Objective: To determine the utility of the somatosensorial evoked potentials of the pudental nerve in the diagnosis of neurogenic impotence.
Methods: 129 patients with impotence were evaluated by physical examination and neuroandrologic profile. The neuroandrologic profile was assessed by bulbocavernous electromyography, determination of S2-S4 evoked potentials, analysis of the somatosensorial potentials of the pudendal nerve, cavernous smooth muscle electromyography (SPACE), sympathetic skin response and cystometry.
Results: The patients with a neurologic lesion presented a significantly longer latency time of the somatosensorial potentials than those with no neurologic lesion. The sensitivity of the somatosensorial potentials was 63% and the specificity was 98%. The sensitivity could be enhanced without significantly lowering specificity by taking 49 msec as the upper limit of normal values in latency time. The determination of the voluntary anal control in the diagnosis of neurogenic impotence was found to have a high specificity (93%), but a low sensitivity (42%).
Conclusion: The determination of the somatosensorial potentials, unlike other techniques, could allow diagnosis of lesions of the suprasacral inneveration in the evaluation of neurogenic impotence. The evoked somatosensorial potentials of the pudendal nerve and physical examination have the inconvenience of their low sensitivity in regard to the diagnosis of neurogenic lesion in impotence, mainly because some conditions only affect the peripheral autonomic innervation and the somatic element is spared.