Botulinum toxin for foot dystonia in patients with Parkinson's disease having deep brain stimulation: A case series and a pilot study.

[BACKGROUND] Six patients with Parkinson's disease with deep brain stimulation who were experiencing disabling foot dystonia were referred to the spasticity clinic for a trial of botulinum toxin. The foot and ankle muscles were injected with onabotulinum toxin (Botox) to determine the effects on foot dystonia, pain and lower limb functional outcomes.

[DESIGN] Case series.

[SUBJECTS/PATIENTS] Six patients with Parkinson's disease with deep brain stimulation experiencing disabling foot dystonia.

[METHODS] Dystonic foot and ankle muscles were identified and injected with 250-400 units botulinum toxin and re-coded pre- and 3 weeks post-injection with the Burke Fahn Marsden Dystonia score, visual analogue score of pain, Unified Parkinson's Disease Rating Scale (UPDRS) - lower limb score, Timed up and Go test (TUG), 6-Minute Walk Test (6MWT), gait velocity, cadence in an instrumented walkway, and Goal Attainment Scale (GAS).

[RESULTS] Three weeks after botulinum toxin injection, significant improvements were noted in dystonia, pain, UPDRS, 6MWT, gait velocity, and cadence. Five out of 6 patients improved on the TUG test. Patients also reported improvements in their GAS goals.

[CONCLUSION] Botox injection significantly improved foot dystonia, pain and lower limb functional outcomes in patients with Parkinson's disease with deep brain stimulation.