Materiały źródłowe

• #1 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Bells palsy is the most common condition involving a rapid and unilateral onset of peripheral paresis/paralysis of the seventh cranial nerve. […] However, the etiology of Bells palsy is unclear, and this affects its treatment. Thus, it is critical to determine the causes of Bells palsy so that targeted treatment approaches can be developed and employed. […] Despite its severe effects, the exact etiology of BP remains unclear. […] The Guideline Development Group (GDG) has identified the diagnosis of BP as one of exclusion, requiring careful clinical elimination of other potential etiologies of facial paralysis/paresis, such as trauma, neoplasms, congenital or syndromic problems, postsurgical facial paralysis/paresis, or infection by agents including zoster and Lyme disease. […] In this review, we sought to summarize potential clinical etiologies of BP, through search for eligible studies on PubMed, Embase, and the Web of Science up to 31 October 2018 using the following search terms: acute facial paresis/paralysis, Bells palsy, idiopathic facial palsy, and/or etiology. There are five major theories regarding the causes of BP including anatomical, viral infection, ischemia, inflammation, and cold stimulation.

• #2 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #3

  https://link.springer.com/article/10.1007/s00415-019-09282-4

  Bells palsy is a health issue causing concern and has an extremely negative effect on both patients and their families. […] However, the etiology of Bells palsy is unclear, and this affects its treatment. Thus, it is critical to determine the causes of Bells palsy so that targeted treatment approaches can be developed and employed. […] Despite its severe effects, the exact etiology of BP remains unclear. […] The Guideline Development Group (GDG) has identified the diagnosis of BP as one of exclusion, requiring careful clinical elimination of other potential etiologies of facial paralysis/paresis, such as trauma, neoplasms, congenital or syndromic problems, postsurgical facial paralysis/paresis, or infection by agents including zoster and Lyme disease. […] In this review, we sought to summarize potential clinical etiologies of BP, through search for eligible studies on PubMed, Embase, and the Web of Science up to 31 October 2018 using the following search terms: acute facial paresis/paralysis, Bells palsy, idiopathic facial palsy, and/or etiology. There are five major theories regarding the causes of BP including anatomical, viral infection, ischemia, inflammation, and cold stimulation.

• #4 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Bells palsy is the most common condition involving a rapid and unilateral onset of peripheral paresis/paralysis of the seventh cranial nerve. […] However, the etiology of Bells palsy is unclear, and this affects its treatment. Thus, it is critical to determine the causes of Bells palsy so that targeted treatment approaches can be developed and employed. […] Despite its severe effects, the exact etiology of BP remains unclear. […] The Guideline Development Group (GDG) has identified the diagnosis of BP as one of exclusion, requiring careful clinical elimination of other potential etiologies of facial paralysis/paresis, such as trauma, neoplasms, congenital or syndromic problems, postsurgical facial paralysis/paresis, or infection by agents including zoster and Lyme disease. […] In this review, we sought to summarize potential clinical etiologies of BP, through search for eligible studies on PubMed, Embase, and the Web of Science up to 31 October 2018 using the following search terms: acute facial paresis/paralysis, Bells palsy, idiopathic facial palsy, and/or etiology. There are five major theories regarding the causes of BP including anatomical, viral infection, ischemia, inflammation, and cold stimulation.

• #5 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #6 Bell Palsy: Practice Essentials, Background, Anatomy

  https://emedicine.medscape.com/article/1146903-overview

  Bell palsy, more appropriately termed idiopathic facial paralysis (IFP), is the most common cause of unilateral facial paralysis. […] The cause of Bell palsy remains unknown, though the disorder appears to be a polyneuritis with possible viral, inflammatory, autoimmune, and ischemic etiologies. Increasing evidence implicates herpes simplex type I and herpes zoster virus reactivation from cranial-nerve ganglia. […] The hypothesis that HSV is the etiologic agent in Bell palsy holds that after causing primary infection on the lips (ie, cold sores), the virus travels up the axons of the sensory nerves and resides in the geniculate ganglion. […] Besides HSV infection, possible etiologies for Bell palsy include other infections (eg, herpes zoster, Lyme disease, syphilis, Epstein-Barr viral infection, cytomegalovirus, human immunodeficiency virus [HIV], mycoplasma); inflammation alone; and microvascular disease (diabetes mellitus and hypertension).

• #7 Bell’s palsy: aetiology, clinical features and multidisciplinary care | Journal of Neurology, Neurosurgery & Psychiatry

  https://jnnp.bmj.com/content/86/12/1356

  The association with HSV-1 is supported by the presence of HSV-1 in intratemporal facial nerve endoneural fluid harvested during nerve decompression, and the ability to incite facial palsy in an animal model through primary infection and reactivation induced by immune modulation. […] A possible cause of neural dysfunction due to HSV-1 is the activation of intra-axonal degradation and apoptotic pathways driven by local direct and indirect responses of the axon to the virus itself in a susceptible phenotype. […] Another possible contributor to the pathogenesis of Bell’s palsy implicates the role of a cell-mediated immune response against myelin, akin to a mononeuropathic form of Guillain-Barr syndrome (GBS).

• #8 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] Studies have shown that the mean NLR and neutrophil values in adult and pediatric patients with BP were found to be significantly higher than in healthy controls. […] The presence of small round lymphatic cells and the breakdown of myelin sheaths are common histologic features of autoimmune responses, with viral infection prompting an autoimmune reaction against a component of peripheral myelin and resulting in the cranial nerves demyelination and especially facial nerve demyelination. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #9 Bell’s Palsy: Diagnosis and Management | AAFP

  https://www.aafp.org/pubs/afp/issues/2007/1001/p997.html

  Bell’s palsy has been traditionally defined as idiopathic; however, one possible etiology is infection with herpes simplex virus type 1. […] Bell’s palsy is believed to be caused by inflammation of the facial nerve at the geniculate ganglion, which leads to compression and possible ischemia and demyelination. […] Recently, attention has focused on infection with herpes simplex virus type 1 (HSV-1) as a possible cause because research has found elevated HSV-1 titers in affected patients. However, studies have failed to isolate viral DNA in biopsy specimens, leaving the causative role of HSV-1 in question. […] Many conditions can produce isolated facial nerve palsy identical to Bell’s palsy. […] Although influenza vaccines currently available in the United States have not been associated with Bell’s palsy, a recently developed Swiss intranasal vaccine was found to have a very high risk of postvaccine facial nerve palsy and has been withdrawn from use.

