Assessment and Conservative Management of the Neuropathic Bladder

Assessment and Conservative Management of the Neuropathic Bladder By A.M.K. Rickwood Liverpool, England The etiologies and forms of congenital neuropathic bladder are described: contractile (25%), acontractile (15%), and intermediate (60%). The terminology relating to neuropathic bladder is defined and the principles of bladder management are highlighted: (1) must achieve a bladder that can fill at low pressure, (2) must achieve a bladder that can store urine at low pressure, (3) must achieve sphincter resistance that is sufficient to allow urine storage, and (4) must put in place a mechanism of achieving complete voluntary bladder emptying. The approach to investigation is set out in a logical sequence, and the methods of achieving the goals highlighted above are described. All of this is put in the context of managing the handicapped patient as a whole. It also is stressed that the aim is not just to achieve continence but perhaps even more importantly to protect renal function. Copyright 2002, Elsevier Science (USA). All rights reserved.

EUROPATHIC BLADDER was a complaint attracting comparatively little attention until the Second World War when Guttman'sl advocacy of strictly aseptic intermittent catheterization as a means of tiding the cord-injured patient through the stage of spinal shock was a major factor in greatly reducing the then high mortality rate among such patients. Within a few years, this and other aspects of acute management and longerterm rehabilitation, had transformed the life expectancy and quality of life of traumatic paraplegics. At the time, these developments had only minor implications for pediatric practice because, among children, neuropathic bladder was overwhelmingly congenital rather than acquired, and far and away the most common responsible spinal lesion was myelomeningocele. Yet, few born with this condition lived any length of time; the majority died during infancy from the effects of hydrocephalus. It was not until the later 1950s that the development of effective shunting devices to treat hydrocephalus resulted in patients with myelomeningocele surviving in sizeable numbers. Not unnaturally, those surgeons pioneering such treatment anticipated that their results would replicate the success achieved with traumatic paraplegics a generation earlier. 2 Within a few years, however, it became evident that this optimism was misplaced, because pa-

N

From the Alder Hey Children'S Hospital. Liverpool, England. Address reprint requests to Mr A.M.K. Rickwood, Consultant Urological Surgeon, Department of Paediatric Urology, Alder Hey Children's Hospital, Eaton Rd, Liverpool L12 2AP, England. Copyright 2002, Elsevier Science (USA). All rights reserved. 1055-858610211102-0007$35.0010 doi: 10.1 053Ispsu.2002.3181 0 108

tients with myelomeningocele (and, to a lesser extent, those with other congenital cord lesions) were discovered as experiencing a variety of intractable problems over and above those affecting traumatic paraplegics. Some of these problems were urologic, above all, an incidence of secondary upper urinary tract complications 3 far exceeding that occuring among the adult cordinjured and which, in contrast to those patients, affected girls as well as boys. Sex posed a further difficulty in handling urinary incontinence. The majority of traumatic paraplegics were men whose incontinence was manageable with some form of penile urinal, an option that is unavailable for that slight female majority with congenital cord lesions and myelomeningocele included. Given these considerations, it is unsurprising that surgeons saw conduit urinary diversion, then newly introduced, as an ideal solution to both difficulties, as a means of handling urinary incontinence in girls and as treatment for upper urinary tract complications in those of both sexes. 4 Although enthusiasm for urinary diversion varied from one unit to another, it remained the mainstay of management of congenital neuropathic bladder throughout the 1960s and well into the subsequent decade. Only then, following widespread and long-term experience, did it become appreciated that urinary diversion engendered problems of its own, most notably renal deterioration, which, in many instances, was not attributable to any technical deficiency of the original procedure. s Coincidentally, alternative forms of treatment began to become available, and started in 1972 with Lapides'6 introduction of clean intermittent self-catheterisation (CISC). This turned management of neuropathic bladder, congenital or acquired, "on its head." Until then, the principal difficulty was in persuading such bladders to empty: with CISC the problem was persuading them to fill and to do so at low pressure. Although not appreciated in these terms at the time, it soon became apparent that CISC alone rendered only a minority of patients dry and, later, that upper renal tract complications still could supervene or, if already established, could worsen. Subsequent progress was largely consequent on a greater understanding of the pathophysiology of neuropathic bladder dysfunction, as disclosed by urodynamics,1-9 and, with this, appreciation of the factors responsible for limiting bladder capacity or causing upper renal tract complications. This, in tum, led to more rational employment of various forms of treatment, principally detrusor Seminars in Pediatric Surgery. Vol 11, No 2 (May), 2002: pp 108-119

