Extradural motor cortex stimulation in Parkinson's disease

Extradural motor cortex stimulation (EMCS) is a surgical procedure proposed for patients with advanced Parkinson's disease (PD) who cannot undergo deep brain stimulation (DBS). Five PD patients with motor fluctuations and dyskinesia underwent EMCS of the left hemisphere. All fulfilled CAPSIT criteria for DBS, with the exception of age > 70 years. Patients were assessed preoperatively and 6 months after surgery on and off medications, with stimulator on, and 2 weeks later with stimulator off. Outcome measures included changes in mean medication dosage (levodopa and dopamine agonists), Unified Parkinson's Disease Rating Scale (UPDRS Parts II-III and Item 39), and dyskinesias (Abnormal Involuntary Movements Scale [AIMS]). We found no significant mean changes following EMCS. However, there was a trend for a reduction of mean daily medication intake (-30%) and AIMS (-19%). There were 3 patients who reported reduced OFF time (UPDRS Item 39) and 4 of 5 who felt a subjective benefit in stability and gait. In our PD cohort, EMCS induced no objective benefit, although some subjective improvement was reported mostly on axial symptoms.