Neurogenic bladder and dysfunctional voiding: SAQ

This infant has a hostile high-pressure neurogenic bladder. The poorly compliant bladder with a steep pressure rise on filling, the detrusor leak point pressure of 52 cm of water, and the detrusor-sphincter dyssynergia together define a bladder that is unsafe for the upper tracts. The new bilateral hydronephrosis is the early sign that the high storage pressures are already being transmitted to the kidneys, and the incontinence and the palpable bladder reflect the overactivity and the emptying failure. The creatinine is normal now, but it will rise if the bladder is left untreated. ^[2]

Question 1 (10 marks)

Outline the management of this infant's neurogenic bladder, including the goal of treatment and the specific first-line interventions with their rationale. ^[6]

The stated goal of management is a low-pressure, continent, completely emptied bladder that protects the kidneys, and every intervention is judged against the urodynamics rather than the symptoms. The first-line treatment is clean intermittent catheterisation combined with an anticholinergic. Clean intermittent catheterisation, performed every 3 to 4 hours by the parents, empties the bladder completely and at a low pressure regardless of the dyssynergic sphincter, and it is the single intervention that most preserves the upper tracts. ^[6]

An anticholinergic is added to relax the detrusor and lower the storage pressure. The first-line agent is oxybutynin at 0.2 mg per kg per dose twice daily in the young child, titrated to a maximum of 5 mg per dose, which blocks the M3 muscarinic receptor on the detrusor and abolishes the involuntary contractions. The side effects are the dry mouth, the constipation, and the central effects of irritability that reflect the penetration of an immature blood-brain barrier, and tolterodine or solifenacin are alternatives. The bowel is managed in parallel, because the cord lesion affects the bowel as well as the bladder. ^[3]

The urodynamics and the upper-tract ultrasound are repeated after the treatment is established to confirm that the storage pressure has fallen and the hydronephrosis has resolved. The surveillance continues for life, with the blood pressure, the creatinine, and the renal ultrasound at least annually, because the bladder behaviour can change over time. ^[3]