Neurostimulation for pain of spinal origin.

INTRODUCTION Neurosurgical procedures for pain may be anatomic (attempting to correct the physical cause of the pain), ablative (destroying pain pathways), or augmentative (modulating the existing neurological anatomy and physiology). The available augmentative procedures, commonly referred to under the umbrella “neuromodulation,” include spinal cord stimulation (SCS). Although augmentative procedures are reversible and can be tested through screening trials before a device is implanted for chronic use, they have, until recently, been reserved for patients who failed to gain relief through anatomic or ablative procedures and had exhausted the possibilities offered by other alternative therapies. The high initial cost of augmentative therapy might explain this bias. SCS is an augmentative procedure that relies on artificially generated paresthesia to achieve pain relief by replacing the sensation of pain with one that is commonly described as “tingling.” To be effective, the paresthesia must cover the topography of the pain. The major determinant of the distribution of paresthesia is the spinal location of the stimulating cathodes and anodes.2 Programmable pulse generators allow noninvasive, post-implantation selection of various electrode contact combinations. The major indication for SCS in the United States is failed back surgery syndrome (FBSS). This catch-all diagnosis is made when one or more previous operations on the spine fails to provide a patient with long-term pain relief. In part, because FBSS patients are not distinguished on the basis of the various indications for the initial operation or according to the suspected reason for the failures, FBSS is particularly difficult to treat.