Development of reflex activity of detrusor and striated sphincter muscles in experimental paraplegia

Reflexes concerned with viscerosomatic and somatovisceral interplay in the sacral spinal cord were evaluated in spinalized animals, as part of a study on direct spinal cord stimulation of micturition. Urodynamic evaluation consisted of continuous recording of bladder pressure, urethral pressures and electromyograms of striated anal and urethral sphincters. All exteroceptive stimuli to urethral or anal mucosa caused an inappropriate increase in afferent input to the sacral micturition center: such stimuli should be avoided in the evaluation of suprasacral lesions of bladder innervation. Early in the spinal shock phase, hyperreflexia of striated pelvic floor muscles was apparent, in the absence of detrusor reflex activity. Clinical implications for early management of neurogenic bladder dysfunction are discussed. In all spinalized animals early balanced bladder function could be achieved, due to the absence of detrusor-sphincter dyssynergia: the opposite is true for spinalized man.