Neuropathic Bladder

Published on 27/03/2015 by admin

Last modified 22/04/2025

Print this page

This article have been viewed 2661 times

Chapter 536 Neuropathic Bladder

Neuropathic bladder dysfunction in children usually is congenital, generally resulting from neural tube defects or other spinal abnormalities. Acquired diseases and traumatic lesions of the spinal cord are less common. Central nervous system tumors, sacrococcygeal teratoma, spinal abnormalities associated with imperforate anus (Chapter 336), and spinal cord trauma also can result in abnormal innervation of the bladder and/or sphincter.

Neural Tube Defects

Neural tube defects, resulting from failure of the neural tube to close spontaneously between the 3rd and 4th wk in utero, result in abnormalities of the vertebral column that affect spinal cord function, including myelomeningocele and meningocele (Chapter 585). A few medical centers in the USA have been performing antenatal myelomeningocele closure, but follow-up studies of the urinary tract have not shown a definite improvement in lower urinary tract function.

Clinical Manifestations and Diagnosis

The most important urologic consequences of neuropathic bladder dysfunction associated with neural tube defects are urinary incontinence (Chapter 537), urinary tract infections (UTIs; Chapter 532), and hydronephrosis from vesicoureteral reflux or detrusor-sphincter dyssynergia. Pyelonephritis (Chapter 532) and renal functional deterioration (see Chapter 529) are common causes of premature death of affected patients.

In the neonate, renal ultrasonography, assessment of postvoid residual urine volumes, and a voiding cystourethrogram are performed after closure of the myelomeningocele. About 10-15% of patients have hydronephrosis, and renal malformations are common; 25% have vesicoureteral reflux. A urodynamic study also should be performed. This study involves filling the bladder with saline, measuring the bladder volume and pressure, and assessing sphincter tone. During bladder filling, the bladder might show uninhibited (premature) contractions at low volumes, normal bladder volume with contraction at an appropriate volume, or atonia (lack of bladder contraction). Bladder compliance or elasticity also may be reduced. The sphincter can show normal tone with relaxation during bladder contraction, reduced or absent tone, or normal or increased tone that increases during bladder contraction (termed detrusor-sphincter dyssynergia) (Fig. 536-1).

Figure 536-1 Grouping of neurogenic bladder dysfunction according to the innervation, tonicity, and coordination of the detrusor and sphincters described by Guzman. This grouping is based on data from imaging studies, cystometrography, and electromyography of the sphincters. Patients in group B are at risk of developing reflux and hydronephrosis. For guidance in the treatment of incontinence, group A benefits from procedures that increase outlet resistance, group B from anticholinergics or bladder augmentation surgery, and group C from intermittent catheterization. Group D requires both increased outlet resistance and pharmacologic or surgical bladder enlargement. Most patients require intermittent catheterization to empty.

(Modified from Gonzalez R: Urinary incontinence. In Kelalis PK, King LR, Belman AB, editors: Clinical pediatric urology, Philadelphia, 1992, WB Saunders, p 387.)

Renal Damage

Renal damage usually results from failure of the sphincter to relax during a spontaneous bladder contraction. This dyssynergia results in functional obstruction of the bladder outlet, leading to high intravesical pressure, bladder muscle hypertrophy and trabeculation, and transmission of the high pressure into the upper urinary tracts, causing hydronephrosis (Fig. 536-2). Vesicoureteral reflux and UTI compound the problem. Treatment includes reduction of bladder pressure with anticholinergic drugs (oxybutynin, 0.2 mg/kg/24 hr in 2 or 3 divided doses) and clean intermittent catheterization every 3-4 hr. If there is vesicoureteral reflux or UTI, antimicrobial prophylaxis also is prescribed.

Figure 536-2 Voiding cystourethrogram in an infant with myelodysplasia shows a severely trabeculated bladder with multiple diverticula and grade V (out of V) right vesicoureteral reflux. Evaluation showed severe detrusor-sphincter dyssynergia.

Temporary urinary diversion by cutaneous vesicostomy is an alternative in the newborn or infant with severe reflux, if intermittent catheterization is difficult or anticholinergic medications are not well tolerated. Another option to treat the severely trabeculated bladder is transurethral injection of botulinum toxin (Botox) into the detrusor muscle, which reduces bladder hypertonicity for approximately 6 mo. A different approach in these children is to temporarily inactivate the tight sphincter by urethral overdilation or transurethral injection of botulinum toxin into the sphincter.

Clean intermittent catheterization and anticholinergic therapy cure the reflux in up to 80% of children with grade I or II reflux. In children with upper tract changes, continuous overnight bladder drainage allows significant bladder relaxation and can reduce bladder wall thickening and reduce hydronephrosis.

Children with more severe reflux often require endoscopic reflux correction or open antireflux surgery followed by intermittent catheterization and anticholinergic drugs. In older children with myelomeningocele with high-grade reflux, UTI, and hydronephrosis, augmentation enterocystoplasty with intermittent catheterization may be necessary.

Urinary Incontinence

Incontinence in the child with neuropathic bladder can result from total or partial denervation of the sphincter, bladder hyperreflexia, poor bladder compliance, chronic urinary retention, or a combination of these factors.

