Hemifacial Spasm

1 What is Hemifacial Spasm?

Hemifacial spasm is a nervous system disorder in which the muscles on one side of an individual's face twitch involuntarily.

Hemifacial spasm may be caused by a blood vessel touching a facial nerve, a facial nerve injury or a tumor, or it may not have a cause.

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2 Symptoms

Twitching around the eye is the main symptom of hemifacial spasm.

It has been noticed that in 92% of cases, theses spasm occur near the eye and progress down the face over time.

In the remaining 8%, it begins near the chin and moves upwards.

The twitching is not usually painful, but it can be embarrassing and can have an impact on normal expression and vision.

3 Causes

Hemifacial spasm can be caused by the following:

  • Injury to the facial nerve,
  • a tumor or blood vessel compressing the nerve or Bell's palsy.

The most common cause is the compression of the facial nerve by the anterior inferior cerebellar artery where the nerve begins in the brainstem.

The compression causes th nerve to misfdire, making the facial muscle contract.

This condition can be related to trigeminal neuralgia, an irritation of the fifth cranial nerve that causes severe facial pain.

4 Making a Diagnosis

The first step of hemifacial spasm diagnosis will be a careful review on medical history and performance of a neurological exam by a doctor.

An MRI scan can be further ordered to rule out other potential conditions such as a brain tunor, an aneurysm or AVM that may be causing facial nerve compression.

The next stap can be  an electromyogram (EMG) study of the face. An EMG is often done along with a Nerve Conduction Velocity (NVC) study to measure the muscle and nerve electrical activity.

5 Treatment

The following treatments are available for hemifacial spasms: 

  • Medication like carbamazepin and phenytoin can be prescribed by the doctor to block the firing if the nerve.
  • Muscle relaxants such as baclofen, diazepam and clonazepam may also be prescribed.

These drugs have been successful in treating mild cases but cause various side effects which include:

  • drowsiness,
  • unsteadiness,
  • nausea,
  • skin rash
  • and dependance.

Another form of treatment is the form of botox injections. Botulinum toxin, or Botox is a toxin produced by the C. botulinum bacteria that causes musle paralysis by blocking electrical messages that direct the muscle to move.

A very fine needle is used is used to deliver 1 to 3 injections into the facial muscles. Botox usually works within 3 days and lasts for 3 months.

Another part of treatment is surgery. Medications and injection may be inadequate at times to control spasms and cause side effects.

A procedure known as a microvascular decompression can relieve the nerve compression. In this procedure, a neurosurgeon makes a hole in the bone (craniotomy) at the back of the head to expose the facial nerve at the brainstem A teflon sponge is then placed between the offending blood vessel and the facial nerve.

About 90% of patients  return to their regular lifestyle after two months. Like all surgeries, their are risks. More frequent side effects can include decreased hearing and facial weakness.

In general, the results of surgery include the following: 85% experience immedite relief from spasms, 9% report diminished spasm, 2% report delay in facial spasm in the month following surgery and 7% experience  a recurrence of spasms after surgery.

6 Prevention

There is no known way to prevent hemifacial spasms.

7 Risks and Complications

There are several risks associated with hemifacial spasms.

Hemifacial spasms only occur in approximately 0.8 out of 100 000 people.

It is more likely to happen in women over 40 years of age.

Hemifacial spasms are also likely to happen as one ages, about 39.7 people out of 100,000 with the spasms are aged 70 years or older.

Some conditions like cerebellopotine angle syndrome can also increase the risk of developing hemifacial spasms.