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Neurogenic Bladder Dysfunction
Management Principles in Pediatric Urology
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Neurogenic Bladder Dysfunction
Stuart B. Bauer, MD*
Neurogenic bladder dysfunction in children may be caused by a variety of diseases. Some are obvious (such a myelodysplasia) whereas others are occult and discovered only after thoughtful consideration and thorough investigation. This article will describe the various conditions that produce abnormal lower urinary tract function, provide some helpful clues to diagnose several of the less overt causes, and outline a plan of management for affected youngsters. Neurogenic bladder dysfunction is a complex subject that requires a thorough understanding of the neurophysiology of the lower urinary tract to manage the condition properly. (The reader is referred to "Urodymanic Evaluation and Neuromuscular Dysfunction," in Clinical Pediatric Urology if more information is needed.') Lower urinary tract function is under the control of both somatic and autonomic nervous systems; the latter is composed of sympathetic and parasympathetic fibers (Fig. 1). Sympathetic neurons arise from the thoracolumbar region region of the cord, whereas parasympathetic nerves originate from the sacral area. Sympathetic stimulation will affect detrusor function based on the predominant receptor found in a particular area of the bladder. Alpha receptor sites are located primarily in the trigone and proximal portions of the urethra, while beta receptors are located in the fundus or body of th~ bladder (Fig. 2). Stimulation of alpha receptors causes a tightening of the trigonal and proximal urethral muscles and beta receptor stimulation leads to relaxation of the detrusor muscle. During filling of the bladder, sympathetic nerves exert an important regulatory influence which allows the bladder to expand at low pressure while increasing the outflow channel resistance. During this phase no spontaneous contractions of the bladder should occur (Fig. 3). The parasympathetic nerves from S-2 to S-4 (see Fig. 1) innervate cholinergic receptors in the fundus of the bladder (Fig. 2). The somatic nerves also from S-2 to S-4 supply the external sphincter. During voiding, the parasympathetic nerves are active and cause the bladder to contract, while somatic stimulation of the external sphincter ceases, allowing that muscle to relax. Voiding should take place with a steady uninterrupted stream until it is completed (see Fig. 3). The various phases of the micturition cycle are under the influence of the detrusor nucleus in the brain stem, which coordinates the function of the three nervous systems. This center, in turn, is modulated by the cerebral cortex, which integrates sensation and volitional control (see Fig. 1). *Assistant Professor of Urology, Director of Neurourology; Children's Hospital, Harvard Medical School, Boston, Massachesetts
Pediatric Clinics of North America-Vol. 34, No.5, October 1987
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Figure 1. The frontal (A) and parietal (B) lobes of the cerebral cortex, the cingulate gyrus (C), the hypothalamus containing the detrusor nucleus (D), the cerebellum (E), the sympathetic nervous system (F) for T-IO to L-l, the parasympathetic nervous system (G) from 5-2 to 5-4, and the pudendal nerve of the somatic nervous system (G) to the external sphincter all interact in a coordinated way to achieve proper and efficient function of the lower urinary tract.
A lower motoneuron lesion refers to an injury that affects the nerve roots supplying a particular organ, while an upper motoneuron lesion implies an injury to the cord (above the level of the roots innervating that organ), brain stem or cerebral cortex. A lower motoneuron lesion leads to an inability to void, either voluntarily or reflexively. In addition, it can lead to lowered urethral resistance and incontinence with any increase in abdominal pressure, such as coughing or laughing. An upper motor neuron lesion may produce uninhibited contractions (hyperactivity) with voluntary voiding if the lesion is incomplete, or reflex contractions without voluntary control if the lesion is complete. Furthermore, there may be incoordination between the detrusor and sphincter during bladder emptying with an upper motoneuron lesion. Medical treatment of neurogenic bladder dysfunction is based on the functional impairment produced by the specific neurourologic defect (Table 1). Inadequate storage capacity may be enhanced by lowering detrusor tone or abolishing uninhibited contractions with anticholinergic medication, such as propantheline or oxybutynin. These drugs block cholinergic receptor sites in the detrusor muscle, diminishing its tone and suppressing involuntary contractions of the bladder. Other drugs, for example, flavoxate, act directly on the smooth muscle cells and lower
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NEUROGENIC BLADDER DYSFUNCTION
Figure 2. Distribution of alpha- and beta-sympathetic and parasympathetic (cholinergic) receptor sites in the vesicourethral unit.
•
I
U] .a-adrenergic lid Cholinergic
a-adrenergic
NORMAL LOWER URINARY TRACT FUNCTION
I
EMG ........~III ...I_ _ _ _ _ _ _ _ _~ ..
120
i
Voluntary Voiding ----l~
III
- - - Bladder neck _.- Intravesical --- Rectal
I
90
I I~~' I· "', I .1 \
cm/~O
60 30
I I
----------J/
.,,-,-,-,-,-,-,--,
\~
',.
OL-~-~100~~~~~~~--------~
Figure 3. The interaction of intravesical, intraurethral, and rectal pressures, and electromyographic activity of the external urethral sphincter during the micturition cycle are shown.
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Table 1. Types of Medicines that Modulate Lower Urinary Tract Function TYPE
MINIMUM
MAXIMUM
Cholinergic Bethanechol
0.7 mg/kg t.i.d.
0.8 mg/kg q.i.d.
Anticholinergic Propantheline
0.5 mg/kg b.i.d.
Oxybutynin
0.2 mg/kg b.i.d.
0.5 mg/kg q.i.d. 0.2 mg/kg q.i.d.
Sympathomimetic Phenylpropanolamine (alpha) Ephedrine (alpha) Sympatholytic Prazosin (alpha) Phenoxybenzamine (alpha) Propanalol (beta) Smooth muscle relaxant Flavoxate Skeletal muscle relaxant Diazepam Baclofen Other Imipramine
2.5 mg/kg b.i.d. 0.5 mg/kg b.i.d.
2.5 mg/kg t.i.d. 1.0 mg/kg t.i.d.
0.05 mg/kg b.i.d. 0.3 mg/kg b.i.d.
0.1 mglkg t.i.d. 0.3 mg/kg b.i.d. 0.5 mg/kg b.i.d.
0.25 mg/kg b.i.d. 3.0 mg/kg b.i.d.
3.0 mg/kg t.i.d.
0.03 mg/kg b.i.d. 0.1 mg/kg b.i.d.
0.2 mg/kg t.i.d. 0.3 mg/kg t.i.d.
0.7 mg/kg b.i.d.
