Blepharospasm is an involuntary closure of the eyelids.
"Blepharo" refers to the eyelids, and "spasm" to involuntary muscle contraction. In blepharospasm, the eyelids close involuntarily due to an unknown cause within the brain. Blepharospasm is a form of dystonia, a disorder characterized by sustained muscle contraction. The most common form of blepharospasm is called "benign essential blepharospasm," meaning it is not life threatening and is not due to some other identifiable disorder. A condition called hemifacial spasm causes similar symptoms, but affects only one side of the face, and is caused by an irritation of the facial nerve outside of the brain.
Blepharospasm is estimated to affect approximately 15,000 people in the United States. Onset is most commonly between the ages of 40 and 60, but can begin in childhood or old age. Women are affected approximately twice as often as men.
Causes and symptoms
The cause of benign essential blepharospasm is unknown. Evidence suggests it may be genetic in some cases, although genes have not been identified. A person with blepharospasm often has dystonia in another region of the body such as the mouth or the hands (i.e., writer's cramp). Other forms of dystonia or tremor may affect other family members. Blepharospasm is not caused by a problem with the eyes themselves, but rather with the brain regions controlling the muscles of the eyelids.
Secondary blepharospasm occurs due to some identifiable cause. The most-common cause of secondary blepharospasm is a reaction to antipsychotic medications, and is called tardive dystonia. Damage to the brain, either through stroke, multiple sclerosis, or trauma, may also cause blepharospasm.
Blepharospasm often begins with increased frequency of blinking, which may be accompanied by a feeling of irritation in the eyes or "dry eye." It progresses to intermittent, and then sustained, forceful closure of the eyelids. Symptoms are usually worse when the patient is tired, under stress, or exposed to bright light. Symptoms may become severe enough to interfere with activities of daily living, and can render the patient functionally blind.
Blepharospasm is diagnosed by a careful clinical exam. A detailed medical history is taken to determine exposure to drugs or other possible causative agents, and a family history is used to determine if other family members are affected by other forms of dystonia or tremor.
The treatment team consists of a neurologist and possibly a neurosurgeon.
The most effective treatment for blepharospasm is injection of botulinum toxin (BTX) into the muscles controlling the eyelids. BTX temporarily prevents the muscles from contracting, allowing patient to keep their eyes open. BTX is a safe and effective treatment for this condition. Usually the effects are seen within several days of injection, have their maximum effect for 6–8 weeks, and last between 12 and 16 weeks, at which time reinjection is performed. Side effects of BTX injection include mild discomfort at the injection site(s), and occasional double vision or inability to lift the eyelids due to local spread of the toxin to other muscles. Dry eyes or excessive tearing may also occur. Development of resistance to BTX injections is possible if the patient's immune system creates antibodies against the toxin. While this has not been reported in blepharospasm as the injected dose is very low, it has occurred in other conditions in which the doses are higher.
Oral medications are rarely effective for blepharospasm. Among the most widely used are anti-cholinergics (trihexyphenidyl, benztropine), baclofen, and benzodiazepines (diazepam, clonazepam). Surgery is an option for patients who do not respond to BTX injections. The surgical procedures are performed to remove part of the overactive muscles, or to sever the nerve leading to them, or both. Unfortunately, surgery is rarely completely successful, and there is a high rate of recurrence of blepharospasm.
There are no current clinical trials for blepharospasm since effective treatment is available.
Blepharospasm is a chronic condition, which tends to worsen over time. Many patients with blepharospasm develop other dystonias in other body regions.
Benign Essential Blepharospasm Research Foundation. (April 19, 2004.) <http://www.blepharospasm.org/>.
WE MOVE. (April 19, 2004.) <http://www.wemove.org>.