Efficacy of safinamide as add-on therapy after subthalamic nucleus deep brain stimulation in Parkinson disease

Background: Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective surgical treatment for advanced Parkinson’s disease (PD). However, some patients still experience motor fluctuations or dyskinesia after STN-DBS. Safinamide is approved as add-on treatment to levodopa in fluctuating PD patients. In this study, we evaluated the effect of safinamide as adjunctive therapy in PD patients still experiencing motor fluctuations and dyskinesias after STN-DBS. Methods: PD patients treated for at least 2 years with bilateral STN-DBST and with troublesome motor fluctuation and/or dyskinesias were examined by means of the Movement Disorders Society—Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), the quality of life questionnaire Parkinson’s Disease Questionnaire-8 (PDQ-8) and the Non-Motor Symptoms Scale (NMSS) at baseline (T0), after 1 month of treatment with safinamide 50 mg daily (T1) and after another month of treatment with safinamide 100 mg daily (T2). Results: Twenty-nine PD patients were examined. An improvement of the MDS-UPDRS IV score (motor complications) was observed between T0 and T1, T0 and T2, and T1 and T2. The time spent in the OFF state, the functional impact and the complexity of motor fluctuations significantly improved between T0 and T1 and T0 and T2. The mean levodopa equivalent daily dose significantly decreased from T0 to T1 and from T0 to T2. Regarding non-motor symptoms, an improvement on mood and pain was observed. Conclusions: Safinamide seems to be an effective adjunctive treatment in PD patients treated with bilateral STN-DBS, leading to an improvement of motor complications, mood and pain.