1. 2 mg/kg t. i. d.
detrusor tone without affecting contractility. Ifinadequate urethral resistance is the primary reason for impaired storage of urine, alpha-sympathomimetic agents, such as ephedrine sulfate and phenylpropanolamine, stimulate receptors in the bladder neck and proximal urethra to enhance the muscle tone in these areas. There are no drugs commercially available that will increase the contractility of denervated skeletal muscle in the external spincter region. Incomplete emptying of the bladder may be facilitated by cholinergic drugs, such as bethanechol chloride or alphasympatholytic agents, prazosin or phenoxybenzamine. Skeletal muscle relaxants, such as diazepam and baclofen, diminish skeletal muscle tone at the external sphincter region. Intermittent catheterization is begun in all children who cannot empty their bladder completely at low voiding pressure. Frequently, it is combined with medical therapy to maintain continence between catheterizations. When drug therapy fails to increase the capacity of the bladder and lower detrusor tone (to improve upper urinary tract drainage), subtotal cystectomy and augmentation cystoplasty using a segment of bowel is needed. When urethral resistance is low and is the cause of incontinence, and is unaltered by medications, bladder neck reconstruction, or perhaps implantation of an artificial urinary sphincter may be necessary.
MYELOMENINGOCELE The most common cause of neurogenic bladder dysfunction in the pediatric age group (and easiest to diagnose) is myelomeningocele. This condition is due to a failure of the spinal canal to close and the ectodermal elements to fuse superficial to the spinal cord resulting in a segmental outpouching of the meninges, cord or
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nerve roots. This leads to an injury affecting the neural elements involved in the innervation of the bladder and sphincter muscles. The type of lower urinary tract function is unique for each child due to the variable location of the vertebral bony defect and the amount of neural tissue injured. The diagnosis is obvious at birth when an open or flimsily covered sac containing neural elements is noted in the delivery room. Myelominingocele is being detected with increasing frequency prenatally, as a result of the more widespread use of prenatal ultrasound and amniocentesis, especially in high-risk mothers. This includes very young and over40-year-old women, and families in which there are already other children with spina bifida. The incidence of having a child with myelodysplasia increases from 1 per 1000 in the general population to 2 per 100 when the condition is present in another family member, to 10 per cent when a sibling is affected. 5 In the newborn period, all children should get a urine culture, serum creatinine, excretory urogram, and postvoid residual urine volume after the surgery to close the back has healed. A neurologic assessment of the child's lower extremities is also important as a baseline. If feasible, a urodynamic study is performed to characterize the child's initial bladder function. If the excretory urogram is abnormal or the child demonstrates incomplete emptying of the bladder, a voiding cystourethrogram is done. The paramount factor is to make sure the child can empty the bladder adequately. 3, 18, 22 If not, intermittent catheterization is begun, even in newborn males. Only those children with a totally denervated external sphincter (which does not react when intra-abdominal pressure is raised) are placed on a Crede regimen. Most children are not placed on routine antibiotics unless they have vesicoureteral reflux, have recurrent urinary infection, or have been started on intermittent catheterization and then only for a few months until their system gets used to the catheterization program. Urine cultures should be obtained every 3 months throughout infancy and early childhood, for an infection may be the first clue that there is impaired drainage. A postvoid residual urine volume should be checked at least twice a year to make sure bladder emptying is complete. When a specimen has been collected by placing a bag on the perineum, it is accurate only if the child has urinated within a short time after the bag was put in position or it is negative. Otherwise, a catheterized specimen is needed to determine the presence of infection. After the newborn period, imaging studies of the upper urinary tract should be performed on a yearly basis until puberty. 16 Today, renal ultrasonography has replaced excretory urography as the best method to visualize the upper urinary tract sequentially because it minimizes the amount of x-rays to which these children are exposed. If the ultrasound reveals a change from prior studies, however, an excretory urogram is repeated. A voiding cystogram is recommended or repeated if the child has recurrent urinary infection or there are changes in the appearance of the upper urinary tract. Children with reflux are followed similarly to children with normal bladder function; that is, they need to have their urine cultured every 3 months and their reflux reassessed yearly with either a conventional voiding cystogram or a radionuclide cystogram. It is important to ensure that they empty their bladder on a regular basis and this is most easily accomplished with intermittent catheterization. 15 Crede voiding is contraindicated? Antibiotics are administered routinely. The indications for and success rate of antireflux surgery are the same as those for children with normal bladder function (Table 2).'3, I. Attempts at achieving continence are begun between the ages of 3 and 5 years. Intermittent catheterization is started at this time if the child is not on the program already. If the child is still incontinent after beginning intermittent catheterization, it is important to try to determine when the wetting occurs in relation to the catheterization schedule. First, it must be determined if the parents are performing
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Table 2. Indicatons for Antirefiux Surgery in Children with Myelodysplasia Recurrent urinary infection while on appropriate antibiotics Development or progression of pyelonephritic scarring Persistent hydronephrosis of the bladder Severe reflux with a definitive anatomic abnormality at the ureterovesical junction Reflux into puberty Planned anti-incontinence surgery
the catheterizations on a regular basis and how much urine is obtained routinely. Some children who are dry for long periods but wet within a short time of the next catheterization may just need to have their fluid intake curtailed or the frequency of bladder emptying increased. Secondly, it should be noted if the child wets soon after he has emptied or when intra-abdominal pressure is raised (i.e., with straining, laughing, or coughing). In these instances, drugs that increase urethral resistance or lower intravesical pressure might be helpful (see Table 1).20 If the children continue to experience urinary incontinence they will need referral to a pediatric .urologist for surgery to control wetting. At this time, urodynamic studies are indicated to determine the next appropriate step. Augmentation cystoplasty is needed when the bladder is small or hypertonic (high pressure during filling) or has uncontrolled uninhibited contractions. 9 Surgery to increase bladder neck resistance will be necessary when the urethral closure pressure is insufficient to contain the urine within the bladder. Bladder neck reconstruction or placement of an artifical urinary sphincter can accomplish that goal. Today urinary diversion is almost never performed to control urinary incontinence unless the child cannot be catheterized, the abnormal detrusor function prevents adequate drainage of the upper urinary tract, or the social situation warrants it. It is important to proVide a certain degree of sexual counseling for the teenager and young adult. Menarche usually begins early, and pregnancy is not contraindicated in girls. Most women will be able to carry a fetus to term without an increased incidence of abortion. A surprisingly high number of men are potent and a substantial percentage of these men will be fertile. There are few data regarding the possibility of myelodysplastic individuals having affected offspring.
