Bilateral pallidal stimulation improves cervical dystonia for more than a decade

Introduction: Deep brain stimulation (DBS) is an effective treatment in medically resistant cervical dystonia (CD) with a documented therapeutic effect. Long term outcome beyond a decade, however, has not been studied systematically.

Methods: To investigate the impact of pallidal DBS beyond 10 years in CD we followed a series of five consecutive patients with severe medication-resistant CD. Severity of head and neck deviation, disability, and pain related to dystonia were assessed by the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) in the frame of a prospective study. The primary endpoint of this study was a change in the TWSTRS total score. Secondary endpoints were changes in the subscores of the TWSTRS.

Results: The mean follow-up time was 11.5 years (range 10-12.8). Comparing baseline and the last follow-up, CD improved by 53% on the total TWSTRS score, by 54.1% on the severity score, and by 70.1% on the disability score, while pain did not improve significantly. Improvement was stable over time. Patients with a tonic pattern of CD responded less to DBS than patients with a phasic pattern. DBS had no significant effect on mood and cognition. Two patients underwent electrode revisions. One patient had an infection of the proximal cable two years after surgery.

Conclusions: Chronic bilateral pallidal stimulation improves severity of dystonia and disability over more than a decade in treatment resistant CD. Results may vary among individual patients.