Urethral sphincter activity following acute spinal cord injury

We studied 44 patients with spinal cord injury during the first 72 hours after injury to determine the functional status of the bladder and external urethral sphincter. The studies included determination of the bulbocavernosus reflex, cystometry and sphincter electromyogram. In patients with lesions above the sacral cord the bulbocavernosus reflex was present. In nearly all of these patients the external sphincter activity increased with bladder filling. In all but 1 patient with injury to the sacral cord the bulbocavernosus reflex could not be elicited and the sphincter electromyogram did not increase with bladder filling.