• #10 Bell’s Palsy: Causes, Symptoms, and Treatment

  https://www.webmd.com/brain/understanding-bells-palsy-basics

  Bell’s palsy is also known as acute facial palsy of unknown cause. […] Doctors don’t know what causes it but think it may result from some kind of trauma to the seventh cranial nerve, which controls your facial muscles. […] Most doctors think that Bell’s palsy is caused by damage to the facial nerve, which causes swelling. This nerve passes through a narrow, bony area in your skull. When the nerve swells — even a little bit — it pushes against your skull’s hard surface, which affects how well the nerve works. […] Researchers have long believed that viral infections may also play a role in Bell’s palsy. They’ve found evidence that suggests the herpes simplex 1 virus (a common cause of cold sores) may be the cause of a lot of cases. Other viruses that are linked to Bells palsy include: Adenovirus (respiratory conditions), Coxsackievirus (hand-foot-mouth disease), Cytomegalovirus, Epstein-Barr (infectious mononucleosis), Herpes zoster (chickenpox and shingles), HIV/AIDS, Influenza B (flu), Lyme disease, Middle ear infection, Mumps, Rubella (German measles). […] The main cause of Bells palsy is thought to be swelling of your seventh cranial nerve, which is the nerve that controls your facial muscles.

• #11 Bell Palsy: Practice Essentials, Background, Anatomy

  https://emedicine.medscape.com/article/1146903-overview

  Bell palsy, more appropriately termed idiopathic facial paralysis (IFP), is the most common cause of unilateral facial paralysis. […] The cause of Bell palsy remains unknown, though the disorder appears to be a polyneuritis with possible viral, inflammatory, autoimmune, and ischemic etiologies. Increasing evidence implicates herpes simplex type I and herpes zoster virus reactivation from cranial-nerve ganglia. […] The hypothesis that HSV is the etiologic agent in Bell palsy holds that after causing primary infection on the lips (ie, cold sores), the virus travels up the axons of the sensory nerves and resides in the geniculate ganglion. […] Besides HSV infection, possible etiologies for Bell palsy include other infections (eg, herpes zoster, Lyme disease, syphilis, Epstein-Barr viral infection, cytomegalovirus, human immunodeficiency virus [HIV], mycoplasma); inflammation alone; and microvascular disease (diabetes mellitus and hypertension).

• #12

  https://link.springer.com/article/10.1007/s00415-019-09282-4

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] BP, an acute idiopathic lower motor neuron palsy, is commonly a unilateral and self-limiting inflammatory condition. […] Numerous lines of evidence have suggested that BP results from acute, inflammation-caused demyelination. […] There are several possible risk factors for BP, including severe preeclampsia, psychological factors, glucose metabolism abnormalities, radiation exposure, hypertension, and migraine. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #13 Bell’s Palsy: Causes, Symptoms, and Treatment

  https://www.webmd.com/brain/understanding-bells-palsy-basics

  Bell’s palsy is also known as acute facial palsy of unknown cause. […] Doctors don’t know what causes it but think it may result from some kind of trauma to the seventh cranial nerve, which controls your facial muscles. […] Most doctors think that Bell’s palsy is caused by damage to the facial nerve, which causes swelling. This nerve passes through a narrow, bony area in your skull. When the nerve swells — even a little bit — it pushes against your skull’s hard surface, which affects how well the nerve works. […] Researchers have long believed that viral infections may also play a role in Bell’s palsy. They’ve found evidence that suggests the herpes simplex 1 virus (a common cause of cold sores) may be the cause of a lot of cases. Other viruses that are linked to Bells palsy include: Adenovirus (respiratory conditions), Coxsackievirus (hand-foot-mouth disease), Cytomegalovirus, Epstein-Barr (infectious mononucleosis), Herpes zoster (chickenpox and shingles), HIV/AIDS, Influenza B (flu), Lyme disease, Middle ear infection, Mumps, Rubella (German measles). […] The main cause of Bells palsy is thought to be swelling of your seventh cranial nerve, which is the nerve that controls your facial muscles.

• #14 Bell’s Palsy: Causes, Symptoms, and Treatment

  https://www.webmd.com/brain/understanding-bells-palsy-basics

  Bell’s palsy is also known as acute facial palsy of unknown cause. […] Doctors don’t know what causes it but think it may result from some kind of trauma to the seventh cranial nerve, which controls your facial muscles. […] Most doctors think that Bell’s palsy is caused by damage to the facial nerve, which causes swelling. This nerve passes through a narrow, bony area in your skull. When the nerve swells — even a little bit — it pushes against your skull’s hard surface, which affects how well the nerve works. […] Researchers have long believed that viral infections may also play a role in Bell’s palsy. They’ve found evidence that suggests the herpes simplex 1 virus (a common cause of cold sores) may be the cause of a lot of cases. Other viruses that are linked to Bells palsy include: Adenovirus (respiratory conditions), Coxsackievirus (hand-foot-mouth disease), Cytomegalovirus, Epstein-Barr (infectious mononucleosis), Herpes zoster (chickenpox and shingles), HIV/AIDS, Influenza B (flu), Lyme disease, Middle ear infection, Mumps, Rubella (German measles). […] The main cause of Bells palsy is thought to be swelling of your seventh cranial nerve, which is the nerve that controls your facial muscles.

• #15 Bell Palsy – Brain, Spinal Cord, and Nerve Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/cranial-nerve-disorders/bell-palsy

  The cause of Bell palsy may be a viral infection or an immune disorder that causes the facial nerve to swell, or the cause may be unknown. […] Bell palsy is a type of facial nerve palsy, which was originally thought to have no identifiable cause (idiopathic facial nerve palsy). However, current evidence suggests that in some cases, Bell palsy can be caused by a viral infection or another disorder. […] Evidence suggests that common causes of Bell palsy include infection by herpes simplex virus type 1 (which causes mouth infections, such as cold sores) and shingles. […] Other viruses, such as coxsackievirus, cytomegalovirus, and the viruses that cause COVID-19, mumps, rubella, mononucleosis, or influenza or the vaccines for these viruses may also cause Bell palsy. […] Infection causes the nerve to swell. When the nerve is swollen, it is squeezed (compressed) by the narrow passageways in the skull that it passes through. […] Other disorders can cause other types of facial nerve palsy. Lyme disease can cause facial nerve palsy that, unlike Bell palsy, may affect both sides of the face. In African-Americans, sarcoidosis is a common cause of facial nerve palsy. Sometimes tumors and skull fractures cause facial palsy.

• #16 Bell Palsy – Brain, Spinal Cord, and Nerve Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/cranial-nerve-disorders/bell-palsy

  The cause of Bell palsy may be a viral infection or an immune disorder that causes the facial nerve to swell, or the cause may be unknown. […] Bell palsy is a type of facial nerve palsy, which was originally thought to have no identifiable cause (idiopathic facial nerve palsy). However, current evidence suggests that in some cases, Bell palsy can be caused by a viral infection or another disorder. […] Evidence suggests that common causes of Bell palsy include infection by herpes simplex virus type 1 (which causes mouth infections, such as cold sores) and shingles. […] Other viruses, such as coxsackievirus, cytomegalovirus, and the viruses that cause COVID-19, mumps, rubella, mononucleosis, or influenza or the vaccines for these viruses may also cause Bell palsy. […] Infection causes the nerve to swell. When the nerve is swollen, it is squeezed (compressed) by the narrow passageways in the skull that it passes through. […] Other disorders can cause other types of facial nerve palsy. Lyme disease can cause facial nerve palsy that, unlike Bell palsy, may affect both sides of the face. In African-Americans, sarcoidosis is a common cause of facial nerve palsy. Sometimes tumors and skull fractures cause facial palsy.

