"This is the first large trial to show that botulinum toxin type A improved function and muscle tone following a stroke," said Indiana University neurologist Allison Brashear, principal investigator of the study. "A number of studies have demonstrated that botulinum toxin type A decreases muscle rigidity in spastic muscles, and one small study has shown functional improvement from this therapy. However, use of the therapy has become common practice, so the point of this clinical trial was to assess the effects of one-time treatment on a large, controlled group."

The prevalence of arm and hand spasticity associated with stroke is high. Upper-limb spasticity is especially debilitating because it can interfere with daily activities, including personal hygiene and dressing.

All the 126 volunteers enrolled in the 12-week study had some degree of spasticity in their wrist or fingers after a stroke. Half the study participants received one-time injections of 200 to 240 units of botulinum toxin type A--a highly purified and diluted form of the toxin that causes botulism. The remaining patients were injected with an inactive substance.

Significant improvement in wrist and finger flexors was observed in the majority of patients one week after the Botox injection. The improvement was sustained at the 12-week follow-up. Following the conclusion of the study, 111 of the 126 participants volunteered to receive up to three additional treatments. Researchers say each set of injections had positive effects that lasted as long as 24 weeks.

In 2000, Botox therapy was FDA-approved for the treatment of cervical dystonia, a movement disorder characterized by involuntary muscle contractions. In April 2002, Botox Cosmetic was approved for the temporary improvement in moderate to severe forehead wrinkles in men and women age 65 or younger.