What is hemifacial spasm?
There is a facial nerve for each side of the face which is control muscles of the face. It starts deep inside your brain and makes its way past many structures to reach the face. The facial nerve carries signals from the brain to make your facial muscles contract or relax.
If something presses on the nerve somewhere along its course, it can affect how the signals are carried to the face. This may cause muscles to twitch, or to go into spasm (a sudden, involuntary contraction of muscles).
The cause of hemifacial spasm is not fully understood. At the moment, doctors believe the main cause is pressure on the facial nerve from a structure or abnormality within the brain. The most common finding is a blood vessel at the base of the brain, pressing on the nerve. There are other, rare causes too such as infections or strokes.
Medicine: These can be helpful when the spasms are mild or infrequent. These medicines work by quieting nerve impulses or relaxing muscle spasms (sedatives).
Injection: Botulinum toxin when it is used in controlled doses is injected into the facial muscles and blocks the signal from the nerve. This helps to stop the spasms. About 7-8 people out of 10 with hemifacial spasm are helped by botulinum injections.
Surgery: Medications and injections sometimes fail to control spasms or cause side effects. Surgery is usually reserved for cases where the spasms are severe. In 90% of surgical cases there appears to be a blood vessel compressing the nerve. A type of procedure (Microvascular Decompression), can relieve the nerve compression. A neurosurgeon makes a hole in the skull at the back of your ear to expose the facial nerve at the brainstem. A tiny pad (Teflon sponge) is placed between the offending blood vessel and the facial nerve. Thus, the connection between the facial nerve and blood vessel is cut off and spasm is treated.