Bulbocavernosus Reflex: Its Validity as a Diagnostic Test of Neurogenic Impotence

Abstract

Measurement of the bulbocavernosus reflex is used widely to diagnose underlying neurogenic disorders in erectile dysfunction. A prolonged bulbocavernosus reflex latency (that is more than 45 msec.) or the absence of a reflex response of the bulbocavernosus muscles during electrical stimulation of the glans penis is considered a sign of neurological disease. Since only a few experimental studies have been performed in man related to the neurophysiological mechanism of erection, and since the results of these studies were contradictory the diagnostic validity of bulbocavernosus reflex measurement was reassessed. We determine whether men with abnormal bulbocavernosus reflex latencies have concomitant organic erectile dysfunction as confirmed by nocturnal plethysmographic and rigidity recordings. The bulbocavernosus reflex was recorded in 90 subjects and 19 had abnormal bulbocavernosus reflex latencies. Of these 19 subjects 8 had normal nocturnal erections, thus, confirming a diagnosis of psychogenic impotence. These results cast some doubts on the validity of bulbocavernosus reflex measurement for the diagnosis of organic erectile dysfunction due to a neurological disease.

Neurophysiological Investigations of Two Hundred Men with Erectile Dysfunction

“…The results suggest that the discovery of an increased BCR and/or PER latency, even with an associated neurological abnormality, does not always imply that impotence is neurogenic: 4 of our patients with abnormal BCR are not impotent and 10 patients with abnormal BCR and/or PER but no relevant neuro logical cause had a vascular abnormality that could explain the impotence. Similar results were found by Lavoisier et al [14] and Desai et al [15]. A questionable relationship between an abnormal BCR and impotence was also found in a previous study which showed that 6 of 10 perfectly potent diabetic men had nevertheless an increased BCR and/or PER latency [19].…”

“…Two main rea sons may explain this odd relationship. The first one is that BCR is testing myelinated sensory and motor fibers of pudendal nerves which have been demonstrated to play an important part in sexual function [14,20,21]. Nevertheless, erection primarily depends on the integ rity of small nonmyelinated parasympathic fibers which are not tested by the BCR.…”

“…Some objective diagnostic methods have been developed in order to differentiate the nature of the erectile failure: nocturnal penile plethysmography, pa paverine tests, penile doppler, cavemosography, penile angiography, and neurophysiological investigations [1,2,4], The incidence of neurogenic impotence accounts for 10-15 % of those identified as having an organic etiology [2], Neurogenic impotence occurs if there is impairment of normal neuromuscular transmission between the pel vic cavernosus nerves and surrounding lacunar and arte BCR and PER have been widely used in the evalua tion of neurogenic sexual dysfunctions, but with conflict ing results. The aim of this study was to determine whether BCR and PER are useful in the investigation of impotent men and whether an abnormal BCR and PER necessarily imply neurogenic impotence [10,[13][14][15][16][17][18], BCR was performed in all using a MEDELEC-PA-63 (Medelec Ltd., England). The dorsal nerve of penis was stimulated using a pair of ring electrodes placed around the penis at 3 cm distance, with the cathode as the proximal electrode.…”

Bulbocavernosus-reflex latencies and pudendal nerve SSEP compared to penile vascular testing in 669 patients with erectile failure and other sexual dysfunction

“…(BCR-L) measurements and (pudSSEP) recordings M Fabra and H Porst Another issue worthwhile being discussed is the interpretation of several authors, that in patients with normal Rigiscan but pathological BCR-L andaor pudendal SSEP, the etiology of impotence should be considered psychogenic as the Rigiscan recordings could disprove the neurophysiological investigations. 2,3 Concerning these statements it must be realised, that the occurrence of nocturnal penile reactions and voluntarily penile erections, induced by sexual arousal, are subject of activation of completely different neurological pathways and are therefore hardly comparable to each other; 58 further remarks to the method of penile tumescence measuring are given by Goldstein. 59 Furthermore, normal nocturnal erections will occur, when the efference from the spinal cord to the penis is intact, BCR-L and pudendal SSEP however may be just pathological, when the afference from the penis to spinal cord is impaired.…”

Les troubles sensitifs péniens. Étude clinique et électrophysiologique. À propos de 39 cas

“…L'étude de la latence du réflexe bulbocaverneux n'est pas très contributive au diagnostic d'atteinte du nerf dorsal de la verge [17][18][19][20][21][22]. En effet, le trajet anatomique de l'arc réflexe nerf pudendal-S2, S3, S4 que teste la latence sacrée est long, et une atteinte purement distale du nerf pudendal, qui plus est uniquement sensitive, ne suffit pas le plus souvent à allonger la latence qui peut, par ailleurs, être altérée du fait d'une lésion radiculomédullaire ou plexique [23][24][25]. Dans notre série, elle était perturbée dans seulement 20 % des cas.…”