Chronic Pelvic Pain: Neurogenic or Non-Neurogenic? Warm Detection Threshold Testing Supports a Diagnosis of Pudendal Neuropathy.

Background: Chronic pelvic pain (CPP) in men is rarely considered to have a neurogenic (neuropathic) basis. Separation of neurogenic from non-neurogenic pain is possible using clinical examination and neurophysiologic tests. A definite diagnosis of neuropathic pain can be made.

Objectives: We aim to demonstrate that definite pudendal neuropathic abnormalities can be supported by a quantitative sensory test (QST) called the warm temperature threshold detection (WDT) test in men with CPP.

Study Design: This is a retrospective review of 25 consecutive, unrecruited men evaluated in a private clinical practice beginning on January 1, 2010. The techniques of examination and neurophysiological testing have been standard since 2003.

Setting: A private practice that is a referral center because of its focus on CPP of a neuropathic basis.

Methods: Pinprick sensation was evaluated at 6 sites in the pudendal nerve territory (3 branches on each side). A WDT was performed at each nerve branch using a Physitemp NTE-2C Thermoprobe and Controller. This used a stepping algorithm from a neutral baseline of 31.5°C. Quantitative and subjective "qualitative responses" were recorded. Our preferred symptom score to evaluate pain level at consultation is the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI). The results become the benchmark for comparison of responses following future treatments (not discussed). When possible, microscopy was used to evaluate prostate secretions for inflammatory prostatitis except in 2 men with CPP who had undergone previous radical prostatectomy for cancer. Observations were made of the skin in the pudendal territory. Our specific evaluation for neuropathy also sought evidence of multiple additional neuropathic pelvic pain generators.

Results: The WDT was abnormal in all men (88% quantitative), and pinprick sensation was abnormal in 92% of the men. The combination of tests provided a diagnosis of pudendal neuropathy in all patients, resulting in an accurate and timely explanation of the neurogenic basis of their CPP symptoms. The NIH-CPSI scores ranged from 10 to 35 (median 25). Four of 15 men had inflammatory prostatitis in addition to pudendal neuropathy.

Limitations: There is selection bias because the men were either self-referred, suspecting their diagnosis from internet searches, or were referred by physicians who were aware of the focus of this clinical practice. The warm temperature testing used established normal values for the men. The NIH-CPSI does not evaluate sexual or bowel symptoms. Sensitivity or specificity values for the tests could not be obtained.

Conclusions: A possible neuropathic basis for CPP in men can be suspected from symptoms and history of activities. A probable diagnosis of neuropathy can be determined using a pinprick sensory evaluation in the pudendal territory. A definite diagnosis of pudendal neuropathy can be made using WDT. The combination of these 2 examinations demonstrated pudendal neuropathy in 100% of this cohort.The institutional review board deemed this study met criteria for exemption.

Key Words: Chronic pelvic pain, pudendal neuropathy, quantitative sensory testing, warm temperature detection threshold test, neuropathic pelvic pain, definite diagnosis of neuropathy, chronic prostatitis.