Intractable pain of spinal cord origin: clinical features and implications for surgery.

The clinical features and types of pain affecting 127 patients with central pain caused by lesions in the spinal cord were studied and correlated with the results of surgical procedures performed on 103 of them. The surgical procedures consisted of percutaneous cordotomy in 39 cases, cordectomy in 12, dorsal root entry zone (DREZ) surgery in four, dorsal cord stimulation in 35, and brain stimulation in 13. The three most common types of pain in the 127 patients were characterized as: steady in 95% of cases, intermittent (usually shooting) in 31%, and evoked (allodynia, hyperpathia, or hyperesthesia) in 45%. Steady pain was usually causalgic (74.8%) or dysesthetic (27.6%). The only obvious clinical correlation with pain type was the association of intermittent pain with lesions at the T10-L2 vertebral level. Destructive surgery (cordotomy, DREZ surgery, or cordectomy) affected the three chief types of pain differently from treatment with cord or brain stimulation. Destructive surgery resulted in reduction of steady pain in 26% of affected cases, of intermittent pain in 89%, and of evoked pain in 84%, while stimulation resulted in pain reductions in 36%, 0%, and 16% of cases, respectively. The differential effect of destructive surgery on steady and intermittent pain is consistent with published experience. These observations suggest differing mechanisms for the three types of pain.