com/diseases-diagnoses/stroke/subarachnoid-hemorrhage-vasospasm-and-delayed-cerebral-ischemia/30142/

  Transcranial Doppler ultrasound (TCD) or transcranial color-coded duplex Doppler ultrasound (TCCD) is the preferred primary imaging method for diagnosis and monitoring of vasospasm. […] All patients with SAH should undergo CT or MRI imaging (which will serve as a baseline) 24 to 48 hours after aneurysm treatment. […] Although the criterion standard for detection of vasospasm is DSA, this modality is invasive with the disadvantages of radiation exposure, contrast administration, risk of complications, and transfer of the patient from intensive care to an angiography suite. […] Oral nimodipine is the only agent approved for DCI prophylaxis. […] A Cochrane review of 16 studies showed that oral nimodipine significantly reduces risk of poor outcome and secondary ischemia after SAH. […] For many years, prophylactic or therapeutic use of induced hypertension, hypervolemia, and hemodilution—triple-H therapy—was the principal approach of restoring impaired cerebral perfusion in patients with DCI after SAH. […] When hemodynamic management fails to reverse a focal neurologic deficit consistent with vasospasm or is contraindicated, endovascular management is preferred. […] Vasospasm and DCI contribute substantially to mortality and morbidity of patients who experienced SAH.

• #57 Clinical management guidelines for subarachnoid haemorrhage. Diagnosis and treatment | Neurología (English Edition)

  https://www.elsevier.es/pt-revista-neurologia-english-edition–495-articulo-clinical-management-guidelines-for-subarachnoid-S2173580814000819

  The source of the SAH is identified with CT, MRI, or conventional 4-vessel digital subtraction angiography. […] The bleed pattern may lead us to suspect an aneurysmal component. […] It has been calculated that a second angiography study will detect about 5% of all new aneurysms. […] Transcranial Doppler ultrasonography. This non-invasive technique is a very useful diagnostic tool because it is largely accessible. […] The main objective of medical treatment for SAH is to place the patient in the best clinical situation in order to exclude the ruptured aneurysm from the circulation as safely as possible. […] If there is a clinical suspicion of SAH, the patient must be referred to a specialist centre immediately in order to receive the best management and treatment.

• #58 Clinical management guidelines for subarachnoid haemorrhage. Diagnosis and treatment | Neurología (English Edition)

  https://www.elsevier.es/pt-revista-neurologia-english-edition–495-articulo-clinical-management-guidelines-for-subarachnoid-S2173580814000819

  The source of the SAH is identified with CT, MRI, or conventional 4-vessel digital subtraction angiography. […] The bleed pattern may lead us to suspect an aneurysmal component. […] It has been calculated that a second angiography study will detect about 5% of all new aneurysms. […] Transcranial Doppler ultrasonography. This non-invasive technique is a very useful diagnostic tool because it is largely accessible. […] The main objective of medical treatment for SAH is to place the patient in the best clinical situation in order to exclude the ruptured aneurysm from the circulation as safely as possible. […] If there is a clinical suspicion of SAH, the patient must be referred to a specialist centre immediately in order to receive the best management and treatment.

• #59 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]). […] Given the sensitivity of the CT discussed above, shared decision-making should be conducted with regard to LP. In particular, with sensitivity of near 99% for an adequate study if completed within six hours, and meeting the criteria outlined above, patients should be made aware of the low diagnostic utility of LP if completed after a CT. In this setting, risks (adverse events and false positives) generally outweigh benefits and LP is advised against.

• #60 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  True xanthochromia is pathognomonic for SAH. This is valuable when there is high clinical suspicion and RBC count is not sufficiently elevated to differentiate from a traumatic tap diagnostic. Xanthochromia is detected either by visual inspection of the CSF tube vs a tube of water, or by spectrophotometry. […] Many tools are available to assess for SAH including non-contrast CT, LP, CTA, and MRI. Understanding the potentially high mortality in the case of a missed SAH should mandate a diagnostic strategy with the highest sensitivity possible, which is currently accepted to be non-contrast CT followed, if negative, by LP. This is the algorithm supported by both the American Heart Association (AHA) and American College of Emergency Physicians (ACEP).

• #61 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage – The Western Journal of Emergency Medicine

  https://westjem.com/articles/approach-to-the-diagnosis-and-management-of-subarachnoid-hemorrhage.html

  When a clinical suspicion for SAH exists based on history and physical exam, non-contrast computed tomography (CT) is the first diagnostic tool. It is also valuable in excluding other pathologies such as intracranial hemorrhage, malignancy, or abscess. […] A meta-analysis published in 2016 attempted to answer the question of CT sensitivity with relation to time from symptom onset.18 The analysis, which included five studies, assessed patients with a thunderclap headache and normal neurologic exam. While the results carry many of the limitations of a meta-analysis, a conservative statistical analysis showed that a non-contrast CT completed within six hours of headache onset had a sensitivity of 98.7% with confidence intervals 97.1%99.4%. […] If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]).

• #62 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  When scanned within 6h of headache onset, modern third generation CT scans are 100% sensitive (95% CI, 97.0%-100.0%) for the detection of SAH when interpreted by a radiologist. […] If the CT is negative no other investigations are required. […] After 6h from headache onset, CT scanning is only 85.7% sensitive. Therefore, patients with delayed imaging and a negative scan require further investigations (LP). […] If a detailed neurologic examination is normal, there are no signs of papilledema on examination, there is no bleeding disorder or use of anticoagulants, and there is no history of intracranial pathology, it is reasonable to perform a lumbar puncture to rule out SAH. […] All aneurysmal SAHs were identified by the presence of xanthochromia on visual inspection of the cerebrospinal fluid or the presence of >2000 x 10^6 red blood cells/L in the cerebrospinal fluid (sensitivity 100%; 95% CI 74.7%-100.0%). […] If the LP is positive or if clinical suspicion is high, the next diagnostic step is cerebral angiography to identify cerebral aneurysms. […] All patients with an SAH diagnosed with CT or positive LP will need angiography.

