What is hemifacial spasm?
Hemifacial spasm is a condition which causes spasms in the muscles around the eyelid which cannot be controlled by the sufferer. It usually affects just one side of the face, causing spasms lasting from a few seconds to several minutes.
What causes hemifacial spasm?
It is thought in some people to be caused by compression (squeezing) of the nerve in the muscles of the face. Features such as unusual blood vessels may be seen on brain scans, but in many patients there is no identifiable abnormality.
What are the signs and symptoms of hemifacial spasm?
Hemifacial spasms may develop gradually, with muscle spasms affecting the muscles around one eye. These spasms may then spread to other muscles on the same side of the face (particularly the muscles of the jaw and mouth). There may be some clicking sounds in the ear on the affected side each time there is a muscle spasm.
How is hemifacial spasm treated?
In the past these conditions could only be treated with medicines such as Carbemazepine, Baclofen or Clonazepam, with limited success and significant side effects. Some patients had surgery to remove the muscles around the eyelids or even cut the nerve responsible; this is rarely necessary nowadays.
Today, treatment of hemifacial spasm involves injections of botulinum toxin, using a tiny needle.
Botulinum toxin is a chemical produced by a bacterium called Clostridium botulinum, which in large amounts is toxic. However, in the minute quantities injected it can be used to selectively weaken the muscles causing the spasm.
Most people have between 4 and 8 injections to each side, which are placed just under the skin and cause a slight stinging. These injections need to be repeated every 3-6 months and occasional alterations to the site or dose of the injections may be needed.
It is normal to feel some discomfort during and for a while after the injections. Small bruises occasionally develop but settle quickly. Occasionally other muscles may be affected resulting in a droopy eyelid or double vision. If this happens, it will resolve as the effect of the injections wears off in about 2-3 months.
Botulinum toxin manufactured for treatment purposes is prepared using human albumin (a blood product). The blood used is screened for all known transmissible infections. However, there is no absolute guarantee that the preparation is free from organisms which cannot be tested for or have yet to be identified. Some patients who have been shown on scan to have an abnormally located blood vessel lying close to the facial nerve will be offered referral to the neurosurgeons to consider an operation to provide a permanent cure for the problem.