Pittsburgh, June 12, 2000 -- Giving botulinum toxin (Botox) injections to patients with hemifacial spasms may hinder the patients' response to future definitive surgical treatment, according to a study by neurological surgeons at the University of Pittsburgh Medical Center.

Published in the March 2000 issue of Skull Base Surgery, the study is the first to demonstrate that the use of Botox may have a deleterious effect on patients who may eventually need microvascular decompression surgery.

Decompression surgery is an operation that involves removing the pressure against the facial nerve at its origin in the brain stem. Hemifacial spasm is a condition that causes uncontrollable twitching of the face sometimes resulting in severe convulsions that prevent reading or driving. Botox is a muscle paralytic that disturbs that nerve endings as they insert into the facial muscles, often creating noticeable facial weakness.

In the study, Amin Kassam, MD, assistant professor in the department of neurological surgery at the University of Pittsburgh School of Medicine and director of the Center for Cranial Nerve Disorders and Microvascular Surgery, reviewed records of 88 surgical patients treated over the previous 20 months and performed surveys to assess satisfaction with microvascular decompression surgery.

Overall, 92 percent of patients had at least a 67 percent reduction in spasm, reporting a good result. Fifty patients received Botox prior to surgery with an average of 113 injections per patient. There was no difference between patients with and without Botox as measured by the amount of spasm following surgery.

However, the amount of spasm improvement over the longest follow-up period of 13 months was significantly different between the two groups. Five out of the 50 patients with Botox injections had less than 67 percent reduction in spasms while only one of 18 patients without Botox injection has similar results. In addition, the incidence of recurrence was twofold greater in the Botox group who also had a threefold increase in the incidence of Bell's Palsy.

"Based on these findings, we conclude that Botox injection for hemifacial spasm does impact on the success of microvascular surgical decompression and therefore may hinder a patient's response to definitive surgical treatment," Dr. Kassam said.