Blepharospasm
Blepharospasm is a focal dystonia characterized by increased blinking and involuntary closing of the eyes. This form may be primary or secondary. People with blepharospasm have normal vision. When vision is impaired, it is due solely to the forced closure of the eyelids.
Blepharospasm may be referred to as a ' cranial dystonia.' Cranial dystonia is a broad
description of dystonia that affects any part of the head.
Terms used to describe blepharospasm
include: eye dystonia, cranial dystonia, adult
onset focal dystonia. When blepharospasm
occurs with dystonia in the face, the term
Meige's syndrome may be used.
Symptoms
Blepharospasm affects the eye muscles and
usually begins gradually with excessive blinking and/or eye irritation. In the early stages it may only occur with specific precipitating stressors such as bright lights, fatigue, and emotional tension. It is almost always present in both eyes.
As the condition progresses, symptoms may
occur frequently during the day. The spasms
disappear in sleep, and some people find that
after a good night's sleep, spasms do not
appear for several hours after waking. In a few cases, spasms may intensify so that the eyelids remain forcefully closed for several hours at a time.
Blepharospasm can occur with dystonia affecting the mouth and/or jaw (oromandibular dystonia). When blepharospasm and oromandibular dystonia occur together, the condition may be referred to as Meige's syndrome. In such cases, spasms of the eyelids are accompanied by jaw clenching or mouth opening, grimacing, and tongue protrusion.
Cause
Blepharospasm may develop spontaneously
with no known precipitating factor or be inherited. Some people with blepharospasm
have family members with dystonia affecting different body areas.
Blepharospasm may be secondary due to drug exposure or occur in association with disorders such as parkinsonian syndromes and Wilson's disease.
Diagnosis
Diagnosis of blepharospasm is based on
information from the affected individual and
the physical and neurological examination. At
this time, there is no test to confirm diagnosis of blepharospasm, and, in most cases, assorted laboratory tests are normal.
Blepharospasm should not be confused with:
Ptosis- drooping of the eyelids caused by
weakness or paralysis of a levator muscle of
the upper eyelid.
Blepharitis- an inflammatory condition of the
lids due to infection or allergies.
Hemifacial spasm- a non-dystonic condition
involving various muscles on one side of the
face, often including the eyelid, and caused by irritation of the facial nerve. The muscle
contractions are more rapid and transient than those of blepharospasm, and the condition is always confined to one side.
Treatment
One of the most effective treatments for
blepharospasm is regular botulinum toxin
injections to the affected muscles.
Medications
including clonazepam, lorazepam, and
trihexyphenidyl are helpful in some cases. If
botulinum toxin injections and medications are not effective, myectomy surgery in which
portions of muscle are removed may also
alleviate symptoms. Botulinum toxin injections may or may not be required following myectomy surgery.