Pediatrics

Neuropathic bladder

OVERVIEW: What every practitioner needs to know

Are you sure your patient has a neuropathic bladder? What are the typical findings for this disease?

Normal bladder function requires coordination between the cerebral cortex, somatic and autonomic nervous system, and the bladder smooth muscle and urinary sphincter. A neurologic insult at any level of this system can lead to the development of a neuropathic bladder and the associated problems.

Classification

Children with neuropathic bladder are categorized in three groups, depending on the level of neurologic insult:

1. Neuropathic bladder due to lesions above the Sacral Micturition Center:

Patients have bladder spasticity and hyperreflexia with a balanced or unbalanced coordination between sphincter and bladder. Lesions above the brain stem (e.g., vascular accidents, tumors, inflammation) can result in urge, frequency, urinary retention, and gross incontinence.

Spinal injuries (e.g., trauma, spina bifida, tumor, iatrogenic) present with sphincter spasticity and detrusor-sphincter dyssynergia. It results in detrusor hypertrophy, high voiding pressure, ureteral reflux or obstruction. There is a significant increase in the risk of infection and renal function impairment.

Lesions above cervical level can cause a condition named autonomic dysreflexia. Due to the lack of inhibition on sympathetic outflow, patients may have hypertensive blood pressure fluctuations, bradycardia, and sweating when the bladder is filled or a catheter is inserted into the bladder. This condition is not uncommon in pediatrics.

2. Neuropathic bladder due to lesions at or below the Sacral Micturition Center:

Patients suffer from flaccid, atonic bladder with loss of the ability of the bladder to contract. Most common cause is the spinal injury at the micturition center (S2-4) followed by anterior horn cell damage (infection, trauma) and myelodysplasia. There is a compensatory bladder capacity increase which results in lower rates of incontinence despite weak sphincter and perineal muscles.

Post-nucleus neuropathies and loss of dorsal horn function lead to loss of perception of the bladder filling and over distention. Examples include diabetes, and Tabes Dorsalis.

Injury to the peripheral nerves innervating the bladder muscle also causes neuropathic bladder. This type of injury leads to disorganized detrusor muscle activity and a steep rise in intravesical pressure during filling.

3. Mixed disorders:

They have characteristics of both categories. This is the most common presentation of neuropathic bladder in children with neural tube defects.

Typical Findings

History and physical examination as well as radiologic and urodynamic evaluations characterize the disease.

Children with spastic neuropathic bladder usually present with:

- Small bladder capacity for age.

- Involuntary urination associated with lower extremity spasms.

- Lower limb spastic paralysis and sensory deficit levels.

- Loss of normal reflexes (anal, bulbocavernous, knee, and ankle).

- Diminished levator muscle or anal tone.

- In milder cases (e.g., mild demyelination, incomplete spinal injuries) the most common findings are frequency, nocturia, and urgency.

- It is important to remember that the severity of neurologic deficits does not necessarily correlate with the degree of voiding dysfunction.

Flaccid neuropathic bladder in children is usually the result of trauma and presents with:

- Urinary retention with overflow incontinence.

- Limb paralysis and dermatomal loss of sensation and typical lower motor neuron symptoms are present depending on the site of spinal lesion.

- Large bladder capacity with low intravesical pressure.

Neuropathic bladder in children with neural tube defect present with:

- Urinary incontinence.

- Urinary tract infections.

- Hydronephrosis from vesicoureteral reflux or detrusor-sphincter dyssynergia.

- Pyelonephritis and renal function deterioration are long-term consequences.

What other disease/condition shares some of these symptoms?

Some conditions that can be confused with neuropathic bladders include:

Cystitis: inflamed bladder can mimic signs and symptoms of a spastic neuropathic bladder (e.g., urgency, frequency) as well as the uninhibited contractions on urodynamic study.

Bladder outlet obstruction: urethral stricture and congenital abnormalities (e.g., posterior urethral valve) can cause significant urine residue and detrusor trabeculation. If the condition decompensates, the bladder may lose regular tone and become a characteristic flaccid neuropathic bladder even with overflow incontinence. Typically, once the obstruction is removed the bladder function returns to normal unless it is longstanding and the damage is permanent.