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

antispasmodics, augmentation cystoplasty, and the artificial urinary sphincter. Now, nearly 30 years after introduction of elSe, we have reached the position, at least in theory, where this form of treatment, combined, if necessary, with other adjunctive measures, offers every child with neuropathic bladder the prospect of becoming both continent and retaining normal upper renal tracts. Practice still lags behind theory, however, owing to the limitations inherent in these various adjunctive forms of treatment. ETIOLOGY

Myelomeningocele Historically, this has been far the most common cause of congenital neuropathic bladder, accounting for almost 90% of cases (Table 1). However, for several reasons, the incidence of this condition has declined greatly during the last 30 years so that it now accounts for little more than 50% of new cases. Myelomeningocele results from partial failure of tubularization of the neural crest, and because this process begins at midpoint, to proceed both cranially and caudally, the conus medullaris is almost always affected in this failure, with only 6% of patients avoiding neurologic involvement of bladder and bowel. 10 The nontubularized neural crest, termed the neural plaque, lies exposed at the surface, and, because neural tissue within it is grossly disorganized, the more extensive the plaque, the more extensive both the sensory and motor deficit. In 25% of cases, however, conus reflexes (anocutaneous, glans-bulbar) are retained, and the likelihood of this is unrelated to the extent of the neural plaque. I I Incomplete cord lesions, with sacral sensory or motor sparing (or both), occur only in association with the smaller (sacral, lumbosacral) plaques; those few patients with normal bladder and bowel function are confined within this group. Hydrocephalus, even if not always requiring shunting, is an almost invariable accompaniment of myelomeningocele and, as a general rule, the more extensive the neural plaque the greater the degree of hydrocephalus. Again, as a general rule, the more severe the hydrocephalus the greater the likelihood of intellectual impairment, so that myelomeningocele is unique among cord lesions in that increasing physical and mental disabilities tend to

Table 1. Etiology of Congenital Neuropathic Bladder (Department of Urology, Alder Hey Children's Hospital, 1984-2000) Myelomeningocele Sacral agenesis Isolated lesion Imperforate anus Lumbosacral lipoma Other occulta lesions

468 (83%) 43 (8%)

28 15 36(6%) 15 (3%)

109

go hand in hand. 12 Additionally, the effects of hydrocephalus on mentation are skewed, with verbal aptitude relatively spared, whereas performance abilities, including the hand-eye coordination necessary for elSe or sphincter manipulation, tend to be more severely affected. Although difficult to quantify, self-motivation and initiative also are adversely affected by hydrocephalus and, once more, seemingly in proportion to its severity. Mobility, a further factor to be considered in relation to urologic management, depends on the motor neurologic level and, hence, the degree of paralysis. As a rule, patients with motor level at or below L3, therefore having normal quadriceps function, achieve ambulation and retain this facility on into adolescence and adulthood. By contrast, those with a level above L3 almost always come to adopt a wheelchair existence once reaching adolescence no matter what they may have achieved when younger. 13 Spinal deformities are prevalent among myelomeningocele patients, and the likelihood and severity of these is, again, dependent on the extent of the neural plaque. Sacral and lumbosacral lesions seldom are associated with significant deformities and lumbar lesions usually with no more than a degree of lordosis. However, the most severe, thoracolumbar, lesions are accompanied frequently by the development of marked or gross kyphoscoliosis, a deformity often rendering urethral selfcatheterization impracticable and making for difficulties with the siting of abdominal stomas of any sort. In their most extreme form, such deformities may compromise the respiratory reserve and so pose an extra anesthetic risk. Especially among the more severely affected myelomeningocele patients, these various considerations often influence urologic management as much as the nature of the bladder dysfunction itself. Other Congenital Lesions of the Spinal Cord Because these lesions are not associated with hydrocephalus nor, as a rule, with major neurologic deficits or spinal deformities, urologic management rarely is influenced by factors other than the nature of the bladder dysfunction itself. Most affected patients have negative conus reflexes, including the minority with incomplete cord lesions. Depending on the type of lesion, any neurologic deficit (including detrusor and sphincteric innervation) may be primary or may occur as a secondary phenomenon as a result of traction or compression of the spinal cord or cauda equina. Only this latter phenomenon is amenable to neurosurgical correction. Whether such intervention carries any urologic benefits is often debatable, because although it is usual for the urodynamic parameters to