• #63 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage – The Western Journal of Emergency Medicine

  https://westjem.com/articles/approach-to-the-diagnosis-and-management-of-subarachnoid-hemorrhage.html

  When a clinical suspicion for SAH exists based on history and physical exam, non-contrast computed tomography (CT) is the first diagnostic tool. It is also valuable in excluding other pathologies such as intracranial hemorrhage, malignancy, or abscess. […] A meta-analysis published in 2016 attempted to answer the question of CT sensitivity with relation to time from symptom onset.18 The analysis, which included five studies, assessed patients with a thunderclap headache and normal neurologic exam. While the results carry many of the limitations of a meta-analysis, a conservative statistical analysis showed that a non-contrast CT completed within six hours of headache onset had a sensitivity of 98.7% with confidence intervals 97.1%99.4%. […] If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]).

• #64 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  When scanned within 6h of headache onset, modern third generation CT scans are 100% sensitive (95% CI, 97.0%-100.0%) for the detection of SAH when interpreted by a radiologist. […] If the CT is negative no other investigations are required. […] After 6h from headache onset, CT scanning is only 85.7% sensitive. Therefore, patients with delayed imaging and a negative scan require further investigations (LP). […] If a detailed neurologic examination is normal, there are no signs of papilledema on examination, there is no bleeding disorder or use of anticoagulants, and there is no history of intracranial pathology, it is reasonable to perform a lumbar puncture to rule out SAH. […] All aneurysmal SAHs were identified by the presence of xanthochromia on visual inspection of the cerebrospinal fluid or the presence of >2000 x 10^6 red blood cells/L in the cerebrospinal fluid (sensitivity 100%; 95% CI 74.7%-100.0%). […] If the LP is positive or if clinical suspicion is high, the next diagnostic step is cerebral angiography to identify cerebral aneurysms. […] All patients with an SAH diagnosed with CT or positive LP will need angiography.

• #65 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  However, in 2017 there are three problems with that approach: (1) contemporary CTs are far better at identifying blood in the subarachnoid space; (2) LPs frequently identify blood that is not in the subarachnoid space (traumatic LPs); and (3) CSF xanthochromia is not an accurate diagnostic test for SAH. […] Both Perry 2011 and Backes 2012 demonstrate acceptably safe CT accuracy for SAH when imaging is obtained within 6-hours of headache onset (summary LR+ 235, summary LR- 0.01). […] Recent meta-analyses indicate that visible xanthochromia can rule-in SAH (LR+ 25) but is less accurate to rule it out (LR- 0.22). […] Importantly, up to 30% of patients experience worsening post-LP headache, in addition to the risks of post-LP back pain, epidural bleeding, and introduction of skin flora into the central nervous system.

• #66 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  When scanned within 6h of headache onset, modern third generation CT scans are 100% sensitive (95% CI, 97.0%-100.0%) for the detection of SAH when interpreted by a radiologist. […] If the CT is negative no other investigations are required. […] After 6h from headache onset, CT scanning is only 85.7% sensitive. Therefore, patients with delayed imaging and a negative scan require further investigations (LP). […] If a detailed neurologic examination is normal, there are no signs of papilledema on examination, there is no bleeding disorder or use of anticoagulants, and there is no history of intracranial pathology, it is reasonable to perform a lumbar puncture to rule out SAH. […] All aneurysmal SAHs were identified by the presence of xanthochromia on visual inspection of the cerebrospinal fluid or the presence of >2000 x 10^6 red blood cells/L in the cerebrospinal fluid (sensitivity 100%; 95% CI 74.7%-100.0%). […] If the LP is positive or if clinical suspicion is high, the next diagnostic step is cerebral angiography to identify cerebral aneurysms. […] All patients with an SAH diagnosed with CT or positive LP will need angiography.

• #67 Diagnosis and Initial Emergency Department Management of Subarachnoid Hemorrhage | Anesthesia Key

  https://aneskey.com/diagnosis-and-initial-emergency-department-management-of-subarachnoid-hemorrhage/

  In patients with a negative head CT scan more than 6 hours after the onset of headache, lumbar puncture to assess for the presence of red blood cells (RBCs) or xanthochromia will definitively rule out SAH. […] For patients in whom the CSF analysis is suggestive of SAH, the next steps in the workup and management include vascular imaging and neurosurgical consultation. […] The 2019 American College of Emergency Physicians Clinical Policy thus makes a Level C recommendation to perform either a lumbar puncture or CTA after a negative noncontrast brain CT scan in patients for whom SAH is still suspected.

• #68 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  Subarachnoid hemorrhage (SAH) typically presents to emergency departments with acute (peaking in 1h) non-traumatic headaches. […] Prompt diagnosis is key, as patients with normal neurological findings have the most to lose from a missed diagnosis. […] Investigate if any of the following high-risk variables are present: Age > 40 y, Neck pain or stiffness, Witnessed loss of consciousness, Onset during exertion, Thunderclap headache (instantly peaking pain), Limited neck flexion on examination (inability to touch chin to chest or lift head 8 cm off the bed). […] If one or more features are present, this rule is 100% (95% CI, 98.6%-100%) sensitive and 17.8% (95% CI, 16.6%-19.1%) specific for the diagnosis of SAH. […] Investigations include a plain (unenhanced) CT scan of the head (if available), and may require lumbar puncture and/or cerebral angiography.

• #69 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  subarachnoid hemorrhage (SAH) should be considered in any patient presenting with a severe, sudden-onset, or rapidly worsening headache […] deciding which patients require evaluation for SAH is often challenging in emergency care; the Ottawa SAH Rule can help identify patients needing urgent imaging in the emergency setting (Perry, 2017) […] initial diagnosis is usually made with non-contrast CT (NCCT), which is 95% sensitive within 6 hours of onset […] if NCCT confirms SAH, CT angiography (CTA) is performed to identify the bleeding source (e.g., aneurysm) […] if NCCT is negative but SAH is strongly suspected, lumbar puncture (LP) with CSF analysis should be performed […] CT scan sensitivity for SAH is 90-98% within the first 24 hours, depending on SAH volume and location (Gee, 2012)

• #70 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  Subarachnoid hemorrhage (SAH) typically presents to emergency departments with acute (peaking in 1h) non-traumatic headaches. […] Prompt diagnosis is key, as patients with normal neurological findings have the most to lose from a missed diagnosis. […] Investigate if any of the following high-risk variables are present: Age > 40 y, Neck pain or stiffness, Witnessed loss of consciousness, Onset during exertion, Thunderclap headache (instantly peaking pain), Limited neck flexion on examination (inability to touch chin to chest or lift head 8 cm off the bed). […] If one or more features are present, this rule is 100% (95% CI, 98.6%-100%) sensitive and 17.8% (95% CI, 16.6%-19.1%) specific for the diagnosis of SAH. […] Investigations include a plain (unenhanced) CT scan of the head (if available), and may require lumbar puncture and/or cerebral angiography.

