Sacral signal tracing: the electrophysiology of the bulbocavernosus reflex.

We studied 52 men with electrophysiologic testing of the bulbocavernosus reflex to determine reflex latency. The bulbocavernosus reflex was demonstrated to be a segmental polysynaptic reflex with cross-over in the sacral spinal cord. Excellent correlation was obtained between prolonged latency and clinical evidence of neuropathy. The examination may be useful clinically to evaluate patients suspected to have sacral cord lesions or pudendal neuropathy (for example impotence, chronic back pain and lesions of the cauda equina and peripheral nerves).