Hemifacial Spasm: When a Wink Is Not a Wink

I'm sure it's happened to you. Someone caught your eye by apparently winking at you. But when you looked again, you realized that the person wasn't winking. Instead, he or she had recurrent muscular contractions around one eye unrelated to any attempts to flirt or send a personal message. Moreover, the person might have had twitching on one side of the mouth, as well. What you observed is called hemifacial spasm, an involuntary movement disorder.

This condition typically afflicts people over forty years old and affects women more often than men. The prevalence of this condition is unknown. While about ten people out of a population of 100,000 receive treatment for this condition, other cases probably go uncounted because they don't enter the medical system or get misdiagnosed.

For the person with the movement disorder this is an everyday, all-day phenomenon. It's usually annoying, and sometimes more than just annoying. The repetitive muscular twitches and contractions affecting the upper and lower eyelids can even interfere with vision. Fortunately, just one eye is impacted, so the other eye remains open. But even if the person has normal vision in the unaffected eye, viewing the world with just one eye reduces depth-perception. We need both eyes looking simultaneously in order to accurately judge how far away objects are. If you want to prove this to yourself, walk around your house with one eye closed.

We read so much into the facial expressions of the people around us--and, in particular, what their eyes are doing--that when an involuntary movement disorder generates its own facial distortions, it disrupts communication and disconcerts not just the affected individual, but those around him or her, as well.

Hemifacial spasm can be confused with other conditions affecting the face. Like hemifacial spasm, Bell's palsy affects the muscles on just one side of the face, but causes weakness rather than over-activity. Also like hemifacial spasm, trigeminal neuralgia affects just one side of the face, but causes pain instead of twitching. Finally, a condition known as blepharospasm (or Meige syndrome) involves involuntary contractions of eye and face muscles, but affects both sides of the face simultaneously.

What causes hemifacial spasm? The various muscles affected by this disorder are connected to the so-called facial nerve which is like a telephone cable containing many individual nerve-fibers. The nerve-fibers transmit electrical impulses to the facial muscles. We have two facial nerves, one for each side of the face, and either can be afflicted by this condition. In hemifacial spasm, one facial nerve transmits excessive and inappropriate nerve-impulses to its associated muscles, causing unwanted movements. The nerves are capable of conducting normal nerve-messages, too, so affected individuals can still use their facial muscles for more appropriate movements.

The excessive impulses causing the movement disorder can be generated in the nerve-fibers themselves, or in the brainstem (located at the base of the skull, connecting the brain above to the spinal cord below) which is where the nerves originate. A dangerous underlying cause is not found in most people with hemifacial spasm, but occasionally this disorder is found due to tumors, strokes or multiple sclerosis, so medical evaluation is definitely warranted.

What can be done for this annoying condition? Until a decade or so ago, the main treatment was with certain drugs also used in patients with epileptic seizures. Hemifacial spasm is not epilepsy, but it's not hard to imagine why some of the same drugs might be useful. In epilepsy excessive electrical discharges are generated in brain cells. Antiepileptic drugs simmer down or prevent these excessive discharges. Because the facial nerve-cells share many electrical characteristics with brain cells, the same drugs can also reduce the extra nerve-impulses causing hemifacial spasm. Some of the more frequently prescribed drugs include carbamazepine (brand name Tegretol), gabapentin (Neurontin) and clonazepam (Klonopin).

Also, surgical treatments have been applied to some patients with hemifacial spasm. The operation seeks to lift a small, abnormal blood vessel compressing the facial nerve where it emerges from the brainstem, but this treatment carries significant risk and its beneficial effects do not always persist.

In the last decade or so, botulinum toxin has emerged as an extremely helpful treatment for hemifacial spasm and is now the usual treatment of first choice. Botulinum toxin is available in two formulations--Botox (made by the Allergan company) and Myobloc (made by Solstice Neurosciences). Thus far, the U.S. Food and Drug Administration has approved just the Botox formulation for treatment of hemifacial spasm.

Botulinum toxin is injected via a fine needle. In the case of the thin muscles around the eye, the drug is usually deposited over the surfaces of the muscles. When used for muscles lower in the face, the drug is injected inside the muscles. The drug acts at the microscopic connections between nerve-fibers and muscles by blocking the activation of muscle-cells by incoming nerve-impulses. So treatment with botulinum toxin interferes with both the wanted as well as unwanted muscular contractions.

The drug is administered no more often than every three months. In many cases, less frequent treatments suffice. A beneficial weakening effect is usually noticed within the first 7-10 days and the weakness is maximal by 4-6 weeks. Gradual strengthening (and increased twitching) of treated muscles occurs thereafter. With repeated injections the dosing format is optimized to achieve the best result for each individual.

Although hemifacial spasm is not a life-or-death condition, it can interfere with quality of life. While the available treatments are not necessarily curative--or even convenient--they can reduce distress, improve function, and keep those apparent winks from sending unintended messages.