OCCULT SPINAL DYSRAPHISM Occult spinal dysraphisms are concealed vertebral bony disorders that affect the lower spinal cord or nerve roots but that may not be obvious to the unsuspecting eye. 1 A variety of diseases compose this group. They include lipoma and small lipomeningocele, diastematomyelia (an intraspinal bony or fibrous spur or protrusion), tight filum terminale, aberrant nerve roots, and anterior meningocele. These lesions prevent the cord from "receding" up the canal as the child grows. Thus, the cord is tethered. An injury to the neural elements can occur from any or all of these factors. 8 Almost 90 per cent of affected children have a cutaneous skin manifestation in the midline lower spine area, 1 but unless this region is inspected carefully the diagnosis often is missed until the signs of neurogenic bladder dysfunction or lower extremity disturbances become evident. The types of skin lesions and lower extremity changes are listed in Table 3. Underneath the cutaneous lesion (Fig. 4) there may be a vertebral bony abnormality consisting of widened, extra, or abnormal vertebrae. If the back is not examined in the newborn period, these signs can be missed until searched for at a later age when symptoms relating to bladder and bowel dysfunction or lower extremity weakness become evident. Any suspicious
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Table 3. Clinical Manifestations of Occult Spinal Dysraphism Cutaneous back lesions Small lipoma Dermal vascular malformation Hair patch (hypertrichosis) Dimple Sinus tract Aberrant gluteal cleft Lower extremity discrepancy or deformity Gait abnormality Bladder or bowel dysfunction
lesion should be followed up with an anteroposterior (AP) and lateral radiograph of the spine area and a thorough neurologic examination of the lower extremities, including an assessment of gait (if the child is walking), strength, size, deep tendon reflexes and sensation of each lower limb, and perianal sensation and bulbocavernosus reflex. The latter is performed by either observing the rectal muscles or placing a finger at the anal verge and scratching the pigmented skin surrounding the anus briskly, first on one side and then the other, looking or feeling for a contraction of the external anal muscle. Any question of an abnormality warrants referral of the child to a neurosurgeon for further evaluation. In the past, approximately 40 per cent of children with occult dysraphism developed neurogenic bladder dysfunction. 17 With the increased awareness of these lesions and earlier diagnosis and treatment, often this sequelae has been avoided. 11 The signs of bladder dysfunction depend on the age of the child. In infancy, the child may have either continuous dribbling or leaking with crying. The older child may have considerable difficulty with toilet training and be wet despite voluntarily voiding on a regular basis. Incontinence may recur at the time of puberty in some children who had been totally dry previously, when the growth spurt puts undue stress or traction on the cord or its nerve roots. Finally, urinary infection at any age may signify incomplete emptying of the bladder due to a neurologic lesion. Thus, every child with urinary signs and symptoms warrants a careful inspection of his or her back. In addition, fecal incontinence or a disturbance in gait should alert the pediatrician to a possible spinal abnormality. We have found that a majority (65 per cent) of infants less than 3 years of age with a dysraphic state have normal lumbar and sacral innervation. 21 Of those who already have a nerve injury, two-thirds will return to normal function following corrective surgery. Almost all children over the age of 5 have evidence of neurogenic bladder dysfunction; unfortunately, only one-third will improve with surgery to correct the problem?' Thus, early diagnosis is essential if these children are to be prevented from having permanent damage from their spinal abnormality. Once a child has been diagnosed as having a spinal dysraphism, a urine analysis and culture are mandatory. In addition, the child should have x-ray assessment of his or her upper urinary tract with either a renal ultrasound, excretory urogram, or renal scan, to make sure the urine drains properly and there is no abnormality. Because the lesions are varied, their effects on sacral nerves are not uniform; thus, bladder function studies are needed to characterize the exact injury to the nerves innervating the bladder and the type of treatment required. Findings at the time of urodynamic studies may help to guide the neurosurgeon in his or her assessment and operative treatment.
SACRAL AGENESIS Sacral agenesis is another bony abnormality of the spine that warrants special discussion. It is defined as an absence of all or part of two or more vertebral bodies
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BAUER
Figure 4. The various but subtle skin manifestations of an underlying spinal dysraphism are shown: A, small lipoma, B, dermal vascular malformation; C, hair patch; D, dimple; E, aberrant gluteal cleft.
at the lower end of the spinal column (Fig. 5). Sometimes, the entire sacral and even some of the lumbar vertebrae may be missing, and this has been labeled the caudal regression syndrome. 7 The exact cause is unknown, but it is associated with maternal diabetes. One per cent of insulin-dependent diabetic mothers will have a child with sacral agenesis, whereas 16 per cent of children with sacral agenesis will have had a mother who took insulin during her pregnancy.'· Other teratogenic factors have not been so clearly implicated. The true incidence of neurogenic bladder dysfunction has not been accurately
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Figure 5. The diagnosis of partial or complete sacral agenesis is best confirmed by an anteroposterior (A) and (B) film of the spine.
determined because, if the bladder or bowel is unaffected, there may be no other manifestations of this disease and the condition will go undetected. It is important to recognize the presence of sacral agenesis as early as possible because of its subsequent implications. The pediatrician should be aware of this possible abnormality at birth whenever a pregnant woman has been taking insulin. Urologic signs and symptoms are similar to those found in children with spinal dysraphism. These children are usually very difficult to toilet-train and they have day and night incontinence. Many learn to void voluntarily but still have urgency incontinence. This disease is not thought to be progressive so it is unlikely that incontinence will occur after a child has been trained completely. The gait is normal despite an abnormal bony pelvic ring (due to absent sacral vertebrae) because the lesion rarely affects the nerves above the sacral roots. The diagnosis is often missed because the manifestations of sacral agenesis are subtle. Flattened buttocks and an absent gluteal cleft (Fig. 6) may be the only clues on physical examination.23 Occasionally, a patulous anal opening may be seen. Sensation in the sacral area is usually intact and motor function of the lower extremities is normal. The nerves most commonly affected are the motor efferents originating from S-2 to S-4 in the spinal cord. 10 These roots are incorporated into the fibrous mass that develops in place of the absent vertebrae and they may be injured in the process. It is impossible to predict which type of bladder and sphincter function will occur based on the number of absent or affected vertebrae. ' ° Some children have hyperactive bladders with uninhibited contractions suggesting an upper motor neuron type of injury, while others have flaccid bladders with no contractions and
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Figure 6. The gluteal cleft (arrows) is characteristically absent in children with sacral agenesis.
overflow incontinence signifYing a lower motoneuron lesion. '2 Therefore, treatment cannot be empirical but must be based on findings at the time of urodynamic studies for it to be effective. The children with hyperactive bladders may need anticholinergic medication to diminish this activity, whereas those without contractions may need intermittent catheterization to empty and be continent.