• #71 Subarachnoid Hemorrhage – Diagnosis : Emergency Care BC

  https://emergencycarebc.ca/clinical_resource/clinical-summary/subarachnoid-hemorrhage-diagnosis/

  Subarachnoid hemorrhage (SAH) typically presents to emergency departments with acute (peaking in 1h) non-traumatic headaches. […] Prompt diagnosis is key, as patients with normal neurological findings have the most to lose from a missed diagnosis. […] Investigate if any of the following high-risk variables are present: Age > 40 y, Neck pain or stiffness, Witnessed loss of consciousness, Onset during exertion, Thunderclap headache (instantly peaking pain), Limited neck flexion on examination (inability to touch chin to chest or lift head 8 cm off the bed). […] If one or more features are present, this rule is 100% (95% CI, 98.6%-100%) sensitive and 17.8% (95% CI, 16.6%-19.1%) specific for the diagnosis of SAH. […] Investigations include a plain (unenhanced) CT scan of the head (if available), and may require lumbar puncture and/or cerebral angiography.

• #72 An Evidence-Based Approach To Diagnosis And Management Of Subarachnoid Hemorrhage In The Emergency Department (Stroke CME)

  https://www.ebmedicine.net/topics/neurologic/subarachnoid-hemorrhage-stroke

  The emergency clinician must be able to quickly and accurately identify and categorize SAH, and should be aware of the secondary complications that affect both the central nervous system and other major organs. Initial management and treatment decisions should be made to minimize effects of the initial neurologic injury. […] The most relevant guidelines for emergency clinicians are the 2008 American College of Emergency Physicians (ACEP) Clinical Policy on acute headache, the 2012 American Heart Association (AHA) Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage, and the 2011 Neurocritical Care Society (NCS) Guidelines on the critical care management of patients with aSAH. […] CT may be negative in 2% to 7% of patients with SAH, and sensitivity is highly time-dependent. In a patient with suspected SAH, LP is required to rule out the diagnosis, regardless of other circumstances.

• #73 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  True xanthochromia is pathognomonic for SAH. This is valuable when there is high clinical suspicion and RBC count is not sufficiently elevated to differentiate from a traumatic tap diagnostic. Xanthochromia is detected either by visual inspection of the CSF tube vs a tube of water, or by spectrophotometry. […] Many tools are available to assess for SAH including non-contrast CT, LP, CTA, and MRI. Understanding the potentially high mortality in the case of a missed SAH should mandate a diagnostic strategy with the highest sensitivity possible, which is currently accepted to be non-contrast CT followed, if negative, by LP. This is the algorithm supported by both the American Heart Association (AHA) and American College of Emergency Physicians (ACEP).

• #74 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  True xanthochromia is pathognomonic for SAH. This is valuable when there is high clinical suspicion and RBC count is not sufficiently elevated to differentiate from a traumatic tap diagnostic. Xanthochromia is detected either by visual inspection of the CSF tube vs a tube of water, or by spectrophotometry. […] Many tools are available to assess for SAH including non-contrast CT, LP, CTA, and MRI. Understanding the potentially high mortality in the case of a missed SAH should mandate a diagnostic strategy with the highest sensitivity possible, which is currently accepted to be non-contrast CT followed, if negative, by LP. This is the algorithm supported by both the American Heart Association (AHA) and American College of Emergency Physicians (ACEP).

• #75 An Evidence-Based Approach To Diagnosis And Management Of Subarachnoid Hemorrhage In The Emergency Department (Stroke CME)

  https://www.ebmedicine.net/topics/neurologic/subarachnoid-hemorrhage-stroke

  The emergency clinician must be able to quickly and accurately identify and categorize SAH, and should be aware of the secondary complications that affect both the central nervous system and other major organs. Initial management and treatment decisions should be made to minimize effects of the initial neurologic injury. […] The most relevant guidelines for emergency clinicians are the 2008 American College of Emergency Physicians (ACEP) Clinical Policy on acute headache, the 2012 American Heart Association (AHA) Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage, and the 2011 Neurocritical Care Society (NCS) Guidelines on the critical care management of patients with aSAH. […] CT may be negative in 2% to 7% of patients with SAH, and sensitivity is highly time-dependent. In a patient with suspected SAH, LP is required to rule out the diagnosis, regardless of other circumstances.

• #76 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  True xanthochromia is pathognomonic for SAH. This is valuable when there is high clinical suspicion and RBC count is not sufficiently elevated to differentiate from a traumatic tap diagnostic. Xanthochromia is detected either by visual inspection of the CSF tube vs a tube of water, or by spectrophotometry. […] Many tools are available to assess for SAH including non-contrast CT, LP, CTA, and MRI. Understanding the potentially high mortality in the case of a missed SAH should mandate a diagnostic strategy with the highest sensitivity possible, which is currently accepted to be non-contrast CT followed, if negative, by LP. This is the algorithm supported by both the American Heart Association (AHA) and American College of Emergency Physicians (ACEP).

• #77 Diagnosis and Initial Emergency Department Management of Subarachnoid Hemorrhage | Anesthesia Key

  https://aneskey.com/diagnosis-and-initial-emergency-department-management-of-subarachnoid-hemorrhage/

  In patients with a negative head CT scan more than 6 hours after the onset of headache, lumbar puncture to assess for the presence of red blood cells (RBCs) or xanthochromia will definitively rule out SAH. […] For patients in whom the CSF analysis is suggestive of SAH, the next steps in the workup and management include vascular imaging and neurosurgical consultation. […] The 2019 American College of Emergency Physicians Clinical Policy thus makes a Level C recommendation to perform either a lumbar puncture or CTA after a negative noncontrast brain CT scan in patients for whom SAH is still suspected.

