Materiały źródłowe

• #1 Hemifacial Spasm – EyeWiki

  https://eyewiki.org/Hemifacial_Spasm

  Hemifacial spasm (HFS) is a movement disorder that is characterized by involuntary tonic – clonic contractions of the mimetic muscles on one side of the face. […] The pathophysiology of primary hemifacial spasm is not well understood and likely varies by etiology. Essentially, compressive forces are felt to incite inappropriate activation of the facial nerve – either in whole or some of its fibres. […] Similarly, a diseased nerve is susceptible to ephaptic excitation as a result of demyelination. This occurs when the electrical activity of one nerve or group of nerves induces activation of a nearby nerve resulting in involuntary muscle activation and subsequent movement.

• #2 A Multidisciplinary Approach in the Management of Hemifacial Spasm – The Journal of Medical Optometry (JoMO)

  https://journalofmedicaloptometry.com/volume1-issue1/a-multidisciplinary-approach-in-the-management-of-hemifacial-spasm/

  Hemifacial spasm is a neuromuscular movement disorder characterized by progressive, involuntary, irregular clonic or tonic movements of the muscles innervated by the facial nerve. Typically, the movements are unilateral. In most cases, the etiology is due to facial nerve compression by an aberrant or ectatic blood vessel at the root exit zone at the level of the brainstem. However, it can also result from an insult to the facial nerve due to a more sinister cause such as a tumor, trauma, infection, or vascular anomaly. […] The pathogenesis of hemifacial spasm is not well understood, but there are two hypotheses that attempt to explain it: the central theory and the peripheral theory. The central theory proposes that irritation of the peripheral afferent facial nerve fibers leads aberrant signaling to the central facial nucleus causing hyperexcitability and abnormal firing, which in turn results in the involuntary contractions of the facial muscles on the ipsilateral side. Conversely, the peripheral theory proposes that the abnormal excessive firing of the facial nerve is due to the demyelination of the facial nerve at the side of insult at the root exit zone, which prevents lateral transmission of impulses to the adjacent fibers, leading to ectopic transmission of impulses.

• #3 Hemifacial Spasm: Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/1170722-overview

  Hemifacial spasm is a segmental myoclonus of muscles innervated by the facial nerve. Hemifacial spasm generally begins with brief clonic movements of the orbicularis oculi and spreads over years to other facial muscles (corrugator, frontalis, orbicularis oris, platysma, zygomaticus). […] Chronic irritation of the facial nerve or nucleus, the near-universal cause of hemifacial spasm, may arise from numerous underlying conditions. […] Irritation of the facial nerve nucleus is believed to lead to hyperexcitability of the nucleus, while irritation of the proximal nerve segment may cause ephaptic transmission within the facial nerve. Either mechanism explains the rhythmic involuntary myoclonic contractions observed in hemifacial spasm. […] Most instances of hemifacial spasm previously thought to be idiopathic were probably caused by aberrant blood vessels (eg, distal branches of the anterior inferior cerebellar artery or vertebral artery) compressing the facial nerve within the cerebellopontine angle.

• #4 Hemifacial Spasm | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/22719

  Chronic irritation of the facial nerve fascicle and proximal nerve segment at the root-exit zone is the primary pathophysiologic mechanism of HFS. […] Compression of the facial nerve root at the junction of the central (point of exit from brainstem) and peripheral segment (root exit/entry zone) by aberrant/ectatic blood vessels is the most common cause of HFS, as reported in the literature. […] Several theories have been proposed to explain the pathophysiological mechanism by which facial nerve compression leads to HFS. […] As proposed in this theory, the ephaptic transmission of impulses, or the lateral spread of excitation to adjacent nerve fibers, leads to abnormally excessive firing of the facial nerve; this firing is due to the facial nerve’s demyelination at the compression site.

• #5 Hemifacial Spasm

  https://pmc.ncbi.nlm.nih.gov/articles/PMC3487151/

  Hemifacial spasm is usually caused by an artery compressing the facial nerve at the root exit zone of the brainstem. […] The underlying cause of hemifacial spasm is in most cases an ectatic or atypically aberrant blood vessel, which compresses the facial nerve at the place where it exits the brainstem. […] The pathogenesis of hemifacial spasm by compression of the facial nerve is explained by using several theories. According to the peripheral hypothesis, ephaptic and ectopic excitations occur in the root-exit zone. […] The central hypothesis assumes hyperexcitability of the facial motor nucleus in the brainstem. […] It is assumed that this leads in turn to focal demyelination, which leads to the electrophysiological processes mentioned above. […] In our own series of 110 patients, we found that clear compression of the root-exit zone was the cause of hemifacial spasm in all but two patients.

