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 clear 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.