• #78 Subarachnoid Haemorrhage: Causes, Symptoms, Treatment

  https://patient.info/doctor/subarachnoid-haemorrhage-pro

  Urgent investigation to confirm a diagnosis of subarachnoid haemorrhage facilitates early treatment to prevent re-bleeding from a ruptured aneurysm and minimises disability and death. […] A person should be referred for an urgent non-contrast CT head scan if review in secondary care by a senior clinical decision-maker confirms unexplained thunderclap headache, or other signs and symptoms that suggest subarachnoid haemorrhage. Diagnostic accuracy of CT head scans is highest within six hours of symptom onset. A subarachnoid haemorrhage is diagnosed if the non-contrast CT head scan shows blood in the subarachnoid space. […] If a CT head scan done within six hours of symptom onset and reported and documented by a radiologist shows no evidence of a subarachnoid haemorrhage, a lumbar puncture should not be routinely offered and alternative diagnoses should be considered.

• #79 Subarachnoid Haemorrhage: Causes, Symptoms, Treatment

  https://patient.info/doctor/subarachnoid-haemorrhage-pro

  A lumbar puncture should be considered if a CT head scan done more than six hours after symptom onset shows no evidence of a subarachnoid haemorrhage. […] Subarachnoid haemorrhage should be diagnosed if the lumbar puncture sample of cerebrospinal fluid (CSF) shows evidence of elevated bilirubin (xanthochromia) on spectrophotometry. […] A person with a diagnosis of subarachnoid haemorrhage should be urgently transferred to a specialist neurosurgical centre. […] CT angiography of the head should be offered without delay to people with a confirmed diagnosis of subarachnoid haemorrhage to identify the cause of the bleeding and to guide treatment.

• #80 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  Missed SAH diagnosis occurs between 12%-53% of cases with ED providers estimated to miss 5% of them. […] Up to 80% of SAH cases result from a ruptured cerebral aneurysm. […] Therefore, the possibility of aneurysmal SAH must be considered in ED patients presenting with severe headaches. […] Understanding the SAH diagnostic evidence available for bedside evaluation, advanced imaging, and the role for lumbar puncture (LP) is therefore essential and the landscape is shifting. […] Early CTs were 4-slice and radiologists interpretative learning curves were steep. […] These early CTs were imperfect (sensitivity ~90%) for identifying small amounts of blood in the subarachnoid space, so textbooks, guidelines, and several generations of emergency medicine trainees advised against a CT-only approach to rule-out aneurysmal SAH.

• #81 Subarachnoid hemorrhage in the emergency department | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-021-00353-w

  Subarachnoid hemorrhage accounts for more than 30,000 cases of stroke annually in North America and encompasses a 4.4% mortality rate. Since a vast number of subarachnoid hemorrhage cases present in a younger population and can range from benign to severe, an accurate diagnosis is imperative to avoid premature morbidity and mortality. […] Once a subarachnoid hemorrhage is suspected, a computed tomography of the head with the assistance of the Ottawa subarachnoid hemorrhage rule should be utilized as an initial diagnostic measure. […] Subarachnoid hemorrhages are frequently misdiagnosed; therefore, we believe it is imperative to address the diagnosis and initiation of early management in the emergency medicine department to minimize poor outcomes in the future. […] Diagnosis is often missed due to the various clinical manifestations and inconsistencies in individual findings.

• #82 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  the diagnosis usually involves a CT scan of the head, which is effective in detecting blood in the subarachnoid space […] if the CT scan is inconclusive, a lumbar puncture (spinal tap) may be performed to look for blood in the cerebrospinal fluid […] a CT scan should be performed as soon as possible, ideally within the first few hours after symptom onset, for the highest sensitivity in detecting a subarachnoid hemorrhage […] MRI, particularly fluid-attenuated inversion recovery (FLAIR) and gradient echo (GRE) sequences, can be used to diagnose SAH […] MRI is typically more sensitive than CT for subacute or chronic hemorrhage […] a lumbar puncture is particularly useful when the CT scan is negative but clinical suspicion remains high. It can detect blood in the cerebrospinal fluid that might not be visible on a CT scan, especially in cases of minor hemorrhages […] yes, SAH can be misdiagnosed, especially if symptoms are mild or atypical. Misdiagnosis can occur in emergency settings if the symptoms are attributed to less serious conditions like migraine or tension headache.

• #83 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  Mrs. Z. is a healthy 30-year-old female who presents to your emergency department 2-hours after onset of the worst headache of my life which peaked within 1 minute of onset but was not thunderclap. […] As you consider the diagnosis of subarachnoid hemorrhage and await her CT, you weigh the value of a post-CT lumbar puncture. […] The myriad causes of sudden onset headaches include cough, exertion, and post-coital, but can also include potentially life-threatening conditions like sinus thrombosis, vascular dissection, intracerebral hemorrhage, vasospasm, and aneurysmal subarachnoid hemorrhage. […] Observational studies indicate that migraine headaches are at least 50-times more common than SAH amongst ED headache patients, so SAH represents a needle in a haystack for a very common chief complaint.

• #84 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  Mrs. Z. is a healthy 30-year-old female who presents to your emergency department 2-hours after onset of the worst headache of my life which peaked within 1 minute of onset but was not thunderclap. […] As you consider the diagnosis of subarachnoid hemorrhage and await her CT, you weigh the value of a post-CT lumbar puncture. […] The myriad causes of sudden onset headaches include cough, exertion, and post-coital, but can also include potentially life-threatening conditions like sinus thrombosis, vascular dissection, intracerebral hemorrhage, vasospasm, and aneurysmal subarachnoid hemorrhage. […] Observational studies indicate that migraine headaches are at least 50-times more common than SAH amongst ED headache patients, so SAH represents a needle in a haystack for a very common chief complaint.

