A Novel Electrophysiological Method in the Diagnosis of Pudendal Neuropathy: Position-related Changes in Pudendal Sensory Evoked Potentials.

OBJECTIVE: To examine the diagnostic value of pudendal somatosensory evoked potentials (SEPs) in pudendal nerve entrapment (PNE) neuropathy by stimulating the 2 sides separately after provocation by a standard sitting position. Routine pudendal SEPs performed in the supine position with bilateral simultaneous stimulation may fail to show the abnormality because the complaints of PNE appear or worsen in the sitting position.

METHODS: Forty-nine patients with PNE and 16 controls were included. SEP recordings were performed by stimulating the dorsal nerve of penis or clitoris on either side. The recordings were performed at the initial supine position, at the beginning and end of the provocation by sitting position, and at the second supine position.

RESULTS: Amplitude loss in the SEP responses after prolonged sitting was significantly more pronounced on the symptomatic sides of the patients. Approximately 45% decrease in the SEP amplitude or an amplitude value less than 1.5 µV at the end of sitting are the parameters to be used with high selectivity.

CONCLUSION: The dynamic pudendal SEP study described herein seems to be more helpful in PNE diagnosis than in conventional SEPs.