INTRAOPERATIVE RECORDING OF THE BULBOCAVERNOSUS REFLEX

OBJECTIVE: To demonstrate the feasibility of intraoperative monitoring of the bulbocavernosus reflex (BCR) as an indicator of the functional integrity of sacral nervous structures to aid in preventing their int raoperative injury. METHODS: Intraoperative BCR was elicited by electr ical stimulation of the dorsal penile/clitoral nerve in 119 patients a nesthetized with propofol, fentanyl, and nitrous oxide, with short-act ing relaxant. Thirty-eight patients underwent surgery without risk, wh ereas 81 underwent surgery with risk of damage to sacral structures. D ifferent patterns of stimuli were applied through silver/silver chlori de disc electrodes placed on the dorsal aspect of the penis in males a nd over the clitoris (cathode) and adjacent labia (anode) in females. Recordings were made from the anal sphincter using intramuscular wire electrodes introduced within a 27.5 gauge needle, with two electrodes each inserted in the right and left hemisphincter muscles. Preoperativ ely, some patients had minor urinary problems in controlling their sph incters. RESULTS: The BCR was reliably recorded without habituation un der this anesthetic regime. Optimal stimulating parameters were found to be double pulses (0.5-ms duration), with an interstimulus interval of 3 ms, stimulating rate of 2.3 Hz, and intensity of 20 mA. With thes e parameters, it was possible to record the BCR intraoperatively in al l patients. Isoflurane and nitrous oxide significantly suppressed the BCR, and muscle relaxant completely abolished it. CONCLUSION: We demon strated that if is feasible, under certain anesthetic regimes, to intr aoperatively monitor the BCR in both children and adults (24 d to 74 y r of age) who did not have significantly affected function in sacral n ervous structures.