A.M.K. RICKWOOD

110

change postoperatively, this rarely has any advantage to the patient. A most important exception exists in those patients gaining normal bladder and bowel control and which subsequently deteriorates. Here, neurosurgical intervention frequently effects a cure if undertaken expeditiously, within 3 months of the onset of symptoms. Any change for the worse in bladder or bowel control in these patients therefore should be regarded as an emergency, calling for prompt urodynamic assessment and, if features of neuropathic bladder are confirmed, for immediate neurosurgical referral. Sacral Agenesis Occurring as part of the caudal regression syndrome, 14 this may be found in association with imperforate anus or as an isolated anomaly. In the latter instance, the mother often is an insulin-dependent diabetic. The extent of the lesion varies and, in extreme cases, even the lower lumbar spine is involved. At least 3 sacral segments must be absent to result in neuropathic bladder.15 Such a deficit is always detectable by palpation, and, in most cases, there also is characteristic flattening of the buttocks superiorly. The cord lesion invariably is incomplete and, uniquely to this condition, any peripheral neurologic deficit bears no predictable relation to bladder and sphincteric dysfunction. 16

sons) why this may be compromised, whether in terms of capacity, excessive intravesical pressure, or both. Terminology Because understanding of neuropathic bladder dysfunction sometimes has been hampered by inexact use of terms, we define them here. Detrusor hyperreflexia is used for any reflex detrusor activity and should not be taken as implying that such detrusor contractions necessarily occur at suboptimal capacity or always generate pathologically excessive pressures. Detrusor-sphincter dyssynergia, occurring as part of a mass pelvic reflex, represents simultaneous contraction of both detrusor and striated external urethral sphincter. 17 The phenomenon is readily detectable by electromyography (EMG) recordings from the sphincter (Fig 1) and is recognizable radiologically as a sharp cutoff at this level and with uniform dilatation of the urethra above (Fig 2). Static sphincteric obstruction is that obstruction occurring at the level of the external urethral sphincter in the absence of a simultaneous detrusor contraction. 9 Associated with absent or weak EMG activity, the phenomenon is usually radiologically distinguishable from detrusor-sphincter dyssynergia by more gradual tapering of the proximal urethra down to the level of obstruction (Fig 3). In contrast to detrusor-sphincter dyssynergia, a dynamic if inappropriate process, static sphincteric ob-

PATHOPHYSIOLOGY

Management aims to replicate the 3 essentials of normal bladder function: (1) fill: this implies adequate, low-pressure, functional capacity; (2) empty: this maximizes effective capacity (ie, functional capacity minus residual urine volume); and (3) void at will: in all but a very small minority of patients with neuropathic bladder, some abnormal means must be used, whether by else or by abdominal compression or straining. The latter is possible only when there is some element of sphincteric incompetence and achieves continence only when urethral resistance can be varied at will (eg, by use of the artificial urinary sphincter). Some sensation of bladder fullness, present in a proportion of patients and all those with incomplete cord lesions, is helpful but by no means essential because those lacking this attribute may compensate by timed voiding. Some neuropathic bladders fill well, albeit often at the expense of raised intravesical pressure, but do not empty, and others do the opposite, whereas many function imperfectly in both respects. With the near-universal adoption of else as the means of achieving both "empty" and "void at will," attention correspondingly focuses on the filling phase of bladder function and the reason (or rea-

A B Racial Pressure (em/H,O)

8060 40-

Intrinsic: Bladder Pressure

6040-

(em/HzO)

external Anal Sphincter

E.M.G.

11

20--------------~---

~

2O-------...J

~

~ ,

I

,

2 3 Minute.

,

J

4

Fig 1. Detrusor-Sphincter Dyssynergia. A reflux detrusor contraction (A) is associated with a surge in anal sphincter EMG and initially complete detrusor-sphincter dyssynergia.' Voiding occurs after partial sphincteric relaxation (8).

