What are possible causes of involuntary muscle twitching of the face? Particularly the mouth? No previous history.

Hemifacial spasm. Hemifacial spasm is an involuntary twitching of the facial muscles. Usually around the eye and corner of the mouth. It is thought to be caused by an artery that compresses the seventh cranial nerve. Treatment begins with medications to calm the nerve irritation. Botoxin injections is the next option and surgical microvascular decompression of the seventh nerve is performed for intractable spasms.