Hemifacial spasm (HFS) is a form of peripheral myoclonus, characterized by progressive, involuntary, irregular, and clonic or sometimes more long-lasting tonic movements of muscles innervated by the seventh cranial nerve on one side of the face. The upper and/or lower eyelids are the most common site of initial involvement, followed by the cheek and perioral regions. Complete unilateral eye closure may interfere with vision and cause social embarrassment. HFS is relatively uncommon but is a disturbing symptom when it occurs. Mean age of onset is 49 years, and there is a slight female preponderance. The most frequent cause of HFS is compression of the facial nerve at the pontine root exit zone by an ectopic anatomical or pathological structure which results in ephaptic transmission.
The patient exhibits continuous tonic right HFS involving predominantly orbicularis oculi, zygomaticus major, nasalis, and platysma muscles.
Hemifacial spasm.mp4 (MP4 2,425KB)