• #17 Bell’s Palsy: Causes, Symptoms, and Treatment

  https://www.webmd.com/brain/understanding-bells-palsy-basics

  Bell’s palsy is also known as acute facial palsy of unknown cause. […] Doctors don’t know what causes it but think it may result from some kind of trauma to the seventh cranial nerve, which controls your facial muscles. […] Most doctors think that Bell’s palsy is caused by damage to the facial nerve, which causes swelling. This nerve passes through a narrow, bony area in your skull. When the nerve swells — even a little bit — it pushes against your skull’s hard surface, which affects how well the nerve works. […] Researchers have long believed that viral infections may also play a role in Bell’s palsy. They’ve found evidence that suggests the herpes simplex 1 virus (a common cause of cold sores) may be the cause of a lot of cases. Other viruses that are linked to Bells palsy include: Adenovirus (respiratory conditions), Coxsackievirus (hand-foot-mouth disease), Cytomegalovirus, Epstein-Barr (infectious mononucleosis), Herpes zoster (chickenpox and shingles), HIV/AIDS, Influenza B (flu), Lyme disease, Middle ear infection, Mumps, Rubella (German measles). […] The main cause of Bells palsy is thought to be swelling of your seventh cranial nerve, which is the nerve that controls your facial muscles.

• #18 Bell palsy – UF Health

  https://ufhealth.org/conditions-and-treatments/bell-palsy

  Bell palsy is thought to be due to swelling (inflammation) of the facial nerve in the area where it travels through the bones of the skull. This nerve controls movement of the muscles of the face. […] The cause is often not clear. A type of herpes infection called herpes simplex or herpes zoster might be involved. Other conditions that may cause Bell palsy include: HIV/AIDS infection, Lyme disease, middle ear infection, sarcoidosis (inflammation of the lymph nodes, lungs, liver, eyes, skin, or other tissues). […] Having diabetes and being pregnant may increase the risk for Bell palsy.

• #19 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #20 Bell Palsy: Practice Essentials, Background, Anatomy

  https://emedicine.medscape.com/article/1146903-overview

  Bell palsy, more appropriately termed idiopathic facial paralysis (IFP), is the most common cause of unilateral facial paralysis. […] The cause of Bell palsy remains unknown, though the disorder appears to be a polyneuritis with possible viral, inflammatory, autoimmune, and ischemic etiologies. Increasing evidence implicates herpes simplex type I and herpes zoster virus reactivation from cranial-nerve ganglia. […] The hypothesis that HSV is the etiologic agent in Bell palsy holds that after causing primary infection on the lips (ie, cold sores), the virus travels up the axons of the sensory nerves and resides in the geniculate ganglion. […] Besides HSV infection, possible etiologies for Bell palsy include other infections (eg, herpes zoster, Lyme disease, syphilis, Epstein-Barr viral infection, cytomegalovirus, human immunodeficiency virus [HIV], mycoplasma); inflammation alone; and microvascular disease (diabetes mellitus and hypertension).

• #21 Patient education: Bell’s palsy (Beyond the Basics) – UpToDate

  https://www.uptodate.com/contents/bells-palsy-beyond-the-basics/print

  Bell’s palsy is caused by an inflammation of the facial nerve. This inflammation may be caused by a virus. There is some evidence that the virus is often herpes simplex virus (HSV), the same virus that causes cold sores and genital herpes. Other viruses may also cause the condition, including herpes zoster virus, cytomegalovirus, and Epstein-Barr virus. […] The inflammation causes swelling of the nerve that controls movement of one side of the face. The nerve, as well as adjacent blood vessels that supply the nerve with blood, must travel through a narrow canal surrounded by bone. As the nerve swells, it becomes compressed (pinched) and its protective covering breaks down, interfering with the nerve’s ability to communicate with the muscles. This causes weakness or paralysis of the muscles in one side of the face. Weakness of these muscles can make it difficult to smile or close the eye.

• #22 Bell’s Palsy: Causes, Symptoms, Diagnosis, Treatment, Outlook

  https://www.healthline.com/health/bells-palsy

  The thought is that the facial nerve reacts to the infection by swelling, which causes pressure in the bony canal (known as the Fallopian canal) that the facial nerve passes through to the side of the face. […] According to the National Institute of Neurological Disorders and Stroke, the inflammation of the facial nerve reduces blood flow and oxygen to the nerve cells. This damage to the cranial nerve and nerve cells can cause paralysis of the facial muscles. […] The National Organization for Rare Disorders also notes that some people might even have an inherited predisposition to developing Bells palsy.

• #23 Patient education: Bell’s palsy (Beyond the Basics) – UpToDate

  https://www.uptodate.com/contents/bells-palsy-beyond-the-basics/print

  Bell’s palsy is caused by an inflammation of the facial nerve. This inflammation may be caused by a virus. There is some evidence that the virus is often herpes simplex virus (HSV), the same virus that causes cold sores and genital herpes. Other viruses may also cause the condition, including herpes zoster virus, cytomegalovirus, and Epstein-Barr virus. […] The inflammation causes swelling of the nerve that controls movement of one side of the face. The nerve, as well as adjacent blood vessels that supply the nerve with blood, must travel through a narrow canal surrounded by bone. As the nerve swells, it becomes compressed (pinched) and its protective covering breaks down, interfering with the nerve’s ability to communicate with the muscles. This causes weakness or paralysis of the muscles in one side of the face. Weakness of these muscles can make it difficult to smile or close the eye.

• #24 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] Studies have shown that the mean NLR and neutrophil values in adult and pediatric patients with BP were found to be significantly higher than in healthy controls. […] The presence of small round lymphatic cells and the breakdown of myelin sheaths are common histologic features of autoimmune responses, with viral infection prompting an autoimmune reaction against a component of peripheral myelin and resulting in the cranial nerves demyelination and especially facial nerve demyelination. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #25 Bell’s palsy: aetiology, clinical features and multidisciplinary care | Journal of Neurology, Neurosurgery & Psychiatry

  https://jnnp.bmj.com/content/86/12/1356

  The association with HSV-1 is supported by the presence of HSV-1 in intratemporal facial nerve endoneural fluid harvested during nerve decompression, and the ability to incite facial palsy in an animal model through primary infection and reactivation induced by immune modulation. […] A possible cause of neural dysfunction due to HSV-1 is the activation of intra-axonal degradation and apoptotic pathways driven by local direct and indirect responses of the axon to the virus itself in a susceptible phenotype. […] Another possible contributor to the pathogenesis of Bell’s palsy implicates the role of a cell-mediated immune response against myelin, akin to a mononeuropathic form of Guillain-Barr syndrome (GBS).

