Sensory evoked potentials of the bladder and urethra in middle-aged women: the effect of age.

Abstract

To investigate feasibility, reproducibility and age dependency of sensory evoked cortical potentials (SEPs) after electrical stimulation of different locations in the lower urinary tract (LUT) in a cohort of middle-aged healthy women. In a group of 10 healthy middle-aged women [mean (sd) height 165 (5) cm and age 43 (6) years), electrical stimulation (0.5 and 3 Hz) was applied to the bladder dome, trigone, and proximal and distal urethra. SEPs were recorded at the Cz electrode with reference to Fz. All measurements were repeated three times with an interval of 3-5 weeks. Current perception thresholds (CPT), SEP latencies and amplitudes were analysed. Results were compared with a group of younger women published previously. LUT SEPs demonstrated two positive (P1, P2) and one negative peak (N1). The mean (sd) N1 latency was 108.9 (7.8), 116.2 (10.7), 113.2 (13.4) and 131.3 (35.6) ms for the bladder dome, trigone, proximal and distal urethra, respectively. N1 latencies, except for the distal urethra, were significantly shorter than those in younger women. Taking all data, i.e. young and middle-aged women, into account, there was a significant negative correlation between the variable age and CPT/dome (r = -0.462, P = 0.04) and N1 latency/dome (r = -0.605, P = 0.005) and a significant positive correlation between the variable age and N1P2 amplitude/dome (r = 0.542, P = 0.014). LUT SEPs can be induced in middle-aged women with reliable N1 responses. Unexpectedly, N1 responses reveal a shortening with increasing age particularly when compared with younger women. Changes in sensory afferents may be explained by age-related qualitative reorganisations within the urothelium and suburothelium potentially altering afferent nerve excitability, which may have an impact on the development of non-neurological LUT symptoms (LUTS, e.g. overactive bladder) in women.