Hemifacial spasm is a condition in which the facial muscles on one side of the face contract involuntarily.
Hemifacial spasm more commonly affects women than men. It can be caused by a loop of artery irritating or compressing the facial nerve. Tumours or previous injury of the facial nerve (e.g. trauma, Bell’s palsy) can also cause hemifacial spasm. However, often no cause can be identified.
Hemifacial spasm usually starts with twitching of the eyelid muscle, slowly spreading to other facial muscles on the same side over months or years. This leads to eyelid twitching and pulling of the corner of the mouth. Muscle twitching can be worsened by stress, chewing and speaking. Mild weakness and asymmetry of the facial muscles on the affected side is not uncommon.
While certain anti-seizure medications may sometimes be helpful, symptoms are rarely controlled satisfactorily. Local injection of botulinum toxin into twitching facial muscles is the most effective treatment. In cases not responding to treatment where an artery can be seen pressing on the facial nerve, surgery to relief the compression can be considered.
There is no cure for hemifacial spasm and symptoms are likely to persist indefinitely. However, many patients can achieve good control of their symptoms with botulinum toxin treatment.