How do different tests evaluate sensation in the lower urinary tract?

Abstract

Different tests can be used to evaluate lower urinary tract (LUT) sensation. The purpose of this study is to compare sensory tests in patients with voiding disorders. Seventy patients with various functional disorders of the LUT were admitted for a cystometry and an electrical perception threshold test of the bladder (bEPT) and distal urethra (uEPT). A pudendal EPT (pEPT) and pudendal somatosensory evoked potentials (pSSEP) were also determined. Correlations were calculated for somatosensory (uEPT, pEPT and pSSEP latency) and viscerosensory tests (volumes at filling sensations and bEPT). Fifty of the 70 patients (71%) had normal bladder filling sensations, with abnormal bEPT in 21/50 (41%), including 11 (22%) with no sensation at maximal electrical stimulation. Twenty out of 70 (29%) had an abnormal pattern of filling sensation, with increased bEPT in 13/20 (65%) and no sensation at electrical stimulation in 8/13 (40%). No significant correlation exists between filling sensation and bladder electrical perception thresholds (r < 0.005, p > 0.243). pEPT correlated with uEPT and SSEP (r > 0.035, p < 0.041). In patients with functional voiding disorders, the EPT can be disturbed independently of the bladder filling sensation. No significant correlation exists between volumes of filling sensations and bEPT (r < 0.005, p > 0.243). Therefore, both tests provide complementary information. Somatosensory tests of the pudendal nerve are correlated, so performing SSEP, pEPT and uEPT provides poor additional information to one of these tests alone. Somatosensory pudendal tests cannot be used to quantify filling sensation.