Sensory recovery after decompression of the distal pudendal nerve: Anatomical review and quantitative neurosensory data of a prospective clinical study

Objectives. Decompression of peripheral nerves at different anatomic sites leads to long-lasting improvement of nerve function. For the pudendal nerve such compression sites have also been described, however, indication for surgical decompression at the dorsal nerve canal, and outcome measures have not been presented. In the following work, we review the detailed anatomy of the pudendal nerve at its passage through the urogenital diaphragm into the base of the penis and present the results of our first five patients. Methods. Normative neurosensory data of the penis of 20 normal individuals and 10 diabetics were obtained. Both One- and Two-Point Discrimination values were obtained. Five male patients were identified to have isolated distal pudendal nerve entrapment and a nerve release was performed. Both pre and postoperatively detailed neurosensory data was obtained, with a mean follow up of 18 months. Results. Neurosensory evaluation revealed that classic two-point discrimination was an invalid parameter in penile sensation. However, one point pressure threshold testing was significantly higher in diabetics (25 ± 14 gm/mm²) than in normal subjects (1.1 ± 0.6 gm/mm²). Surgical exposure showed signs of nerve entrapment in two patients. All patients showed sensory improvement after decompression. Conclusions. The distal pudendal nerve is susceptible to compression at the passage from Alcocks canal to the dorsum of the penis. Diabetic patients with peripheral neuropathy can suffer from additional compression neuropathy with decreased penile sensibility and dysaesthesia. One-point pressure threshold testing proved to be a sensitive parameter in the diagnosis and finally, patients would benefit from decompression of the pudendal nerve.