• #85 Diagnosis of a subarachnoid hemorrhage with only mild symptoms using computed tomography in Japan | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-016-0726-9

  The first diagnostic study in these patients should be a non-contrast CT. […] The sensitivity of CT for SAH ranges from 90 to 95 %, implying that CT has a high sensitivity but should not be applied as a sole diagnostic modality for SAH diagnosis. […] The key CT finding of SAH is blood in the basilar cistern at the base of the brain where the Circle of Willis is located. […] If there is only a small quantity of blood which is mixed with CSF, it can appear isoattenuating (gray, similar to brain tissue) in these regions. […] CT is therefore less sensitive at detecting SAH after 24 h. […] However, if Sylvian fissures are not clearly visualized bilaterally, as in the case of our patient, and the difference between left and right visualization of Sylvian fissures are recognized, we should pay attention to minute details with suspicion of SAH.

• #86 Diagnosis of a subarachnoid hemorrhage with only mild symptoms using computed tomography in Japan | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-016-0726-9

  In summary, when we perform a simple interpretation of CT in which white areas represent hemorrhage and black represents infraction, we are unable to detect SAH with low grade symptoms. […] Although magnetic resonance technology is continually advancing and can detect aneurysms, standard magnetic resonance imaging (MRI) is inferior to CT in terms of detecting acute SAH. […] The sensitivity and specificity of the CTA approach for detecting aneurysms 3 mm are currently approaching 100 %.

• #87 Diagnosis of a subarachnoid hemorrhage with only mild symptoms using computed tomography in Japan | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-016-0726-9

  In summary, when we perform a simple interpretation of CT in which white areas represent hemorrhage and black represents infraction, we are unable to detect SAH with low grade symptoms. […] Although magnetic resonance technology is continually advancing and can detect aneurysms, standard magnetic resonance imaging (MRI) is inferior to CT in terms of detecting acute SAH. […] The sensitivity and specificity of the CTA approach for detecting aneurysms 3 mm are currently approaching 100 %.

• #88 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  However, in 2017 there are three problems with that approach: (1) contemporary CTs are far better at identifying blood in the subarachnoid space; (2) LPs frequently identify blood that is not in the subarachnoid space (traumatic LPs); and (3) CSF xanthochromia is not an accurate diagnostic test for SAH. […] Both Perry 2011 and Backes 2012 demonstrate acceptably safe CT accuracy for SAH when imaging is obtained within 6-hours of headache onset (summary LR+ 235, summary LR- 0.01). […] Recent meta-analyses indicate that visible xanthochromia can rule-in SAH (LR+ 25) but is less accurate to rule it out (LR- 0.22). […] Importantly, up to 30% of patients experience worsening post-LP headache, in addition to the risks of post-LP back pain, epidural bleeding, and introduction of skin flora into the central nervous system.

• #89 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]). […] Given the sensitivity of the CT discussed above, shared decision-making should be conducted with regard to LP. In particular, with sensitivity of near 99% for an adequate study if completed within six hours, and meeting the criteria outlined above, patients should be made aware of the low diagnostic utility of LP if completed after a CT. In this setting, risks (adverse events and false positives) generally outweigh benefits and LP is advised against.

• #90 Diagnosis of subarachnoid hemorrhage | STROKE MANUAL

  https://www.stroke-manual.com/diagnosis-of-subarachnoid-hemorrhage/

  CT scan sensitivity decreases over time ~ 98% in the first 6 hours, to 70% by day 3, and to 50% a week later […] most SAH blood clears within ~7-10 days, so persistent or increasing blood suggests rebleeding […] MRI is sensitive to subarachnoid blood and can visualize it within the first 12 hours […] MRI can also detect thrombosed aneurysms (T1/2), sometimes not visible on CTA or DSA […] MR angiography can detect aneurysms (3mm) or other sources of bleeding […] it is recommended to wait 9-12 hours from the onset of presenting symptoms before performing lumbar puncture (LP) to allow for the breakdown of RBCs […] rapid analysis of collected CSF is required […] bedside multiple-tube test is useful to exclude traumatic tap […] xanthochromia typically appears 9-12 hours after bleeding and can persist for up to 2-4 weeks

• #91 Cerebrospinal fluid analyses for the diagnosis of subarachnoid haemorrhage and experience from a Swedish study. What method is preferable when diagnosing a subarachnoid haemorrhage?

  https://www.degruyter.com/document/doi/10.1515/cclm-2012-0783/html?lang=en

  Clinical examination is insufficient for SAH diagnosis. The most commonly used first line of investigation is noncontrast computed tomography (CT) of the brain. CT has an excellent sensitivity for SAH in the acute stage, especially using modern scanners, with sensitivities up to 98%100% within the first hours from symptom onset. However, subtle abnormalities may not be detected by inexperienced or nonspecialized physicians, and expert neuroradiologists are not available at all hospitals. […] There are several widely used CSF analyses for SAH, with different diagnostic performance, availability, and technical requirements. A consequence in clinical practice of differences between methods and how they are implemented is that patients may receive different diagnoses and treatments at different hospitals.

• #92 Laboratory Diagnosis of Subarachnoid Haemorrhage | SpringerLink

  https://link.springer.com/chapter/10.1007/978-3-319-01225-4_22

  The diagnosis of CT-negative subarachnoid haemorrhage (SAH) is an important clinical challenge in clinical neurology. Cerebrospinal fluid (CSF) analysis via lumbar puncture is the method of first choice. The diagnosis of SAH in CSF is based on a bloody or xanthochromic discoloration of the CSF as well as on findings in nonautomated CSF cytology including the detection of erythrophages and siderophages. […] The automated determination of CSF ferritin concentrations or spectrophotometric detection of xanthochromia may contribute to the diagnosis but are only useful with regard to the overall clinical picture. Generally, the knowledge of the time flow of the CSF changes associated with SAH (812 h after onset of headache) is essential for a correct interpretation of CSF findings.