Other chronic urethral or vesical irritation (chronic urethritis, interstitial cystitis, cystocele) can reproduce similar manifestations; however, most of them are in the adult population.

What caused this disease to develop at this time?

Examples for insults that can lead to neuropathic bladders are spinal and sacral root injuries, cerebrovascular accidents, diabetes, and Parkinson's disease. Congenital malformations (e.g., neural tube defects, sacral agenesis, etc.), tumors, and poor voiding habits are more common in pediatric population.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

Laboratory investigations are not diagnostic however they are used for long-term management.

Urine culture should be obtained if the child has fever, a change in clinical picture, or a new onset change in their urinary symptoms.

Renal function panel (BUN, Creatinine, electrolytes) and GFR. The risk of renal failure is higher in patients with increased detrusor pressures, recurrent pyelonephritis, and renal calculi.

Metabolic evaluations and 24 hour urine collection for evaluation of serum and urine Ca, urine oxalate, and uric acid in cases of urolithiasis.

Would imaging studies be helpful? If so, which ones?

Abdominal radiograph (x-ray) with lateral views of the sacrum is important if congenital malformations (e.g., spina bifida) are suspected or in case of spinal trauma.

Urodynamic studies are essential for diagnosis, categorization, and following the bladder function in long term. This study involves filling the bladder with normal saline, measuring the blade volume and pressure, and assessing sphincter tone:

- Spastic bladders are small and have a spastic dyssynergia of the external sphincter. Uninhibited detrusor activity with or without clinical manifestations is common. There is usually high voiding pressure and values above 40 cm of water increase the risk of reflux and upper tract compromise.

- Patients with flaccid neuropathic bladders have low sphincter tone, low bladder filling pressures, weak detrusor contractions, and high residuals.

- Neural tube defects can have mixed manifestations on urodynamic study.

Voiding cystourethogram (VCUG) evaluates reflux grade, bladder contour, urethral obstruction and sphincter competence.

Renal and bladder ultrasound is used to evaluate hydronephrosis and renal size.

Magnetic resonance imaging (MRI) assists in the evaluation of spinal lesions.

Cystoscopy and direct visualization of the bladder is performed in case of possible complications such as congenital diverticulum, stones, and urethral strictures.

Confirming the diagnosis

If neuropathic bladder is suspected, one should perform a renal ultrasound with post-void residual evaluation. If the child is unable to void, a urine catheter is necessary, and the child should be referred to a pediatric urologist.

If you are able to confirm that the patient has a neuropathic bladder, what treatment should be initiated?

Treatment goals are maintaining a low-pressure bladder, preserving renal function, providing continence, and avoiding infection in a patient with neuropathic bladder. Nonetheless, there are specific treatments available depending on the cause of the disorder:

Spinal shock: Damage could be permanent or temporary depending on the level and severity of spinal injury.

During the spinal shock stage, bladder drainage via foley catheter, clean intermittent catheterization (CIC), or suprapubic cystostomy is necessary. Bladder irrigations with antibiotics or systemic antibiotics have not proven effective in preventing infection in contrast with ample fluid intake and early ambulation. Dietary calcium and oxalate restriction can decrease the risk of stone formation. Vesicoureteral reflux should be ruled out and urodynamic studies may be necessary for long-term management.

Spastic bladders: If there is reasonable bladder capacity (early stages of neuropathic bladder) timed voiding is initiated and low dose anticholinergics can also help. If there is markedly decreased bladder capacity (depending on age), CIC with or without anticholinergic medications are necessary. Bladder pressure must be monitored and maintained below 30-40 cm of water. CIC is the first line of treatment; however, surgical treatment options include sphincterotomy, sacral rhizotomy, or urinary diversion and are generally reserved as final options. Pharmacologic treatment are mostly anticholinergics.

Flaccid bladders: In partial lower motor neuron injuries bladder training and care including timed voiding with manual suprapubic pressure is necessary. If there is no high-grade ureteral reflux and the patient or parents are compliant, clean intermittent catheterization is an excellent option for urine emptying and is associated with very low complication rate and high patient acceptance.

