Hemifacial spasm is a neuromuscular disorder characterized by frequent involuntary contractions of the facial muscles. The disorder is typically a vascular compression condition, where an abnormally shaped blood vessel or benign (non-cancerous) tumor is responsible is applying pressure on the seventh cranial nerve (VIIth). This pressure causes the nerve to fire intermittently on its own, causing the involuntary facial spasms.
Hemifacial spasm occurs equally between both men and women, however in women, it more frequently affects those in middle age or later.
Hemifacial spasm generally begins with a twitching eyelid muscle that can lead to a forced closure of the eye. The spasm can spread to lower face muscles, which can cause the mouth to be pulled to one side. Eventually the spasms may involve all of the muscles on one side of the face on nearly a continual basis.
Medical treatment of hemifacial spasm is can include injections of Botulinum Toxin (Botox) into the affected facial muscles. A surgical approach to treating hemifacial spasm involves Microvascular Decompression (MVD). In some cases, medical therapy in the form of oral medication can improve or alleviate symptoms.