Cerebral electrical response on urinary bladder filling: first experimental findings

Micturition disorders in neurologic diseases are often combined with reduced bladder sensation. Bladder sensation is important to time the void appropriately and to prevent bladder overdistension. We attempted to evaluate cerebral evoked potentials by bladder distension to objectively determine bladder sensation. In six rabbits, cerebral evoked potentials were evaluated by averaging cerebral responses to bladder distension. We stimulated the bladder with a computerized air pump system, resulting in repeated filling and emptying of the bladder. The number of stimulations, stimulation intensity, and different electroencephalograph electrode positions (both mastoids and frontal) were investigated. In all rabbits, cerebral evoked potentials were observed after 500 stimulations when stimulation pressure exceeded a certain threshold. Optimum response was observed after 1,000 stimulations. The latency of response of the frontal electrode position was observed after the mastoidal response with a significant delay of approximately 0.8 seconds. The latencies were significantly different when using different stimulation intensities. At lower intensity (mean pressure, 16.6 mm Hg), the response was observed after 4.531 +/- 0.909 seconds. At higher intensity (mean pressure, 19.0 mm Hg), cerebral response was observed after a latency of 3.971 +/- 0.735 seconds. We conclude that recording of cerebral evoked potentials by bladder distension is possible, resulting in an objective evaluation of afferent pathways from the bladder. In combination with subjective perception of bladder fullness, this finding may be a conceivable basis for a biofeedback training program to recover bladder sensation in patients with reduced bladder sensation.