Influence of adrenergic agonists and antagonists on urethral pressure, bladder pressure and detrusor hyperactivity in children with myelodysplasia.

In children with myelodysplasia and a low lumbar or sacral level of spinal cord lesions detrusor hyperactivity with pressure fluctuations is an almost constant phenomenon contributing to incontinence. In thirteen children with this type of dysfunction the effect of adrenergic agonists and antagonists on bladder and urethral pressures were studied by means of intravesical and urethral pressure recordings during the normal bladder-filling phase. Intravenous infusion of noradrenaline during the bladder-filling phase slightly reduced detrusor hyperactivity and the urethral pressure was increased. Following i.m. injection of the alpha-adrenergic antagonist phentolamine both the intravesical and proximal urethral pressures were reduced to about the same extent and the detrusor hyperactivity decreased. It is concluded that noradrenaline mainly changed urethral pressure while alpha-adrenergic blockade caused decreased tone in both the detrusor and the urethra as well as decreased detrusor hyperactivity.