• #26 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] Studies have shown that the mean NLR and neutrophil values in adult and pediatric patients with BP were found to be significantly higher than in healthy controls. […] The presence of small round lymphatic cells and the breakdown of myelin sheaths are common histologic features of autoimmune responses, with viral infection prompting an autoimmune reaction against a component of peripheral myelin and resulting in the cranial nerves demyelination and especially facial nerve demyelination. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #27 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] Studies have shown that the mean NLR and neutrophil values in adult and pediatric patients with BP were found to be significantly higher than in healthy controls. […] The presence of small round lymphatic cells and the breakdown of myelin sheaths are common histologic features of autoimmune responses, with viral infection prompting an autoimmune reaction against a component of peripheral myelin and resulting in the cranial nerves demyelination and especially facial nerve demyelination. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #28 Bell’s palsy: aetiology, clinical features and multidisciplinary care | Journal of Neurology, Neurosurgery & Psychiatry

  https://jnnp.bmj.com/content/86/12/1356

  The association with HSV-1 is supported by the presence of HSV-1 in intratemporal facial nerve endoneural fluid harvested during nerve decompression, and the ability to incite facial palsy in an animal model through primary infection and reactivation induced by immune modulation. […] A possible cause of neural dysfunction due to HSV-1 is the activation of intra-axonal degradation and apoptotic pathways driven by local direct and indirect responses of the axon to the virus itself in a susceptible phenotype. […] Another possible contributor to the pathogenesis of Bell’s palsy implicates the role of a cell-mediated immune response against myelin, akin to a mononeuropathic form of Guillain-Barr syndrome (GBS).

• #29 What Causes Bell’s Palsy? – The New York Times

  https://www.nytimes.com/2017/12/01/well/live/what-causes-bells-palsy.html

  Q. What causes Bell’s palsy? […] A. Bell’s palsy is a temporary partial facial paralysis that occurs when the nerve controlling the facial muscles is inflamed. But identifying the underlying cause of the inflammation “is a question for the ages,” said Dr. Joseph Safdieh, a neurologist at Weill Cornell Medicine and a fellow of the American Academy of Neurology. […] […] […] The current prevailing theory is that Bell’s palsy develops after a viral infection activates the immune system, Dr. Safdieh said, adding that “once the immune system is activated, it goes and attacks a nerve.” […] […] […] Some experts believe Bell’s palsy is related to the herpes simplex or common cold sore virus. But several large randomized controlled trials that compared treatment with antiviral agents and prednisolone, an oral steroid that suppresses the immune system, found the steroid to be most effective. The results reinforce the idea that the condition is caused by an immune system reaction rather than the virus itself, Dr. Safdieh said.

• #30 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #31 Bell’s Palsy

  https://www.healthhub.sg/a-z/diseases-and-conditions/bells-palsy-facial-nerve-paralysis

  Bell’s palsy is thought to develop because of an inflammatory condition leading to a swelling of the facial nerve, which leads to nerve inhibition and compression. This causes the blocking of the transmission of neural signals or damage to the nerve, resulting in paralysis. Viral and bacterial infections, as well as autoimmune disorders, appear to be emerging as the most frequent common cause of Bells Palsy. […] Conditions that compromise the immune system, such as HIV and diabetes […] In addition, people suffering from diabetes are more than four times more likely to develop Bells palsy than the general population. The last trimester of pregnancy is considered to be a time of increased risk for Bell’s palsy. Conditions that compromise the immune system such as HIV or sarcoidosis increase the odds of facial paralysis occurring and recurring. […] Regardless of the trigger, Bell’s palsy is best described as an event trauma to the nerve.

• #32 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #33 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #34 Bell’s Palsy: Symptoms, Causes, and Recovery – Premier Neurology & Wellness Center

  https://premierneurologycenter.com/blog/bells-palsy-symptoms-causes-and-recovery/

  Bell’s Palsy is believed to be primarily caused by viral infections, particularly the herpes simplex virus (HSV), although the exact mechanism is not fully understood. […] The herpes simplex virus, which is responsible for cold sores and genital herpes, is often associated with Bell’s Palsy. It is thought that viral replication and inflammation of the facial nerve may contribute to the development of the condition. […] In addition to viral infections, inflammation and swelling of the facial nerve (cranial nerve VII) can occur, leading to compression and dysfunction. This inflammatory response may be triggered by various factors, including infections, autoimmune reactions, and environmental factors. […] Certain individuals may be at a higher risk of developing Bell’s Palsy. These risk factors include diabetes mellitus, pregnancy (especially during the third trimester and immediately postpartum), upper respiratory infections, and a history of previous Bell’s Palsy episodes.

• #35 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #36

  https://link.springer.com/article/10.1007/s00415-019-09282-4

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] BP, an acute idiopathic lower motor neuron palsy, is commonly a unilateral and self-limiting inflammatory condition. […] Numerous lines of evidence have suggested that BP results from acute, inflammation-caused demyelination. […] There are several possible risk factors for BP, including severe preeclampsia, psychological factors, glucose metabolism abnormalities, radiation exposure, hypertension, and migraine. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #37 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #38

  https://link.springer.com/article/10.1007/s00415-019-09282-4

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] BP, an acute idiopathic lower motor neuron palsy, is commonly a unilateral and self-limiting inflammatory condition. […] Numerous lines of evidence have suggested that BP results from acute, inflammation-caused demyelination. […] There are several possible risk factors for BP, including severe preeclampsia, psychological factors, glucose metabolism abnormalities, radiation exposure, hypertension, and migraine. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #39 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #40 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #41 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #42 Facial Paralysis: Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/symptoms/24525-facial-paralysis

  Facial nerve damage can occur for several reasons, including infection, trauma or stroke. It can also occur without a known cause, which is referred to as Bells palsy. […] Facial paralysis causes may include: […] Bells palsy. […] Though experts havent been able to prove it yet, many healthcare providers recognize a significant link between stress and the onset of Bells palsy. Experts believe that stress can weaken your immune system, resulting in damage to your facial nerve.

• #43 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #44 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #45 Is Bells Palsy Contagious? | Otolaryngology | Head and Neck Surgery

  https://ohns.ucsf.edu/facialnerve/bells-palsy-contagious

  Bell’s palsy occurs when the facial nerves on one side of the face become swollen or irritated and proper function stops. Nerve irritation and inflammation cause muscle weakness and facial dropping associated with Bell’s palsy. […] Anything that causes the facial nerve sheaths to swell could cause Bell’s palsy. Pregnancy, obesity, and diabetes mellitus are risk factors for Bell’s palsy. […] While the condition is not contagious, it is likely caused by the reactivation of a virus. These include upper respiratory illnesses, like the flu or a cold, herpes simplex 1, measles or chickenpox, mumps, amongst other kinds of viruses. […] Some things may make the facial nerve swelling more likely to occur; Bell’s palsy is still considered an idiopathic condition or one with no identifiable cause that seems to happen randomly. Other reasons why Bell’s palsy might develop include injury or trauma to the face. […] High amounts of stress may also be a cause, and sleep deprivation has been associated with the onset of Bell’s palsy. If you have an underlying autoimmune condition, you may also be at a higher risk, as you would have more sensitivity to inflammation.

