Neurophysiology of the human lower urinary tract
10 July 2018
UAntwerp - Campus Drie Eiken - Building O - Auditorium O8 - Universiteitsplein 1 - 2610 WILRIJK (route: UAntwerpen, Campus Drie Eiken
Organization / co-organization:
Faculty of Medicine and Health Sciences
Prof S. De Wachter & Prof L. Bachmann
PhD defence Stephanie Knüpfer - Faculty of Medicine and Health Sciences
Presentation in English
This thesis addresses the evaluation of sensory evoked cortical potentials (SEPs) and current perception thresholds (CPTs) as reliable diagnostic tools to objectively assess and investigate integrity and function of the afferent human lower urinary tract (LUT).
In the first study (Chapter 2) we investigated the effect of age on LUT SEPs and CPTs and compared findings from subjects younger than 35 years (23 ±3.7 years) with findings from subjects older than 35 years (42.5 ±5.5 years) [1, 2]. Similar to the younger subjects, older subjects demonstrated reproducible SEPs at all four LUT stimulation sites using 0.5Hz but not 3Hz. Our selection of stimulation frequencies was based on the assumption that Aδ fibers and C-fibers are the two main afferent fiber types in the human LUT [1-3]. The older subjects demonstrated significantly shorter N1 latencies whereas the reliability of latencies was lower than in the younger subjects. A significant correlation between N1 latency and age could not be observed.
In the next study (Chapter 3) we evaluated in twelve healthy men (29.6 ±7.2 years) the feasibility and reliability of CPT measurement at five different LUT locations using 3Hz and 0.5Hz stimulation frequencies with a pulse width of 0.2ms and 1ms, respectively . CPTs for the bladder dome were higher compared to the proximal and distal urethra, which might be due to the more unequal distribution of the suburothelial sensory nerve plexus. CPTs of the LUT could safely and reliably identified using rather slow stimulation frequencies (i.e. 0.5-3Hz) with slightly higher ICC values for the slower compared to the faster stimulation protocol .
The aim of the third study (Chapter 4) was to assess the afferent innervation of various locations in the male LUT using SEPs. Typical SEPs with P1, N1, and P2 components were successfully detected (100% responder rate) for slow stimulation (0.5Hz/1ms) but less successful for fast stimulation (3Hz/0.2ms). The slow stimulation provided reproducible SEPs with position specific N1 latencies with decreased latencies from form proximal to distal LUT stimulation sites, which may be indicative for a location specific composition of afferent innervation. The mean amplitudes at BD are significantly higher compared to other LUT locations. Despite good inter-rater agreements, latency variability between and within subjects was higher for LUTSEPs than for standard somatic, i.e. tibial, SEPs, related to the more challenging approach and afferent fiber access within the LUT.
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