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.