ASSESSMENT OF THE RELIABILITY OF CEREBRAL POTENTIALS-EVOKED BY ELECTRICAL-STIMULATION OF THE ANAL-CANAL

The aim of this study was to assess the reliability of cortical evoked potentials after electrical stimulation of the anal canal. Cortical e voked potentials were recorded on 243 patients presenting with perinea l pain (28 patients), impotence (55 patients), anal incontinence (52 p atients), urinary continence (30 patients), constipation (49 patients) , and on 29 neurological patients, by stimulating the external anal sp hincter and penis (or clitoris). The inter-and intra-observer reproduc ibility was studied by coding recordings interpreted by three differen t observers on two separate occasions. The influence of recording char acteristics and clinical data were assessed. To study operator depende nce, five operators investigated the patients. Only one of them was we ll trained in this technique. The interpretation of the coded curves b y the observers was poorly reproducible in about 15% of cases, dependi ng on time between the two readings and the quality of recordings. The interpretation of cerebral responses after anal stimulation were obse rver-dependent and influenced by the knowledge of clinical data. This was also observed with cortical evoked potentials after electrical sti mulation of the penis or clitoris, but to a lesser extent. The cerebra l evoked potentials method was also operator-dependent, mainly after a nal stimulation. When a study of cortical evoked potentials by perinea l stimulation is needed in clinical practice, it seems logical to pref er cortical evoked potentials by penile or clitoral stimulation as the y seem easier to obtain than those evoked by anal stimulation if the i nvestigators are not well trained for the performance of electrophysio logical studies as the former are much less operator- and observer-dep endent.