Chronic motor cortex stimulation in the treatment of central and neuropathic pain. Correlations between clinical, electrophysiological and anatomicaldata

Thirty-two patients with refractory central and neuropathic pain of periphe ral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27.3 months. The first 24 patients were operated according to the technique described by Tsubokawa. The last 13 cases (eight new patients and five reinterventions) were operat ed by a technique including localisation by superficial CT reconstruction o f the central region and neuronavigator guidance. The position of the centr al sulcus was confirmed by the use of intraoperative somatosensory evoked p otentials. The somatotopic organisation of the motor cortex was established peroperatively by studying the motor responses at stimulation of the motor cortex through the dura. Ten of the 13 patients with central pain (77%) an d ten of the 12 patients with neuropathic facial pain had experienced subst antial pain relief (75%). One of the three patients with post-paraplegia pa in was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related t o intercostal herpes zooster. None of the patients developed epileptic seiz ures. The position of the stimulating poles effective on pain corresponded to the somatotopic representation of the motor cortex. The neuronavigator l ocalisation and guidance technique proved to be most useful identifying the appropriate portion of the motor gyrus. It also allowed the establishment of reliable correlations between electrophysiological-clinic al and anatomi cal data which may be used to improve the clinical results and possibly to extend the indications of this technique. (C) 1999 International Associatio n for the Study of Pain. Published by Elsevier Science B.V.