Causes of neuropathic bladder or neuromuscular dysfunction of the lower urinary tract:
| Congenital | Acquired |
| · Neural tube defect
· Spina bifida occulta · Sacral agenesis (caudal regression) · Anorectal malformations |
· Pelvic surgery
· CNS insults (tumour, encephalopathy) · Spinal cord insults (transverse myelitis, tumour) · Cerebral palsy · Trauma |
Most common cause is abnormal spinal cord development and consequently failure of the normal enveloped spinal cord – neural tube defects
- Myelomeningocele still most common cause of congenital neuropathic bladder but incidence is markedly reduced.
- Aetiology is failure of tubularisation of the neural crest, almost always involving the conus medullaris
- Risk factors including low folate levels, family history (if one child with NTD – next child 20-50 x risk), maternal NTD, young or advanced maternal age, maternal obesity, maternal diabetes.
Pathogenesis of spina bifida:
- Almost all born with NTD/spina bifida have Arnold-Chiari malformation -> hydrocephalus which often managed in infancy with VP shunt
- Up to 98 % of patients with myelomeningocele have neurogenic bladder
- The neurologic lesion produced by the myelomeningocele is variable – and often unpredictable and unrelated to the bony level of the lesion
- Therefore urodynamic and functional classifications are much more useful for planning treatment
Antenatal treatment of spina bifida appears to improve neuromotor function and decrease need for VP shunts, but increases risk of preterm labour. Bladder and bowel function appears to not be changed with antenatal treatment.
Other conditions causing neuropathic bladder – sacral agenesis, cerebral palsy, spinal/brain problems – can be managed with same principles.
Goals of management
- Protect and preserve kidney function
- Optimise urinary continence
- Optimise bowel continence
- Prevent urinary tract infections
- Optimise sexual function
Principles of managing children with neuropathic bladder:
- Proactive assessment and identification of changes allowing early management, i.e. regular urodynamics even if no clinical changes
- Alternative is ‘expectant’ approach, i.e. UDS if clinical changes
- Early intervention with intermittent catheterisation and pharmacotherapy can reduce complications later
- The lower urinary tract can change throughout childhood and adolescence – must remain vigilant
- Spinal cord tethering can occur with growth (early childhood, puberty)
- Take into account the whole picture – patients age, sex, social circumstances, physical ability, other issues
- Lifelong urological follow up
Initial assessment / management
- Ultrasound and renal function testing soon after birth and spinal closure, before discharge
- Urodynamics, preferably videourodynamics +/- MCUG in first 3 months
- Baseline DMSA first 6 – 12 months
- Regular (3-6 monthly) ultrasounds and bloods + annual urodynamics/MCUG as indicated +/- DMSA as indicated
- And if any change in clinical symptoms, increase in infections, worsening renal function or sonographic parameters, etc
Early clean intermittent catheterisation (CIC) in children with neuropathic bladders has been shown to prevent UTIs, renal scarring and VUR.
- It is probably best to be proactive and start this very early, and is better accepted by patients and families if started very early.
- Mandatory in high voiding pressures, DSD, VUR, overactivity, residual volumes
- Consider catheterisable channel as patients transition to self-catherisation, or in those with difficult urethras to access.
Anticholinergics also useful when started early for overactive or high pressure bladders.
- Follow up and adjust dose as weight changes
- Consider B3 agonists or botox as needed.
Classification
The key seems to be understanding the detrusor and sphincter relationship and figuring out and constantly assessing whether the detrusor is overactive or underactive, and whether the sphincter is overactive or normal/underactive, or what combination of the two.
Overactive bladder
- Antimuscarinics – oxybutynin
- ISC if high residual volumes
- Botox if failing oxybutynin (10-12 units/kg, max 300 units)
- Augmentation
Detrusor sphincter dyssynergia
- Antimuscarinics
- ISC (+/- catheterisable channel)
- Botox to bladder or sphincter
- Augmentation
Underactive bladder
- ISC (+/- catheterisable channel)
Underactive sphincter
- Must first ensure bladder overactivity / poor compliance is managed or excluded before treating sphincteric incontinence
- Alpha agonists – minimal efficacy
- Bulking agents
- AUS
- Bladder neck slings in girls
- Pippi Salle urethral lengthening procedure in girls
- Bladder neck closure (with catheterisable channel)
Other urological procedures in difficult cases
- Vesicostomy in infants as temporary measure to protect the upper tracts
- Sphincterotomy in boys to protect the upper tracts – usually in severely disabled, accepting incontinence
- Conduit diversion in severely disabled, reflux still often an issue
Other considerations
- Manage the bowels – bowel regime with or without MACE, Chait tube, colostomy
- High risk of stones in future requiring bespoke management
- Don’t forget about metabolic complications if augmenting bladder etc, B12 etc
- Adolescent transition of care
- Consider prophylactic antibiotics, especially in children with VUR
Sexual health and considerations
- Most patients with spina bifida will have normal desires for sexual function, coupling and fertility
- The degree of sexual activity is inversely proportional to severity of neurological function
- 40 – 70 % of men have normal erections (mobile men more likely)
- 40 – 70 % of men have normal ejaculation
- Self-reporting of sexual activity is vary variable
- 70 – 80 % of women were able to become pregnant and have children
- Both men and women with spina bifida have higher risks of their children having neural tube defects
- Sildenafil seems effective in men with spina bifida at improving erections
Assessment of neuropathic patient
History:
- General health, mobility, level of function including upper limb function, motivation, caregivers
- Other co-morbidities – orthopaedic, neurological, VP shunt, etc
- Current bladder management
- Self catheterising, natural voiding, Crede manoeuvre, degree of continence or incontinence, containment devices
- Symptomatology
- UTIs and continence
- Febrile UTIs vs non-febrile vs asymptomatic bacteriuria
- Urinary flow – continuous dribbling vs discrete flow vs intermittency
- Current bowel regime
- Previous investigations and compliance with follow up
- Previous ultrasounds, renal function, urodynamics, MCUGs, DMSAs
- Previous surgery
- Urological
- Non urological – bowels, neurosurgical, orthopaedic, appendicectomy
- Current medications
- Anti-cholinergics, antibiotics, previous botox
Examination:
- General health, level of understanding, barriers to management, mobility
- Abdomen
- Suitability for surgery
- Is the bladder palpable, expression of urine (crude marker of emptying ability and sphincteric function)
- Scars, previous surgery
- Genitals
- Catheterisability
- Foreskin
- Bulbocavernosus reflex – contraction of bulbospongiosus muscle and anal sphincter in response to squeezing glans or clitoris
- If present – intact spinal reflexes and pudendal nerve – upper motor neuron lesion – likely overactivity and DSD, more likely preserved sexual function
- If absent – lower motor neuron lesion – likely underactive bladder and weak sphincter, worse sexual function
Investigations:
- Look at previous studies as baseline
- Renal function testing (creatinine, or cystatin C may be more accurate due to reduced muscle mass affecting serum creatinine)
- Urine culture esp if UTIs or symptomatic
- Ultrasound – hydro, bladder emptying, stones
- Urodynamics (if not done for a while, or change in symptoms)
- Preferably video urodynamics
- MCUG, if no video available for urodynamics
- DMSA
- Spine MRI if late presentation, to look for tethered cord etc
Other considerations:
- Abdo x-ray for constipation or stones
- Review of ISC technique or frequency
- Cystoscopy depending on scenario