Definition and Overview
Neurogenic bladder refers to bladder dysfunction caused by neurological damage affecting the neural pathways that control bladder storage and emptying. Depending on the level of neurological injury, it can manifest as either an overactive (spastic) or underactive (flaccid) bladder [1].
Neuroanatomy of Bladder Control
The pontine micturition center coordinates the voiding reflex. Sacral parasympathetic nerves (S2-S4) cause detrusor contraction. Sympathetic nerves (T11-L2) promote bladder relaxation and sphincter contraction during storage. The pudendal nerve provides voluntary control of the external urethral sphincter [2].
Causes
- Suprapontine lesions (stroke, brain tumor, dementia): detrusor overactivity with coordinated sphincter
- Spinal cord lesions above sacral segments (spinal cord injury, MS): detrusor-sphincter dyssynergia
- Sacral/peripheral lesions (cauda equina, diabetic neuropathy): detrusor underactivity with retention
- Parkinson's disease: detrusor overactivity (most common urinary symptom)
Symptoms
Overactive bladder: urgency, frequency, nocturia, urge incontinence. Underactive bladder: hesitancy, weak stream, incomplete emptying, overflow incontinence [3].
Complications include recurrent UTIs, hydronephrosis, renal damage, and autonomic dysreflexia (in spinal cord injury above T6).
Diagnosis
Urodynamic study is the gold-standard test, measuring intravesical pressure, detrusor pressure, and flow rate during filling and voiding. Post-void residual (PVR) measurement quantifies incomplete emptying [4].
Video-urodynamics combine fluoroscopy with pressure measurements. Renal ultrasound assesses for hydronephrosis. Cystoscopy may be needed to rule out structural abnormalities.
Treatment
For overactive bladder: antimuscarinics (oxybutynin, solifenacin, tolterodine) or beta-3 agonists (mirabegron). Intravesical botulinum toxin injection for refractory cases [5].
For underactive bladder: clean intermittent catheterization (CIC) is the cornerstone. Alpha-blockers may improve outlet resistance. Sacral neuromodulation can improve both storage and emptying dysfunction.
General measures: timed voiding, pelvic floor exercises, adequate fluid intake, and infection prevention.