In neurogenic bladder, urodynamics can evaluate which dysfunction?

• A. Detrusor-sphincter dyssynergia
• B. Prostate size
• C. Kidney stones
• D. Urinary tract infections only

Answer: (A)

Detrusor-sphincter dyssynergia is a coordination problem where the bladder (detrusor) contracts to void while the external urethral sphincter does not relax, or even contracts, leading to obstruction. In neurogenic bladder, neurological injury disrupts the normal signaling that coordinates bladder contraction with sphincter relaxation. Urodynamics can capture this mismatch by measuring detrusor pressure during voiding and sphincter activity (often with EMG) at the same time. In dyssynergia, you’ll see the detrusor drive up pressure while the sphincter remains tight or tightens, producing poor flow and high voiding pressures. This direct assessment of how the bladder and outlet behave during storage and voiding is why urodynamics are suited to evaluate this dysfunction. Prostate size, kidney stones, and urinary tract infections are diagnosed or evaluated by other means (physical exam, imaging, labs) and are not defined by the functional voiding patterns that urodynamics reveals.