• #46 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #47 Some things you may not have known about Bell’s palsy

  https://www.samitivejhospitals.com/article/detail/bells-palsy-causes

  People at risk of developing Bells palsy are those suffering from stress or who dont get enough rest, diabetics and people who have experienced respiratory conditions, such as a common cold or the influenza virus. […] As of now, the actual causes of Bells palsy remain unknown, but the condition is believed to occur when there is an irregularity affecting the 7th pair of cranial nerves, which then leads to swelling and a subsequent lack of blood being transported to the facial muscles, thus causing paralysis.

• #48 A general practice approach to Bell’s palsy

  https://www.racgp.org.au/afp/2016/november/a-general-practice-approach-to-bell-s-palsy

  Bells palsy is characterised by an acute onset of unilateral, lower motor neuron weakness of the facial nerve in the absence of an identifiable cause. […] The exact mechanism of Bells palsy is unknown, although a viral aetiology is suspected. […] The unilateral facial weakness associated with Bells palsy is thought to result from facial nerve inflammation and oedema induced by reactivation of Herpes simplex or Varicella zoster virus. […] Specific risk factors for Bells palsy include pregnancy, severe pre-eclampsia, obesity, hypertension, diabetes and upper respiratory illnesses such as influenza. […] Although rare, recurrence of Bells palsy is possible. […] Underlying medical problems such as previous stroke, brain tumour, cutaneous cancers of the face and neck, parotid tumour, head or facial trauma or recent infection can also predispose patients to facial weakness and should also be considered.

• #49 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #50 Bell’s Palsy: What It Is, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/5457-bells-palsy

  Bells palsy happens when theres inflammation and swelling of your seventh cranial nerve the nerve that controls facial muscles. Certain conditions (like viral infections) can cause inflammation, but many cases of Bells palsy have no clear cause (idiopathic). […] Inflammation and compression of your seventh cranial nerve is the main cause of Bells palsy. […] Scientists have found that some viral infections may trigger inflammation of the seventh cranial nerve and cause Bells palsy. They include: Herpes simplex 1 (a virus that causes mouth infections, like cold sores), Varicella-zoster virus (chickenpox and shingles), Epstein-Barr virus (mononucleosis), COVID-19. […] Other triggers may include having a weakened immune system from: Stress, Illnesses, Sleep deprivation, Physical trauma, Autoimmune conditions. […] Healthcare providers usually cant find a specific trigger of Bells palsy.

• #51 Is Bells Palsy Contagious? | Otolaryngology | Head and Neck Surgery

  https://ohns.ucsf.edu/facialnerve/bells-palsy-contagious

  Bell’s palsy occurs when the facial nerves on one side of the face become swollen or irritated and proper function stops. Nerve irritation and inflammation cause muscle weakness and facial dropping associated with Bell’s palsy. […] Anything that causes the facial nerve sheaths to swell could cause Bell’s palsy. Pregnancy, obesity, and diabetes mellitus are risk factors for Bell’s palsy. […] While the condition is not contagious, it is likely caused by the reactivation of a virus. These include upper respiratory illnesses, like the flu or a cold, herpes simplex 1, measles or chickenpox, mumps, amongst other kinds of viruses. […] Some things may make the facial nerve swelling more likely to occur; Bell’s palsy is still considered an idiopathic condition or one with no identifiable cause that seems to happen randomly. Other reasons why Bell’s palsy might develop include injury or trauma to the face. […] High amounts of stress may also be a cause, and sleep deprivation has been associated with the onset of Bell’s palsy. If you have an underlying autoimmune condition, you may also be at a higher risk, as you would have more sensitivity to inflammation.

• #52 Bell’s palsy: Causes, treatment, and symptoms

  https://www.medicalnewstoday.com/articles/158863

  A 2019 study concludes that people with migraine may have a higher risk of Bells palsy, especially if they are between the ages of 3060 years. […] Bells palsy is a type of facial palsy. It results from inflammation in the seventh cranial nerve, also known as the facial nerve, and can lead to weakness or paralysis on one side of the face. In 6075% of cases, doctors do not know why it happens.

• #53 Bell’s palsy – Wikipedia

  https://en.wikipedia.org/wiki/Bell%27s_palsy

  The cause of Bell’s palsy is unknown. […] Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy. […] Many believe that this is due to a viral infection that results in swelling. […] Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g., the varicella zoster virus and the Epstein-Barr virus, both of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell’s palsy. […] Other viruses and bacteria that have been linked to the development of Bell’s palsy include HIV, sarcoidosis and Lyme disease. […] Familial inheritance has been found in 41-4% of cases. […] There may also be an association with migraines. […] In December 2020, the U.S. FDA recommended that recipients of the Pfizer and Moderna COVID-19 vaccines should be monitored for symptoms of Bell’s palsy after several cases were reported among clinical trial participants, though the data were not sufficient to determine a causal link.

• #54 Bell’s palsy – Wikipedia

  https://en.wikipedia.org/wiki/Bell%27s_palsy

  The cause of Bell’s palsy is unknown. […] Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy. […] Many believe that this is due to a viral infection that results in swelling. […] Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g., the varicella zoster virus and the Epstein-Barr virus, both of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell’s palsy. […] Other viruses and bacteria that have been linked to the development of Bell’s palsy include HIV, sarcoidosis and Lyme disease. […] Familial inheritance has been found in 41-4% of cases. […] There may also be an association with migraines. […] In December 2020, the U.S. FDA recommended that recipients of the Pfizer and Moderna COVID-19 vaccines should be monitored for symptoms of Bell’s palsy after several cases were reported among clinical trial participants, though the data were not sufficient to determine a causal link.

• #55 Bell Palsy: Practice Essentials, Background, Anatomy

  https://emedicine.medscape.com/article/1146903-overview

  Bell palsy may be secondary to viral and/or autoimmune reactions that cause the facial nerve to demyelinate, resulting in unilateral facial paralysis. […] A family history of Bell palsy has been reported in approximately 4% of cases. […] Because there is a strong environmental predisposition to Bell palsy, due to the common viral etiology, a positive family history may or may not indicate a true genetic etiology.

• #56 What Is Bell’s Palsy? | Conditions | Changing Faces

  https://www.changingfaces.org.uk/advice-guidance/condition-specific-information/bells-palsy/

  Bell’s palsy is caused when inflammation of the seventh cranial nerve (known as the facial nerve), causes partial or complete facial paralysis, usually on one side of the face. […] The cause of Bell’s palsy is still unclear and is described as an idiopathic condition, meaning no conclusive cause has been identified. Research suggests links with viral causes, for example, herpes, influenza, and respiratory tract infections. It is also associated with a weakened immune system and a period of stress. […] Bell’s palsy tends to be caused by a viral infection. However, some evidence suggests that there may be a genetic element in between 4 and 14% of cases. Recurrence of Bell’s palsy is rare but when it does recur, there is often a family history of episodes of Bell’s palsy, suggesting that there may be a genetic dimension.

