detrusorsphincter

Detrusor-sphincter refers to the functional relationship between the detrusor muscle of the bladder wall and the urethral sphincters that regulate urine storage and voiding. The detrusor is a layer of smooth muscle that contracts to increase bladder pressure and expel urine. The bladder outlet is guarded by an internal urethral sphincter (smooth muscle at the bladder neck) and an external urethral sphincter (striated muscle under voluntary control). At rest, detrusor tone is low and the outlet remains closed to retain urine. During micturition, sensory signals from bladder stretch receptors trigger a reflex that, with higher-level input, causes detrusor contraction and coordinated relaxation of the sphincters to permit urine flow.

Neural control involves sympathetic pathways that support storage by relaxing the detrusor and contracting the internal sphincter, somatic control of the external sphincter via the pudendal nerve, and parasympathetic activation of the detrusor during voiding. A healthy detrusor-sphincter system maintains continence during filling and enables efficient emptying when appropriate.

Dysfunction in detrusor-sphincter coordination is described in various clinical contexts, particularly in neurological conditions. Detrusor-sphincter dyssynergia (DSD) occurs when detrusor contraction is accompanied by simultaneous contraction or inadequate relaxation of the sphincters, creating outlet obstruction, elevated bladder pressures, and potential risk to the upper urinary tract. Diagnosis is typically via urodynamic studies and clinical history. Treatment aims to improve storage pressures and facilitate voiding, using strategies such as timed voiding, catheterization, anticholinergic or alpha-blocker medications, botulinum toxin injections, and, in some cases, surgical interventions.