• #6 Hemifacial spasm | MedLink Neurology

  https://www.medlink.com/articles/hemifacial-spasm

  Hemifacial spasm is thought to result from compression of the facial nerve at its junction with the brainstem. […] In most cases, the compression is by blood vessels adjacent to the zone of exit of the facial nerve. […] Vascular compression or irritation of the facial nerve is the most common pathogenic mechanism of hemifacial spasm. […] Neuroimaging studies frequently show contact between the nerve and the offending structures. […] Support for the theory that compression of the nerve at the root exit zone incites the development of hemifacial spasm comes from several sources. […] The theory that focal demyelination or nerve degeneration causes aberrant regeneration similar to that which follows facial nerve injury is untenable as it fails to explain the spasms spontaneity and synchronous occurrence in muscles supplied by different nerve branches.

• #7 Hemifacial spasm | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/hemifacial-spasm?lang=us

  Hemifacial spasm is characterized by episodic facial spasms due to irritation of the facial nerve (CN VII). […] Irritation of the nerve at the root exit zone by an aberrant vascular structure is usually a cause. In one study, up to 100% of cases had a vessel contacting the nerve in symptomatic patients, whereas up to 30% of asymptomatic patients had a similar finding. This is a similar mechanism to what is seen in trigeminal neuralgia, nervus intermedius neuralgia, glossopharyngeal neuralgia, and vagoglossopharyngeal neuralgia. […] Most commonly, an elongated and ectatic vertebrobasilar system is commonly seen incidentally. The vessels most commonly implicated, in decreasing order of frequency, are the AICA, PICA and vertebral artery.

• #8 Microvascular decompression for hemifacial spasm: a review of twenty-one operated cases | The Egyptian Journal of Neurology, Psychiatry and Neurosurgery | Full Text

  https://ejnpn.springeropen.com/articles/10.1186/s41983-020-00179-y

  Microvascular decompression of facial nerve provides definitive and long-term cure for hemifacial spasm. […] Hemifacial spasm is a gradually progressive disorder characterised by intermittent, tonic, involuntary twitching of the face, usually unilateral and rarely bilateral. It is caused by an aberrant vascular loop compressing the facial nerve at its point of exit from the brainstem. […] Microvascular decompression of the facial nerve, first described by Janetta, provides the definitive cure for this condition. […] It is important to differentiate primary hemifacial spasm caused by atraumatic pulsatile vascular compression from secondary hemifacial spasm and other conditions like blepharospasm and fasciculation, as treatment strategy for both is different. […] The responsible vessel was anterior inferior cerebellar artery (AICA) in eighteen cases, posterior inferior cerebellar artery (PICA) in two cases and veins in one case.

• #9

  https://journals.lww.com/neur/fulltext/2020/68002/microsurgery_and_neuromodulation_for_facial_spasms.7.aspx

  Primary HFS is defined as an entity without any underlying disease. The cause is most commonly observed to be compression or distortion of the nerve root by an aberrant vascular loop. The offending vessels found are anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), vertebral artery (VA), basilar artery (BA), or veins, in descending order of frequency. […] The mechanism has been found to be demyelination of nerve axons at the REZ, also called Obersteiner-Redlich Zone, due to chronic compression or irritation, leading to hyperexcitability of axons. Ephaptic transmission of impulses occurs due to abnormal excitation of surrounding demyelinated axons by an action potential conducted from a single axon. This is analogous to the mechanism behind trigeminal neuralgia. […] A central hypothesis of HFS is also proposed, involving hyperexcitability of neural circuits at the facial nucleus or supranuclear levels. This may be a direct consequence of the neurovascular conflict.