• #57 Bell Palsy: Practice Essentials, Background, Anatomy

  https://emedicine.medscape.com/article/1146903-overview

  Bell palsy may be secondary to viral and/or autoimmune reactions that cause the facial nerve to demyelinate, resulting in unilateral facial paralysis. […] A family history of Bell palsy has been reported in approximately 4% of cases. […] Because there is a strong environmental predisposition to Bell palsy, due to the common viral etiology, a positive family history may or may not indicate a true genetic etiology.

• #58 A meta-analysis uncovers the first sequence variant conferring risk of Bell’s palsy | Scientific Reports

  https://www.nature.com/articles/s41598-021-82736-w

  Bells palsy is the most common cause of unilateral facial paralysis and is defined as an idiopathic and acute inability to control movements of the facial muscles on the affected side. […] While the exact etiology of Bells palsy is unknown, it has been suggested that the disorder is caused by inflammation or compression of the seventh cranial nerve. […] The literature has highlighted several viral illnesses such as herpes simplex type 1, which has been detected in 31-79% of cases, human immunodeficiency viruses, varicella-zoster, and Epstein-Barr. […] In Bells palsy, a viral infection is considered one of the possible causes. […] The main treatment is corticosteroids, which supports the theory of edema induced entrapment neuropathy. […] We were unable to determine a gene at 6p21.1 involved in Bells palsy pathology. However, the association of rs9357446-A with IDD brings up the possibility that the variant may confer risk of Bells palsy through an effect on cartilage and bone development. […] Although more studies are needed, the identification of this variant contributes to the limited understanding of Bells palsy.

• #59 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] Studies have shown that the mean NLR and neutrophil values in adult and pediatric patients with BP were found to be significantly higher than in healthy controls. […] The presence of small round lymphatic cells and the breakdown of myelin sheaths are common histologic features of autoimmune responses, with viral infection prompting an autoimmune reaction against a component of peripheral myelin and resulting in the cranial nerves demyelination and especially facial nerve demyelination. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #60

  https://link.springer.com/article/10.1007/s00415-019-09282-4

  Another possible etiology of BP that has been suggested is infection by reactivated viruses, such as the varicella zoster virus (VZV), herpes simplex virus type 1 (HSV-1), human herpes virus 6, and the Usutu virus. […] BP, an acute idiopathic lower motor neuron palsy, is commonly a unilateral and self-limiting inflammatory condition. […] Numerous lines of evidence have suggested that BP results from acute, inflammation-caused demyelination. […] There are several possible risk factors for BP, including severe preeclampsia, psychological factors, glucose metabolism abnormalities, radiation exposure, hypertension, and migraine. […] Collectively, these studies and those discussed above demonstrate that the incidence of BP increases with acute cold exposure and in places with large diurnal temperature differences, indicating that sharp temperature changes may be a risk factor for facial nerve palsy.

• #61 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #62 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #63 Causes of Facial Palsy | Bells Palsy

  http://bellspalsy.ws/causes-of-facial-palsy/

  Lyme disease can cause facial paralysis and the same symptoms as Bells palsy. […] Bacteria from some acute or chronic middle ear infections can invade the canal around the nerve through small portals. […] Bells palsy and Ramsey Hunt syndrome can be bilateral, but its extremely rare. […] Melkersson-Rosenthal syndrome can result in unilateral or bilateral palsy. […] Facial and surgical wounds, trauma due to a blunt force, temporal bone fractures, brain stem injuries, acoustic neuromas, cysts and tumors can result in facial palsy.

• #64 Facial Paralysis | Condition | UT Southwestern Medical Center

  https://utswmed.org/conditions-treatments/facial-paralysis/

  Several viruses, including varicella-zoster, herpes simplex, and Epstein-Barr (EBV) may cause facial paralysis. […] Another known infectious cause for facial paralysis is Lyme disease, seen more on the East Coast and caused by ticks commonly found on deer. Approximately 11 percent of patients with Lyme disease develop facial paralysis.

• #65 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #66 Bell Palsy – Brain, Spinal Cord, and Nerve Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/cranial-nerve-disorders/bell-palsy

  The cause of Bell palsy may be a viral infection or an immune disorder that causes the facial nerve to swell, or the cause may be unknown. […] Bell palsy is a type of facial nerve palsy, which was originally thought to have no identifiable cause (idiopathic facial nerve palsy). However, current evidence suggests that in some cases, Bell palsy can be caused by a viral infection or another disorder. […] Evidence suggests that common causes of Bell palsy include infection by herpes simplex virus type 1 (which causes mouth infections, such as cold sores) and shingles. […] Other viruses, such as coxsackievirus, cytomegalovirus, and the viruses that cause COVID-19, mumps, rubella, mononucleosis, or influenza or the vaccines for these viruses may also cause Bell palsy. […] Infection causes the nerve to swell. When the nerve is swollen, it is squeezed (compressed) by the narrow passageways in the skull that it passes through. […] Other disorders can cause other types of facial nerve palsy. Lyme disease can cause facial nerve palsy that, unlike Bell palsy, may affect both sides of the face. In African-Americans, sarcoidosis is a common cause of facial nerve palsy. Sometimes tumors and skull fractures cause facial palsy.

• #67 Bell palsy – UF Health

  https://ufhealth.org/conditions-and-treatments/bell-palsy

  Bell palsy is thought to be due to swelling (inflammation) of the facial nerve in the area where it travels through the bones of the skull. This nerve controls movement of the muscles of the face. […] The cause is often not clear. A type of herpes infection called herpes simplex or herpes zoster might be involved. Other conditions that may cause Bell palsy include: HIV/AIDS infection, Lyme disease, middle ear infection, sarcoidosis (inflammation of the lymph nodes, lungs, liver, eyes, skin, or other tissues). […] Having diabetes and being pregnant may increase the risk for Bell palsy.

• #68 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #69 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #70 Bell Palsy Causes and Diagnoses | Northwestern Medicine

  https://www.nm.org/conditions-and-care-areas/ent-ear-nose-throat/bells-palsy/causes-and-diagnoses

  Bell palsy occurs when the facial nerve is inflamed, swollen or compressed. The cause of the inflammation is not exactly known. Most researchers believe the swelling and inflammation comes from a viral infection, such as herpes simplex (the cold sore virus) or viral meningitis. […] Bell palsy is found in people with a variety of disorders, but more research must be conducted to understand its frequent connection to conditions such as: Diabetes, Hypertension (high blood pressure), Otitis media (chronic middle ear infection), Lyme disease, Guillain-Barr syndrome, Tumors, Sarcoidosis, Myasthenia gravis, Multiple sclerosis, Trauma, such as facial injury or fractured skull, Exposure to toxins.