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

Fig 2. Cystogram shows detrusor-sphincter dyssynergia. Note the sharp cutoff at external sphincteric level and uniform and gross dilatation ofthe urethra proximally. There is also bladder sacculation and gross left vesico-ureteric reflux. (Reprinted with permission from Freeman, Burge, Griffiths, and Malone (eds): Surgery of the Newborn; Copyright 1994, by permission of the publisher Churchill Livingstone.)

struction is purely passive and represents a fixed urethral resistance. The cause is unknown, although a degree of denervation fibrosis is the most plausible of the several explanations so far advanced. Detrusor noncompliance denotes a rise in baseline intravesical pressure occurring during the filling phase. In a normal bladder, such a rise takes place only when the viscoelastic limit of the detrusor is reached, far beyond physiologic capacity, whereas noncompliance in the pathologic sense exists when a rise occurs within the normal range of capacity and to an excessive degree. Both these latter factors need to be taken into consideration when assessing the significance of noncompliance. If, for example, a pressure exceeding 20 cm H20 is taken as that leading to secondary ureterovesical obstruction, such a pressure is evidently of significance if occurring at a low filling volume but far less so if only well beyond expected bladder capacity.

111

By the same token, the greater and the more rapid the pressure rise, the more significant 18 and vice-versa, with pressures remaining below 20 cm H20 within expected capacity unlikely to cause secondary upper renal tract complications. The cause of detrusor noncompliance remains to be determined precisely although, once again, a degree of denervation fibrosis, with deposition of excessive or abnormal collagen, represents at least a partial explanation. Sphincteric incompetence is evidenced by leakage of urine solely caused by a rise in intraabdominal pressure. Absent in normal bladders and in those neuropathic bladders associated with suprasacral cord lesions, the degree of sphincteric incompetence depends largely on the level of fixed urethral resistance (ie, static sphincteric obstruction) so that, paradoxically, outlet obstruction and stress urinary leakage frequently coexist. Also, a high degree of static sphincteric obstruction can result in effective, if abnormal, sphincteric competence. In practice, the degree of outlet obstruction needed to maintain continence depends on the patient's day-to-day activities: the more strenuous the greater the necessary obstruction. As a rule, however, urinary leakages occurring in response to rises in intraabdominal pressure of less than 40 cm H2 0 always are of clinical significance. Functional bladder capacity is that existing during the course of ordinary day-to-day life and that frequently is appreciably less than absolute capacity, that achievable under ideal conditions, motionless and supine. Functional capacity should increase with growth and for children 0 to 12 months of age is estimated by the formula: capacity (mL) = weight (kg) X 7, and for children 1 to 12 years of age as: capacity (mL) (age [years] X 30) + 30.

Fig 3. Cystogram shows static sphincteric obstruction. Note the gradual tapering of the urethra down to the level of the obstruction at the level of the external sphincter. The bladder is mildly sacculated.

A.M.K. RICKWOOD

112

Classification As with acquired forms of the complaint, congenital neuropathic bladder dysfunction is determined largely by the caudal extent of the cord lesion, suprasacral or sacral,19 although with the difference that an intermediate pattern of function commonly is seen. 8 A further distinguishing feature is that although in cord trauma suprasacral lesions predominate, in congenital lesions of the cord, the converse applies. ll Suprasacral Lesions (Contractile Bladder) The conus medullaris remains intact and so also, although isolated from higher centers, the innervation of both detrusor and external urethral sphincter is normal. Conus reflexes (anocutaneous, glans-bulbar) are positive. Voiding occurs solely by hyperreflexic detrusor contractions, and the sphincteric mechanism is competent, in most instances with the bladder neck remaining closed except during the course of detrusor activity. In those few cases in which detrusor noncompliance renders the bladder neck incompetent, this is compensated by overactivity of the external urethral sphincter. Hyperreflexic detrusor contractions, typically occurring only at capacity and not during the filling phase, almost are invariably associated with detrusorsphincteric dyssynergia. This may be continuous or interrupted (Fig 4) and frequently is initially complete so that voiding does not occur for some time after the onset of a detrusor contraction. As a result of this obstruction, the contractions tend to generate excessive pressures, often exceeding 100 cm H20 and, despite this strength, frequently fade away before the bladder is empty (nonsustained contractions). Significant detrusor noncompliance is comparatively uncommon, and perhaps for this reason the sacculation typical of neuropathy is seldom seen in contractible bladders. The capacity of these bladders depends solely on the point at which filling stimulates voiding detrusor hyperreflexia, and this varies widely from one patient to another. In any individual case, the point may be influenced, for the worse, by urinary infection or a fall in ambient temperature. Detrusor hyperreflexia also may often be provoked, either incidentally by coughing or laughing or deliberately by suprapubic tapping, although rarely, if ever, can this latter phenomenon be turned to practical advantage (ie, as a means of voiding at will) in patients with congenital neuropathic bladder. Sacral Lesions (A contractile Bladder) The conus medullaris is destroyed and with it the innervation of both detrusor and external urethral sphincter. Conus reflexes are negative. There is no detrusor hyperreflexia, and although there always is some element of detrusor noncompliance, this

