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Hemifacial spasm is a painless condition in which one side of the face intermittently twitches uncontrollably. The twitches do not last a long time, but they can come in a long series that distorts the face quite a bit.
The twitches usually are first noticed around the eye, but over years can progress to involve the rest of the face. Over time, some weakness in the facial muscles may develop that is visible between twitches. This condition is rare in children and is most often diagnosed in the fifth decade. It is not life threatening but can be most annoying, and uncontrolled blinking can interfere with reading and driving.
Making the Diagnosis:
Hemifacial spasm is diagnosed by the characteristic appearance of the facial twitches. It must be distinguished from: "habit tics", involuntary facial movements that are side effects of some medications, abnormal facial movements following injury to the facial nerve, blepharospasm (bilateral involuntary eyelid closure) and facial myokymia (a more sustained small amplitude contraction of facial muscle fibers). Usually simple observation of the movements is enough to distinguish these disorders. If not, a facial electromyographic (EMG) examination can make the distinction.
None knows why some people get hemifacial spasm and others do not. We do know, however, that most people who have hemifacial spasm are found to have an artery pressing on the facial nerve just as it leaves the brain to head toward the face. Moving that vessel away from the nerve, and keeping the pressure off the nerve, is associated with relief from the spasm in most people. Therefore, this contact between nerve and artery, called "vascular compression" is thought to be the cause of hemifacial spasm. In rare instances, other blood vessel abnormalities, or even small benign tumors, can cause such compression.
Medications (such as antispasmotics like diazepam, lorazepam, baclofen and dantrium, or anticonvulsants like carbemazepine) are rarely effective. This makes sense since the cause of the spasms is structural. Until the development of microvascular decompression (MVD), surgical treatment for hemifacial spasm consisted primarily of ways to partially injure the facial nerve, causing temporary weakness that eliminated or reduced the spasm until the nerve recovered.
Botulinum (Botox) injections are the modern way to accomplish this. Such procedures can control the symptoms for some period of time but must be repeated, may lose effectiveness over time and often cause noticeable weakness of the face. MVD is an operation that eliminates the spasm by removing the pressure of the artery on the nerve near the brain. While a major operation, in experienced hands the risks are quite low and approximately 85% of patients will have complete relief of spasm without facial weakness.
Hemifacial spasm is not a dangerous disease. People can live with it for their entire life without treatment. It can, however, be disfiguring and interfere with normal daily activities such as driving and reading. Microvascular decompression offers 85% of people with hemifacial spasm the possibility of returning to normal facial function and appearance.