BOTULINUM TOXIN A IN NON-DYSTONIC TREMORS

The present pilot study evaluated the effect of botulinum toxin A on p rimarily non-dystonic tremors using accelerometry in a single-blind, p lacebo-controlled design. Resting, postural, intention, or head tremor were assessed before and approximately 1 month after intramuscular sa line and botulinum toxin A (25-50 U) respectively. Half of the patient s showed greater than or equal to 30% placebo effect. Tremor in 10 of 17 patients (60%) studied improved further after botulinum toxin A (ra nge 30-95%), exceeding the placebo effect by greater than or equal to 30%. Nine patients demonstrated clinically significant focal weakness in the extensor muscles after botulinum toxin A which interfered with fine movements. Patients were subdivided into PD-like and ET-like trem or(s). Both groups experienced large placebo effects for resting tremo r, with little or no further improvement after botulinum toxin A. The improvement in postural tremor after botulinum toxin A, of 40% in the PD-like and 57% in the ET-like groups, however, was approximately twic e that of placebo. In conclusion, botulinum toxin A exerts a modest tr emorlytic effect, however the dose, and its distribution over the site s injected, need to be optimised to minimise focal weakness.