Motor cortex stimulation for Parkinson's disease

In 2000, Canavero and Paolotti reported the improvement of symptoms in a case of advanced Parkinson disease (PD), following chronic epidural motor cortex stimulation (MCS). In 2002, the same group reported the results obtained in 2 patients with PD. Unilateral MCS proved to be beneficial bilaterally. They concluded that MCS may represent a cost-effective alternative to deep brain stimulation. In 2003, Pagni promoted an Italian Multicenter Study and in June 2005 the results in the first 29 cases were reported. Any symptom of PD could be modulated by MCS, but improvement of different symptoms was variable and unpredictable, with some patients being unresponsive. L-Dopa induced dyskinesias, painful dystonia and motor fluctuations were satisfactorily controlled. In the author's series, 2 patients were unresponsive and 5 patients showed a clinical improvement, particularly evident in the off-medication state; UPDRS-III mean improvement was 30% at 3 months and 22% at 12 months. Quality of life (QOL) also improved. Assessment by the Parkinon's disease quality of life (PDQL) scale showed a mean decrease by 26% at 12 months. No complication or adverse events were observed. These preliminary data indicated the possibility to modulate PD symptoms by MCS. Several unsettled issues remain such as the optimal electrode position, the best stimulation parameters, the usefulness of unilateral versus bilateral stimulation, the prognostic factors for best selection of patients, and the optimal assessment of clinical effects. The mechanisms of MCS may be only the subject of hypothesis.