Hemifacial Spasm

Definition: What is Hemifacial Spasm?

Hemifacial Spasm refers to involuntary and constantly relapsing twitching (spasm) of one side (hemi) of the face triggered by a lesion of the facial nerve (facial nerve). The disease usually begins after age 40 and does not regress without therapy. The symptoms are often very burdensome to the patients and can lead to social isolation.

Cause: How Does Hemifacial Spasm Develop?

The cause of this clinical picture is an irritation of the 7th cranial nerve, the facial nerve. This nerve is paired and is responsible, among others, for controlling the facial musculature of both face halves.

In over 90% of cases, there is a point of contact between the nerve and a blood vessel in the most sensitive nerve area immediately after it exits the brainstem. The pulsatile vessel exerts pressure on the nerve and damages the myelin sheaths that electrically isolate the nerve.

Because the cerebral vessels can become even longer and wider with age, direct contact with the facial nerve can occur throughout life.

Women are about twice as likely as men to be affected by the disease. In addition, long-standing high blood pressure increases the risk.

Other less common causes of hemifacial spasms include:

• Multiple sclerosis
• Brainstem tumors
• Vascular malformations (angiomas)
• Brainstem infarcts (stroke in the area of the brainstem)
• Occurrence after having undergone paresis (paralysis) of the facial nerve

Symptoms: How Does this Condition Manifest?

The leading symptom of hemifacial spasm is the involuntary twitching of the muscles on one side of the face that occurs several times a minute, even during sleep. Usually, the eyelids are affected first, and as the condition progresses, the entire half of the face is affected. The frequency may increase with a longer duration of the disease.

These spasms are usually painless. However, they are aggravated by stress and fatigue and, in turn, represent a strong psychological burden for many patients. In long courses of the disease, paralysis of the affected muscles may occur.

Since the facial nerve also innervates the lacrimal glands, the flow of tears may be increased. A disturbance of bilateral vision is also possible.

Diagnosis: How Does a Medical Specialist Make a Diagnosis for Hemifacial Spasm?

Although the symptoms of hemifacial spasm are very typical of this condition, an MRI (magnetic resonance imaging) scan is carried out to provide definitive evidence of vascular-nerve contact. In addition, MRI can rule out other causes of hemifacial spasms that may require different therapy.

Unlike X-ray or computed tomography examinations, MRI does not use X-ray radiation but rather a high-frequency magnetic field. The image is created by the varying degree of magnetization of different tissues. This results in no radiation exposure for the patient. A computer assembles the many images of individual slices into a complete brain image.

To better visualize blood vessels, injecting a contrast agent through venous access, for example, in the crook of the arm, may be necessary.

The specialist can see where the vessel and nerve are adjacent on a multi-layered MRI image. If this is not the cause of the hemifacial spasm, tumors, vascular malformations, or lesions typical of multiple sclerosis can also be visualized with the help of MRI.

Therapy & Treatment: What Are the Options?

Depending on how severe the symptoms are and how much they limit the patient, symptomatic, conservative therapy can be initially attempted. However, hemifacial spasms can only be cured by surgery.

Injection of botulinum toxin (colloquially Botox) into the facial muscles can reduce the spasms. This treatment is initially successful in 90% of cases but must be repeated every 3-4 months, and its effect diminishes with more extended treatment duration. In addition, side effects such as temporary facial paralysis, drooping eyelids, or double vision are possible.

In mild cases of hemifacial spasm, the symptoms can also be improved by antispasmodic drugs. Side effects may include fatigue and tiredness.

The only causal therapy and, therefore, the possibility for a lasting improvement is surgery.

Procedure & Goal of a Surgery for Hemifacial Spasm

Surgery aims to break the contact between the nerve and the blood vessel. To do this, either a small piece of soft material, such as Teflon padding, is placed between the two structures as a cushion, or the vessel is minimally moved to the side.

The procedure is carried out under general anesthesia. First, a small hole is drilled into the top of the skull through which microsurgical instruments can be inserted. Then, its electrical potential is permanently monitored to ensure the facial nerve is not injured. The surgeon can also tell from the change in conduction when contact with the vessel has been successfully separated.

Prognosis: Course and Chances of Recovery

If left untreated, hemifacial spasm shows no spontaneous tendency to regress. Anticonvulsant drugs or botulinum toxin injections can improve the symptoms, especially in mild cases, but a cure is only possible through surgical therapy.

Surgery has a high success rate. A significant improvement can be felt immediately after surgery. The myelin sheaths regenerate in the following weeks, so the symptoms continue to improve or disappear entirely. After six months, spasms are reduced by over 90% in about 85% of patients.

Relapses occasionally occur when the padding material slips or the blood vessel continues to grow, and there is renewed contact with the nerve. In these cases, repeat surgery is possible.

Which Doctors & Clinics are Specialists in Hemifacial Spasms?

Since hemifacial spasms can be treated surgically, symptomatic treatment is also possible conservatively. Therefore, both neurosurgeons and neurologists are contacts for the patients. In any case, an MRI examination should be performed and evaluated by an experienced radiologist.

Even if the patient has not yet decided in favor of or against surgery, a neurosurgical appointment is worthwhile to obtain further information about the procedure, chances, and risks of a possible intervention.

Posterior fossa surgery, such as this one, requires particular expertise and should be carried out in a specialized clinic by an experienced neurosurgeon.

• eref.thieme.de/ebooks/955291
• neurochirurgie.insel.ch/funktionell-schmerz/hemispasmus-facialis
• www.msdmanuals.com/de/profi/neurologische-krankheiten/neuroophthalmologische-erkrankungen-und-störungen-der-hirnnerven/fazialisparese
• www.mayoclinic.org/diseases-conditions/hemifacial-spasm/diagnosis-treatment/drc-20373299
• www.barmherzige-regensburg.de/neurochirurgie/unser-behandlungsangebot/gefaesserkrankungen-an-gehirn-und-rueckenmark/hemispasmus-facialis.html