Hemifacial Spasm (HFS)

 

What is hemifacial spasm?

Hemifacial spasm (HFS) is a neurological condition causing involuntary paroxysmal or repeated contraction and twitching of muscles of one side of face. The condition may be subtle but, in some patients, it may be severe, sometimes causing significant social embarrassment.  Facial muscles causing this condition are supplied by the facial nerve.

 

What causes HFS?

It is caused by compression or irritation of the facial nerve. A nerve is like an electric wire, covered by a plastic like material called myelin. If a nerve is pressed or irritated, its coating can be damaged, which makes the inside fibers bare. If something touches or irritates the inside of nerve, it may lead to an electric jolts like phenomenon, which may cause facial muscle contraction. Its usual cause is an artery close to the nerve. Common arteries that may be involved are the branches of the anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), or vestibular artery.   

Other causes include trauma, chronic Bell’s palsy, a mass close to the nerve, arteriovenous malformation, cerebral aneurysm, infection, parotid gland tumor, Chiari malformation, or multiple sclerosis.

 

How common is HFS?

It is a rare condition, about 10 per 100,000, but is about twice as common in women than in men.

 

Does HFS causes facial pain?

Not really, except little feeling of discomfort with a muscle twitch. Attacks of facial pain are caused by a different condition, which is a problem with trigeminal nerve, not facial nerve.

 

How is HFS diagnosed?

It is diagnosed by taking proper history and physical examination. For diagnosis, no test is needed. Testing may be done to find the cause of HFS.

 

How is HFS treated?

Treating the cause of HFS is preferred. For example, if MRI confirms an artery close to the nerve, surgery might be an option. Similarly, there might be some other treatable causes of HFS. In many cases, no treatable cause is found. In such cases, the treatment of choice is Botox injection to weaken the muscle involved. Botox is a reasonably safe and effective treatment.

 

Where may I find more information about HFS?

American Academy of Neurology

International Parkinson and Movement Disorder Society