• #71 Bell palsy | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/bell-palsy?lang=us

  Bell’s palsy, also known as idiopathic peripheral facial paralysis, is characterized by rapid onset facial nerve paralysis, often with resolution in 6-8 weeks, without an identifiable etiology. […] The etiology of Bell palsy is yet to be elucidated, and thus the diagnosis remains one of exclusion after other etiologies for facial palsy have been considered. Prominent theories include reactivation of a virus with herpes simplex virus type 1 (HSV-1) being the strongest pathogenic candidate, an immune-mediated phenomenon, or a microvascular issue. […] Anatomical predisposing factors, such as narrowing of the path of the facial nerve through the internal auditory canal, have also been suggested as contributory.

• #72 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Risk factors associated with the development of synkinesis include complete paralysis, age 60 years or older, and decreased salivation or taste on the ipsilateral side. […] Cases of multiple recurrent Bell palsy may be due to narrow Fallopian canals that exacerbate vascular insufficiency caused by nerve inflammation and edema within the enclosed space of the canal.

• #73 Bell’s Palsy – Uncovering the structural causes of facial paralysis & associated symptoms –

  https://caringmedical.com/prolotherapy-news/bells-palsy-uncovering-the-structural-causes-of-facial-paralysis-associated-symptoms/

  What causes elongated styloid? When there’s increased stress on the mandibular stylomandibular ligament, the ligament that goes from the styloid to the mandible so that ligament so that the ligament is under stretch and increase pressure by jutting the jaw forward, the ligament gets calcified. […] If somebody had facial nerve paralysis I would ask them questions regarding do they have other signs or symptoms compatible with a vagus nerve issue if a person has a vagus nerve issue plus a facial nerve issue well what could cause both of those could be a problem in the cranial cervical junction not only an elongated styloid but upper cervical instability. […] Another problem is where the facial nerve runs across the temporomandibular joint (TMJ). Instability in the TMJ can produce popping, clicking, and grinding when a person smiles. With ligamentous temporomandibular joint instability the mandible pops out and it could possibly stretch and compress the facial nerve. […] Summary What are some contributing factors to Bell’s Palsy? TMJ instability, Upper cervical instability, Elongated styloid, misaligned Atlas.

• #74 Bell’s Palsy – Uncovering the structural causes of facial paralysis & associated symptoms –

  https://caringmedical.com/prolotherapy-news/bells-palsy-uncovering-the-structural-causes-of-facial-paralysis-associated-symptoms/

  Bell’s palsy or facial nerve paralysis where the facial nerve or cranial nerve VII doesn’t innervate the muscles that we use to smile. Bell’s palsy is basically when there’s drooping of the face so the different muscles that help us smile are affected. […] A March 2023 study writes: “Facial nerve palsy may be due to basal cranial injuries, congenital syndromes, tumors, diabetes, viral infections and inflammation and pressure on the facial nerve and chronic middle ear infection, hypertension, neurological disorders and stroke, Lyme disease, surgical lesions, paralysis due to accidents and animal bites, sharp objects, axonal damage, or damage to the motor pattern in the cerebral cortex.” […] The facial nerve exits the brain through the stylomastoid foramen right at the cranial cervical junction and it runs right by the styloid. I think elongated styloids play a role with Bell’s Palsy.

• #75 Bell’s palsy – Wikipedia

  https://en.wikipedia.org/wiki/Bell%27s_palsy

  The cause of Bell’s palsy is unknown. […] Risk factors include diabetes, a recent upper respiratory tract infection, and pregnancy. […] Many believe that this is due to a viral infection that results in swelling. […] Some viruses are thought to establish a persistent (or latent) infection without symptoms, e.g., the varicella zoster virus and the Epstein-Barr virus, both of the herpes family. Reactivation of an existing (dormant) viral infection has been suggested as a cause of acute Bell’s palsy. […] Other viruses and bacteria that have been linked to the development of Bell’s palsy include HIV, sarcoidosis and Lyme disease. […] Familial inheritance has been found in 41-4% of cases. […] There may also be an association with migraines. […] In December 2020, the U.S. FDA recommended that recipients of the Pfizer and Moderna COVID-19 vaccines should be monitored for symptoms of Bell’s palsy after several cases were reported among clinical trial participants, though the data were not sufficient to determine a causal link.

• #76 Bell’s Palsy: Diagnosis and Management | AAFP

  https://www.aafp.org/pubs/afp/issues/2007/1001/p997.html

  Bell’s palsy has been traditionally defined as idiopathic; however, one possible etiology is infection with herpes simplex virus type 1. […] Bell’s palsy is believed to be caused by inflammation of the facial nerve at the geniculate ganglion, which leads to compression and possible ischemia and demyelination. […] Recently, attention has focused on infection with herpes simplex virus type 1 (HSV-1) as a possible cause because research has found elevated HSV-1 titers in affected patients. However, studies have failed to isolate viral DNA in biopsy specimens, leaving the causative role of HSV-1 in question. […] Many conditions can produce isolated facial nerve palsy identical to Bell’s palsy. […] Although influenza vaccines currently available in the United States have not been associated with Bell’s palsy, a recently developed Swiss intranasal vaccine was found to have a very high risk of postvaccine facial nerve palsy and has been withdrawn from use.

• #77 Bell Palsy – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK482290/

  Historically, Bell palsy has been considered a diagnosis of exclusion, to be applied when no other causes of acute-onset facial paralysis are readily apparent. […] While it remains difficult to pin down the exact cause of Bell palsy for any individual patient, there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases. […] Another unsolved mystery regarding Bell palsy is its association with coronavirus disease (COVID) 2019 and the immunizations to prevent this infection. […] The annual incidence of Bell palsy is 15 to 40 per 100,000 individuals, and the lifetime risk is 1 in 60, with a recurrence rate of 8% to 12%. […] There are multiple known risk factors for developing Bell palsy, including diabetes, pregnancy, preeclampsia, obesity, dental procedures, and, debatably, hypertension.

• #78 The etiology of Bell’s palsy: a review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7320932/

  Bells palsy is the most common condition involving a rapid and unilateral onset of peripheral paresis/paralysis of the seventh cranial nerve. […] However, the etiology of Bells palsy is unclear, and this affects its treatment. Thus, it is critical to determine the causes of Bells palsy so that targeted treatment approaches can be developed and employed. […] Despite its severe effects, the exact etiology of BP remains unclear. […] The Guideline Development Group (GDG) has identified the diagnosis of BP as one of exclusion, requiring careful clinical elimination of other potential etiologies of facial paralysis/paresis, such as trauma, neoplasms, congenital or syndromic problems, postsurgical facial paralysis/paresis, or infection by agents including zoster and Lyme disease. […] In this review, we sought to summarize potential clinical etiologies of BP, through search for eligible studies on PubMed, Embase, and the Web of Science up to 31 October 2018 using the following search terms: acute facial paresis/paralysis, Bells palsy, idiopathic facial palsy, and/or etiology. There are five major theories regarding the causes of BP including anatomical, viral infection, ischemia, inflammation, and cold stimulation.

