Objective: To determine the effect of injections of botulinum toxin on simple motor tics.
Background: Case series with unblinded assessments have reported improvement in tic frequency and associated urge with botulinum toxin.
Methods: Patients with suitable simple motor tics were randomized to receive botulinum toxin and placebo in a double blind, crossover design. All outcomes compared week 2 to baseline measurements. The primary outcome measure was the number of treated tics per minute on a videotape segment. Secondary outcome measures were number of untreated tics per minute, the Shapiro Tourette Syndrome Severity Scale score, a numerical assessment of the urge to perform the treated tic (0 to 4), the premonitory sensation associated with the treated tic (0 to 4), and the patient's global impression of change.
Results: Eighteen patients completed the study. The median relative change in treated tics per minute with botulinum toxin was -0.39 (or a 39% reduction) versus 0.058 (or a 5.8% increase) with placebo (net effect -0.37, p = 0.0007). The average change in urge scores (score range 0 to 4) was -0.46 in the treatment phase and +0.49 in the placebo phase (net effect 0.94, p = 0.02). Other secondary outcome measures were not significantly different between the two groups.
Conclusion: Botulinum toxin reduced treated tic frequency and the urge associated with the treated tic. Despite these changes, patients did not report an overall benefit from the treatment. Careful consideration of the contribution of the target tic to the patient's disability is needed before making treatment decisions.