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Overview
Hemifacial spasm is a neuromuscular disorder
characterized by frequent, involuntary muscle
contractions (tics or spasms) in the face. It
usually affects only one side of the face, but in
severe cases, tics may occur on both sides.
The early symptom is usually an intermittent tic
of the eyelid muscle, which may eventually lead to
complete closure of the eye. The spasm may then
spread and eventually involve all of the muscles
in the affected side of the face.
Incidence and Prevalence
Hemifacial spasm usually occurs in middle-aged and
older people and is more common in women. It is
rare, affecting 8 out of 100,000 men and 15 out of
100,000 women in the United States. Left-sided
spasm is slightly more common than right- sided
spasm.
Risk Factors
Being middle-aged or older is a risk factor for
hemifacial spasm. If a person younger than 40 is
affected, there may be an underlying neurological
disease (e.g.,
multiple sclerosis).
Hemifacial spasm may be caused by an injury to the
seventh cranial, or facial, nerve; a tumor or a
blood vessel pressing on the nerve; or
Bell’s palsy.
The cause may also be unknown. One of the most
common triggers is a blood vessel pressing against
the facial nerve, which causes the surrounding
muscles to twitch or spasm.
Symptoms
The symptom is facial muscle spasm that usually
begins in the eyelid and around the eye. The spasm
varies in intensity and in how much of the face it
affects.
Diagnosis
A complete
neurological exam
is performed and if the physician suspects
hemifacial spasm, an electromyogram is
ordered. Most cases of hemifacial spasm are caused
by a blood vessel pressing on the facial nerve,
and this vessel is usually too small to be
detected by magnetic resonance imaging (MRI),
computed tomography (CAT scan), or angiography.
These imaging tests are usually ordered when a
lesion or tumor is suspected.
An electromyogram is used to diagnose muscle
problems caused by nerve dysfunction. The
procedure is performed on an outpatient basis and
takes about 2 hours. A small needle is inserted
into each muscle being examined. The needle is
attached to a wire and connected to a device that
records electrical activity produced when the
patient contracts and releases each muscle.
Treatment
There are three treatments for hemifacial spasm:
medication, surgery, and botulinum toxin
injections. In most cases, the treatment of choice
is
botulinum toxin
injections, also known as Botox or BTX.
Botulinum Toxin
BTX is produced by the Clostridium botulinum
bacterium. It is the same toxin that produces
botulism (i.e., food poisoning). When injected
into the eyelid in minute amounts, BTX is
effective in stopping spasms for several months.
Because the effects are temporary, the treatment
must be repeated periodically. Side effects
include drooping eyelids, double vision, and dry
eyes. These side effects lessen in time.
Medication
Medication is used in mild cases and in patients
who refuse BTX or surgery. Benzodiazepines (anxyolytic
used as muscle relaxant) and carbamazepine (Tegretol®;
antiseizure drug) can help control muscle spasms
but are usually less successful than BTX.
These medications produce side effects in
the central nervous system, including:
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Apathy
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Clouding of mental faculties
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Dizziness
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Fatigue
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Headaches
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Impaired motor coordination
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Nausea and vomiting
Long-term use of benzodiazepines can lead to
dependence. When used with other depressants
(e.g., alcohol), there is a great risk for severe
respiratory and cardiovascular depression. Drug
interactions also can be severe, so the physician
should be informed of all prescription and
over-the-counter drugs being taken.
Carbamazepine can cause potentially serious
adverse effects and the patient is monitored for
low white blood cell or platelet counts, signs of
bone marrow depression, and liver damage. Patients
with high intraocular pressure (IOP) also are
monitored because carbamazepine can increase
pressure.
Surgery
Surgery is indicated for severe symptoms caused by
blood vessel compression that does not respond to
other therapies. In th Janetta procedure, also
called microvascular decompression, the
blood vessel that is pressing on the facial nerve
is repositioned to relieve pressure. This
treatment is usually successful and most patients
do not require further treatment.
Microvascular decompression is performed by a
neurosurgeon in a hospital under general
anesthesia and carries associated risks. Some
patients have a residual spasm, particularly
around the eye, that takes days to months to
resolve.
Prevention
There is no way to prevent hemifacial spasm.
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