B.B.

Total Bladder

Pre ....re

(cm/H,O)

808040-

20 -_....--1'

Reetal

Pressure

(cmflt,O)

Intrinsic: B~

Pr....... (cm/H,o)

Void

R_te (ml/ sec)

,

I

2 3 Mlnut..

I

"

Fig 4. Contractile bladder with phasic detrusor-sphincter dyssynergia, alternating contraction (A) and relaxation (B) resulting in an interrupted urinary stream and isometric rises in detrusor pressure. (Reprinted with permission from Mundy, Stephenson, and Wein (eds): Urodynamics; Copyright 1984, by permission of the publisher Churchill Livingstone.)

tends to be at the milder end of the spectrum. Voiding occurs only by overflow or by raising intraabdominal pressure and which is to say that sphincteric incompetence invariably is present in some measure. Typically, the bladder neck is closed initially only to open passively during filling with subsequent holdup of urine at the level of the external sphincter (static sphincteric obstruction). Once detrusor noncompliance leads intravesical pressure to exceed this urethral resistance, overflow occurs (leak point pressure).7 The degree of static sphincteric obstruction, and hence, conversely, of sphincteric incompetence, varies widely and unpredictably from one patient to another. When high, this leads to a good functional capacity at the expense of a large residual urine, when low, the opposite occurs, and when of middling degree, to a bladder that neither fills nor empties effectively. A further necessary consequence of these considerations is that functional bladder capacity scarcely exceeds residual urine because the intraabdominal pressures generated by everyday activities are, except for the very sedentary, little less than those deliberately generated by abdominal straining. Hence, effective bladder capacity approaches zero, and any attempt to achieve continence by voiding with abdominal straining inevitably is doomed to failure. With acontractile bladder, both functional capacity and intravesical pressure are determined by the interplay

113

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

,-." ~

"

~

'---

Fig 6. Intermediate bladder. The bladder neck is closed initially (A). As the intra-vesical pressure rises, the neck opens, initially with holdup at sphincteric level (B) and subsequently with overflow (C) ("leak point pressure"). There also is low-pressure detrusor hyperreflexia with small voids (0). After voiding by abdominal straining (E), intravesical pressure falls to the initial level. (Reprinted with permission from Mundy, Stephenson, and Wein (eds): Urodynamics; Copyright 1984, by permission of the publisher Churchill Livingstone.)

Fig 5. Intravenous urogram shows the effect of a combination of bladder outflow obstruction and severe detrusor noncompliance. Even at only a low-filling volume, this has resulted in marked secondary ureterovesical obstruction bilaterally.

of 2 factors, static sphincteric obstruction and detrusor noncompliance. At one extreme, a high level of obstruction combined with noncompliance buys capacity at the expense of elevated intravesical pressure 7 and at lesser filling volumes the worse the noncompliance (Fig 5), whereas at the other, with a low level of obstruction, noncompliance serves to further detract from whatever modest capacity there may be. However, no matter how severe, it never can elevate intravesical pressure to "unsafe" levels.

bladder, may be "provokable" as well as occurring spontaneously. As a rule, the radiologic appearances of any outflow obstruction resemble those of static sphincteric obstruction rather than detrusor-sphincter dyssynergia. As indicated, significant detrusor noncompliance is the norm with this pattern of dysfunction and which, more than any other, is apt to lead to the elongation and sacculation classical of neuropathic bladder ("fir tree bladder"; Fig 8).

