The effect of botulinum toxin injections to the calf muscles on freezing of gait in parkinsonism: a pilot study

Background Freezing. of gait (FOG) is a common and very disabling parkinsonian symptom, which is poorly understood and responds unsatisfactorily to medical treatment. We recently reported a unique patient with Parkinson's disease (PD) who had significant alleviation of FOG shortly after she was injected with botulinum. toxin type A (BTX-A) for foot dystonia (Giladi et al. 1997). Objective To assess the effect of BTX-A injections into the calf muscles of parkinsonian patients on FOG. Method BTX-A was injected in an open fashion into the calf muscles of 10 parkinsonian patients (age 55-75 years) with FOG as a predominant symptom. Response of FOG was assessed subjectively by the patient from worsening (-1) to marked improvement (+3). One patient was injected in a single blind fashion with saline or BTX-A after he had an initial good response. Results Seven patients reported different rates of improvement of FOG severity in 15 out of 17 therapeutic sessions. Four patients (40%) reported marked improvement (+3) of FOG in 5 sessions. Two patients reported no effect in two sessions. The mean duration of improvement was 6 weeks. (range 1-12 weeks) with definite deterioration afterwards. The patient who was injected in a single blind fashion did not respond to saline injections but improved significantly with BTX-A treatment. Conclusions We observed a dear temporal relationship between BTX-A injections into the calf muscles of parkinsonian patients and improvement of FOG. A double blind placebo controlled prospective study is needed before any conclusions can be drawn about the role of BTX-A injection in FOG.