Incontinence often is addressed around 4 yr of age and is tailored to the individual child. Nearly all children require clean intermittent catheterization to stay dry. This technique allows efficient bladder emptying with minimal risk of symptomatic UTI. The urinary tract should be re-evaluated with renal ultrasonography, a voiding cystourethrogram, and a urodynamic study, including bladder capacity. If the sphincter tone is sufficient and the bladder has adequate compliance, intermittent catheterization every 3-4 hr usually is successful in keeping the child dry. If there are unstable bladder contractions, an anticholinergic medication such as oxybutynin chloride, hyoscyamine, or tolterodine is prescribed to increase bladder capacity. If there is sphincter incompetence, α-adrenergic medications are prescribed to enhance outlet resistance. Bacteriuria is seen in up to 50% of children using intermittent self-catheterization, but it seldom causes symptoms. In the absence of reflux, there seems to be little cause for concern. Performing intermittent catheterization with a new catheter (hydrophilic or standard silicone) each time also is quite effective in preventing bacteriuria and avoids the need for antibiotic prophylaxis. With this treatment plan, 40-85% of patients are dry, depending on the definition of continence; some children wear a pad in their underwear or a diaper but feel that they are dry.

If there is persistent incontinence despite medical therapy, reconstructive urinary tract surgery nearly always can provide complete or satisfactory continence. If urethral resistance is low, bladder neck reconstructive procedures such as a periurethral sling often are successful. Alternatively, implantation of an artificial sphincter usually is successful. This sphincter consists of an inflatable cuff that is placed around the bladder neck, a pressure-regulating balloon implanted in the extraperitoneal space, and a pumping mechanism that is implanted in the scrotum of boys and in the labia majora of girls. If the bladder capacity or bladder compliance is low, or if there are persistent uninhibited contractions despite anticholinergic therapy, enlargement of the bladder with a patch of small or large intestine, termed augmentation cystoplasty or enterocystoplasty, is effective.

These patients still need to perform clean intermittent catheterization. If urethral catheterization is difficult, a continent urinary stoma may be incorporated into the urinary tract reconstruction. A common method is the Mitrofanoff procedure, in which the appendix is isolated from the cecum on its vascular pedicle and is interposed between the bladder and abdominal wall to allow intermittent catheterization through a dry stoma. An ileal conduit with a bag on the abdominal wall is rarely used.

Complications

Urinary Tract Infection

The urine may be colonized with gram-negative bacteria, and attempts to sterilize the urine for prolonged periods usually fail. There is no evidence that chronic bacteriuria in patients who have had enterocystoplasty is associated with renal damage; therefore, only symptomatic UTIs should be treated.

The enteric mucosal surface in contact with the urine absorbs ammonium, chloride, and hydrogen ions and loses potassium. Hyperchloremic metabolic acidosis can result, possibly requiring medical treatment (Chapter 52); this condition can occur with colocystoplasty but rarely with ileocystoplasty. Chronic acidosis can compromise skeletal growth. Metabolic acidosis is most common in patients with compromised renal function and in those in whom colon has been used to enlarge the bladder. To overcome this limitation of enterocystoplasty in patients with chronic renal insufficiency, a composite augmentation using stomach and small or large bowel gastric segment can be used. The stomach secretes chloride and hydrogen ions; thus, pre-existing metabolic acidosis remains stable or improves.

Future Management

The development of a tissue-engineered bladder using a composite scaffold, which could be attached to the dome of the bladder to increase capacity and compliance, might help patients achieve continence (Fig. 536-3). In addition, a nerve-rerouting procedure has the dorsal nerve root from the lumbar nerve sutured to the ventral sacral nerve root, thus controlling bladder function. The procedure allows the child to scratch the thigh to stimulate a bladder contraction.

Figure 536-3 Gross specimens and cystograms at 11 mo of the cystectomy-only, nonseeded controls, and cell-seeded tissue engineered bladder replacements in dogs. The cystectomy-only bladder had a capacity of 22% of the preoperative value and a decrease in bladder compliance to 10% of the preoperative value. The nonseeded controls showed significant scarring and had a capacity of 46% of the preoperative value and a decrease in bladder compliance to 42% of the preoperative value. An average bladder capacity of 95% of the original precystectomy volume was achieved in the cell-seeded tissue engineered bladder replacements, and the compliance showed almost no difference from preoperative values that were measured when the native bladder was present (106%).

(From Atala A: Bioengineered tissues for urogenital repair in children, Pediatr Res 63:569–575, 2008.)

Associated Disorders

Constipation

Many patients with spina bifida also have bowel problems with constipation, and a vigorous bowel regimen is important. Some benefit from the Malone antegrade continence enema procedure, in which the appendix is brought out to the skin to allow a catheter to be inserted into the cecum for antegrade enema. The stoma is continent, and an antegrade enema can be performed with tap water each day. This form of management allows the patient to be continent of stool and be more self-sufficient.

