Hemifacial Spasm

Excerpt

Hemifacial spasm (HFS) is characterized by paroxysmal, involuntary twitching of facial muscles on one side of the face innervated by the ipsilateral facial nerve (seventh cranial nerve). The abnormal involuntary firing of the peripheral facial nerve triggers short or longer contractions of muscles of facial expression. HFS is considered a subtype of peripheral (neuromuscular) movement disorder. As the name suggests, the disorder is almost always unilateral except in some rare incidences, with a reported prevalence of 2.6% of all HFS cases, during which one can see the bilateral involvement of facial muscles. This condition generally does not cause significant physical disability, yet it often causes social embarrassment, resulting in severe psychosocial issues for the patient.