Detrusor External Sphincter Dyssynergia Therapy in Spinal Cord Injury

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Spinal cord injury commonly results in the loss of the coordinated relationship between the detrusor muscle of the bladder and the external urethral sphincter. Normally, filling of the bladder will result in autonomic (involuntary) contraction of the smooth muscle of the detrusor muscle (including the internal urethral sphincter). With SCI realted bladder dysfunction, instead of being able to voluntarily relax the skeletal muscle of the external urethral sphincter to allow voiding when the detrusor muscle contracts, the former contracts to seal off urine flow from the bladder. If this dyssynergia is not managed, the limited capacity of the bladder will result, in increased pressure within the bladder and, in back pressure and reflux into the ureters and kidneys. These conditions (i.e., increased intravesical pressure, vesicoureteric or vesicorenal reflux), if unmanaged, will ultimately lead to kidney damage (hydronephrosis). Other potential consequences include symptoms of overactive bladder (leaking, increased discomfort and urge incontinence, and nocturia), autonomic dysreflexia, UTI, pyelonephritis, calculi (renal and bladder) and ultimately kidney failure. To manage DESD, goals to reduce bladder outlet obstruction are twofold: 1) to enhance bladder volume while lowering bladder filling pressures, and 2) to empty the bladder regularly in a low pressure manner, usually with intermittent catheterization (IC) in people with an intact external sphincter, or external drainage in people that have had a procedure to physically or chemically obliterate the external sphincter (sphincterotomy). Methods to enhance bladder volumes will be discussed first. Note that this pertains to people usually on concomitant IC for drainage. Occasionally the volume enhancing treatments below will be used in combination with an indwelling catheter to avoid leakage around the catheter.