• #93 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  However, in 2017 there are three problems with that approach: (1) contemporary CTs are far better at identifying blood in the subarachnoid space; (2) LPs frequently identify blood that is not in the subarachnoid space (traumatic LPs); and (3) CSF xanthochromia is not an accurate diagnostic test for SAH. […] Both Perry 2011 and Backes 2012 demonstrate acceptably safe CT accuracy for SAH when imaging is obtained within 6-hours of headache onset (summary LR+ 235, summary LR- 0.01). […] Recent meta-analyses indicate that visible xanthochromia can rule-in SAH (LR+ 25) but is less accurate to rule it out (LR- 0.22). […] Importantly, up to 30% of patients experience worsening post-LP headache, in addition to the risks of post-LP back pain, epidural bleeding, and introduction of skin flora into the central nervous system.

• #94 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  The ultimate objective is not to understand test accuracy; instead, the goal is to deliver the appropriate care to the right patients. […] The test-threshold describes the probability of a diagnosis (aneurysmal SAH) below which continuing to test for the diagnosis will harm more patients than it will help, whereas above the threshold additional testing will benefit more patients than will be harmed. […] Based upon one recent diagnostic meta-analysis, the threshold at which post-CT LP would benefit patients is quite narrow (2-4% for CSF RBC or 2%-7% for visible xanthochromia). […] Therefore, LP appears to benefit relatively few patients within a narrow pretest probability range. […] With improvements in CT technology and an expanding body of evidence, test thresholds for LP may become more precise, obviating the need for a post-CT LP in more acute headache patients.

• #95 Subarachnoid Hemorrhage Workup: Approach Considerations, Computed Tomography, Lumbar Puncture

  https://emedicine.medscape.com/article/1164341-workup

  The diagnosis of subarachnoid hemorrhage (SAH) usually depends on a high index of clinical suspicion combined with radiologic confirmation via urgent computed tomography (CT) scan without contrast. Traditionally, a negative CT scan is followed with lumbar puncture (LP). However, noncontrast CT followed by CT angiography (CTA) of the brain can rule out SAH with greater than 99% sensitivity. […] Compared with the traditional recommendation of CT followed by LP, CT/CTA may offer a less invasive and more informative diagnostic approach for emergency department patients complaining of acute-onset headache and with no significant risk factors for SAH. […] After the diagnosis of SAH is established, further imaging should be performed to characterize the source of the hemorrhage. This effort can include standard angiography, CT angiography, and magnetic resonance (MR) angiography.

• #96 Subarachnoid Hemorrhage Workup: Approach Considerations, Computed Tomography, Lumbar Puncture

  https://emedicine.medscape.com/article/1164341-workup

  The diagnosis of subarachnoid hemorrhage (SAH) usually depends on a high index of clinical suspicion combined with radiologic confirmation via urgent computed tomography (CT) scan without contrast. Traditionally, a negative CT scan is followed with lumbar puncture (LP). However, noncontrast CT followed by CT angiography (CTA) of the brain can rule out SAH with greater than 99% sensitivity. […] Compared with the traditional recommendation of CT followed by LP, CT/CTA may offer a less invasive and more informative diagnostic approach for emergency department patients complaining of acute-onset headache and with no significant risk factors for SAH. […] After the diagnosis of SAH is established, further imaging should be performed to characterize the source of the hemorrhage. This effort can include standard angiography, CT angiography, and magnetic resonance (MR) angiography.

• #97 Subarachnoid hemorrhage – Wikipedia

  https://en.wikipedia.org/wiki/Subarachnoid_hemorrhage

  Its efficacy declines thereafter, and magnetic resonance imaging (MRI) is more sensitive than CT after several days. […] After a subarachnoid hemorrhage is confirmed, its origin needs to be determined. If the bleeding is likely to have originated from an aneurysm (as determined by the CT scan appearance), the choice is between cerebral angiography (injecting radiocontrast through a catheter to the brain arteries) and CT angiography (visualizing blood vessels with radiocontrast on a CT scan) to identify aneurysms. […] In emergency department patients complaining of acute-onset headache without significant risk factors for SAH, evidence suggests that CT scanning of the head followed by CT angiography can reliably exclude SAH without the need for a lumbar puncture. […] A lumbar puncture or CT scan with contrast is therefore regarded as mandatory in people with suspected SAH when imaging is delayed to after six hours from the onset of symptoms and is negative.

• #98 Subarachnoid Hemorrhage Workup: Approach Considerations, Computed Tomography, Lumbar Puncture

  https://emedicine.medscape.com/article/1164341-workup

  The diagnosis of subarachnoid hemorrhage (SAH) usually depends on a high index of clinical suspicion combined with radiologic confirmation via urgent computed tomography (CT) scan without contrast. Traditionally, a negative CT scan is followed with lumbar puncture (LP). However, noncontrast CT followed by CT angiography (CTA) of the brain can rule out SAH with greater than 99% sensitivity. […] Compared with the traditional recommendation of CT followed by LP, CT/CTA may offer a less invasive and more informative diagnostic approach for emergency department patients complaining of acute-onset headache and with no significant risk factors for SAH. […] After the diagnosis of SAH is established, further imaging should be performed to characterize the source of the hemorrhage. This effort can include standard angiography, CT angiography, and magnetic resonance (MR) angiography.

• #99 Subarachnoid Hemorrhage (SAH) – EMCrit Project

  https://emcrit.org/ibcc/sah/

  Noncontrast CT is the standard initial test for possible subarachnoid hemorrhage. […] The sensitivity is nearly 100% within six hours of headache onset, after which time blood starts looking a bit more grey, so the sensitivity may decrease slightly. […] CT angiography (CTA) is highly sensitive and specific (~95%) for aneurysm detection, but may miss very small aneurysms. […] For patients with thunderclap headache, a reasonable diagnostic strategy might be to perform a STAT noncontrast CT scan followed immediately by a CTA of the head and neck. CT/CTA is fast, noninvasive, and safe. […] If CT/CTA leaves remaining confusion about the possibility of SAH, then lumbar puncture and/or MRI/MRA may be considered. […] MRI can be useful to detect subtle underlying pathology (e.g., arteriovenous malformations, infections, malignancy, or inflammatory disorders).

