Objective: To describe the response to treatment with botulinum toxin in a cohort with adult onset lower limb dystonia.

Background: Adult onset, lower limb dystonia is a unique dystonia with few prior published reports. While previous literature focused mostly on the etiology and phenomenology of this condition, response to treatment has rarely been reported. We describe the response to botulinum toxin in a cohort of 9 patients with adult onset lower extremity dystonia treated at our institution.

Methods: Data was extracted from the NIH Movement Disorders Section database. Unpaired t-tests and Fisher’s exact tests were used for comparisons.

Results: Our cohort includes 6 women and 3 men with a mean age of symptom onset of 56 years (range 47-61). Patients developed dystonia an average of 2.9 (SD 2.6) years before botulinum toxin treatment was initiated. The majority of patients (6/9) received on abotulinum toxin A; 3/9 were treated with incobotulinum toxin A. 4/9 patients were “responders,” with self-reported benefit after last dose of >50%, while 5/9 patients reported <50% benefit. 2/9 exhibited consistent benefit of at least 85% after repeated injections. Both patients with consistent benefit were female and achieved this degree of benefit by the 3rd set of injections with selection of muscles and dose titration adjusted to response. Comparing responders to non-responders, although all male patients were non-responders, the difference in response between sexes was not statistically significant. Other factors such as whether patient was a long-distance runner, mean age of dystonia onset, or mean symptom duration prior to initiation of botulinum toxin treatment were not associated with response vs non-response.

Conclusions: Our results demonstrate that the response to botulinum toxin is highly variable in patients with adult onset lower extremity dystonia. While some patients exhibit consistently excellent response over time, others have inconsistent or little to no benefit. While both patients who exhibited consistent benefit were female, there did not appear to be any other factors that correlated with response to botulinum toxin injections. However, given the high degree of symptomatic improvement achievable in some patients, a trial of at least 3 injection sessions, with attention to muscle selection and dose titrated to response, should be considered in patients with adult onset lower limb dystonia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/response-to-botulinum-toxin-in-adult-onset-lower-limb-dystonia/