Merck Manual

Please confirm that you are a health care professional

honeypot link

Hemifacial Spasm


Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Reviewed/Revised Feb 2022 | Modified Sep 2022
View Patient Education

Hemifacial spasm refers to unilateral painless, synchronous contractions of facial muscles due to repetitive involuntary electrical impulses from the 7th cranial (facial) nerve and/or its motor nucleus.

Hemifacial spasm usually results from nerve compression by a pulsating blood vessel that causes ectopic impulse generation (ephaptic nerve impulses), similar to that in trigeminal neuralgia.

Unilateral, involuntary, painless contractions of facial muscles usually begin in the eyelid, then spread to the cheek and mouth. Contractions may be intermittent at first but may become almost continuous.

The pulsating blood vessel is often visible on MRI, but diagnosis of hemifacial spasm is ultimately clinical. Focal seizures, blepharospasm, and tics cause similar symptoms and should be considered.

The most effective treatment for hemifacial spasm is

  • Injection of botulinum toxin (botulinum toxin type A or botulinum toxin type B) into affected muscles

Drugs Mentioned In This Article

Drug Name Select Trade
ED Baclofen, FLEQSUVY, Gablofen, Lioresal, Lioresal Intrathecal, LYVISPAH, OZOBAX
Elavil, Tryptanol, Vanatrip
View Patient Education
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!