• #10 Hemifacial spasm: a neurosurgical perspective in: Journal of Neurosurgery Volume 140 Issue 1 (2023) Journals

  https://thejns.org/view/journals/j-neurosurg/140/1/article-p240.xml

  Hemifacial spasm (HFS) is one of the NVC disorders and the first to be treated with Jannetta’s MVD surgery. The culprit NVC is usually evident on high-resolution MRI when interpreted by a discerning eye familiar with the anatomical details of the facial nerve root. It is, however, common for MRI reports to either overlook the culprit compression at the proximal root exit zone (REZ) or inaccurately implicate the incidental contact between cerebellar arteries and the distal facial nerve. […] The etiology of HFS includes both the chronic blood vessel to nerve juxtaposition (i.e., NVC) and a subsequent pathophysiological change that have been explained through two main hypotheses. The peripheral hypothesis suggests that axo-axonal (ephaptic) transmission occurs at the vascular compression site, where facial nerve demyelination results in „lateral spreading” of orthodromically directed axonal conduction impulses. However, we have found more convincing evidence in support of the central hypothesis of excitability within the facial motor neuron pool/nucleus that results from chronic antidromic signaling produced by the rhythmic pulsing on sensitive facial nerve axons. Intraoperative neurophysiological studies of the abnormal muscle response (i.e., lateral spread) and facial motor evoked potentials have demonstrated this central hyperactivity that is effectively reversed with alleviation of the culprit NVC. […] The key to successful MVD for HFS is a thorough alleviation of the culprit NVC, and this hinges on a clear anatomical understanding of the facial REZ (fREZ).

• #11 < ?php wp_title( '|', true, 'right' ); ?>

  https://surgicalneurologyint.com/surgicalint-articles/tenth-case-of-bilateral-hemifacial-spasm-treated-by-microvascular-decompression-review-of-the-pathophysiology/

  Bilateral hemifacial spasm (BHFS) is a rare neurological syndrome whose diagnosis depends on excluding other facial dyskinesias. […] Regarding HFS pathophysiology, ectopic firing and ephaptic transmissions originate in the root exit zone (REZ) of the facial nerve, due to neurovascular compression (NVC), orthodromically stimulate facial muscles and antidromically stimulate the facial nerve nucleus; this hyperexcitation continuously stimulates the facial muscles. […] The main cause of HFS is NVC in the REZ, which is more vulnerable because this area is devoid of epineurium and Schwann cells because it is only covered by arachnoid cells. […] The hypothesis of the peripheral origin of facial spasm suggests that ectopic firing and peripheral ephaptic transmissions that originate in their REZ due to NVC and demyelination cause hyperexcitability of the facial nerve nucleus, leading to spasms.

• #12 Two Cases of Secondary Hemifacial Spasm: Pathophysiology and Management

  https://www.e-jmd.org/journal/view.php?doi=10.14802/jmd.15004

  Dear Editor, Classical hemifacial spasm (HFS) has been attributed to an atraumatic pulsatile vascular compression of the facial nerve leading to hyperactivity within the central components of the nerve, alleviated via mobilization of the culprit vessel. […] In a small subset of patients the cause may be attributed to lesions involving the facial nerve, most commonly benign cerebellopontine angle (CPA) tumors. […] In such secondary HFS the clinical manifestation is usually a tonic facial contraction rather than the intermittent twitching characteristic of common HFS. […] The potential reversible nature of the primary or secondary HFS related to tumor CPA tumors has been displayed in both cases. […] For the classical HFS symptoms, alleviation of NVC at the REZ of the facial nerve was effective while the tonic facial contractions of secondary HFS were successfully alleviated with tumor decompression, particularly in the IAC.

• #13 Five Common Causes of Hemifacial Spasm in Adults – New York Facial Paralysis

  https://www.newyorkfacialparalysis.com/blog/five-common-causes-of-hemifacial-spasm-in-adults/

  Hemifacial spasms, also known as tic convulsive, occur when the muscles suddenly twitch on one side of the face (typically the left). These spasms are brought on by irritation or damage to the facial nerve, also called the seventh cranial nerve. Facial spasms happen when muscles contract involuntarily due to this nerve irritation. […] Several factors can cause hemifacial spasms, including: Vascular compression of the nerve: Hemifacial spasm is usually caused by a small artery compressing the facial nerve. Your heartbeat presses on the nerve, causing it to misfire and spasm. […] Multiple sclerosis: Multiple sclerosis is an autoimmune disorder in which the body mistakes nerve coverings for foreign substances. The immune system eats the nerve sheath. This exposes the nerve, causing hemifacial spasms.

• #14 Five Common Causes of Hemifacial Spasm in Adults – New York Facial Paralysis

  https://www.newyorkfacialparalysis.com/blog/five-common-causes-of-hemifacial-spasm-in-adults/

  Benign tumor or lesion compression: A tumor or lesion on the nerve sheath can compress the facial nerve. Sometimes, lesions can also arise. Both can press against the nerve, forcing it to malfunction and emit erroneous impulses, causing spasms. […] Vascular malformation: Sometimes arteries or veins do not develop properly, causing them to travel in odd directions throughout the body. In hemifacial spasms, this malformation may compress or constrict the facial nerve. […] Nerve injury: Nerve injuries can cause hemifacial spasms. Most facial nerve injuries are caused by head or neck trauma that pinches or stretches the nerve. Accidents and falls are the most common causes of back, neck and head nerve damage.

