Evoked Potentials from the Lower Urinary Tract

Abstract

Spinal and cerebral evoked potentials (EPs) on stimulation ot the dorsal nerve of the penis, clitoris, bladder wall and posterior urethra were recorded in 20 normal subjects (10 females and 10 males). Responses were obtained by computer averaging of multiple potentials registered over the spinal cord (L1) and cerebral cortex. Responses from the posterior tibial nerve were also recorded. Consistent cortical responses were obtained from the pudendal nerve, bladder wall and posterior urethra, whereas spinal responses were difficult to record. The maximum responses after stimulation of the pudendal nerve, bladder wall and posterior urethra were recorded over the midline of the scalp at C_z—2 cm point. The configuration of the somatosensory evoked potentials of the pudendal nerve had a W-shape with a consistent positive peak P₁ (median 42.0 msec, range 39–45 msec), whereas the responses after endovesical and endourethral stimulation mainly were M-shaped with a prominent negative peak N₁ (Bladder: median 104.0 msec, range 75–112 msec and posterior urethra: median 103.0 msec, range 78–114 msec). Conduction times within the central spinal pathways could be calculated by subtracting the latencies of the peripheral spinal potentials from the central cortical potentials.

Key words:

• Cerebral and spinal evoked potential
• Pudendal nerve
• Posterior urethra
• Bladder wall
• posterior tibial nerve
• afferent nerves
• lower urinary tract innervation