Botulinum toxin type B for gait freezing in Parkinson’s disease

BACKGROUND: Freezing of Gait (FOG) can be a serious problem in Parkinson's disease (PD) and is usually refractory to medical treatment. Botulinum toxin (BTX) type A has been reported to relieve FOG in small open label studies. MATERIAL/METHODS: We performed a double-blind, placebo-controlled, parallel-group study using BTX-B injections on the soleus-gastrocnemius muscle complex of the predominantly affected leg in freezing. Patients were evaluated at baseline and monthly thereafter until endpoint was reached. UPDRS parts II and III, Visual Analog Scale (VAS), Clinical Global Impression Scale (CGIS) and Modified Webster Step-Seconds test were the used to measure efficacy. RESULTS: 14 out of 17 patients screened with idiopathic PD and FOG refractory to medical treatment met inclusion criteria for the study. 9 patients were randomized to 5,000 U of BTX-B treatment and 5 patients to placebo. Our cohort had a mean age of 74 years, and average PD duration of 10 years. Based on the CGIS, 1 patient was much improved, 2 patients had minimal improvement, 9 were unchanged from baseline and 2 were minimally worse. There was no significant difference between the treatment and placebo arms in the number of patients improved versus unchanged. There were no significant differences between the treatment and placebo arms in the UPDRS II and III, VAS, or Modified Webster Step-Seconds scores between the treatment and placebo arms, at baseline and after treatment. CONCLUSIONS: 5,000 U of BTX-B injected in one leg did not significantly improve FOG. However, since the power of the study was low, a small beneficial effect may have been missed.