Determination of Rectal Afferents, Based on the Analysis of Cerebral Evoked Potentials Induced by Rectal Stimulation

ABSTRACT

The rectum is a unique visceral organ, of which afferents are not so obvious. In anorectal surgery ablating the rectum and/or perirectal structure, this issue comes with significant meaning about whether to preserve patient's normal defecatory function, or not. So we planned this study to evaluate which nervous system concerns the afferents from the rectum. METHODS: We recorded cerebral evoked potential (EPs) in 16 healthy male subjects after electrical and mechanical stimulation of the rectum, and compared their waving patterns regarding latencies and amplitudes of each peak with those occuring after electrical stimulation of the pudendal nerve. RESULTS: The EPs after electrical stimulation of the rectum showed distinctly different waving patterns in comparison to those after electrical stimulation of the pudendal nerve. But the EPs after mechanical stimulation of the rectum showed very similar waving patterns with those after electrical stimulation of the pudendal nerve. CONCLUSIONS: Rectal afferents of mechanical stimulation seem to be somatosensory, but those of electrical stimulation seem visceral. In that sense, sensory receptors of mechanical stimulation may lie in the perirectal structure, such as pelvic floor muscle and those of electrical stimulation lie in the rectum, itself.