What is hemifacial spasm?

Hemifacial spasm is a neurologic disorder in which there is chronic twitching of the muscles on one side of the face. Twitching usually begins around the eye and expands to include muscles of the lower face around the mouth. While not dangerous, hemifacial spasm can cause stress and social anxiety as well as cosmetic changes and weakness in the face.

How is hemifacial spasm diagnosed and treated?

Hemifacial spasm is a clinical diagnosis, meaning that a doctor will arrive at the diagnosis by taking a history of your symptoms and performing a physical exam. There is no blood test or X-ray to diagnose hemifacial spasm, though your doctor may often order an MRI of your brain. Several disorders can mimic hemifacial spasm, and your doctor will ask questions to rule out these other disorders. Hemifacial spasm "mimics" include blepharospasm, synkinesis after Bell's palsy, and focal seizures, among others.

The mainstay of therapy for hemifacial spasm is injections of botulinum toxin ("botox"). These injections temporarily paralyze muscles in your face, making the twitching less noticeable. This is not a cure for hemifacial spasm, and the injections need to be repeated every few months. Long-term, these injections can result in permanent facial weakness or cosmetic changes including atrophy of the facial muscles.

For patients who no longer wish to continue botox injections or who have had diminishing effectiveness of the injections over time, microvascular decompression is an effective surgical option.

What is the surgery for hemifacial spasm?

Hemifacial spasm is generally caused by irritation of the facial nerve where it emerges from the brainstem. The facial nerve controls movements of the face. The most common source of irritation is compression of the facial nerve by a nearby blood vessel. Each time the blood vessel pulsates with the heart, it bumps up against the nerve, eventually causing the nerve to misfire and the face to twitch.

The surgery to treat hemifacial spasm is called a microvascular decompression (MVD); a similar procedure is also performed for trigeminal neuralgia and glossopharyngeal neuralgia. In this procedure, a small hole is drilled into the skull behind the ear. The blood vessel and facial nerve are dissected apart and permanently separated with a piece of teflon padding.

Microvascular decompression is very effective for hemifacial spasm, with 80-90% of patients experiencing long-term and complete relief of their facial twitching.