• #100 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  The ultimate objective is not to understand test accuracy; instead, the goal is to deliver the appropriate care to the right patients. […] The test-threshold describes the probability of a diagnosis (aneurysmal SAH) below which continuing to test for the diagnosis will harm more patients than it will help, whereas above the threshold additional testing will benefit more patients than will be harmed. […] Based upon one recent diagnostic meta-analysis, the threshold at which post-CT LP would benefit patients is quite narrow (2-4% for CSF RBC or 2%-7% for visible xanthochromia). […] Therefore, LP appears to benefit relatively few patients within a narrow pretest probability range. […] With improvements in CT technology and an expanding body of evidence, test thresholds for LP may become more precise, obviating the need for a post-CT LP in more acute headache patients.

• #101 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  Existing SAH clinical decision rules await external validation, but offer the potential to identify subsets most likely to benefit from post-CT LP, angiography, or no further testing. […] Nonetheless, the similar test-threshold point-estimate for post-CT LP in comparison to Carpenter et al indicates that current textbook and guideline recommendations (which advocate post-CT for everyone) merit revision. […] The discussion amongst the Journal Club attendees focused around two issues. […] Less than one in 10 headache patients concerning for SAH are ultimately diagnosed with SAH in recent studies. […] While certain symptoms and signs increase or decrease the likelihood of SAH, no single characteristic on history/physical exam is sufficient to rule in or rule out SAH. […] The decades old dogma that acute headache patients in whom SAH is a consideration must uniformly undergo an LP following a nondiagnostic CT appears is unnecessary for a large subset of these patients and may lead to harms via additional downstream testing that results from the imperfect, non-specific findings in CSF.

• #102 Diagnosis of Subarachnoid Hemorrhage – Emergency Medicine

  https://emergencymedicine.wustl.edu/items/diagnosis-of-subarachnoid-hemorrhage/

  The ultimate objective is not to understand test accuracy; instead, the goal is to deliver the appropriate care to the right patients. […] The test-threshold describes the probability of a diagnosis (aneurysmal SAH) below which continuing to test for the diagnosis will harm more patients than it will help, whereas above the threshold additional testing will benefit more patients than will be harmed. […] Based upon one recent diagnostic meta-analysis, the threshold at which post-CT LP would benefit patients is quite narrow (2-4% for CSF RBC or 2%-7% for visible xanthochromia). […] Therefore, LP appears to benefit relatively few patients within a narrow pretest probability range. […] With improvements in CT technology and an expanding body of evidence, test thresholds for LP may become more precise, obviating the need for a post-CT LP in more acute headache patients.

• #103 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  If non-contrast head CT is not definitive (time to study, patient elements [i.e., severe anemia], interpretation limitations [i.e., trainee radiologist, motion artifact], etc) the next recommended diagnostic tool is the LP. In these instances the LP is looking for two elements that raise the concern for SAH: 1) RBCs; and 2) xanthochromia (bilirubin in cerebrospinal fluid [CSF]). […] Given the sensitivity of the CT discussed above, shared decision-making should be conducted with regard to LP. In particular, with sensitivity of near 99% for an adequate study if completed within six hours, and meeting the criteria outlined above, patients should be made aware of the low diagnostic utility of LP if completed after a CT. In this setting, risks (adverse events and false positives) generally outweigh benefits and LP is advised against.

• #104 Subarachnoid Haemorrhage: Causes, Symptoms, Treatment

  https://patient.info/doctor/subarachnoid-haemorrhage-pro

  Urgent investigation to confirm a diagnosis of subarachnoid haemorrhage facilitates early treatment to prevent re-bleeding from a ruptured aneurysm and minimises disability and death. […] A person should be referred for an urgent non-contrast CT head scan if review in secondary care by a senior clinical decision-maker confirms unexplained thunderclap headache, or other signs and symptoms that suggest subarachnoid haemorrhage. Diagnostic accuracy of CT head scans is highest within six hours of symptom onset. A subarachnoid haemorrhage is diagnosed if the non-contrast CT head scan shows blood in the subarachnoid space. […] If a CT head scan done within six hours of symptom onset and reported and documented by a radiologist shows no evidence of a subarachnoid haemorrhage, a lumbar puncture should not be routinely offered and alternative diagnoses should be considered.

• #105 Subarachnoid hemorrhage – Knowledge @ AMBOSS

  https://www.amboss.com/us/knowledge/subarachnoid-hemorrhage/

  Subarachnoid hemorrhage (SAH) refers to bleeding into the subarachnoid space. The best initial diagnostic test is a head CT without contrast, in which acute subarachnoid bleeding can be seen as hyperdensities in the subarachnoid space. If a head CT is negative for SAH, this diagnosis can be ruled out in many patients. However, if clinical suspicion remains high, it may be necessary to perform a lumbar puncture or CT angiography. Once SAH is confirmed, angiography is always necessary in order to identify the source of bleeding (e.g., aneurysms or other vascular abnormalities) and plan definitive treatment. […] Since a missed diagnosis of SAH can have devastating consequences, clinicians should maintain a high index of suspicion when deciding whether to pursue testing. […] Best initial test: immediate head CT without contrast.

• #106 Subarachnoid hemorrhage – Knowledge @ AMBOSS

  https://www.amboss.com/us/knowledge/subarachnoid-hemorrhage/

  Confirmation of SAH: Obtain angiography to confirm source of bleeding and plan treatment. […] Nondiagnostic head CT but persisting suspicion: Perform second-line diagnostic tests. […] Lumbar puncture (LP) positive: Identify the source of bleeding with angiography (e.g., CTA, DSA) and plan intervention. […] LP negative; : SAH can be ruled out in most cases. If suspicion remains high, obtain CTA. […] CTA positive: Consider if additional angiographic imaging is necessary (e.g., DSA, MRA) and plan intervention. […] CTA negative: SAH can be ruled out; consider other diagnoses. If suspicion remains high (which is rare), consider additional imaging (e.g., DSA, MRA). […] If there is a high index of suspicion for SAH, a negative CT head does not exclude the diagnosis and second-line tests are necessary.

