Hemifacial Spasm

Hemifacial spasm is an involuntary muscle twitch that affects one side of the face. Although the condition is not life-threatening, it can have a major bearing on quality of life and affect the way you live day to day.

Hemifacial means half the face and a spasm is a sudden and unexpected contraction of the muscles; in this case, the facial muscles.

How common is hemifacial spasm?

This disorder is rare. It tends to affect women more commonly than men and most cases concern those over 40 years old. It is estimated that there are around 4,000 people living with hemifacial spasm in the UK.

What causes hemifacial spasm?

In some cases, the exact cause is unknown. However, it is thought that hemifacial spasm is linked to compression of the facial nerve. Both sides of the face have a facial nerve and this is responsible for carrying messages from the brain. These messages enable you to carry out actions such as blinking, moving the eyebrows and pursing your lips. If the nerve is compressed, this can affect the delivery of nerve signals, resulting in involuntary movement of the muscles or a sudden spasm.

Most of the time, hemifacial spasm is linked to a blood vessel located at the bottom of the brain (often the anterior inferior cerebellar artery) pressing on the facial nerve and causing signals to become mixed up. Other possible causes include infections around the nerve, injury, the presence of a tumour and strokes. These causes are less common, however. Sometimes, hemifacial spasm may also be linked to Bell’s palsy.

In cases where there is no clear cause, doctors give a diagnosis of idiopathic hemifacial spasm, which means that the cause of muscle spasm is not known.

There is no evidence to suggest that hemifacial spasm is inherited.

What does diagnosis involve?

Most people go to their GP first with symptoms including twitching on just one side of the face. If a doctor suspects hemifacial spasm, they will ask some questions about additional symptoms and carry out a brief examination. If there is a chance that the patient might have hemifacial spasm, they will be referred to a neurologist for further tests, which may include an MRI scan to rule out underlying problems such as a tumour. A test known as an EMG (electromyogram) may also be conducted. This analyses the activity of the nerve.

Which treatments are available for hemifacial spasm?

There are various treatment options available for hemifacial spasm, including:


Medication is usually the first port of call for patients with hemifacial spasm and can be beneficial for mild cases when spasms are uncommon. Types of medication typically used include anti-convulsants, which may also be used to treat epilepsy and sedatives as these are used to relax the nerves. Examples of medicines often prescribed include carbamazepine, topiramate and benzodiazepines. Although these medicines can help to prevent spasms, they may also make you feel drowsy and lethargic. It can also often take a little time to find the best dosage.


Botox is often associated with anti-ageing beauty treatments, but it can also have medical benefits. In this case, it can help to prevent spasms by blocking nerve signals from the brain to the facial muscles. The results of injections usually last up to 3 months. Botox is effective in around 70-80 percent of people with hemifacial spasm. The effects usually become noticeable after a few days and treatment is considered safe when provided by a trained doctor. Possible side effects include a drooping eyelid, double vision and a temporary feeling of weakness in the facial muscles. Side-effects are usually mild and are almost always short-lived.

Surgical treatment

Surgery may be recommended in cases where the nerve is clearly compressed or other treatments have been ineffective. There are various types of procedure that can be of benefit, but the most common is microvascular decompression (MVD), which is designed to release pressure on the facial nerve. MVD aims to prevent future spasms by taking away the vessel compressing the nerve. There are risks involved with surgery and it is generally only considered in severe cases. Possible complications of MVD surgery include weakness in the facial muscles and hearing loss. In cases where surgery is conducted, 85 percent of people experience immediate pain relief and only 7 percent of people develop spasms in the future.

Self-help techniques:

It can be beneficial to learn some relaxation techniques to reduce tension in your muscles and prevent stress.

What is the prognosis for people with hemifacial spasm?

Hemifacial spasm is not life-threatening, but it is often a long-term condition and it can have an impact on your quality of life. It is rare for the condition to improve without any form of treatment, but therapies can often be very effective.


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