[Evidence of sensory bladder inhibitor reflex]

Introduction: Need to void level depends on two parameters, bladder volume and attentional process. If it is well known that the maximum voluntary contraction of the perineal muscles may transiently inhibit the micturition reflex itself, no work demonstrates the effect of this contraction on the intensity of the need itself.

Methods: An experimental, prospective, open, monocentric study was conducted between March and April 2017. In total, 15 subjects with no neurological history or neuro-perineal disorders consulting for functional constipation were included. Need to void level was evaluated by means of an electronic urgentometer. A control contraction of the dominant hand muscles was compared to a voluntary contraction of the external anal sphincter during a strong desire to void (B3). These contractions were recorded by means of surface electromyography. The main evaluation criterion was the comparison between the difference in visual analogic scale of the desire to void before (VAS-base) and after control voluntary contraction (VAS-hand) versus the same index (BAS-base then VAS-anal) after contraction of the external anal sphincter during a new B3. The comparison of maximum bladder capacities (MBC) measured after each record was the secondary endpoint. Wilcoxon signed rank test was used for statistical analysis.

Results: Voiding desire VAS decreased significantly (-13.14±12 vs -1.5±6; P=0.03) and MBC increased significantly (502.43±96.71mL vs 435.78±125.54mL; P=0.02) after anal compared to control contraction.

Conclusion: This study suggests the existence of sensitive pathways inhibition by perineal contraction through a sensitive perineo-vesical inhibitory reflex.

Level of evidence: 3.