OTHER NEUROLOGIC DISORDERS There are many other causes of neurogenic bladder dysfunction in children, but their etiologies are varied and their incidence rare. Cerebral palsy may affect bladder function; however, this is not usually evident until one expects the child to be fully trained but is not. The true incidence of bladder dysfunction in this setting is unknown. In part, it is related to the degree of mental retardation and the ability of the individual to learn. Most children who have the capicity to become trained but are not trained have a disorder consistent with a central nervous system lesion. They have uninhibited contractions of their bladder, incomplete relaxation of the sphincter, or failure of voluntary control over bladder or sphincter function. 6 Sometimes, the children have learned to void voluntarily but are incontinent in between. Children with this type of incontinence without obvious signs of cerebral palsy should have a comprehensive history because such a history may uncover previously unrecognized events during delivery or in the early postnatal period that affected the central nervous system. In addition to the bladder dysfunction these children may have difficulty with fine motor coordination, learning disabilities, or crossed dominance, suggesting an injury to the brain or brain stem. In all of these
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cases the urine should be cultured. Radiographic assessment of the urinary tract is necessary only when infection is present. The residual effects of an infection involving the central nervous system may be either obvious or subtle, with the only abnormality being altered lower urinary tract function. Meningitis may produce an upper motoneuron type of dysfunction, whereas a spinal cord infection, that is, transverse myelitis, may lead to lower motoneuron type of denervation. The development of urinary incontinence or urinary infection in an older child, or failure of an infant to become trained at a subsequent time may be the only sign of residual nerve dysfunction. Episodic urinary incontinence despite voluntary control suggests a hyperactive bladder, a form of upper motoneuron dysfunction. An inability to initiate a bladder contraction voluntarily and to void with a good stream may signify a lower motoneuron deficit. As in most cases of neurogenic bladder dysfunction, the urine should be cultured. A baseline radiographic study to visualize the upper urinary tract is mandatory, whereas lower urinary tract assessment is necessary only when infection has occurred. The ability of the child to empty the bladder should be noted, either at the time of voiding cystourethrography or by catheterization after voiding. Children who cannot empty their bladder may need to be started on intermittent catheterization, whereas those who have uncontrolled wetting between voluntary voidings will need anticholinergic medication. Fortunately, injuries to the spinal cord are rare in children. Because the cord is shorter than the vertebral column, the level of the neurologic lesion does not correlate well with the vertebral injury. If the sacral cord and its nerve roots are spared, an upper motoneuron type of lesion will occur. There may be retained volitional control if the communicating neurons between the sacral cord and the brain stem are not severed. When the injury affects the sacral cord and its nerves, detrusor contractions may be lost. The initial evaluation of these children is the same as other children with neurogenic bladder dysfunction. Once the child is stable, intermittent catheterization is started if bladder emptying is incomplete. Incontinence between catheterizations requires urodynamic assessment to clarify the appropriate next step to take. Neurogenic bladder dysfunction may occur when the blood supply to the anterior spinal artery is affected either during surgery to correct a coarctation or as a result of thrombsis from an umbilical artery catheter. The signs may be obvious or covert, with an inability to control micturition voluntarily as the only manifestation of dysfunction. Neurofibromatosis of the pelvis or retroperitoneum may either cause signs and symptoms of outflow obstruction because of growth around the bladder neck, or affect the pelvic nerves and lead to a lower motoneuron type of dysfunction with difficulty emptying the bladder. Muscular dystrophy may affect a child's ability to initiate voiding. Once urination begins, however, the lower urinary tract works appropriately. As with other forms of neurogenic bladder dysfunction, the urine should be cultured and the upper urinary tract visualized, preferably with ultrasound, with voiding cystography reserved for those with infection. Imperforate anus is an isolated abnormality that almost never affects bladder function. However, in the course of resecting the rectourethral fistula during the anal pull-through, either nerves supplying the external urethral spincter or the muscle itself may be injured, leading to stress incontinence. An incompletely resected fistulous tract may manifest as postvoid dribbling or recurrent urinary infection later on. On the other hand, imperforate anus may be one of several anomalies, that is, VATER syndrome. Vertebral anomalies are common and they can affect the spinal cord and produce an injury of the nerves supplying the bladder and urethral sphincter. Thus, an AP and lateral radiograph of the spine should be
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performed during an evaluation of these children. A urodynamic study may be the only way to accurately define the neurologic injury and propose a rational treatment plan.
REFERENCES 1. Anderson FM: Occult spinal dysraphism: A series of 73 cases. Pediatrics 55:826, 1975 2. Barbalias GA, Klauber GT, Blaivas JG: Critical evaluation of the Crede maneuver: A urodynamic study of 207 patients. J Urol 130:720, 1983 3. Bauer SB, Hallett M, Khoshbin S: Predictive value ofurodynamic evaluation in newborns with myelodysplasia. JAMA 252:650, 1984 4. Bauer SB: Urodynamic evaluation and neuromuscular dysfunction. In Kelalis PP, King LR, Belman AB (eds): Clinical Pediatric Urology, Ed 2, Vol 1. Philadelphia, WB Saunders, 1985, pp 283-308 5. Bauer SB: The management of spine bifida from birth onwards, In Whitaker RH, Woodard JR (eds): Pediatric Urology. London, Butterworths, 1985, pp 87-112 6. Decter RM, Bauer SB, Dyro FM: Voiding dysfunction in children with cerebral palsy. J U rol (In Press) 7. Duhamel B: From the mermaid to anal imperforation: The syndrome of caudal regression. Arch Dis Child 36:152, 1961 8. Emery JL, Lendon RG: The local cord lesion in neurospinal dysraphism (myelomeningocele). J Pathol 110:83, 1973 9. Goldwasser B, Webster GD: Augmentation and substitution enterocystoplasty. J Urol 135:215, 1986 10. Guzman L, Bauer SB, Hallett M et al: The evaluation and management of children with sacral agenesis. Urology 23:506, 1983 11. Hellstrom WJG, Edwards MSB et al: Urologic aspects of tethered cord syndrome. J Urol 135:317, 1986 12. Jakabson H, Holm-Bentzen M, Hald T: Neurogenic bladder dysfunction in sacral agenesis and dysgenesis. Neurourology and Urodynamics 4:99-105, 1985 13. Jeffs RD, Jonas P, Schillinger JF: Surgical correction of vesicoureteral reflux in children with neurogenic bladder. J Urol115:449, 1976 14. Kaplan WE, Firlit CF: Management of reflux in the myelodysplastic child. J Urol 129:1195, 1983 15. Kass EJ, Koff SA Diokno AC: Fate of vesicoureteral reflux in children with neuropathic bladders managed by intermittent catheterization. J U rol 125:63, 1981 16. Klauber GT: Action Committee on Myelodysplasia: Current approaches to evaluation and management of children with myelomeningocele. Pediatrics 63:663, 1979 17. Mandell J, Bauer SB, Hallett M et al: Occult spinal dysraphism: A rare but detectable cause of voiding dysfunction. Urol Clin North Am 7:349, 1980 18. McGuire EJ, Woodside JR, Borden TA, Weiss RM: The prognostic value of urodynamic testing in myelodysplastic patients. J Urol 126:205, 1981 19. Passarge E, Lenz W: Syndrome of caudal regression in infants of diabetic mothers: Observations of further cases. Pediatrics 57:672, 1966 20. Raezer DM, Benson GS, Wein AJ, Duckett JW: The functional approach to the management of the pediatric neuropathic bladder: A clinical study. J Urol 117:649, 1977 21. Rink RC, Bauer SB, Winston KR et al: The value of pre and postoperative urodynamic assessment in the child with occult spinal dysraphism. Presented at American Urological Association, Atlanta, May 15, 1985 22. Sidi AA, Dykstra DD, Gonzalez R: Value of urodynamic testing in management of neonates with myelodysplasia: Prospective study. J Urol 135:90, 1966 23. White RI, Klauber GT: Sacral agenesis: Analysis of 22 cases. Urology 8:521, 1976 Division of Urology The Children's Hospital 300 Longwood Avenue Boston, Massachusetts 02115
