An EMG needle technique for validation of external opening of urethra by levator plate during micturition

Abstract: Background: At present, the commonly accepted notion is that the pelvic floor muscles relax, allowing micturition and defecation
to take place. Significant observational x-ray data evidence indicates that there is an active striated mechanism which opens out both the urethra and anorectum during micturition. Micturition studies with an EMG cylindrical electrode positioned in the posterior vaginal fornix
demonstrated that these contractions preceded the onset of urine flow. In the 1990 Integral Theory publication and subsequently, it was hypothesized that both levator plate and conjoint longitudinal muscles of the anus activate this external opening mechanism. However, this has
never been demonstrated by direct needle EMG. Aim to develop EMG methodology to measure levator plate contraction, thought to be a key
element of this active opening mechanism. Methods: Using ultrasound guidance, an EMG needle was inserted halfway between the anus and
coccyx, 1.5cm laterally from the midline position to a depth of approximately 1.5 cm. Results: The needle EMG showed that muscle contraction preceded urine flow. Conclusions: The technique, though successful, is not easy to perform accurately and requires ultrasound guidance
for accurate needle placement. Further studies are proceeding.
Key words: EMG; Levator plate; Micturition; Pelvic floor contraction.