Neurogenic Bladder

Neurogenic bladder (neurogenic lower urinary tract dysfunction) is bladder and sphincter dysfunction due to disease or injury of the central or peripheral nervous system that controls storage and voiding. The pattern depends on the level of the lesion.

Causes:

• Suprapontine: stroke, Parkinson disease, multiple system atrophy, dementia, brain tumour, traumatic brain injury.
• Spinal cord lesions: traumatic spinal cord injury, multiple sclerosis, transverse myelitis, spinal stenosis, tumour, spina bifida and myelomeningocele (the commonest congenital cause).
• Peripheral and sacral lesions: diabetic autonomic neuropathy, cauda equina, pelvic surgery such as radical hysterectomy and abdominoperineal resection, herpes zoster, Guillain-Barre syndrome.

Patterns by level:

• Suprapontine lesions produce detrusor overactivity with coordinated sphincters (urgency and incontinence).
• Suprasacral spinal lesions (above S2) produce detrusor overactivity with detrusor sphincter dyssynergia. This leads to high pressure storage and voiding with upper tract risk.
• Sacral and infrasacral lesions give an areflexic or underactive detrusor with a flaccid or fixed sphincter. This leads to retention and overflow or stress incontinence.

Complications:

• Recurrent urinary tract infection, vesicoureteral reflux, hydronephrosis and stones.
• Renal failure (historically the leading cause of death after spinal cord injury).
• Bladder cancer (squamous cell carcinoma in long term catheterisation).
• Autonomic dysreflexia in lesions above T6.

• Urgency, frequency, urgency incontinence, nocturia, incomplete emptying, hesitancy, weak stream, retention and overflow incontinence, and recurrent urinary tract infections.
• Detrusor sphincter dyssynergia: interrupted stream, high voiding pressure, and incomplete emptying.
• Autonomic dysreflexia (lesions above T6): paroxysmal severe hypertension (rise of 20 to 40 mm Hg above baseline), pounding headache, flushing and sweating above the lesion, bradycardia, nasal congestion and goosebumps.
• Autonomic dysreflexia is triggered by bladder distension, catheter blockage, bowel impaction or other noxious stimuli below the lesion.
• Associated neurogenic bowel and sexual dysfunction.
• Examination: neurological assessment of the perineal sensation, anal tone, bulbocavernosus and anal wink reflexes, lower limb function, and signs of the underlying cause.
• Children with spina bifida: dribbling incontinence, recurrent infection and hydronephrosis.

• History and bladder diary (3 days), urinary symptom scores, medications, neurological history.
• Urinalysis and urine culture; serum creatinine, eGFR.
• Post-void residual volume by ultrasound or bladder scan (above 100 mL or above 20 to 30 percent of bladder volume indicates incomplete emptying; neurogenic cases may be larger).
• Urodynamic study (video urodynamics) is the key test. It measures bladder capacity, compliance (below 20 mL/cm H2O is poor), detrusor overactivity, and detrusor leak point pressure (above 40 cm H2O is a risk for upper tract damage).
• Urodynamics also measures sphincter activity and dyssynergia, and, with fluoroscopy, reflux.
• Renal and bladder ultrasound at baseline and yearly (hydronephrosis, stones, bladder wall thickening); DMSA or MAG3 renography if there are signs of renal damage; voiding cystourethrogram for reflux.
• Cystoscopy yearly after 10 years of catheterisation in high risk patients (for tumour); for haematuria.
• Neuroimaging (MRI brain or spine) to identify the cause.

The priorities are protection of the upper tracts (preserving renal function), achieving low pressure storage and complete emptying, achieving continence, and improving quality of life.

• Clean intermittent catheterisation is the cornerstone: every 4 to 6 hours (4 to 6 times daily) to keep volumes below 400 to 500 mL. Use a hydrophilic coated catheter (10 to 14 Fr in adults, size according to age in children) with clean technique. It requires manual dexterity or carer assistance.
• Indwelling catheters (urethral or suprapubic) are a last resort, with changes every 4 to 6 weeks (suprapubic is preferred over urethral for a long term). They cause infections, stones, and bladder cancer.
• Antimuscarinic drugs for detrusor overactivity, with caution about cognitive effects:
  • Oxybutynin 5 mg two to four times daily (up to 15 to 20 mg/day, or extended release 5 to 30 mg once daily, or transdermal 3.9 mg/day patch).
  • Tolterodine 2 to 4 mg daily.
  • Solifenacin 5 to 10 mg daily.
  • Trospium 20 mg twice daily (does not cross the blood brain barrier).
  • Fesoterodine 4 to 8 mg daily.
• Higher doses or combinations are common in neurogenic bladder.
• Beta-3 agonist mirabegron 25 to 50 mg daily (or vibegron 75 mg daily) as an alternative or add on; monitor blood pressure.
• Intradetrusor onabotulinumtoxinA injection for refractory neurogenic detrusor overactivity: 200 to 300 units diluted in 20 to 30 mL saline and injected in 20 to 30 sites of the detrusor with cystoscopy, sparing the trigone. Repeat every 6 to 9 months. It improves continence in 60 to 70 percent. Patients must be able to catheterise, as retention may follow.
• Alpha blockers (tamsulosin 0.4 mg, alfuzosin 10 mg daily) for functional outlet obstruction and detrusor sphincter dyssynergia.
• Sphincterotomy (endoscopic or botulinum toxin to the external sphincter, 100 units) in men with dyssynergia, with condom catheter drainage; urethral stents are an alternative.
• Neuromodulation: sacral neuromodulation for non-obstructive retention and overactivity (incomplete lesions), and tibial nerve stimulation.
• Surgery for refractory cases or loss of compliance: bladder augmentation (ileocystoplasty, with catheterisable stoma, Mitrofanoff), urinary diversion (ileal conduit) in the case of severe disease or when catheterisation is not possible, bladder neck closure with suprapubic catheter, and sling or artificial urinary sphincter for sphincteric incompetence.
• Urinary tract infection: treat only symptomatic infection (fever, new incontinence, worsening spasticity, malaise, autonomic dysreflexia) with a short course targeted by culture. Examples are nitrofurantoin 100 mg twice daily for 5 days, trimethoprim-sulfamethoxazole 160/800 mg twice daily for 7 days, or ciprofloxacin 500 mg twice daily for 7 days. Asymptomatic bacteriuria is not treated.
• Prophylaxis with methenamine hippurate 1 g twice daily or cranberry has limited evidence, with antibiotic prophylaxis for refractory recurrent infections.
• Autonomic dysreflexia: sit the patient upright, loosen tight clothing, and check blood pressure every 2 to 5 minutes. Find and remove the trigger (empty the bladder by checking the catheter, or insert a catheter with lidocaine gel; bowel disimpaction with lidocaine jelly).
• If systolic pressure remains above 150 mm Hg, give nifedipine 10 mg (bite and swallow) or glyceryl trinitrate 0.4 mg sublingual or 2 percent nitroglycerin ointment 1 inch topically, with captopril 25 mg sublingually as an alternative. Use intravenous labetalol or nitroprusside if severe.
• Surveillance: renal ultrasound yearly, creatinine, urodynamics every 1 to 2 years in high risk patients, and cystoscopy annually after 10 years for long term catheters.