0031-3955/87 $0.00
+
.20
Neurogenic Bladder Dysfunction
Stuart B. Bauer, MD*
Neurogenic bladder dysfunction in children may be caused by a variety of diseases. Some are obvious (such a myelodysplasia) whereas others are occult and discovered only after thoughtful consideration and thorough investigation. This article will describe the various conditions that produce abnormal lower urinary tract function, provide some helpful clues to diagnose several of the less overt causes, and outline a plan of management for affected youngsters. Neurogenic bladder dysfunction is a complex subject that requires a thorough understanding of the neurophysiology of the lower urinary tract to manage the condition properly. (The reader is referred to "Urodymanic Evaluation and Neuromuscular Dysfunction," in Clinical Pediatric Urology if more information is needed.') Lower urinary tract function is under the control of both somatic and autonomic nervous systems; the latter is composed of sympathetic and parasympathetic fibers (Fig. 1). Sympathetic neurons arise from the thoracolumbar region region of the cord, whereas parasympathetic nerves originate from the sacral area. Sympathetic stimulation will affect detrusor function based on the predominant receptor found in a particular area of the bladder. Alpha receptor sites are located primarily in the trigone and proximal portions of the urethra, while beta receptors are located in the fundus or body of th~ bladder (Fig. 2). Stimulation of alpha receptors causes a tightening of the trigonal and proximal urethral muscles and beta receptor stimulation leads to relaxation of the detrusor muscle. During filling of the bladder, sympathetic nerves exert an important regulatory influence which allows the bladder to expand at low pressure while increasing the outflow channel resistance. During this phase no spontaneous contractions of the bladder should occur (Fig. 3). The parasympathetic nerves from S-2 to S-4 (see Fig. 1) innervate cholinergic receptors in the fundus of the bladder (Fig. 2). The somatic nerves also from S-2 to S-4 supply the external sphincter. During voiding, the parasympathetic nerves are active and cause the bladder to contract, while somatic stimulation of the external sphincter ceases, allowing that muscle to relax. Voiding should take place with a steady uninterrupted stream until it is completed (see Fig. 3). The various phases of the micturition cycle are under the influence of the detrusor nucleus in the brain stem, which coordinates the function of the three nervous systems. This center, in turn, is modulated by the cerebral cortex, which integrates sensation and volitional control (see Fig. 1). *Assistant Professor of Urology, Director of Neurourology; Children's Hospital, Harvard Medical School, Boston, Massachesetts
Pediatric Clinics of North America-Vol. 34, No.5, October 1987
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Figure 1. The frontal (A) and parietal (B) lobes of the cerebral cortex, the cingulate gyrus (C), the hypothalamus containing the detrusor nucleus (D), the cerebellum (E), the sympathetic nervous system (F) for T-IO to L-l, the parasympathetic nervous system (G) from 5-2 to 5-4, and the pudendal nerve of the somatic nervous system (G) to the external sphincter all interact in a coordinated way to achieve proper and efficient function of the lower urinary tract.
A lower motoneuron lesion refers to an injury that affects the nerve roots supplying a particular organ, while an upper motoneuron lesion implies an injury to the cord (above the level of the roots innervating that organ), brain stem or cerebral cortex. A lower motoneuron lesion leads to an inability to void, either voluntarily or reflexively. In addition, it can lead to lowered urethral resistance and incontinence with any increase in abdominal pressure, such as coughing or laughing. An upper motor neuron lesion may produce uninhibited contractions (hyperactivity) with voluntary voiding if the lesion is incomplete, or reflex contractions without voluntary control if the lesion is complete. Furthermore, there may be incoordination between the detrusor and sphincter during bladder emptying with an upper motoneuron lesion. Medical treatment of neurogenic bladder dysfunction is based on the functional impairment produced by the specific neurourologic defect (Table 1). Inadequate storage capacity may be enhanced by lowering detrusor tone or abolishing uninhibited contractions with anticholinergic medication, such as propantheline or oxybutynin. These drugs block cholinergic receptor sites in the detrusor muscle, diminishing its tone and suppressing involuntary contractions of the bladder. Other drugs, for example, flavoxate, act directly on the smooth muscle cells and lower
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NEUROGENIC BLADDER DYSFUNCTION
Figure 2. Distribution of alpha- and beta-sympathetic and parasympathetic (cholinergic) receptor sites in the vesicourethral unit.
•
I
U] .a-adrenergic lid Cholinergic
a-adrenergic
NORMAL LOWER URINARY TRACT FUNCTION
I
EMG ........~III ...I_ _ _ _ _ _ _ _ _~ ..
120
i
Voluntary Voiding ----l~
III
- - - Bladder neck _.- Intravesical --- Rectal
I
90
I I~~' I· "', I .1 \
cm/~O
60 30
I I
----------J/
.,,-,-,-,-,-,-,--,
\~
',.
OL-~-~100~~~~~~~--------~
Figure 3. The interaction of intravesical, intraurethral, and rectal pressures, and electromyographic activity of the external urethral sphincter during the micturition cycle are shown.
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Table 1. Types of Medicines that Modulate Lower Urinary Tract Function TYPE
MINIMUM
MAXIMUM
Cholinergic Bethanechol
0.7 mg/kg t.i.d.
0.8 mg/kg q.i.d.
Anticholinergic Propantheline
0.5 mg/kg b.i.d.
Oxybutynin
0.2 mg/kg b.i.d.
0.5 mg/kg q.i.d. 0.2 mg/kg q.i.d.
Sympathomimetic Phenylpropanolamine (alpha) Ephedrine (alpha) Sympatholytic Prazosin (alpha) Phenoxybenzamine (alpha) Propanalol (beta) Smooth muscle relaxant Flavoxate Skeletal muscle relaxant Diazepam Baclofen Other Imipramine
2.5 mg/kg b.i.d. 0.5 mg/kg b.i.d.
2.5 mg/kg t.i.d. 1.0 mg/kg t.i.d.
0.05 mg/kg b.i.d. 0.3 mg/kg b.i.d.
0.1 mglkg t.i.d. 0.3 mg/kg b.i.d. 0.5 mg/kg b.i.d.
0.25 mg/kg b.i.d. 3.0 mg/kg b.i.d.
3.0 mg/kg t.i.d.
0.03 mg/kg b.i.d. 0.1 mg/kg b.i.d.
0.2 mg/kg t.i.d. 0.3 mg/kg t.i.d.
0.7 mg/kg b.i.d.
1. 2 mg/kg t. i. d.
detrusor tone without affecting contractility. Ifinadequate urethral resistance is the primary reason for impaired storage of urine, alpha-sympathomimetic agents, such as ephedrine sulfate and phenylpropanolamine, stimulate receptors in the bladder neck and proximal urethra to enhance the muscle tone in these areas. There are no drugs commercially available that will increase the contractility of denervated skeletal muscle in the external spincter region. Incomplete emptying of the bladder may be facilitated by cholinergic drugs, such as bethanechol chloride or alphasympatholytic agents, prazosin or phenoxybenzamine. Skeletal muscle relaxants, such as diazepam and baclofen, diminish skeletal muscle tone at the external sphincter region. Intermittent catheterization is begun in all children who cannot empty their bladder completely at low voiding pressure. Frequently, it is combined with medical therapy to maintain continence between catheterizations. When drug therapy fails to increase the capacity of the bladder and lower detrusor tone (to improve upper urinary tract drainage), subtotal cystectomy and augmentation cystoplasty using a segment of bowel is needed. When urethral resistance is low and is the cause of incontinence, and is unaltered by medications, bladder neck reconstruction, or perhaps implantation of an artificial urinary sphincter may be necessary.
