Optimized Measurement Parameters of Sensory Evoked Cortical Potentials to Assess Human Bladder Afferents - A Randomized Study

Overactive bladder and voiding dysfunction are highly prevalent and often associated with malfunction of the bladder afferent pathways. Appropriate diagnostic tools for an objective assessment of afferent nerve function of the human bladder are currently missing. One promising possibility is the assessment of sensory evoked potentials (SEP) during repetitive electrical bladder stimulation, which proved feasible in healthy subjects. For an implementation into clinical practice, however, further refinements for efficient and reliable data acquisition are crucial. The aim of this randomized study was to find the optimal measurement settings regarding stimulation frequency, repetition number, and data acquisition. Forty healthy subjects underwent two visits of SEP (Cz-Fz) assessments using repetitive (500 stimuli) electrical stimulation of 0.5 Hz, 1.1 Hz, and 1.6 Hz and pulse width of 1 ms at the bladder dome or trigone. SEP analyses revealed higher amplitudes and better signal-to-noise ratio (SNR) with lower stimulation frequencies, while latencies remained unchanged. Decreasing amplitudes and SNR were observed with continuing stimulation accompanied by decreasing responder rate (RR). When applying stimuli at a frequency of 0.5 Hz, averaging across 200 stimuli revealed optimal reliability with best SNR, RR and sufficiently high amplitudes. This constitutes an optimal compromise between the duration of the assessment and SEP peak-to-peak amplitudes.