• #15 Arachnoid bands in hemifacial spasm: an overlooked etiology? Illustrative case in: Journal of Neurosurgery: Case Lessons Volume 7 Issue 16 (2024) Journals

  https://thejns.org/caselessons/view/journals/j-neurosurg-case-lessons/7/16/article-CASE24164.xml

  Primary hemifacial spasm (HFS) is usually caused by arterial compression of the facial nerve at the root exit zone at the brainstem. Rarely, a purely venous compression is seen. However, arachnoid bands strangulating the facial nerve have not been recognized as a cause of hemifacial spasm. […] This is the third patient in the authors series of 535 patients who had no vascular conflict but rather a strangulation of the nerve by arachnoid bands. All patients have remained spasm free. To the authors knowledge, no other group has reported arachnoid bands as an etiological factor of HFS so far. […] Arachnoid bands strangulating the facial nerve have not been recognized as a cause of HFS. We present a case of a 24-year-old female who had had HFS for 9 years. Endoscopic inspection of the root exit zone revealed an arachnoid band strangulating the facial nerve. To our knowledge, no other group has reported arachnoid bands as an etiological factor of HFS.

• #16 Journal of Korean Association of EMG Electrodiagnostic Medicine

  https://e-jend.org/m/journal/view.php?number=2245

  The cause of hemifacial spasm (HFS) is commonly linked to vascular compression of the facial nerve at the root exit zone. […] However, despite numerous electrophysiological studies investigating factors such as ephaptic transmission, ectopic excitation between individual nerve fibers, and hyperexcitability of the facial motor nucleus, there is still debate about the exact pathogenesis of HFS. […] Two main hypotheses have been proposed to explain the mechanism of HFS: (1) the peripheral nerve mechanism, which suggests that compression of the facial nerve by a blood vessel leads to injury of the myelin sheath, promoting ectopic excitation and ephaptic transmission between nerve fibers; and (2) the central mechanism, which posits that hyperexcitability of the facial motor nucleus (FMN), triggered by antidromically propagated discharges, induces spasms.

• #17 A Multidisciplinary Approach in the Management of Hemifacial Spasm – The Journal of Medical Optometry (JoMO)

  https://journalofmedicaloptometry.com/volume1-issue1/a-multidisciplinary-approach-in-the-management-of-hemifacial-spasm/

  In summary, the central theory argues that the hyperactivity occurs at the level of the motor nucleus, while the peripheral theory assumes that the abnormal cross-transmission occurs at the level where the facial nerve fibers are being compressed at the root exit zone. As discussed above, the root exit zone is the transition region between the oligodendrocytes and the Schwann cells, making it an area susceptible to insult.

• #18 Hemifacial spasm | MedLink Neurology

  https://www.medlink.com/articles/hemifacial-spasm

  An alternative theory of „ectopic” or „ephaptic” transmission was proposed by Gardner and has been championed by Nielsen. […] These studies suggest that the abnormal activity is generated central to the exit zone, probably at the facial nucleus. […] Moller proposed that aberrant afferent activity generated at the site of vascular compression caused reorganization of the facial nucleus by a mechanism similar to the „kindling” phenomenon described in the hippocampus.

• #19 Hemifacial spasm – Wikipedia

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

  Hemifacial spasm is much more common in some Asian populations. […] It may be caused by a facial nerve injury, compression by a blood vessel, a tumor, or it may have no apparent cause. […] Experts have linked hemifacial spasm to facial nerve injury, Bell’s palsy and tumors. […] The first proposed theory is ephaptic transmission, which is electrical activity crossing from one demyelinated neuron to another resulting in a false synapse. […] The second theory involves abnormal activity of axons at the facial nerve root end zone secondary to compressive damage/demyelination. […] The third theory or „Kindling theory” involves increased excitability of the facial nerve nucleus due to feedback from a damaged facial nerve. […] It is generally accepted as compression of the facial nerve by vessels of the posterior circulation.

