Radiofrequency neurolysis in a clinical model

Abstract

Reports differ on which nerve fibers are affected by radiofrequency lesions made in peripheral nerves, some stating that primarily the myelinated delta and unmyelinated C fibers are destroyed, others stating that the destruction affects all sizes of nerve fibers and both myelinated and unmyelinated fibers. This study was designed to confirm 1 of those 2 findings, and to study the role that different temperatures might play in determining which fibers are affected. Radiofrequency lesions (85.degree. C for 2 min) were made in dogs by placing a temperature-monitored electrode into the lumbar intervertebral foramina. The dogs were killed at intervals up to 6 wk after rhizotomy, and the lesions were studied by light microscopy and EM. In all lesions there was a total loss of unmyelinated fibers and a nearly total loss of myelinated fibers. In other dogs, 2-min lesions were made at 45, 55, 65 and 75.degree. C, and the lesions examined 1 wk later. All sizes and types of fibers were destroyed.