RECTAL SENSORY EVOKED-POTENTIALS - AN ASSESSMENT OF THEIR CLINICAL-VALUE

To assess abnormalities of sensory conduction in anorectal disease we have evaluated peripheral sensory perception and somatosensory evoked potentials produced by rectal stimulation in control subjects and pati ents With either constipation or idiopathic faecal incontinence. Evoke d potentials were also recorded after posterior tibial and dorsal geni tal nerve stimulation. Rectal sensation was also assessed using electr ical stimulation. Reproducible evoked potential recordings after anore ctal stimulation were possible in only a minority of subjects and when recorded showed intersubject and intrasubject variation. In the const ipated group there was a significant difference in rectal electrical s ensation (P < 0.05) from controls. We conclude that peripheral sensory testing demonstrates an abnormality in severe constipation. However, cerebral evoked potentials cannot be reliably recorded after rectal st imulation, and when recorded the latencies are of too broad a range to discriminate between health and disease. This probably relates to the difference between somatic and visceral pathways.