Neurophysiologic testing in chronic pelvic pain syndrome: a pilot study

Area of Science:

• Neurology
• Pain Medicine
• Urology

Background:

• Chronic pelvic pain syndrome (CPPS) in men is often studied focusing on prostate pathology, neglecting the neurological basis of pain.
• Nerve pathways involved in pain sensation include large, myelinated A-fibers (tested by electrodiagnostics) and small, unmyelinated C-fibers (tested by thermal analysis).
• Visceral pain and heat sensation are primarily mediated by C-fibers.

Purpose of the Study:

• To investigate the role of small, unmyelinated C-fibers in the pain experienced by men with CPPS.
• To differentiate between A-fiber and C-fiber involvement in CPPS pathophysiology.

Main Methods:

• Phase I involved electrodiagnostic testing (pudendal somatosensory evoked potentials, bulbocavernosus reflex latency) in 14 CPPS patients.
• Phase II utilized thermal sensory analysis with noxious heat stimuli on the perineum and anterior thigh in 31 CPPS patients and 14 controls.
• Subjects dynamically reported discomfort using a visual analog scale, with peak and slope analyzed.

Main Results:

• Electrodiagnostic testing showed minimal abnormalities in Phase I, with no clear lesions found via MRI.
• Thermal sensory analysis in Phase II revealed that men with CPPS reported significantly higher pain intensity at lower temperatures (P=0.03).
• CPPS patients exhibited higher peak visual analog scale scores during perineal heat testing, but no differences were observed in anterior thigh testing.

Conclusions:

• Large, myelinated somatic nerve fibers do not appear to be significantly involved in the underlying mechanisms of CPPS.
• CPPS patients demonstrate an altered perception of perineal pain in response to heat, indicative of a potential C-fiber-mediated pathway.
• Findings suggest a C-fiber dysfunction contributes to the neuropathic pain experienced in male CPPS.