Extradural motor cortex stimulation in advanced Parkinson's disease: the Turin experience: technical case report

At our institution, extradural motor cortex stimulation (EMCS) has recently been applied for treating Parkinson's disease symptoms. We report our results and review the literature supporting this application of EMCS.

Since 1998, six patients affected by advanced Parkinson's disease and not fulfilling inclusion criteria for deep brain stimulation underwent EMCS.

A quadripolar electrode was introduced in the extradural space over the motor cortex, opposite to the side on which parkinsonian symptoms had begun. Bipolar chronic electrostimulation was delivered at 2.5 to 6 V, 150 to 180 microseconds, and 25 to 40 Hz. Preoperative and postoperative clinical status was assessed by the Unified Parkinson's Disease Rating Scale (UPDRS) and recorded on videotapes. The follow-up of this series varied from 4 months to 2.5 years. After EMCS, the overall UPDRS score decreased by 42 to 62%; Section III UPDRS score (motility evaluation) by 32 to 83%; and Section IV UPDRS score (therapy complications) by 100% in two patients, by 50 to 67% in four patients, and by 33% in one patient. L-Dopa therapy was reduced by 11 to 33% in three patients and by 70 to 73% in the other two patients. No postoperative complications or negative side effects of electrostimulation were recorded, except for a misplacement of the electrodes in one patient.

Unilateral EMCS relieves, at least partially, but sometimes dramatically, the whole spectrum of symptoms in advanced Parkinson's disease. L-Dopa may be reduced up to 70%. The symptoms of long-term L-dopa syndrome are usually markedly improved. The neurophysiological mechanisms involved are still under debate. Our clinical experience adds favorable data to enlarge the series of parkinsonian patients treated by EMCS.