Functional striated sphincter component at the bladder neck: clinical implications

Anatomical proximal extension of the striated urethral sphincter muscle towards the bladder neck was assessed functionally in normal male subjects and in patients with upper motor neuron lesions. Synchronous cystosphincterometric studies were performed and urethral pressure responses were studied (contraction complexes) at the vesicourethral junction, the supramontane prostatic urethra and the membranous urethra to repeated bulbocavernosus stimuli. All subjects demonstrated positive responses at the membranous urethra. Contraction complexes with amplitudes of less magnitude were elicited at the vesicourethral junction and at the supramontane prostatic urethra in 48 and 71 per cent of the total number of subjects, respectively. The functional significance of the striated muscle component at the bladder neck in patients with detrusor-striated sphincter dyssynergia is described.