Neuropathic bladder associated with spina bifida can be spastic, flaccid, or mixed. CIC is still the mainstay of treatment. Mild symptoms can be managed by 2 hour voiding using suprapubic pressure. More severe symptoms in the presence of a flaccid bladder and reflux necessitate anti-reflux surgery and CIC 4-6 times a day. In spastic cases anticholinergics and indwelling catheters are initiated followed by CIC after upper tract dilation is resolved and bladder gains maximum growth. For more complex cases urinary diversion is required.

What are the adverse effects associated with each treatment option?

Clean intermittent catheterization is associated with increased risk of bacterial colonization; however, if performed correctly, it does not increase symptomatic and febrile infections. Anticholinergic therapy is associated with dry mouth and constipation and should be addressed accordingly. If surgical options are considered, the risks and benefits of each specific procedure should be explained to patients and their families.

What are the possible outcomes of neuropathic bladder?

Outcome directly depends on severity of the inducing insult and is determined by the morbidity they cause. As far as the neuropathic bladder is concerned, it generally has favorable prognosis. Children cope well with the CIC and are able to maintain low-pressure bladders and preserve urinary continence.

With proper adherence to treatment plan, the risk of infection and renal function loss is low, but poor compliance can be catastrophic.

What causes this disease and how frequent is it?

Neural tube defects and other spinal malformation are the most common reasons for neuropathic bladders but have significantly decreased due to prenatal ultrasounds.

Annually, there are approximately 2000 live births with neural tube defects in the United States.

Traumatic lesions of the spinal cord, CNS tumors, and sacrococcygeal teratoma, are less common causes of neuropathic bladder in children in the United States.

How do these pathogens/genes/exposures cause the disease?

Neural tube defects are associated with low folic acid consumption during and before pregnancy, certain medication, and also there is a genetic component. The risk increases with advanced maternal age.

Trauma and spinal tumors may also cause neuropathic bladders with different mechanisms.

Other clinical manifestations that might help with diagnosis and management

Common clinical manifestations are explained above.

What complications might you expect from the disease or treatment of the disease?

Major complications associated with neuropathic bladders are recurrent urinary tract infections; renal damage, reflux, hydronephrosis, and stone formation.

Children with neuropathic bladder due to spina bifida undergo several surgical procedures and are specifically prone to latex allergy.

Are additional laboratory studies available; even some that are not widely available?

No other laboratory studies are necessary.

How can neuropathic bladder be prevented?

Proper family planning and counseling, access to appropriate prenatal care and screening modalities, as well as adherence to nutritional recommendations before and during pregnancy can significantly decrease the rate of children born with neural tube defects or other congenital abnormalities.

Safety practices during work and recreation can prevent many spinal cord injuries in children as well as adults.

What is the evidence?

Congenital malformations leading to neuropathic bladders are relatively rare, so are spinal injuries in pediatric population. Therefore most of the evidence is based on retrospective studies with small sample sizes as well as the expert opinions in the field.

de Jong, TP, Chrzan, R, Klijn, AJ, Dik, P. "Treatment of the neurogenic bladder in spina bifida". Pediatric Nephrology. vol. 23. 2008 Jun. pp. 889-96.

Kasabian, NG, Bauer, SB, Dyro, FM, Colodny, AH, Mandell, J, Retik, AB. "The prophylactic value of clean intermittent catheterization and anticholinergic medication in newborns and infants with myelodysplasia at risk of developing urinary tract deterioration". Am J Dis Chield. vol. 146. 1992. pp. 840.

Cain, MP, Casale, AJ, King, SJ, Rink, R C. "Appendovesicostomy and newer alternatives for the Mitrifanoff procedure: results in the last 100 patients at Riley Children's Hospital". J Urol. vol. 162. 1999. pp. 1749.

Ongoing controversies regarding etiology, diagnosis, treatment

Controversies exist in the role of corticosteroid and timing of surgery in the setting of acute spinal cord injury after trauma.

Off-label use of intravesical Botulinum Toxin-A injection is a popular practice; however, some experts believe that sufficient evidence in efficacy and the procedure details are still lacking for implementation in practical guidelines. Moreover, it is yet to be approved by the FDA for use in pediatric population.

Despite some encouraging results, prenatal repair of neural tube defects is still a matter of debate among experts and there are several ongoing trials on this issue.

Recent advances in tissue engineering, stem cell research, and laboratory organ growth have opened new horizons for the treatment of neuropathic bladder and many other diseases in the future.

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