1. What is Hemifacial spasm?
Hemifacial spasm is a type of movement disorder characterized by involuntary unilateral tonic and clonic contractions of the face. Most of the patients have unilateral Hemifacial spasm, but some could have bilateral symptoms.
2. How common is Hemifacial spasm?
Hemifacial spasm is more common in women (2:1), with overall prevalence of about 10/100,000 but more common in Asian communities. Most of the cases are sporadic, i.e., not spread in hereditary pattern. It should be differentiated from other movement disorders of face such as tics, myokymia, tardive dyskinesia and psychogenic facial spasm.
3. Why does Hemifacial spasm occur?
In most of the patients no clear cause can be attributed. But it has been noted that many patients have an aberrant vessel compressing the VII cranial nerve (Facial nerve). However, it has also been noted that upto 25% of normal controls also have an aberrant vessel, suggesting multiple factors playing the role in pathogenesis. These factors include abnormal signal transmission in the nerve. In few patients secondary causes may be the culprit and include meningioma, schwannoma, parotid gland tumor or pilocytic astrocytoma of the fourth ventricle.
4. Is any type of investigation required for diagnosing the disorders?
Hemifacial spasm is a clinical diagnosis which does not require any specific investigation. However, few patients do require brain imaging. Imaging of the brain (MRI with special sequences to trace facial nerve) is usually indicated in patients who have atypical features such as facial weakness, numbness, or other associated findings.
5. How do you treat Hemifacial spasm?