• #20 Hemifacial Spasm (12.10.2012)

  https://di.aerzteblatt.de/int/archive/article/131637

  Hemifacial spasm is usually caused by an artery compressing the facial nerve at the root exit zone of the brainstem. […] The underlying cause of hemifacial spasm is in most cases an ectatic or atypically aberrant blood vessel, which compresses the facial nerve at the place where it exits the brainstem. […] The pathogenesis of hemifacial spasm by compression of the facial nerve is explained by using several theories. According to the peripheral hypothesis, ephaptic and ectopic excitations occur in the root-exit zone. […] The ephaptic impulse conduction is characterized by a pathological transfer of impulses between neighboring nerve fibers. […] Ectopic impulse conduction describes the spontaneous development of neural impulses in the compression area. […] By contrast, the central hypothesis assumes hyperexcitability of the facial motor nucleus in the brainstem. […] It is assumed that this leads in turn to focal demyelination, which leads to the electrophysiological processes mentioned above. […] In our own series of 110 patients, we found that clear compression of the root-exit zone was the cause of hemifacial spasm in all but two patients.

• #21 Pathogenesis and Treatment of Hemifacial Spasm | Thoracic Key

  https://thoracickey.com/pathogenesis-and-treatment-of-hemifacial-spasm/

  It is also known that symptoms of HFS may be caused by close contact between a vessel and other parts of the intracranial portion of the facial nerve than the ObersteinerRedlich zone. […] Two hypotheses explaining the role of the close vascular contact have prevailed. One suggests that hyperactivity of the facial motonucleus is the cause of the spasm and synkinesis. […] The other hypothesis states that cross talk (ephaptic transmission) between individual nerve axons of the facial nerve occurs (ephaptic communication) where it is in contact with a blood vessel causing ectopic excitation that could explain the signs of HFS. […] Results of studies using electrophysiological recording during MVD operations of patients with HFS reported by Mller and Jannetta provided physiological evidence against the ephaptic hypothesis and in favor of the hyperactivity hypothesis. […] Studies using the recording of the AMR during MVD operations for HFS supported the hypothesis that the anatomical location of the physiological abnormalities in HFS that causes spasm and synkinesis is the facial motonucleus.

• #22 Hemifacial Spasm | Treatment & Management | Point of Care

  https://www.statpearls.com/point-of-care/22719

  Irritation of peripheral afferent facial nerve fibers leads to aberrant signaling to the central facial nerve nucleus, inducing abnormal firing of the nucleus. […] Bell palsy has a clinically similar appearance to other HFS, yet the pathophysiology is different. […] The abnormal facial movement after Bell palsy is synkinesis caused by aberrant reinnervation of the facial nerve so that when the eye blinks, the orbicularis oris muscle or other lower facial muscles may contract simultaneously or vice versa as the orbicularis oculi.

• #23 < ?php wp_title( '|', true, 'right' ); ?>

  https://surgicalneurologyint.com/surgicalint-articles/tenth-case-of-bilateral-hemifacial-spasm-treated-by-microvascular-decompression-review-of-the-pathophysiology/

  The hypothesis of the nuclear origin suggests that some form of reorganization of the synapses occurs in the facial nerve nucleus, leading to motor neuron hyperexcitability due to demyelination caused by NVC. […] Thus, neither the nuclear nor the peripheral hypotheses can be rejected. […] The study of transcranial magnetic stimulation (TMS) showed cortical influence on HFS, which, through cortical mechanisms, such as postexcitatory inhibition of motoneurons after excitation of the corticonuclear tract, may activate the corticonuclear inhibitory system controlled by intracortical mechanisms modulated by basal and thalamus ganglia. […] Considering the data outlined here, we argue that the most probable explanation is ectopic firing and ephaptic transmissions, originating in the REZ of the facial nerve due to NVC, orthodromically stimulate the facial muscles and antidromically stimulate the facial nerve nucleus, while the latter, in its hyperexcited state, also intermittently stimulates the facial muscles.

• #24 Pathogenesis and Treatment of Hemifacial Spasm | Thoracic Key

  https://thoracickey.com/pathogenesis-and-treatment-of-hemifacial-spasm/

  Hemifacial spasm can be cured by microvascular decompression (MVD) operations of the root exit zone of the facial nerve. […] However, later intracranial recording from the facial nerve provided strong experimental support of a different hypothesis about the pathology of HFS, namely, that the anatomical location of the pathology is the facial motonucleus. Intraoperative measurements of neural conduction times provided evidence against the ephaptic hypothesis and showed evidence that hyperactivity of the facial motonucleus could explain the symptoms of HFS. […] It was hypothesized that the abnormalities in the facial motonucleus in HFS were caused by activation of maladaptive neuroplasticity that was activated by the irritation of the root of the facial nerve by a blood vessel. […] A second factor in addition to vascular contact with the facial nerve root must be present in order to create the signs of HFS.

