Hemifacial spasm refers to unilateral painless, synchronous contractions of facial muscles due to dysfunction of the 7th cranial (facial) nerve and/or its motor nucleus. Hemifacial spasm results from nerve compression by a pulsating blood vessel, similar to that in trigeminal neuralgia.
The pulsating blood vessel is often visible on MRI, but diagnosis is ultimately clinical. Focal seizures, blepharospasm, and tics cause similar symptoms and should be considered.
Injection of botulinum toxin (botulinum toxin type A or botulinum toxin type B) is the most effective treatment.
Last full review/revision July 2012 by Michael Rubin, MDCM