MYELOMENINGOCELE The most common cause of neurogenic bladder dysfunction in the pediatric age group (and easiest to diagnose) is myelomeningocele. This condition is due to a failure of the spinal canal to close and the ectodermal elements to fuse superficial to the spinal cord resulting in a segmental outpouching of the meninges, cord or
--NEUROGENIC BLADDER DYSFUNCTION
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nerve roots. This leads to an injury affecting the neural elements involved in the innervation of the bladder and sphincter muscles. The type of lower urinary tract function is unique for each child due to the variable location of the vertebral bony defect and the amount of neural tissue injured. The diagnosis is obvious at birth when an open or flimsily covered sac containing neural elements is noted in the delivery room. Myelominingocele is being detected with increasing frequency prenatally, as a result of the more widespread use of prenatal ultrasound and amniocentesis, especially in high-risk mothers. This includes very young and over40-year-old women, and families in which there are already other children with spina bifida. The incidence of having a child with myelodysplasia increases from 1 per 1000 in the general population to 2 per 100 when the condition is present in another family member, to 10 per cent when a sibling is affected. 5 In the newborn period, all children should get a urine culture, serum creatinine, excretory urogram, and postvoid residual urine volume after the surgery to close the back has healed. A neurologic assessment of the child's lower extremities is also important as a baseline. If feasible, a urodynamic study is performed to characterize the child's initial bladder function. If the excretory urogram is abnormal or the child demonstrates incomplete emptying of the bladder, a voiding cystourethrogram is done. The paramount factor is to make sure the child can empty the bladder adequately. 3, 18, 22 If not, intermittent catheterization is begun, even in newborn males. Only those children with a totally denervated external sphincter (which does not react when intra-abdominal pressure is raised) are placed on a Crede regimen. Most children are not placed on routine antibiotics unless they have vesicoureteral reflux, have recurrent urinary infection, or have been started on intermittent catheterization and then only for a few months until their system gets used to the catheterization program. Urine cultures should be obtained every 3 months throughout infancy and early childhood, for an infection may be the first clue that there is impaired drainage. A postvoid residual urine volume should be checked at least twice a year to make sure bladder emptying is complete. When a specimen has been collected by placing a bag on the perineum, it is accurate only if the child has urinated within a short time after the bag was put in position or it is negative. Otherwise, a catheterized specimen is needed to determine the presence of infection. After the newborn period, imaging studies of the upper urinary tract should be performed on a yearly basis until puberty. 16 Today, renal ultrasonography has replaced excretory urography as the best method to visualize the upper urinary tract sequentially because it minimizes the amount of x-rays to which these children are exposed. If the ultrasound reveals a change from prior studies, however, an excretory urogram is repeated. A voiding cystogram is recommended or repeated if the child has recurrent urinary infection or there are changes in the appearance of the upper urinary tract. Children with reflux are followed similarly to children with normal bladder function; that is, they need to have their urine cultured every 3 months and their reflux reassessed yearly with either a conventional voiding cystogram or a radionuclide cystogram. It is important to ensure that they empty their bladder on a regular basis and this is most easily accomplished with intermittent catheterization. 15 Crede voiding is contraindicated? Antibiotics are administered routinely. The indications for and success rate of antireflux surgery are the same as those for children with normal bladder function (Table 2).'3, I. Attempts at achieving continence are begun between the ages of 3 and 5 years. Intermittent catheterization is started at this time if the child is not on the program already. If the child is still incontinent after beginning intermittent catheterization, it is important to try to determine when the wetting occurs in relation to the catheterization schedule. First, it must be determined if the parents are performing
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Table 2. Indicatons for Antirefiux Surgery in Children with Myelodysplasia Recurrent urinary infection while on appropriate antibiotics Development or progression of pyelonephritic scarring Persistent hydronephrosis of the bladder Severe reflux with a definitive anatomic abnormality at the ureterovesical junction Reflux into puberty Planned anti-incontinence surgery
the catheterizations on a regular basis and how much urine is obtained routinely. Some children who are dry for long periods but wet within a short time of the next catheterization may just need to have their fluid intake curtailed or the frequency of bladder emptying increased. Secondly, it should be noted if the child wets soon after he has emptied or when intra-abdominal pressure is raised (i.e., with straining, laughing, or coughing). In these instances, drugs that increase urethral resistance or lower intravesical pressure might be helpful (see Table 1).20 If the children continue to experience urinary incontinence they will need referral to a pediatric .urologist for surgery to control wetting. At this time, urodynamic studies are indicated to determine the next appropriate step. Augmentation cystoplasty is needed when the bladder is small or hypertonic (high pressure during filling) or has uncontrolled uninhibited contractions. 9 Surgery to increase bladder neck resistance will be necessary when the urethral closure pressure is insufficient to contain the urine within the bladder. Bladder neck reconstruction or placement of an artifical urinary sphincter can accomplish that goal. Today urinary diversion is almost never performed to control urinary incontinence unless the child cannot be catheterized, the abnormal detrusor function prevents adequate drainage of the upper urinary tract, or the social situation warrants it. It is important to proVide a certain degree of sexual counseling for the teenager and young adult. Menarche usually begins early, and pregnancy is not contraindicated in girls. Most women will be able to carry a fetus to term without an increased incidence of abortion. A surprisingly high number of men are potent and a substantial percentage of these men will be fertile. There are few data regarding the possibility of myelodysplastic individuals having affected offspring.