• #25 Journal of Korean Association of EMG Electrodiagnostic Medicine

  https://e-jend.org/m/journal/view.php?number=2245

  Despite four decades of research, the peripheral nerve mechanism had long been the dominant theory, but recent studies increasingly support the central mechanism as the primary driver of HFS. […] The pathogenesis of HFS has long been debated, with discussions centering on whether it originates from ephaptic transmission/ectopic excitation among individual nerve fibers or from the hyperexcitability of the FMN. […] Based on the collective evidence from previous studies, hyperexcitability of the FMN is considered to be the main mechanism involved in the pathogenesis of HFS.

• #26 Electrophysiologic Investigation During Facial Motor Neuron Suppression in Patients With Hemifacial Spasm: Possible Pathophysiology of Hemifacial Spasm: A Pilot Study

  https://www.e-arm.org/journal/view.php?number=342

  Therefore, we inhibited the facial motor nucleus using diazepam to test the central origin hypothesis in the present study. […] These findings suggest that diazepam suppresses facial motor neurons effectively. If the facial nucleus is the site of abnormal cross transmission, then the orbicularis oris muscle response in a lateral spread test should be a waveform with delayed latency instead of a sustained response, as observed in supraorbital nerve stimulation. […] In conclusion, the orbicularis oris muscle response to supraorbital nerve stimulation in patients with HFS may be caused by increased facial motor neuronal hyperexcitability or the ephaptic response. Stimulating the supraorbital nerve with an electrical stimulus activates the supraorbital nerve afferents that reach the facial motor neurons of the orbicularis oculi muscles. […] These findings suggest that the orbicularis oris muscle response to the lateral spread test is caused by cross-transmission of facial nerve fibers at the site of vascular compression, rather than arising from hyperexcitable facial motor neurons.

• #27 Hemifacial Spasm | Baylor Medicine

  https://www.bcm.edu/healthcare/specialties/neurology/parkinsons-disease-and-movement-disorders/hemifacial-spasm

  Most cases of HFS do not have an obvious cause and are referred to as idiopathic. However, HFS is often attributable to an irritation or a compression of the facial nerve by a blood vessel as it exits from the brainstem and is the most common peripherally induced movement disorder. This nerve supplies muscle power to the facial and superficial neck muscles. […] A competing hypothesis states that HFS is due to abnormality of the facial motor nucleus in the brainstem. […] Injuries to the facial nerve can also result in secondary HFS. For example, patients who have had Bell’s palsy can develop HFS after they recover from the weakness. The post-Bells palsy HFS may look similar to the idiopathic variety, but voluntary contraction of the facial muscles often results in an involuntary contraction of adjacent muscles due to misdirection of the recovering facial nerve and its branches (synkinesis). Other uncommon causes of HFS include aneurysms, brain tumors, trauma and demyelinating diseases such as multiple sclerosis.

• #28 Blepharospasm and hemifacial spasm – Overview | Guy’s and St Thomas’ NHS Foundation Trust

  https://www.guysandstthomas.nhs.uk/health-information/blepharospasm-and-hemifacial-spasm

  Hemifacial spasm causes similar spasms around the eye, but only affects 1 side and usually involves other muscles (such as cheek or mouth) on the same side of the face. […] Some patients with hemifacial spasm have a blood vessel in the brain that is too close to the facial nerve. When the blood vessel touches the nerve it can cause the spasms. […] Another cause is abnormal rewiring of the facial nerve after a facial nerve paralysis, as it heals again over time. This is called aberrant facial nerve regeneration.

• #29 Two Cases of Secondary Hemifacial Spasm: Pathophysiology and Management

  https://www.e-jmd.org/journal/view.php?number=136

  Dear Editor, Classical hemifacial spasm (HFS) has been attributed to an atraumatic pulsatile vascular compression of the facial nerve leading to hyperactivity within the central components of the nerve, alleviated via mobilization of the culprit vessel. […] In a small subset of patients the cause may be attributed to lesions involving the facial nerve, most commonly benign cerebellopontine angle (CPA) tumors. […] In such secondary HFS the clinical manifestation is usually a tonic facial contraction rather than the intermittent twitching characteristic of common HFS. […] There may, however, also be rare patients with a common presentation of HFS but with an associated CPA tumor; the role of neurovascular compression (NVC) in these cases is uncertain. […] A few important points can be taken from these cases. First, the atypical clinical presentation (case 2) highlights the difference between classic primary HFS (case 1), related to pulsatile vascular compression of the facial nerve, and compression secondary to a CPA/IAC tumor.

