What is Hemifacial Spasm?
Hemifacial means half the face. Spasm means involuntary contractions of a muscle. Hemifacial spasm is when half the face (either the right half or the left half) twitches uncontrollably.
What Causes it?
The muscles of the face are controlled by the facial nerve, which starts in the brain and travels to the face. If something presses on the nerve somewhere along its course, it can cause muscles to twitch or go into spasm. Most commonly, you may have a blood vessel at the base of the brain which loops near the nerve and presses on the nerve. There are other rarer causes as well.
What are the Symptoms?
- The spasm is usually confined to one side of the face, although some patients do get it on both sides.
- It starts at the eyelids, and may progress to involve the cheek, mouth and chin.
- This may lead to difficulty keeping that eye open, and also cause the corner of the mouth to be pulled up.
What can I do About it?
Your doctor may offer you an MRI scan of the brain region to make sure there are no dangerous lesions pressing on your nerve (although this is extremely rare).
Treatment options include:
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Botulinum toxin injections - This is the main and most widely-used treatment option and is further explained below.
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Oral medications - These often carry side effects such as drowsiness and are not as effective.
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Rarely, surgery may be performed - This involves surgery to the brain, to either remove the identified blood vessel which may be pressing on the facial nerve, or to insert an implant to prevent it from pressing on the facial nerve. However, surgery may lead to several serious side effects, and is thus only reserved for extremely disabling cases.
What are the Injections like?
Botulinum toxin is commonly known as "Botox", although it may come as different brand names, depending on the manufacturer. The toxin is produced by the bacterium
Clostridium botulinum, which can be associated with food poisoning called botulism. However, when used in controlled doses, it can safely relax excessive muscle spasms by blocking the signals from the nerve to the muscles.
Key points to note are:
- The injection is into the muscles around the eye and face.
- It starts to work only a few days after the injection.
- The effects last for two to three months. Therefore you may need regular injections.
- The number of injections required each time will vary according to each individual's condition.
- You may experience some pain during the injection, despite application of anaesthetic cream. However, this is transient and usually mild.
- There can be side-effects of the injection. These include drooping of the eyelid and double vision. These will wear off when the medication effect wears off (usually a maximum of 3 months).
- If you experience any side effects or discomfort following the injection, you should return to see your doctor immediately.
Illustration of a patient with left hemifacial spasm.
What is the Outlook for this Condition?
Hemifacial spasm is a long-term condition. However, it is not life-threatening and will not damage your vision. With regular treatment, most individuals continue to enjoy good quality of life.
