Patient-interactive, computer-controlled neurological stimulation system: clinical efficacy in spinal cord stimulator adjustment.

Abstract

Over the past 20 years, continuing technical advances have rendered spinal cord stimulation an easily implemented low-morbidity technique for the management of chronic intractable pain in properly selected patients. Percutaneous methods for the insertion of arrays of multiple epidural electrodes, which are driven by noninvasively programmable "multichannel" implanted devices, have been among the most important of these technical improvements. The same implanted electronics may be used with peripheral nerve or intracerebral electrodes. If the capabilities of this new hardware are to be used to full advantage, a major investment of time and effort is required to adjust the system postoperatively for optimum effect. Ideally, these adjustments should be based upon psychophysical data, obtained in a manner that minimizes influences such as potential operator bias or stimulus presentation-order effects. These requirements have been met by the development of a computerized system designed for direct patient interaction and for greater ease of operation than the standard external devices used with these implants. The system has been tested clinically in 25 patients with spinal cord stimulation for pain. It rapidly tests the available electrode combinations and stimulus pulse parameters at a rate comparable to or greater than that of a skilled human operator using the standard device. It records detailed graphic data and patient analog ratings at varying thresholds and implements "pain drawing" methods with novel input and analytical techniques. This patient-interactive computerized system has proved to be safe and effective clinically. The time required by the average patient working with this system to adjust the stimulator is comparable to or less than the time required by the same patient working with a physician's assistant. Psychophysical data collected by the system may be correlated with clinical observations. Ongoing development will permit delivery of novel pulse sequences and protocols to assess the mechanisms by which stimulation affords relief from pain.