• #30

• #31 Hemifacial spasm and vestibular paroxysmia: co-presence of two neurovascular compression syndromes in a patient | Neurología (English Edition)

  https://www.elsevier.es/en-revista-neurologia-english-edition–495-articulo-hemifacial-spasm-vestibular-paroxysmia-co-presence-S2173580818301378

  Hemifacial spasm is a movement disorder characterised by tonic or clonic contractions of the muscles on one side of the face, which may manifest in short episodes or persistently. […] Both entities are included in the group of neurovascular compression syndromes, caused by vascular compression of the entry/exit site of the cranial nerves, close to the brainstem. […] Some authors have proposed that vascular contacts involving the entry/exit zone of the cranial nerves may lead to ephaptic transmission of nerve impulses between adjacent nerve fibres, as a consequence of the demyelination caused by the pulsatile compression of the nerve. […] Given the anatomical proximity of the paths of the seventh and eighth cranial nerves through the posterior fossa, it seems logical to consider that coexistence of hemifacial spasm and vestibular paroxysmia should not be exceptional.

• #32 Hemifacial Spasm (Facial Twitching): A Definitive Guide

  https://kamranaghayev.com/hemifacial-spasm/

  Neuro-vascular conflict is progressive i.e. arterial loops exert more and more pressure on the nerve with aging. […] Hemifacial spasm is very similar to trigeminal neuralgia (TN). These diseases have much in common, the only difference is the affected nerve. Trigeminal nerve (V cranial nerve) is implicated in TN and the main symptom is facial pain.

• #33 Facial twitch, Hemifacial spasm (HFS), tic convulsif, facial tic | Mayfield Brain & Spine

  https://mayfieldclinic.com/pe-hfs.htm

  Hemifacial spasm can be caused by injury to the facial nerve, a tumor or blood vessel compressing the nerve, or Bells palsy. […] The most common cause is compression of your facial nerve by the anterior inferior cerebellar artery where the nerve begins at your brainstem. The compression causes the nerve to misfire making your facial muscles contract. […] Both hemifacial spasm and trigeminal neuralgia are caused by nerve compression from a blood vessel, yet differ in whether the sensory nerve or motor nerve is compressed. […] A procedure, called microvascular decompression (MVD), can relieve the nerve compression. […] A Teflon sponge is placed between the offending blood vessel and the facial nerve to relieve the pressure and stop the facial muscle spasms. […] In 90% of surgical cases there appears to be a blood vessel compressing the nerve.

• #34

  https://link.springer.com/article/10.1007/s11940-004-0009-4

  Hemifacial spasm (HFS) is a peripheral movement disorder caused by direct or indirect compression or distortion of the root exit zone of the seventh cranial nerve, which is most commonly compressed by an arterial loop, but also may be compressed by a tumor, cyst, or aneurysm. […] All patients with HFS should undergo magnetic resonance imaging, with particular attention to the seventh cranial nerve. […] Microvascular surgical decompression has the advantage of being potentially curative, and obviates the need for chronic injections with botulinum toxin. […] However, surgery carries much greater risk than botulinum toxin and the spasm may recur. […] It is important that surgery is carried out by an experienced neurosurgeon to reduce the risk.

• #35 Research on the Pathogenesis of Hemifacial Spasm through Electrophysiological Studies

  https://www.kci.go.kr/kciportal/landing/article.kci?arti_id=ART003030058

  The cause of hemifacial spasm (HFS) is commonly linked to vascular compression of the facial nerve at the root exit zone. […] However, despite numerous electrophysiological studies investigating factors such as ephaptic transmission, ectopic excitation between individual nerve fibers, and hyperexcitability of the facial motor nucleus, there is still debate about the exact pathogenesis of HFS. […] For over 40 years, researchers have been conducting electrophysiological studies in clinical settings to better understand the pathogenesis of HFS. […] Although a peripheral nerve mechanism was historically considered most likely to be responsible for this condition, recent studies are increasingly pointing to a central mechanism as the primary culprit behind HFS. […] This article seeks to shed light on the pathogenesis of HFS by reviewing the key findings from electrophysiological studies carried out over the years.

