Quantitative electrical pain threshold assessment in the lower urinary tract

Abstract

Aims: Assessing the reliability of electrical pain threshold (PT) and evaluating the impact of stimulation frequency at different locations in the healthy lower urinary tract (LUT). Methods: Ninety subjects (age: 18.3-35.8 years, 40 females, 50 males) were randomly allocated to one stimulation site (bladder dome [BD], trigone, proximal, membranous (only males), or distal urethra). Using 0.5 Hz/1.1 Hz/ 1.6 Hz electrical stimulation (square wave, pulse width:1 ms), current perception thresholds (CPTs), PTs and tolerance thresholds were assessed at two visits. Analyses were performed using linear mixed models, intraclass correlation coefficients (ICC) and Bland-Altman method.Results: PTs vary in relation to stimulation frequency, location and between genders. PT decreased with higher stimulation frequency. The highest PTs were measured at the BD and membranous urethra with males reporting higher PTs than females. Reliability of PT assessments according to ICC was good to excellent across all frequencies, locations, and genders (ICC = 0.61-0.97), except for BD and distal urethra in females showing poor to fair reliability (BD: all frequencies, distal urethra: 0.5 Hz).Conclusions: PTs can be safely and reliably assessed from bladder and urethral locations. Semi-objective PT assessment may provide additional information on functionality and sensitivity of the LUT slow fiber afferents and complement findings from urodynamic investigations and CPT assessments. In conclusion, the developed methodology may open new opportunities for using electrical stimulation paradigms for LUT PT assessments and diagnostics. All this allows a more precise, location-specific characterization of pain origin and pain reaction towards therapy. K E Y W O R D S afferent nerve fibers, electrical stimulation, humans, lower urinary tract, neurophysiology, pain threshold Stéphanie van der Lely and Martina D. Liechti shared the firstauthorship.

Lower urinary tract electrical sensory assessment: a systematic review and meta‐analysis

“…Gender‐specific LUTESA results were shown by six studies, but only five of 80 studies (6.3%) statistically assessed the influence of gender on LUTESA. While these studies revealed conflicting results [22,26,27,74,75,77], the meta‐analyses of this review indicated no influence of gender on LUTCPTs.…”

“…Out of 80 studies, 61 exclusively applied CPTs [6,7,13–71], but four reported incomplete or no CPT results [14,32,61,64] (Table S2).…”

“…Of 80 studies, 13 (16.3%) reported the impact of age on LUTESA, but with conflicting results [15,19,20,21,22,23,24,25,72,73,74,75,76]. Pooling the data of all available studies in a univariate model, increasing age was significantly correlated with higher LUTCPTs ( r = 0.03, P = 0.011; only HS: r = 0.04, P = 0.079 [trend]).…”

“…Reliability across visits was assessed by 10 studies (12.5%; interval: 7 days to 12 weeks). In general, LUTCPT reliability across visits was shown to be good to excellent [25,27,45], but reliability differed between locations [22,58]. In addition, a better reliability was shown for slow compared to faster stimulation frequencies (i.e.…”

“…When the catheter‐mounted stimulation electrodes were positioned in the trigone or urethra, lower CPTs were reported by several studies compared to a positioning at the bladder dome [20,22,26,27,57,58,73]. Accordingly, the conducted meta‐analysis showed increased sensitivity at the vesicourethral junction (including also bladder neck, proximal urethra [pUR]), distal urethra (dUR) and female urethra compared to the bladder area, but only when using SqWS (Fig.…”