• #79 Facial Palsy – Causes – Differential Diagnosis – Management – TeachMeSurgery

  https://teachmesurgery.com/ent/presentations/facial-palsy/

  A facial palsy is weakness or paralysis of the muscles of the face. Whilst the majority of cases are idiopathic, termed Bell’s Palsy, there are a wide range of potential causes of a facial palsy. […] Bell’s palsy is an idiopathic LMN facial palsy. It is a diagnosis of exclusion and hence all possible causes have to be excluded first prior to diagnosing Bell’s palsy. […] Bell’s palsy remains a poorly understood condition. Many causative associations have been proposed, the most universally accepted theory suggests a viral origin, yet no conclusive evidence is available at present. The main risk factor for developing Bell’s palsy is known concurrent viral infection, such as HSV-1, CMV, and EBV, whilst less common risk factors include diabetes mellitus and pregnancy. […] The factors that suggest a poor prognosis from a facial palsy include: Complete palsy, No signs of recovery within 3 weeks, Age 60yrs, Associated pain, Ramsay Hunt syndrome, Associated hypertension, diabetes mellitus, or pregnancy.

• #80 Bell’s Palsy: Diagnosis and Management | AAFP

  https://www.aafp.org/pubs/afp/issues/2007/1001/p997.html

  Bell’s palsy has been traditionally defined as idiopathic; however, one possible etiology is infection with herpes simplex virus type 1. […] Bell’s palsy is believed to be caused by inflammation of the facial nerve at the geniculate ganglion, which leads to compression and possible ischemia and demyelination. […] Recently, attention has focused on infection with herpes simplex virus type 1 (HSV-1) as a possible cause because research has found elevated HSV-1 titers in affected patients. However, studies have failed to isolate viral DNA in biopsy specimens, leaving the causative role of HSV-1 in question. […] Many conditions can produce isolated facial nerve palsy identical to Bell’s palsy. […] Although influenza vaccines currently available in the United States have not been associated with Bell’s palsy, a recently developed Swiss intranasal vaccine was found to have a very high risk of postvaccine facial nerve palsy and has been withdrawn from use.

• #81

  https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwid=hw179177

  Bell’s palsy is not the result of a stroke or a transient ischemic attack (TIA). […] The cause of Bell’s palsy is not clear. Most cases are thought to be caused by the herpes virus that causes cold sores. […] In most cases of Bell’s palsy, the nerve that controls muscles on one side of the face is damaged by inflammation. […] Many health problems can cause weakness or paralysis of the face. If a specific reason cannot be found for the weakness, the condition is called Bell’s palsy.

• #82 Bell’s Palsy Information & Treatment

  https://www.columbiadoctors.org/health-library/condition/bell-s-palsy/

  Bell’s palsy is not the result of a stroke or a transient ischemic attack (TIA). While stroke and TIA can cause facial paralysis, there is no link between Bell’s palsy and either of these conditions. […] The cause of Bell’s palsy is not clear. Most cases are thought to be caused by the herpes virus that causes cold sores. […] In most cases of Bell’s palsy, the nerve that controls muscles on one side of the face is damaged by inflammation. […] Many health problems can cause weakness or paralysis of the face. If a specific reason cannot be found for the weakness, the condition is called Bell’s palsy.

• #83 Bell’s palsy: aetiology, clinical features and multidisciplinary care | Journal of Neurology, Neurosurgery & Psychiatry

  https://jnnp.bmj.com/content/86/12/1356

  Bell’s palsy is a common cranial neuropathy causing acute unilateral lower motor neuron facial paralysis. Immune, infective and ischaemic mechanisms are all potential contributors to the development of Bell’s palsy, but the precise cause remains unclear. […] Despite extensive study of the condition, the exact pathogenesis of Bell’s palsy is still controversial. Infection (herpes simplex type-1), nerve compression and autoimmunity may all play a role, yet the exact sequence and magnitude of these influences remains unclear. […] There is a diverse body of evidence implicating immune, infective and ischaemic mechanisms as potential contributors to the development of Bell’s palsy, but the cause of classical Bell’s palsy remains unclear. One possible cause that has been suggested is that of a reactivated herpes simplex virus (HSV-1) infection centred around the geniculate ganglion, a theory first outlined by McCormick.

• #84 Patient education: Bell’s palsy (Beyond the Basics) – UpToDate

  https://www.uptodate.com/contents/bells-palsy-beyond-the-basics/print

  Bell’s palsy is caused by an inflammation of the facial nerve. This inflammation may be caused by a virus. There is some evidence that the virus is often herpes simplex virus (HSV), the same virus that causes cold sores and genital herpes. Other viruses may also cause the condition, including herpes zoster virus, cytomegalovirus, and Epstein-Barr virus. […] The inflammation causes swelling of the nerve that controls movement of one side of the face. The nerve, as well as adjacent blood vessels that supply the nerve with blood, must travel through a narrow canal surrounded by bone. As the nerve swells, it becomes compressed (pinched) and its protective covering breaks down, interfering with the nerve’s ability to communicate with the muscles. This causes weakness or paralysis of the muscles in one side of the face. Weakness of these muscles can make it difficult to smile or close the eye.

• #85 Quick Facts:Bell Palsy – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/quick-facts-brain-spinal-cord-and-nerve-disorders/cranial-nerve-disorders/bell-palsy

  Doctors dont always know what causes Bell palsy. An infection may cause the nerve to swell. In some cases, its caused by a virus like those that cause shingles, cold sores, mono, or the flu. […] If youve had symptoms for less than 48 hours, doctors may give you medicine called a corticosteroid that can make full recovery even more likely.

• #86 A general practice approach to Bell’s palsy

  https://www.racgp.org.au/afp/2016/november/a-general-practice-approach-to-bell-s-palsy

  To date, there is no evidence to suggest that oral antiviral therapy alone is effective for the management of Bells palsy. […] Well-designed clinical trials have shown that antiviral therapy in combination with corticosteroid therapy is of no additional benefit, compared with corticosteroid therapy alone; however, a small benefit cannot be completely excluded. […] Management of Ramsay Hunt syndrome entails antiviral therapy, often given intravenously, in addition to corticosteroids.

• #87 Bell s Palsy

  https://www.brainfacts.org/diseases-and-disorders/neurological-disorders-az/diseases-a-to-z-from-ninds/bell-s-palsy

  Bell’s palsy is a form of temporary facial paralysis resulting from damage or trauma to one of the facial nerves. […] Most scientists believe that a viral infection such as viral meningitis or the common cold sore virus — herpes simplex– can cause the disorder when the facial nerve swells and becomes inflamed in reaction to the infection. […] Part of this research program focuses on learning more about the circumstances that lead to nerve damage and the conditions that cause injuries and damage to nerves. […] Knowledge gained from this research may help scientists find the definitive cause of Bell’s palsy, leading to the discovery of new effective treatments for the disorder.

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