Interventional neurophysiology of the sacral nervous system

Clinical neurophysiological tests have been introduced for the sacral neuromuscular system to aid with diagnosis of neurogenic conditions involving the lower urinary tract, anorectal and sexual dysfunction. The tests have, however, the potential to be of value in different interventions outside of the neurophysiological laboratory. EMG monitoring can be used for exact application of botulinum toxin by the relatively non-invasive transcutaneous approach in treatment of male detrusor sphincter dyssynergia. Checking for compound muscle action potentials of the external anal sphincter is proposed as the best method for exact placement of wire electrodes close to the 3rd sacral roots in treating lower urinary tract dysfunction by 'neuromodulation'. Presently the most established use of clinical neurophysiological techniques--outside the laboratory--as related to the sacral neuromuscular system is in the operating theatre. These tests have been introduced to identify relevant structures, for instance pudendal afferents within dorsal sacral roots, which should be spared during rhizotomy procedures for treatment of spasticity. Modified techniques are used intraoperatively to monitor the integrity of the lower sacral reflex arc (the bulbocavernosus reflex) or the lower sacral afferents throughout the spinal cord (pudendal SEP). Clinical neurophysiological tests are expected to become established in several interventions involving the sacral neuromuscular system.