ABSTRACT
The convergence of multiple neuromuscular inputs to the pelvic floor muscles (PFM) contributes to the pro-continence guarding reflexes. Clinically it was established that voluntary pre-contraction of the PFM produces a dramatic reduction of stress urinary incontinence (SUI). The effect of pre-contraction (knack) is interpreted as a consequence of the mechanical stabilization of the vesical neck resulting in reduced mobility. Transmission studies suggest that the procontinence biomechanical forces involved are applied by the supporting structures of the-urethra and indicate a considerable PFM contribution. Practically, localization of the region of action of the PFM can be made directly using vaginal palpation and more recently using probes. Vaginal probes currently in use are spatially limited in localizing the region over which forces from PFM are applied. Consequently neither the strength nor distribution of the forces involved has been recognized. Using a novel directional vaginal probe, we demonstrate in this paper the distribution of forces applied to the vaginal wall. The spatial and temporal distribution of PFM activation was mapped along the proximal, mid and distal vaginal wall. We repeatedly used the knack to activate a voluntary pre-contraction followed by the cough reflex as a test stimulus employing asymptomatic volunteers.