• #36 Botulinum Toxin for the Treatment of Hemifacial Spasm: An Update on Clinical Studies

  https://www.mdpi.com/2072-6651/13/12/881

  The regulation of a fusion of the synaptic vesicle with the plasma membrane involves a complex group of proteins referred to as SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptor). […] Despite limited data from high-quality clinical trials, BoNT-A is considered the treatment of choice for HFS patients. […] Overall, 76% to 100% of patients have at least a 75% improvement with a typical duration of response lasting from 3 to 4 months. […] The first line surgical procedure is microvascular decompression (MVD) of the facial nerve, which consists of removing the compression of the seventh nerve at the root exit zone by the aberrant/ectatic vessel. […] The resolution of an abnormal muscle response on electromyography following decompression confirms the absence of a zone of vascular compression.

• #37 Microvascular decompression for hemifacial spasm: a review of twenty-one operated cases | The Egyptian Journal of Neurology, Psychiatry and Neurosurgery | Full Text

  https://ejnpn.springeropen.com/articles/10.1186/s41983-020-00179-y

  Our cure rate of 95% compares favourably with those in the existing literature which ranges from 90-98%. […] Hemifacial spasm is best treated by microvascular decompression. However, surgical technique is of paramount importance to achieve good results and to make the surgery acceptable and popular among the population.

• #38 Hemifacial spasm – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hemifacial-spasm/symptoms-causes/syc-20373296

  Hemifacial spasm is a nervous system condition in which the muscles on one side of the face twitch. The cause of hemifacial spasm is most often a blood vessel touching or pulsing against a facial nerve. A facial nerve injury or a tumor also can cause it. Sometimes there is no known cause. […] A blood vessel touching a facial nerve is the most common cause of hemifacial spasm. A facial nerve injury or a tumor also can cause it. Sometimes the cause isn’t known. […] Hemifacial spasm sometimes starts as a result of: Moving the muscles in the face. Anxiety. Stress. Being tired.

• #39

  https://omim.org/entry/141405

  Hemifacial spasm is usually diagnosed in persons in their mid-forties. It often begins with involuntary clonic contractions or twitching of the orbicularis oculi muscle and progresses to involve the entire musculature innervated by the facial nerve (summary by Coad et al., 1991 and Miwa et al., 2002). […] Campbell and Keedy (1947) proposed that most cases of hemifacial spasm are due to microvascular compression of the seventh cranial nerve (facial nerve). In the family reported by Coad et al. (1991), a woman and her first cousin and daughter were affected; the 88-year-old proposita was found on postmortem examination to have cross-compression of the seventh cranial nerve root in its 'exit zone’ by a redundant loop of the anterior inferior cerebellar artery and associated vascular plexus. Both posterior inferior cerebellar arteries were congenitally absent in this case, which may have increased the flow and tortuosity of the anterior inferior cerebellar artery.

• #40 Hemifacial spasm – Wikipedia

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

  In detail compression of the seventh cranial nerve by a dolichoectatic (a distorted, dilated, and elongated) anterior inferior cerebellar artery, or posterior inferior cerebellar artery is accepted to be the general cause of hemifacial spasm. […] Clarifying the role of genetic susceptibility in hemifacial spasm may help to better understand the pathogenesis of this disease. […] The results illustrated nerve-vessel conflicts (or cholesteatoma) to be located at the root exit zone of the facial nerve in all cases. […] The results of the experiment strengthened the theory that vascular compression of the facial nerve was the primary cause of hemifacial spasm, and proposed a specific region of the facial nerve where the effects of longstanding compression results in nerve dysfunction.

• #41 Hemifacial Spasm » Lillian S. Wells Department of Neurosurgery at the University of Florida » College of Medicine » University of Florida

  https://neurosurgery.ufl.edu/patient-care/diseases-conditions/hemifacial-spasm/

  Hemifacial spasm is a condition similar to trigeminal neuralgia and is due to an abnormal discharge of another nerve called the facial nerve. […] In hemifacial spasm the abnormal discharge is in the facial nerve which supplies the muscles of the face and thus causes twitching or spasms of the muscles of the face and not pain. […] No drug has proven effective in preventing or stopping hemifacial spasm. […] The most effective treatment of hemifacial spasm is a vascular decompression procedure of the facial nerve. […] The operation relieves the spasm permanently in the great majority of patients, however, as with trigeminal neuralgia, the problem may persist or recur in a few patients in spite of treatment.

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