More MS news articles for May 2001

Botulinum Toxin for Simple Motor Tics

A Randomized, Double-Blind, Controlled Clinical Trial

Extracted from:

March 13, 2001 (Volume 56, Number 5)
Marras C, Andrews D, Sime E, et al
Neurology. 2001;56:605-610

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:

In total, 18 patients completed the study -- 13 men and 5 women with a median age of 31.5 years (range, 15-55). Fourteen patients had Tourette syndrome and 4 had been diagnosed with a chronic motor tic disorder. The results demonstrated a significant reduction in the frequency of treated tics and the associated urge. The median relative change in treated tics per minute with botulinum toxin was -0.39 <<coders: note minus signs thruout>> (39% reduction) compared with 0.058 (5.8% increase) with placebo (net effect was -0.37; P = .0007). The average change in urge scores was -0.46 in the treatment phase and +0.49 in the placebo phase (net effect 0.94; P = .02). Unfortunately, despite the objective improvement, the participants did not report any significant clinical benefit of the treatment. There were no changes in the indices for overall patient well-being. The authors pointed out some limitations of the study, including the small sample size and the lack of an evident placebo response, suggesting possible patient unblinding. Since botulinum toxin frequently results in weakness of the injected muscles, the presence or absence of such an effect may have been noted by some of the patients thus providing a clue about the treatment administered. Careful patient selection is important before the administration of botulinum toxin therapy. The tic targeted for treatment should cause some significant functional impairment and be assessable for injection.