A Randomized, Double-Blind, Controlled Clinical Trial
March 13, 2001 (Volume 56, Number 5)
Marras C, Andrews D, Sime E, et al
Botulinum toxin, produced by the anaerobic bacterium Clostridium botulinum, creates a paralytic effect by inhibiting the release of acetylcholine from the presynaptic nerve terminal. Botulinum toxin therapy has been used in a variety of movement disorders, including cervical dystonia and hemifacial spasm. The "success" of the treatment depends on several factors, including the severity of the underlying movement disorder and the amount of toxin administered. Marras and colleagues conducted a randomized, placebo-controlled, double-blind study to evaluate the effect of botulinum toxin injections on simple motor tics. Previous studies have demonstrated positive responses to the treatment.
The patients were eligible for enrollment if they had at least 1 simple motor tic from an idiopathic tic disorder and the muscle involved was amenable to injection. The study group was assembled from individuals enrolled in a movement disorders clinic and Tourette syndrome center. Advertisements were also placed in the local Tourette Syndrome Society newsletter. No alteration in medication was allowed for 1 month before the start of the trial. At each visit, the patients were examined and videotaped, and clinical assessment scales were completed to determine the severity of the underlying tic disorder and urge to perform the tic. The amount of pain and premonitory sensations were also assessed. With regard to clinical results, the patients were asked about adverse reactions and whether they felt the injections had any effect on the tic disorder.
The participants were randomized to receive botulinum toxin and placebo in a double-blind, crossover design. Evaluations were made at weeks 2, 6, and 12 and, if required, every 4 weeks thereafter until the patient and examiners felt the tic disorder had returned to baseline. The patient then crossed over into the second phase of the trial where the opposite treatment was given. The primary outcome measure was the number of treated tics per minute of a videotape segment. The secondary outcome measures included: