Cortical evoked responses from the perineal nerve

Purpose: We characterize and determine normal reference latencies for the c ortical evoked response from the perineal nerve. Materials and Methods: A total of 15 healthy, potent men with a mean age of 31.3 +/- 6.8 years underwent genital electrophysiological testing. Square wave stimuli were applied to the perineal nerve at the ventral base of the penis and the perineal floor. Cortical evoked responses were recorded, and onset latencies were measured at baseline and after anesthetization of the dorsal nerve of the penis. Results: In all 15 subjects a cortical evoked response was elicited after s timulation of the perineal nerve at the ventral base of the penis with a me an latency measured from the first positive deflection (P1) of 48.4 +/- 7.8 milliseconds. Penile block of the dorsal nerve of the penis did not change or abolish the cortical evoked response. A similar cortical evoked respons e was obtained, although less consistently, after stimulation of the perine al nerve through its course in the perineal floor. Conclusions: A cortical evoked response from the perineal nerve can be elic ited reliably at the ventral penis. This neural pathway is independent of t he dorsal nerve of the penis. The study of perineal somatic innervation may prove important in understanding the physiology of ejaculatory and erectil e dysfunction.