C.tt.

---T....

!em"""1

......

8080-

1"'"",,1

40 -

o.-

00 -

-

20 -

"'-

1..,"""1

Intermediate Bladder

Possibly resulting from patchy maldevelopment of the conus medullaris and always associated with negative conus reflexes, intermediate bladder is characterized by a combination of detrusor hyperreflexia and sphincteric incompetence, both in varying measures and frequently further compounded by detrusor noncompliance (Figs 6 and 7). Perhaps largely as a result of the sphincteric incompetence, detrusor contractions seldom generate more than modest pressures, but as with the contractile

.... ....

(../-'1

1&-

5:

3

•

5

Fig 7. Intermediate bladder (contrast-filled urethral catheter in situ). In this case there is more marked detrusor hyperreflexia, initially with holdup at sphincteric level (A) and subsequently with small voids (B). After voiding by abdominal straining (e) there is only modest residual urine (0) and baseline intra-vesical pressure, about 50 cm H2 0 at capacity, falls to zero.

114

A.M.K. RICKWOOD

Fig 8. Intermediate bladder. Cystography shows gross sacculation and a little elongation of the bladder ("fir tree bladder"). There also is gross left vesico-ureteric reflux. (Reprinted with permission from Freeman, Burge, Griffiths, and Malone (eds): Surgery of the Newborn; Copyright 1994, by permission of the publisher Churchill Livingstone.)

As with the acontractile bladder, functional capacity and intravesical pressure are determined by the interplay of detrusor noncompliance and outlet obstruction and to which must be added the contribution of detrusor hyperreflexia. Factors responsible for limiting functional capacity of the neuropathic bladder are summarized in Table 2. Among myelomeningocele patients, the patterns of dysfunction are contractile, 25%; acontractile, 15%, and intermediate, 60%. Acontractile and intermediate dysfunction is even more prevalent among patients with other congenital lesions of the cord.

Incomplete Cord Lesions Incomplete cord lesions with sacral sensory sparing (and occasionally motor sparing) are in most instances associated with suprasacral cord lesions and hence with

contractile bladder dysfunction. ~,ecause of this sensory sparing, patients are aware not so much of bladder filling as such but rather of the occurrence of hyperreflexic detrusor contractions and therefore experience gross urgency of micturition. A significant proportion of them achieve spontaneous, if precarious, urinary continence. This state requires a combination of a suitably prolonged period of initial complete detrusor-sphincter dyssynergia, mobility good enough to reach a toilet quickly, and a useful effective bladder capacity.2o Those with motor sparing also are rather more likely to become continent, not because of any voluntary control of the detrusor, which scarcely is ever seen, but for the ability to contract the external urethral sphincter and pelvic floor muscles so as to "hold on" that much longer. It is important to distinguish these patients from that minority having genuinely normal bladder function, because, unlike them, their upper renal tracts are at risk. It remains to be added that a proportion become wet again, a phenomenon usually attributable to increasing residual urine and a corresponding decline in effective bladder capacity. Those occasional patients with incomplete neurologic lesions associated with negative conus reflexes enjoy no particular advantage with respect to continence but, like those with positive reflexes, do retain both bladder and urethral sensation, with the latter sometimes causing difficulties with self-catheterization.

Natural History of Neuropathic Bladder Dysfunction Congenital neuropathic bladder dysfunction can change over time, more often quantitatively than qualitatively and almost always for the worse. With only occasional exceptions, those few experiencing a qualitative change do so after a corresponding alteration in neurology, typically a change from positive to negative conus reflexes and which, in a majority of cases, results from spinal surgery. Quantitative changes may comprise increasing hyperreflexia, outflow obstruction, and residual urine and deteriorating detrusor compliance. The most common combination is one of increasing static sphincteric obstruction and deteriorating compliance. Worsening sphincteric incompetence is comparatively rare. Although no time of life is free of these problems, the periods of greatest risk are the first 2 years of life, when about 28% of neonatally "safe" bladders become "unsafe",21 and, during the course of puberty, this latter occurring more commonly in boys than girls, possibly

Table 2. Causes of Impaired Bladder Capacity Contractile Bladder

Acontractile Bladder

Intermediate Bladder

Detrusor hyperreflexia

Sphincteric incompetence Detrusor noncompliance Combinations

Sphincteric incompetence Detrusor noncompliance Detrusor hyperreflexia Combinations

115

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

because prostatic growth enhances static sphincteric obstruction. This same phenomenon probably also accounts for the occasional boy with sphincteric incompetence becoming dry through puberty.

