Stimulation of the Motor Cortex for Chronic Neuropathic Pain: Anatomo- Clinical Correlations
Afif AFIF and Patrick MERTENS
Department of Neurosurgery, Pain center, Pierre WERTHEIMER Hospital, Hospices Civils de LYON, France
: J Spine Neurosurg
Abstract
The aim of this study was to search the relationship between the anatomical location of contactsand the eventual analgesic effect. Materials and Methods: 22 patients suffering from central and / or peripheral neuropathic pain were implanted withextradural stimulation of the precentral cortex. Implantation electrodes were performed using intraoperative: 1) Anatomical identification by Neuronavigation with 3D MRI, 2) Somestheticevoqued potentials monitoring, 3) Electricalstimulations to identify the motor responses. In order to locate postoperatively the electrodes, a 3D-CT was performed and fused with thepreoperative MRI. The clinical analgesic effects of cortical stimulation were collected on aregular basis (VAS reduction > 50%, drugs consumption). Results: Post implantation analgesic effects were obtained in 19 patients out of 22. The analgesic effectwas companied with reduction of the drugs consumption in 17 patients. The post-operative3 D CT analysis shows a correspondence between the effective contacts localization andthe motor cerebral cortex somatotopy in the patients with post-operative good analgesic effects. No correspondence was found between the contacts localization and the motor cerebral cortexsomatotopy in the 4 patients with no analgesic effects. In three out of these four patients,analgesic effects were obtained after a new surgery allowing a replacement of the electrodeposition over the motor cortex somatotopy corresponding to the painful area. Conclusion: This study shows the correlation between position of the contact (cathode) overthe precentral cortex and the analgesia obtained when the somatotopy of the stimulated cortexcorrespond to the painful area.
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