Voiding Dysfunction and Neurourology
Core concepts
This domain links lower urinary tract symptoms to underlying physiology and neurologic control. Understand the micturition cycle and the coordination between detrusor contraction and sphincter relaxation. Classify neurogenic lower urinary tract dysfunction by lesion level: suprapontine lesions (e.g., stroke) cause detrusor overactivity with coordinated sphincter; spinal cord lesions above the conus cause detrusor overactivity with detrusor-sphincter dyssynergia (risk of upper tract damage); cauda equina and peripheral lesions cause areflexia and retention. Know the role of urodynamics in neurogenic patients and the importance of protecting the upper tracts with low-pressure storage and adequate emptying. Understand bladder outlet obstruction in men (BPH) and its assessment, plus the meaning of post-void residual and pressure-flow studies. Recognize that antimuscarinics and beta-3 agonists treat overactivity, while clean intermittent catheterization manages incomplete emptying.
Traps
Questions test lesion localization and the risk of dyssynergia causing renal deterioration. Do not give antimuscarinics to a patient with significant retention without addressing emptying. Distinguish detrusor underactivity from outlet obstruction - both cause retention but management differs.
Worked example / rule of thumb
A patient with a T6 spinal cord injury has high storage pressures and detrusor-sphincter dyssynergia: prioritize lowering storage pressure and ensuring emptying to protect the kidneys. Rule of thumb: suprasacral cord lesions risk dyssynergia and upper tract damage; sacral/peripheral lesions cause areflexia.