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

Abstract

ObjectivesTo 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. Subjects and MethodsIn 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. ResultsLUT 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). ConclusionLUT 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.

Sensory function assessment of the human male lower urinary tract using current perception thresholds

“…CPTs from the bd were found to be consistently higher compared to other sites, which is in agreement with previous studies, including our own findings from women . An explanation for this finding might be the less dense and more unequal distribution of the suburothelial sensory nerve plexus, which is supposed to be particularly prominent at the bladder base and neck but relatively sparse at the bd .…”

Sensory evoked cortical potentials of the lower urinary tract in healthy men

“…Similar to previous results from healthy women, slow ES revealed typical LUTSEPs with a v‐shaped waveform and clearly detectable components resulting in high responder rates, specifically when using the semiautomatic peak detection approach. Using fast ES, however, LUTSEP components were less consistent and more difficult to detect resulting in low responder rates .…”

“…Identifiable LUTSEPs comprising a set of three components as described previously, that is, P1, N1, and P2, with good agreement between odd and even waveforms and corresponding latencies falling into the time intervals of 40‐110 ms, 90‐170 ms, and 150‐330 ms for P1, N1, and P2, respectively (Figure A). These intervals were determined based on the peak latencies of the group means under co‐consideration of the individual trajectories in the overlaid SEPs from 12 subjects across all five stimulated LUT locations.…”

“…Similar to previous results from healthy women, slow ES revealed typical LUTSEPs with a v‐shaped waveform and clearly detectable components resulting in high responder rates, specifically when using the semiautomatic peak detection approach. Using fast ES, however, LUTSEP components were less consistent and more difficult to detect resulting in low responder rates . This may be related to the lack of faster conducting fibers in the LUT, that is, Aβ, and to refractoriness, chronodispersion, and phase cancellation within slower conducting LUT fibers, that is, Aδ‐ and C‐fibres, in conditions with faster stimulation frequencies.…”

“…Previous studies reported the feasibility of SEP recording following LUT electrical stimulation (ES) at the vesico‐urethral junction and the posterior urethra in healthy subjects and patients . However, methodological aspects varied largely and a systematic evaluation including reliability of the method was lacking until recently in healthy female subjects . Using the same methodology we now investigated healthy male subjects including measurements in the membranous urethra (mUR).…”