Utility of sphincter electromyography and sacral reflex studies in women with cauda equina lesions

Abstract

Sacral neurophysiologic studies have demonstrated their utility in men with suspected neurogenic sacral dysfunction. However, no similar studies have been performed in women. The present study aimed to test the utility of sacral neurophysiologic assessment in women with chronic cauda equina lesions. Twenty-four women with clinical and radiological signs supportive of chronic cauda equina lesions, and a group of 60 control women without clinical symptoms or signs of sacral neuropathic lesion were included. Clinical examination, including testing of saddle sensation, and neurophysiologic testing, including quantitative anal sphincter EMG and clitoro-cavernosus reflex testing (on single and double electrical, and mechanical stimulation), were performed on each side separately. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Respective sensitivities, specificities, positive predictive values, and negative predictive values were 63%, 92%, 83%, and 86% for quantitative anal sphincter EMG, 92-96%, 67-80%, 52-59%, and 95-96% for neurophysiologic testing of the clitoro-cavernosus reflex (using different stimulation techniques), and 96-100%, 62-75%, 50-55%, and 97-98% for their combinations. This study complements previous reports in men supporting the clinical utility of an neurophysiologic protocol that includes both quantitative anal sphincter EMG and sacral reflex studies for assessment of patients with suspected peripheral sacral lesions. Very high sensitivity and negative predictive value confirm high utility of sacral neurophysiologic studies in confirmation and exclusion of sacral neuropathic lesion.