OCCULT SPINAL DYSRAPHISM Occult spinal dysraphisms are concealed vertebral bony disorders that affect the lower spinal cord or nerve roots but that may not be obvious to the unsuspecting eye. 1 A variety of diseases compose this group. They include lipoma and small lipomeningocele, diastematomyelia (an intraspinal bony or fibrous spur or protrusion), tight filum terminale, aberrant nerve roots, and anterior meningocele. These lesions prevent the cord from "receding" up the canal as the child grows. Thus, the cord is tethered. An injury to the neural elements can occur from any or all of these factors. 8 Almost 90 per cent of affected children have a cutaneous skin manifestation in the midline lower spine area, 1 but unless this region is inspected carefully the diagnosis often is missed until the signs of neurogenic bladder dysfunction or lower extremity disturbances become evident. The types of skin lesions and lower extremity changes are listed in Table 3. Underneath the cutaneous lesion (Fig. 4) there may be a vertebral bony abnormality consisting of widened, extra, or abnormal vertebrae. If the back is not examined in the newborn period, these signs can be missed until searched for at a later age when symptoms relating to bladder and bowel dysfunction or lower extremity weakness become evident. Any suspicious
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1127
Table 3. Clinical Manifestations of Occult Spinal Dysraphism Cutaneous back lesions Small lipoma Dermal vascular malformation Hair patch (hypertrichosis) Dimple Sinus tract Aberrant gluteal cleft Lower extremity discrepancy or deformity Gait abnormality Bladder or bowel dysfunction
lesion should be followed up with an anteroposterior (AP) and lateral radiograph of the spine area and a thorough neurologic examination of the lower extremities, including an assessment of gait (if the child is walking), strength, size, deep tendon reflexes and sensation of each lower limb, and perianal sensation and bulbocavernosus reflex. The latter is performed by either observing the rectal muscles or placing a finger at the anal verge and scratching the pigmented skin surrounding the anus briskly, first on one side and then the other, looking or feeling for a contraction of the external anal muscle. Any question of an abnormality warrants referral of the child to a neurosurgeon for further evaluation. In the past, approximately 40 per cent of children with occult dysraphism developed neurogenic bladder dysfunction. 17 With the increased awareness of these lesions and earlier diagnosis and treatment, often this sequelae has been avoided. 11 The signs of bladder dysfunction depend on the age of the child. In infancy, the child may have either continuous dribbling or leaking with crying. The older child may have considerable difficulty with toilet training and be wet despite voluntarily voiding on a regular basis. Incontinence may recur at the time of puberty in some children who had been totally dry previously, when the growth spurt puts undue stress or traction on the cord or its nerve roots. Finally, urinary infection at any age may signify incomplete emptying of the bladder due to a neurologic lesion. Thus, every child with urinary signs and symptoms warrants a careful inspection of his or her back. In addition, fecal incontinence or a disturbance in gait should alert the pediatrician to a possible spinal abnormality. We have found that a majority (65 per cent) of infants less than 3 years of age with a dysraphic state have normal lumbar and sacral innervation. 21 Of those who already have a nerve injury, two-thirds will return to normal function following corrective surgery. Almost all children over the age of 5 have evidence of neurogenic bladder dysfunction; unfortunately, only one-third will improve with surgery to correct the problem?' Thus, early diagnosis is essential if these children are to be prevented from having permanent damage from their spinal abnormality. Once a child has been diagnosed as having a spinal dysraphism, a urine analysis and culture are mandatory. In addition, the child should have x-ray assessment of his or her upper urinary tract with either a renal ultrasound, excretory urogram, or renal scan, to make sure the urine drains properly and there is no abnormality. Because the lesions are varied, their effects on sacral nerves are not uniform; thus, bladder function studies are needed to characterize the exact injury to the nerves innervating the bladder and the type of treatment required. Findings at the time of urodynamic studies may help to guide the neurosurgeon in his or her assessment and operative treatment.
SACRAL AGENESIS Sacral agenesis is another bony abnormality of the spine that warrants special discussion. It is defined as an absence of all or part of two or more vertebral bodies
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STUART
B.
BAUER
Figure 4. The various but subtle skin manifestations of an underlying spinal dysraphism are shown: A, small lipoma, B, dermal vascular malformation; C, hair patch; D, dimple; E, aberrant gluteal cleft.
at the lower end of the spinal column (Fig. 5). Sometimes, the entire sacral and even some of the lumbar vertebrae may be missing, and this has been labeled the caudal regression syndrome. 7 The exact cause is unknown, but it is associated with maternal diabetes. One per cent of insulin-dependent diabetic mothers will have a child with sacral agenesis, whereas 16 per cent of children with sacral agenesis will have had a mother who took insulin during her pregnancy.'· Other teratogenic factors have not been so clearly implicated. The true incidence of neurogenic bladder dysfunction has not been accurately
NEUROGENIC BLADDER DYSFUNCTION
1129
Figure 5. The diagnosis of partial or complete sacral agenesis is best confirmed by an anteroposterior (A) and (B) film of the spine.
determined because, if the bladder or bowel is unaffected, there may be no other manifestations of this disease and the condition will go undetected. It is important to recognize the presence of sacral agenesis as early as possible because of its subsequent implications. The pediatrician should be aware of this possible abnormality at birth whenever a pregnant woman has been taking insulin. Urologic signs and symptoms are similar to those found in children with spinal dysraphism. These children are usually very difficult to toilet-train and they have day and night incontinence. Many learn to void voluntarily but still have urgency incontinence. This disease is not thought to be progressive so it is unlikely that incontinence will occur after a child has been trained completely. The gait is normal despite an abnormal bony pelvic ring (due to absent sacral vertebrae) because the lesion rarely affects the nerves above the sacral roots. The diagnosis is often missed because the manifestations of sacral agenesis are subtle. Flattened buttocks and an absent gluteal cleft (Fig. 6) may be the only clues on physical examination.23 Occasionally, a patulous anal opening may be seen. Sensation in the sacral area is usually intact and motor function of the lower extremities is normal. The nerves most commonly affected are the motor efferents originating from S-2 to S-4 in the spinal cord. 10 These roots are incorporated into the fibrous mass that develops in place of the absent vertebrae and they may be injured in the process. It is impossible to predict which type of bladder and sphincter function will occur based on the number of absent or affected vertebrae. ' ° Some children have hyperactive bladders with uninhibited contractions suggesting an upper motor neuron type of injury, while others have flaccid bladders with no contractions and
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STUART B. BAUER
Figure 6. The gluteal cleft (arrows) is characteristically absent in children with sacral agenesis.
overflow incontinence signifYing a lower motoneuron lesion. '2 Therefore, treatment cannot be empirical but must be based on findings at the time of urodynamic studies for it to be effective. The children with hyperactive bladders may need anticholinergic medication to diminish this activity, whereas those without contractions may need intermittent catheterization to empty and be continent.
