Hemifacial spasm is a neuromuscular disorder. Individuals with this disorder often have frequent involuntary contractions of the muscles on one side of the face. The disorder occurs in both men and women. It occurs more frequently in middle-aged or elderly women.
The first symptom is usually an intermittent twitching of the eyelid muscle. This symptom can lead to forced closure of the eye. The spasms may gradually spread to the muscles of the lower face. This can cause the mouth to be pulled to one side. Eventually the spasms involve all of the muscles on one side of the face and occur almost continuously. The condition is sometimes caused by a facial nerve injury or tumor, although frequently no cause is identified.
Treatment of hemifacial spasm frequently consists of injecting botox (botulinum toxin) into the affected muscles. Surgery may be used for some cases. The likely outcome for treated cases varies from patient to patient.