Neurophysiologic testing in chronic pelvic pain syndrome: a pilot study

Studies of male chronic pelvic pain syndrome (CPPS) have generally centered on the pathologic features of the prostate rather than on the neurology of pain. Electrodiagnostic studies examine the integrity of somatosensory nerve pathways consisting of large, group A fibers. Heat sensation and visceral (autonomic) pain is mediated through small, unmyelinated C fibers, which can be tested cutaneously by thermal sensory analysis. We hypothesized that CPPS pain is mediated by these small C fibers.

All subjects and controls had no history of neurologic disease and had normal neurologic examinations. Phase I: 14 patients with CPPS underwent electrodiagnostic testing using pudendal somatosensory evoked potentials and bulbocavernosus reflex latency measurements. Phase II: 31 patients with CPPS and 14 controls underwent thermal sensory analysis testing on the perineum and anterior thigh using noxious heat stimuli. Subjects used a computer-generated visual analog scale to dynamically report their discomfort. The peak and slope of the computer-generated visual analog scale were analyzed.

Phase I: two patients had delayed latency of the somatosensory evoked potentials, but additional evaluation with magnetic resonance imaging revealed no definable lesion. Phase II: with thermal sensory analysis, men with CPPS reported higher intensity pain at lower temperatures (P = 0.03). Men with CPPS also had higher peak computer-generated visual analog scale scores on perineal testing. No difference in thermal testing on the anterior thigh was found between the two groups.

Large, myelinated somatic fibers do not play a significant role in the pathophysiology of CPPS. Patients with CPPS have an altered sensation of perineal pain elicited by heat, which may represent a C-fiber-mediated effect.