OTHER NEUROLOGIC DISORDERS There are many other causes of neurogenic bladder dysfunction in children, but their etiologies are varied and their incidence rare. Cerebral palsy may affect bladder function; however, this is not usually evident until one expects the child to be fully trained but is not. The true incidence of bladder dysfunction in this setting is unknown. In part, it is related to the degree of mental retardation and the ability of the individual to learn. Most children who have the capicity to become trained but are not trained have a disorder consistent with a central nervous system lesion. They have uninhibited contractions of their bladder, incomplete relaxation of the sphincter, or failure of voluntary control over bladder or sphincter function. 6 Sometimes, the children have learned to void voluntarily but are incontinent in between. Children with this type of incontinence without obvious signs of cerebral palsy should have a comprehensive history because such a history may uncover previously unrecognized events during delivery or in the early postnatal period that affected the central nervous system. In addition to the bladder dysfunction these children may have difficulty with fine motor coordination, learning disabilities, or crossed dominance, suggesting an injury to the brain or brain stem. In all of these
NEUROGENIC BLADDER DYSFUNCTION
1131
cases the urine should be cultured. Radiographic assessment of the urinary tract is necessary only when infection is present. The residual effects of an infection involving the central nervous system may be either obvious or subtle, with the only abnormality being altered lower urinary tract function. Meningitis may produce an upper motoneuron type of dysfunction, whereas a spinal cord infection, that is, transverse myelitis, may lead to lower motoneuron type of denervation. The development of urinary incontinence or urinary infection in an older child, or failure of an infant to become trained at a subsequent time may be the only sign of residual nerve dysfunction. Episodic urinary incontinence despite voluntary control suggests a hyperactive bladder, a form of upper motoneuron dysfunction. An inability to initiate a bladder contraction voluntarily and to void with a good stream may signify a lower motoneuron deficit. As in most cases of neurogenic bladder dysfunction, the urine should be cultured. A baseline radiographic study to visualize the upper urinary tract is mandatory, whereas lower urinary tract assessment is necessary only when infection has occurred. The ability of the child to empty the bladder should be noted, either at the time of voiding cystourethrography or by catheterization after voiding. Children who cannot empty their bladder may need to be started on intermittent catheterization, whereas those who have uncontrolled wetting between voluntary voidings will need anticholinergic medication. Fortunately, injuries to the spinal cord are rare in children. Because the cord is shorter than the vertebral column, the level of the neurologic lesion does not correlate well with the vertebral injury. If the sacral cord and its nerve roots are spared, an upper motoneuron type of lesion will occur. There may be retained volitional control if the communicating neurons between the sacral cord and the brain stem are not severed. When the injury affects the sacral cord and its nerves, detrusor contractions may be lost. The initial evaluation of these children is the same as other children with neurogenic bladder dysfunction. Once the child is stable, intermittent catheterization is started if bladder emptying is incomplete. Incontinence between catheterizations requires urodynamic assessment to clarify the appropriate next step to take. Neurogenic bladder dysfunction may occur when the blood supply to the anterior spinal artery is affected either during surgery to correct a coarctation or as a result of thrombsis from an umbilical artery catheter. The signs may be obvious or covert, with an inability to control micturition voluntarily as the only manifestation of dysfunction. Neurofibromatosis of the pelvis or retroperitoneum may either cause signs and symptoms of outflow obstruction because of growth around the bladder neck, or affect the pelvic nerves and lead to a lower motoneuron type of dysfunction with difficulty emptying the bladder. Muscular dystrophy may affect a child's ability to initiate voiding. Once urination begins, however, the lower urinary tract works appropriately. As with other forms of neurogenic bladder dysfunction, the urine should be cultured and the upper urinary tract visualized, preferably with ultrasound, with voiding cystography reserved for those with infection. Imperforate anus is an isolated abnormality that almost never affects bladder function. However, in the course of resecting the rectourethral fistula during the anal pull-through, either nerves supplying the external urethral spincter or the muscle itself may be injured, leading to stress incontinence. An incompletely resected fistulous tract may manifest as postvoid dribbling or recurrent urinary infection later on. On the other hand, imperforate anus may be one of several anomalies, that is, VATER syndrome. Vertebral anomalies are common and they can affect the spinal cord and produce an injury of the nerves supplying the bladder and urethral sphincter. Thus, an AP and lateral radiograph of the spine should be
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STUART B. BAUER
performed during an evaluation of these children. A urodynamic study may be the only way to accurately define the neurologic injury and propose a rational treatment plan.
REFERENCES 1. Anderson FM: Occult spinal dysraphism: A series of 73 cases. Pediatrics 55:826, 1975 2. Barbalias GA, Klauber GT, Blaivas JG: Critical evaluation of the Crede maneuver: A urodynamic study of 207 patients. J Urol 130:720, 1983 3. Bauer SB, Hallett M, Khoshbin S: Predictive value ofurodynamic evaluation in newborns with myelodysplasia. JAMA 252:650, 1984 4. Bauer SB: Urodynamic evaluation and neuromuscular dysfunction. In Kelalis PP, King LR, Belman AB (eds): Clinical Pediatric Urology, Ed 2, Vol 1. Philadelphia, WB Saunders, 1985, pp 283-308 5. Bauer SB: The management of spine bifida from birth onwards, In Whitaker RH, Woodard JR (eds): Pediatric Urology. London, Butterworths, 1985, pp 87-112 6. Decter RM, Bauer SB, Dyro FM: Voiding dysfunction in children with cerebral palsy. J U rol (In Press) 7. Duhamel B: From the mermaid to anal imperforation: The syndrome of caudal regression. Arch Dis Child 36:152, 1961 8. Emery JL, Lendon RG: The local cord lesion in neurospinal dysraphism (myelomeningocele). J Pathol 110:83, 1973 9. Goldwasser B, Webster GD: Augmentation and substitution enterocystoplasty. J Urol 135:215, 1986 10. Guzman L, Bauer SB, Hallett M et al: The evaluation and management of children with sacral agenesis. Urology 23:506, 1983 11. Hellstrom WJG, Edwards MSB et al: Urologic aspects of tethered cord syndrome. J Urol 135:317, 1986 12. Jakabson H, Holm-Bentzen M, Hald T: Neurogenic bladder dysfunction in sacral agenesis and dysgenesis. Neurourology and Urodynamics 4:99-105, 1985 13. Jeffs RD, Jonas P, Schillinger JF: Surgical correction of vesicoureteral reflux in children with neurogenic bladder. J Urol115:449, 1976 14. Kaplan WE, Firlit CF: Management of reflux in the myelodysplastic child. J Urol 129:1195, 1983 15. Kass EJ, Koff SA Diokno AC: Fate of vesicoureteral reflux in children with neuropathic bladders managed by intermittent catheterization. J U rol 125:63, 1981 16. Klauber GT: Action Committee on Myelodysplasia: Current approaches to evaluation and management of children with myelomeningocele. Pediatrics 63:663, 1979 17. Mandell J, Bauer SB, Hallett M et al: Occult spinal dysraphism: A rare but detectable cause of voiding dysfunction. Urol Clin North Am 7:349, 1980 18. McGuire EJ, Woodside JR, Borden TA, Weiss RM: The prognostic value of urodynamic testing in myelodysplastic patients. J Urol 126:205, 1981 19. Passarge E, Lenz W: Syndrome of caudal regression in infants of diabetic mothers: Observations of further cases. Pediatrics 57:672, 1966 20. Raezer DM, Benson GS, Wein AJ, Duckett JW: The functional approach to the management of the pediatric neuropathic bladder: A clinical study. J Urol 117:649, 1977 21. Rink RC, Bauer SB, Winston KR et al: The value of pre and postoperative urodynamic assessment in the child with occult spinal dysraphism. Presented at American Urological Association, Atlanta, May 15, 1985 22. Sidi AA, Dykstra DD, Gonzalez R: Value of urodynamic testing in management of neonates with myelodysplasia: Prospective study. J Urol 135:90, 1966 23. White RI, Klauber GT: Sacral agenesis: Analysis of 22 cases. Urology 8:521, 1976 Division of Urology The Children's Hospital 300 Longwood Avenue Boston, Massachusetts 02115