<b>Spinal cord stimulation and thalamic surgery for the treatment of central post-stroke pain </b>

Abstract

Objective. We studied the surgical results and indications of spinal cord stimulation and thalamic surgery for the purpose of treating central post-stroke pain (CPSP). Subjects and Methods. CPSP due to unilateral cerebrovascular disease (CVD) lesion was studied in 17 subjects. Pain was localized on the limb (localized type CPSP) in 7 cases and distributed on the hemibody (diffuse type CPSP) in the other 10 cases. All cases of localized type CPSP were treated by epidural spinal cord stimulation. For cases with diffuse type CPSP, stereotactic Vim-Vcpc thalamotomy was performed in 6 cases and thalamic Vim-Vcpc stimulation in 4 cases using depth micro-recording. Evoked pain was dominant in the former and continuous, sometimes intermittent, pain was dominant in the latter. Prior to the operation, we studied somatosensory evoked potentials (SEP) in all cases of localized type CPSP and in 6 cases with diffuse type CPSP treated by thalamotomy. In cases involving thalamic surgery, electrophysiological data obtained during surgery included background neural activity (BNA), sensory response (SR) and burst discharge (burst), and responses to micro-stimulation in the thalamic sensory nucleus. Results. In 7 cases with localized type CPSP treated by spinal cord stimulation, sufficient pain relief was achieved in 4 cases, moderate in 2 cases and fair in one case. In 10 cases with diffuse type CPSP, good was achieved in 3, moderate in one, fair in 2 out of 6 cases treated by thalamotomy, and good in 2 and moderate in 2 out of 4 cases treated by thalamic stimulation. With the exception of one "fair" respondent to spinal cord stimulation, we recognized definite SEP originating in the sensory cortex (N20). However, SEPs were flat in 4 cases and the amplitude of N20 markedly decreased in the other 2 cases treated by thalamo tomy. Using results taken from the electrophysiological study during thalamic surgery, these patients could be classified into 3 groups. In group A (3 cases), we found SR frequently and rarely encountered bursts in a wide area of the thalamic sensory nucleus. In group B (5 cases), we encountered marked burst discharges with high amplitude and of various duration. These were recogn ized around decreased or voided areas of thalamic neural activity. In 2 cases, which were classified as group C, we found a decrease of BNA, few bursts 146 M. Hirato et al.