• #107 Approach to the Diagnosis and Management of Subarachnoid Hemorrhage

  https://pmc.ncbi.nlm.nih.gov/articles/PMC6404699/

  Headache is one of the most common reasons for presentation to the emergency department (ED), seen in up to 2% of patients. Most are benign, but it is imperative to understand and discern the life-threatening causes of headache when they present. Headache caused by a subarachnoid hemorrhage (SAH) from a ruptured aneurysm is one of the most deadly, with a median case-fatality of 27-44%. Fortunately, it is also rare, comprising only 1% of all headaches presenting to the ED. On initial presentation, the one-year mortality of untreated SAH is up to 65%. With appropriate diagnosis and treatment, mortality can be reduced to 18%. The implications are profound: Our careful assessment leading to the detection of a SAH as the cause of headache can significantly decrease our patients’ mortality. If this were an easy task, the 12% reported rate of missed diagnosis would not exist. We have multiple tools and strategies to evaluate the patient with severe headache and must understand the strengths and limitations of each tool.

• #108 Subarachnoid hemorrhage in the emergency department | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-021-00353-w

  The American College of Emergency Physicians shares a level C recommendation to obtain an LP or a CT angiography of the brain to investigate patients at high risk for SAH in the setting of a negative CTH. […] A lumbar puncture will reveal xanthochromia, indicating heme metabolism, in the cerebrospinal fluid (CSF), diagnostic of SAH. […] The American Heart Association/American Stroke Association states a CTA could be considered in the workup for suspected aneurysmal SAH. […] Once the diagnosis of SAH hemorrhage is made, it is important to classify and grade the patients risk to guide the urgency of further management. […] The 1-year mortality for untreated SAH is nearly 65%, which is reduced to 18% with the appropriate diagnosis and initiation of treatment. […] Making a timely diagnosis, initiating management in the ED, and employing suitable consultations/admission for possible early intervention is crucial for care.

• #109 Subarachnoid hemorrhage in the emergency department | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-021-00353-w

  The American College of Emergency Physicians shares a level C recommendation to obtain an LP or a CT angiography of the brain to investigate patients at high risk for SAH in the setting of a negative CTH. […] A lumbar puncture will reveal xanthochromia, indicating heme metabolism, in the cerebrospinal fluid (CSF), diagnostic of SAH. […] The American Heart Association/American Stroke Association states a CTA could be considered in the workup for suspected aneurysmal SAH. […] Once the diagnosis of SAH hemorrhage is made, it is important to classify and grade the patients risk to guide the urgency of further management. […] The 1-year mortality for untreated SAH is nearly 65%, which is reduced to 18% with the appropriate diagnosis and initiation of treatment. […] Making a timely diagnosis, initiating management in the ED, and employing suitable consultations/admission for possible early intervention is crucial for care.

• #110 Subarachnoid haemorrhage – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/3000106

  Subarachnoid haemorrhage (SAH) presents as a sudden, severe headache that peaks within 1 to 5 minutes (thunderclap headache) and lasts more than an hour; typically alongside vomiting, photophobia, and non-focal neurological signs. […] Order an urgent non-contrast computed tomography (CT) head scan for all patients with suspected SAH. The CT scan should ideally be within 6 hours of symptom onset. SAH is confirmed by the hyperdense appearance of blood in the subarachnoid space/basal cisterns. […] As soon as the diagnosis of SAH is confirmed, urgently discuss with a specialist neurosurgical centre the need for transfer of care of the patient to the specialist centre. […] An interventional neuroradiologist and a neurosurgeon should decide the best mode of intervention to manage the culprit aneurysm, taking into account the patient’s clinical condition, the characteristics of the aneurysm, and the amount and location of subarachnoid blood.

• #111 Clinical management guidelines for subarachnoid haemorrhage. Diagnosis and treatment | Neurología (English Edition)

  https://www.elsevier.es/en-revista-neurologia-english-edition–495-articulo-clinical-management-guidelines-for-subarachnoid-S2173580814000819

  Aneurysms may be excluded from cerebral circulation by either endovascular or surgical treatment. […] If there is a clinical suspicion of SAH, the patient must be referred to a specialist centre immediately in order to receive the best management and treatment. […] All patients with SAH should ideally be treated in hospitals that include a neurologist, neurosurgeon, neurointerventionist, CT scanner, MRI scanner, digital angiograph, stroke unit, and an intensive care unit.

• #112 Subarachnoid hemorrhage in the emergency department | International Journal of Emergency Medicine | Full Text

  https://intjem.biomedcentral.com/articles/10.1186/s12245-021-00353-w

  Subarachnoid hemorrhage accounts for more than 30,000 cases of stroke annually in North America and encompasses a 4.4% mortality rate. Since a vast number of subarachnoid hemorrhage cases present in a younger population and can range from benign to severe, an accurate diagnosis is imperative to avoid premature morbidity and mortality. […] Once a subarachnoid hemorrhage is suspected, a computed tomography of the head with the assistance of the Ottawa subarachnoid hemorrhage rule should be utilized as an initial diagnostic measure. […] Subarachnoid hemorrhages are frequently misdiagnosed; therefore, we believe it is imperative to address the diagnosis and initiation of early management in the emergency medicine department to minimize poor outcomes in the future. […] Diagnosis is often missed due to the various clinical manifestations and inconsistencies in individual findings.

• #113 Diagnosis of a subarachnoid hemorrhage with only mild symptoms using computed tomography in Japan | BMC Neurology | Full Text

  https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-016-0726-9

  Japan is currently an aging society, with a huge proportion of elderly citizens. Consequently, the incidence and severity of subarachnoid hemorrhage (SAH) is predicted to increase in the future. Computed tomography (CT) is very important in the initial diagnosis of SAH. […] However, misdiagnosis of SAH is a relatively common problem and is associated with increased mortality and morbidity, even in individuals who initially present in good condition. […] Thus, we diagnosed our patient with SAH and provided appropriate treatment (aneurysm clipping). Following this, the patient progressed without development of the initial complications, and he was subsequently discharged from our hospital without sequela. […] Thus, physicians should be able to recognize subtle characteristics of CT imaging in case of SAH patients with low grade symptoms, as this can facilitate early diagnosis.

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