To Örebro University

Background: Dyskinesia is among the most troublesome symptoms of advanced Parkinson's disease (PD). The recently developed Unified Dyskinesia Rating Scale (UDysRS) can simultaneously measure several subjective and objective aspects of dyskinesia, irrespective of the other motor symptoms of PD. Despite the advantages of deep brain stimulation (DBS), previous studies on DBS have not used the UDysRS yet.

Methods: In this prospective study, 71 consecutive patients undergoing DBS implantation were enrolled. Patients were examined twice: 1 week prior to the DBS implantation (baseline) and 12 months postoperatively. The severity of PD-related symptoms was assessed by the Movement Disorders Society Unified PD Rating Scale (MDS-UPDRS). The presence and severity of dyskinesia were specifically measured by the UDysRS and patient diaries.

Results: At baseline, all 71 patients had dyskinesia, but 1 year after DBS implantation, 25 patients were dyskinesia-free, and an additional 19 had only mild dyskinesia. The total score on the UDysRS decreased from 38.0 ± 17.8 to 10.8 ± 13.0 (p < 0.001). Besides this, all parts of the UDysRS showed significant improvement after STN DBS treatment, and the magnitude of these changes had a large effect size. The total score of MDS-UPDRS improved from 76.5 ± 24.3 to 60.4 ± 21.4 points (p < 0.001).

Conclusions: Based on our results, UDysRS can reliably detect improvements in dyskinesia after DBS implantation.