A five-year analysis of botulinum toxin type A injections: some unusual features.
We analyzed patients treated during the past five years with botulinum toxin type A for strabismus and blepharospasm, reviewed our successes, failures, and unusual cases, and drew conclusions based on these treatments. Thirty-seven percent of the strabismus patients were cured, but many patients who were outside the strict definitions, still believed that they were significantly improved. A prominent feature in the treatment of strabismus was variability. Frequently, patients expected to do poorly had encouraging results. One permanent overcorrection occurred, and it converted an esotopic patient into an exotropic one with diplopia. This has persisted for 2.5 years and is the longest reported overcorrection to our knowledge. Our results indicate that larger doses of botulinum toxin produce longer spasm-free intervals in the treatment of blepharospasm. One patient receiving injections for her blepharospasm discovered that its cause was her sedative medication. This is the first reported case of a benzodiazepine inducing blepharospasm to our knowledge.