[Assessment of sensory thresholds of the penile dorsal nerve as screening technique for neurologic lesion in impotence]. / Valoración de los umbrales sensoriales del nervio dorsal del pene como técnica de screening de lesión neurológica en la impotencia.

OBJECTIVE: The present study was conducted to determine the usefulness of the perception and stimulation thresholds of the penile dorsal nerve in the diagnosis of neurogenic impotence. METHODS: A study was conducted to determine the neuroandrologic profile in 130 patients. According to the results of the neuroandrologic profile, they were classified as patients without neurogenic impotence (44 pts.; 34%) or with neurogenic impotence (86 pts.; 66%). The perception and stimulation thresholds (expressed in milliAmperes) were determined in all patients. Furthermore, the perineal sensation was clinically tested. Both thresholds were also studied in relation to a demonstrated neurologic lesion (sympathetic, parasympathetic, afferent pudendal, efferent pudendal and suprasacral lesions). RESULTS: Assessment of the perineal sensation demonstrated a high specificity and a low sensitivity in the diagnosis of neurogenic impotence. A significant difference was observed between both groups for the perception (confidence interval of difference between the neurogenic and non-neurogenic group; from 0.02 to 4.95 mA) and stimulation thresholds (from 2.0 to 11 mA). Morever, the stimulation threshold was significantly higher in patients with alteration of the perineal sensation). Significant differences in the perception threshold were also demonstrated between patients with and without demonstration of efferent lesion, and in the stimulation threshold between patients with and without demonstration of pudendal afferent, pudendal efferent and sympathetic lesion. These differences are attributed to the presence of mixed lesions. However, given the width of the interval of normal values, it was not possible to find a useful cut-off point in both sensory thresholds. It could only be determined that the maximum value of the perception threshold in healthy subjects should be less than 9.45 mA. CONCLUSION: The sensorial thresholds of the electrical stimulation of the penile dorsal nerve and the data from the physical examination of perineal sensation are not useful for the diagnosis of neurogenic impotence. It is necessary to carry out a complete neuroandrologic profile.