THERAPEUTIC FORUM

Deadly Toxin Holds Treatment
For Chronic Eyelid Spasm

by Christopher J. Quinn, O.D.

Essential blepharospasm is a bilateral condition characterized by over-action of the orbicularis muscle, and results in spastic eyelid closure. Intermittent spasmodic contraction of other facial muscles often accompanies this spasticity.

Patients with this condition, by definition, have no other evidence of neurological or ocular disease.

Recently, purified botulinum toxin has been used effectively to reduce the symptoms and spasticity of essential blepharospasm.

Essential blepharospasm disorder is most commonly seen in patients over the age of 50, and is also most common in women. The condition starts with an increased frequency of blinking which can be exacerbated by sunlight or by dry, windy environmental conditions.

The disorder, instead of resolving, progresses to involuntary spasms of initially one and then both eyes. Spastic closure of the eye becomes progressively worse until the patient develops severe spasms. Occasionally, the spastic eyelid closure can progress to the point where patients are functionally disabled. They may also develop severe depression and social isolation as a result.

In the most severe cases, the condition can even progress to the point where the patient becomes functionally blind due to constant spastic closure of the eyelids.

Because no known cause for essential blepharospasm has been identified, in the past patients have been labeled with "functional or psychiatric disorders." Today, essential blepharospasm is recognized as a distinctive clinical entity that is not necessarily functional in origin.

Effective treatment for essential blepharospasm has been elusive. Behavior modification and biofeedback techniques have been partially successful in reducing the associated facial movements. Surgical treatment has attempted to reduce the spastic component of blepharospasm. However, complications, recurrence and the variable effectiveness of these procedures have led to less than optimal results.

The latest and most effective treatment however involves botulinum toxin injections. These can provide symptomatic relief from essential blepharospasm's potentially debilitating symptoms.

Botulinum toxin is produced from a strain of Clostridium botulinum bacteria. In larger ingested doses, this deadly poison is the root of botulism. But in the past few years, botulinum toxin type A (Botox, Allergan) has been used in very low dose injections to partially paralyze muscle.

The toxin inhibits neuromuscular activity by binding to the receptor sites on the motor nerve terminals, blocking neurotransmission.

Because the muscle is chemically denervated, it atrophies. The resulting paralytic effect can reduce the abnormal contraction associated with blepharospasm.

The treatment is relatively benign and requires multiple injections directly to the orbicularis muscle to be effective. The paralytic effect of the injections usually peaks within one to two weeks following treatment and lasts for approximately three months. Injections must be repeated indefinitely in order to have a continued effect.

The injections are generally well-tolerated; however, post-injection complications include excessive effect, which can result in ptosis, an incomplete blink and/or lagophthalmos. Exposure keratitis can also be a potentially serious complication. There is no antidote to reverse the action of the botulinum toxin.

These injections are most commonly done by either a neuro- or oculoplastic ophthalmologist, although an O.D. could perform this procedure if appropriately trained and authorized.

Botulinum toxin injections in even lesser doses have also been used effectively for cosmetic purposes. Injected to decrease muscle tone around the eye, the treatment can reduce skin wrinkles.