Cortical evoked potentials obtained after stimulation of the lower urinary tract

Cortical evoked potentials following stimulation of the lower urinary tract have been recorded in humans. Of 26 patients investigated 9 had no urinary signs or symptoms except genuine stress incontinence, while the remaining 17 had various neurogenic bladder disorders. Monopolar and bipolar stimulation of the bladder and urethra was performed using conventional and newly designed suction-type electrodes. While no cortical evoked potentials could be obtained from patients with complete transverse spinal cord lesions polyphasic cortical evoked potentials (N45, P60, N80 and P100 msec.) were recorded in response to monopolar bladder stimulation in all patients with stress incontinence. Following bipolar stimulation a response with lower amplitude and with latencies slightly divergent could be recorded. This response is assumed to be evoked only from bladder afferent nerves, while the monopolar response could include activity from adjacent structures. The most consistent pattern was recorded at the Cz site. Cortical evoked potentials following stimulation of the urethra were more difficult to evoke but they resembled those obtained after bipolar stimulation of the bladder. The method, when fully developed, may be helpful in the clinical investigation of patients affected by various neurogenic disorders of the lower urinary tract. So far, in our limited series a delayed response at P2 has been observed in patients with uninhibited neurogenic bladders.