Differences in activation of pelvic floor muscles in response to electrical stimulation in men using different electrode montages

Objective: To measure contraction of the striated urethral sphincter, bulbocavernosus and puborectalis muscles with transperineal ultrasound imaging in response to electrical stimulation with three electrode montages. Materials and methods: Electrical stimulation was applied via anal, perineal and perineal-to-suprapubic electrode montages in ten healthy men. Induced pelvic landmark displacement was recorded with transperineal ultrasound imaging. Threshold current to evoke contraction of each muscle and maximum displacement was identified from displacement of relevant landmarks. outcomes were compared between landmarks and montages. Results: Contraction of all muscles (identified from landmark displacement) could be evoked with each electrode montage. Contraction of puborectalis was evoked in less men than the sphincter for the perineal montage. Threshold current was lower for the anal montage than either perineal montage and lower for contraction of the sphincter than puborectalis. Conclusion: Although electrical stimulation can evokes contraction of all pelvic floor muscles tested, differences in frequency of contraction and threshold imply different electrode montages may have different clinical applications. A perineal montage biases contraction to the sphincter and bulbocavernosus.