[Centro-median thalamotomy for central pain following stroke --its effectiveness and limits]

Centro-median thalamotomy was performed on 18 patients with central pain caused by cerebrovascular disease. Fourteen were males and four were females. Clinical diagnoses were thalamic pain in 17 cases including cheiro-orale syndrome in one case and phantom limb pain in one case. CT scans were performed on six recent cases. Four cases had a small low density sera in the thalamus. The other two cases had no remarkable findings. The target was 7.5-11.0 nm posterior to the middle point of the intercommissural line, 1.0 mm below-2.0 mm above that line and 5.5-10.0 mm from the midline. Unilateral lesion was made on 15 cases. Postoperatively, five cases had almost completely relief of pain and four cases had partial improvement. The duration of pain relief was, however, less than two months in four cases, and between three and seven months in four cases. One case had a pain free period for seven months. But, then, severe dysesthesia appeared. Six cases had no pain relief by unilateral lesion. Two cases had no pain relief by bilateral lesions. In the remaining case, unilateral lesion was effective for six months. Then lesion of opposite side was made, but the result was unsatisfactory. The durations from the onset of apoplectic attack to the occurrence of pain were between four months and three years in ten effective cases, and within three months in six among eight failed cases. Many surgical and medical treatments have been attempted for central pain. However, ideal method is still not appeared. Centro-median thalamotomy was effective for 56% of the patients with central pain. But in most of the cases, the duration of pain relief is about a half year at the longest. And may be, this is the limit of effectiveness of centro-median thalamotomy for central pain.