A neuromuscular disorder that results in muscles on one side of the face twitching in an involuntary manner, hemifacial spasms arise from the seventh cranial nerve that controls these muscles. Beginning at the brain stem, this nerve exits the skull below the ear and branches off to control the eyebrows, eyelids, mouth and lips.

Injuries and irritations (such as from a tumor) to the facial nerve resulting in compression of that nerve are the most common causes of hemifacial spasms, although they can also occur for unknown reasons. Signs of the condition begin with an uncontrollable contraction and “twitching” of the eyelids that spreads downward and becomes confined to one side of the face.

A neurological examination coupled with an MRI (to determine if a tumor, aneurysm or arteriovenous malformation is present and the cause) will confirm a diagnosis, and once diagnosed a variety of treatments options are available: medications (anti-convulsants) can block the misfiring of the nerve, and muscle relaxants can ease the strain of the facial muscles; injections of botox can stop the nerve from contracting; and, if other treatments fail, a surgical procedure known as microvascular decompression can relieve nerve compression.