ABSTRACT
BACKGROUND: We hypothesize that the current practice of sphincter assessment in anorectal malformations (ARMs) by direct muscle stimulation can be improved by sacral nerve stimulation (SNS). Focusing on the specific adjustments for infants, we highlight the anatomical and neurophysiologic basis of SNS and its further diagnostic and therapeutic implications. PATIENTS AND METHODS: We examined 20 patients: 12 patients with ARM, 3 with Hirschsprung disease, 3 with sacrococcygeal teratoma, and 2 with cloacal exstrophies. Under general anesthesia and ultrasound guidance, percutaneous needle electrodes were placed within the sacral neural foramina. Electrical stimulation was applied to assess the presence, pattern, and extent of the neuromuscular response of the external anal sphincter. RESULTS: We successfully modified the traditional method used in adults replacing radiographic controls by ultrasound guidance. In 20 SNS procedures with no complications, we found a muscle response on stimulation of the third and/or fourth sacral nerves in 18 of 20 patients (anal sphincter contraction and/or ipsilateral plantar flexion). CONCLUSION: We demonstrated the feasibility of SNS for intraoperative sphincter mapping and detection of primary innervation abnormalities in ARM as well as for the assessment of secondary deficits in postoperative follow-up. Sacral nerve stimulation broadens the spectrum of intraoperative information concerning the sacral innervation pattern by a direct assessment of the sacral nerves. Furthermore, electrophysiologic data may allow prospective criteria for sphincter function to be established. These may improve the accuracy of the present classification-based prognosis as well as the understanding of sphincter physiology in general.