Latex Allergy

Latex allergy (Chapter 143) is a very serious problem encountered by as many as half of patients with spina bifida and other urologic conditions who require clean intermittent catheterization and urinary tract reconstructive procedures. This IgE-mediated allergy is acquired and is secondary to repeated exposure to the latex allergen. Latex allergy can manifest as watery eyes, sneezing, itching, hives, or anaphylaxis when blowing up a balloon or if an examiner is using latex gloves. Intraoperatively, a sensitized patient can experience anaphylactic shock. A latex-free environment should be provided for all children with spina bifida in the office, during hospitalization, and during operative procedures. Affected children also should wear a medical alert bracelet.

Occult Spinal Dysraphism

Approximately 1/4,000 patients have occult spinal dysraphism, a category that includes lipomeningocele, intradural lipoma, diastematomyelia, tight filum terminale, dermoid cyst-sinus, aberrant nerve roots, anterior sacral meningocele, and cauda equina tumor (Chapter 585). More than 90% of patients have a cutaneous abnormality overlying the lower spine, including a small dimple, tuft of hair, dermal vascular malformation, or subcutaneous lipoma (Fig. 536-4). Often these children have high-arched feet, discrepancy in muscle size and strength between the legs, and a gait abnormality. Newborns and young infants often have a normal neurologic examination. Older children often have absent perineal sensation and back pain. Lower urinary tract function is abnormal in 40% of patients, including incontinence, recurrent UTI, and fecal soiling. The likelihood of a normal examination is inversely related to the child’s age at surgical correction of the spinal lesion. In infants with abnormal urodynamics, 60% revert to normal; in older children, only 27% become normal. Management of the urinary tract in other children is similar to that described earlier for neural tube defects.

Figure 536-4 A, Buttocks of teenage boy with tethered cord secondary to lipomeningocele. Note sacral dimple and deviation of gluteal fold to the left. B, Fat deposit over sacrum in girl with tethered cord secondary to lipomeningocele. C, Deep sacral pit in child with neuropathic bladder.

Sacral Agenesis

Sacral agenesis is defined as the absence of part or all of ≥2 lower vertebral bodies. This condition is more common in the offspring of women with diabetes. These children have a flattened buttock and a low, short gluteal cleft but usually have no orthopedic deformity, although some have high-arched feet. Palpation of the coccygeal area detects the absent vertebrae. Approximately 20% of cases are undetected until the age of 3-4 yr; many are diagnosed after unsuccessful toilet training. Urodynamic studies in these children show a variety of patterns, and most need clean intermittent catheterization and pharmacotherapy to stay dry.

Imperforate Anus

About 30-45% of children with a high imperforate anus have a neuropathic bladder, often because of sacral agenesis. Newborns with imperforate anus should undergo a spinal ultrasound during their initial evaluation, and if these children have difficulty with toilet training, complete urologic evaluation with upper and lower urinary tract imaging and urodynamics should be performed. See Chapter 336 for further details.

Cerebral Palsy

Children with cerebral palsy (Chapter 591.1) have reasonable bladder control. However, they achieve continence at a later age than unaffected children. Overall, 25-50% are incontinent, and the risk is directly related to the severity of physical impairment. Their upper urinary tracts usually are normal. Urodynamic studies have shown that most have uninhibited bladder contractions. Timed voiding and anticholinergic therapy are usually effective. Clean intermittent catheterization rarely is necessary.

Bibliography

Atala A. Bioengineered tissues for urogenital repair in children. Pediatr Res. 2008;63:569-575.

Atala A. Regenerative medicine and tissue engineering in urology. Urol Clin North Am. 2009;36:199-209.

Bowman RM, Mohan A, Ito J, et al. Tethered cord release: a long-term study in 114 patients. J Neurosurg Pediatr. 2009;3:181-187.

Castellan M, Gosalbez R, Perez-Brayfield M, et al. Tumor in bladder reservoir after gastrocystoplasty. J Urol. 2007;178:1771-1774.

Catti M, Lortat-Jacob S, Morineau M, et al. Artificial urinary sphincter in children—voiding or emptying? An evaluation of functional results in 44 patients. J Urol. 2008;180:690-693.

deJong TP, Chrzan R, Klihn AJ, et al. treatment of the neurogenic bladder in spina bifida. Pediatr Nephrol. 2008;23:889-896.

Dodson JL, Furth SL, Hsaio CJ, et al. Health related quality of life in adolescents with abnormal bladder function: an assessment using the Child Health and Illness Profile—Adolescent Edition. J Urol. 2008;180:1846-1851.

Elder JS, Pippi Salle JS. Bladder outlet surgery for congenital incontinence. In: Gearhart JP, Rink RC, Mouriquand PDE, editors. Pediatric urology. ed 2. Philadelphia: Saunders; 2010:761-774.

Hensle TW, Gilbert SM. A review of metabolic consequences and long-term complications of enterocystoplasty in children. Curr Urol Rep. 2007;8:157-162.

Johal NS, Hamid R, Aslam Z, et al. Ureterocystoplasty: long-term functional results. J Urol. 2008;179:2373-2375.

Kim BS, Atala A, Yoo JJ. A collagen matrix derived from bladder can be used to engineer smooth muscle tissue. World J Urol. 2008;26:307-314.