Table 3. Causes of Secondary Upper Renal Tract Complications Urinary infection Vesico-ureteric reflux Bladder outflow obstruction Detrusor hyperreflexia Detrusor noncompliance

THE UPPER RENAL TRACTS

Primary Anomalies Primary anomalies of the upper renal tracts are more prevalent among myelomeningocele patients than in the population at large. 22 Mostly comprising anomalies of position and fusion, they only rarely have any bearing on practical management. Vesico-ureteric reflux also is more prevalent than the norm, but an unquantifiable proportion of this is secondary rather than primary. Secondary Upper Renal Tract Complications Incidence. Such complications, in the form of obstruction or reflux, are prevalent in patients with all lesions causing congenital neuropathic bladder and are best documented in those with myelomeningocele, among whom 10% to 20% are reported to have complications at birth, 20% to 30% at I year of age, and 30% to 50% by 2 years of age. 23 -25 These figures, however, probably exaggerate the extent of the problem because they include lesser degrees of vesico-ureteric reflux, a proportion of which may be primary rather than secondary, and examples of minor and sometimes self-limiting nonrefluxing dilatation. During these early years of life, there is no conspicuous difference in the incidence of complications between girls and boys. The natural incidence beyond 2 years of age is not determinable with any accuracy, having frequently been influenced, for better and for worse, by treatment and especially so in girls, for worse, by urinary diversion. 5 Certainly, during later childhood and puberty, boys are more at risk, about 50% by the time of physical maturity. The proportion among girls would be somewhat smaller, probably about 30%. It remains to be added that the risk of complications runs on indefinitely into adult life, although to what extent remains to be established. 26 Unanswered also is the question of why children with congenital neuropathic bladder should be at so much greater risk than are cord-injured adults, and, similarly, why this risk, among girls, is confined almost entirely to the former group. A possible explanation is that the effects of a neurologic deficit are more severe' on a developing bladder, as opposed to a mature one, and that, in turn, the effects of this, especially in the form of secondary vesico-ureteric reflux, are more severe on developing upper renal tracts. Etiology. Factors implicated in secondary upper renal tract complications are summarized in Table 3.

Urinary infection. Urinary infection is extremely common 24 ,25 and, in the very young, may lead to renal scarring even in the absence of vesico-ureteric reflux. Most infections result from bladder malfunction, and their treatment should be directed to rectifying this rather than ceaseless pursuit with antibiotics. Vesico-ureteric reflux. As described previously, this may be primary or secondary and, if the latter, its management is principally that of the responsible bladder malfunction. Whether high-pressure reflux, as commonly seen with neuropathic bladder, causes renal damage in the absence of infection remains open to doubt. It is, however, common experience that a combination of high-pressure reflux and urinary infections is apt to be rapidly and more than usually damaging. In contrast to low-pressure reflux, it remains so throughout childhood and probably even on into adult life. Bladder outflow obstruction. Whether as detrusorsphincter dyssynergia or static sphincteric obstruction, outflow obstruction is an invariable precursor of secondary upper urinary tract obstruction or reflux but leads to these complications only when associated with raised intravesical pressure caused by detrusor hyperreflexia, detrusor noncompliance, or some combination of both. The relative contributions of these 2 factors are a matter of some dispute; detrusor noncompliance is seemingly the more important by conventional urodynamics 7 and detrusor hyperreflexia by ambulatory examinations.27 As for detrusor noncompliance, baseline pressures exceeding 20 cm H2 0 within the physiologic range of capacity on conventional slow-fill urodynamics should be regarded as "unsafe." Whatever the detrusor behavior, secondary upper renal tract complications never occur in the presence of gross sphincteric incompetence and a permanently empty bladder. This happy state of affairs may, of course, be reversed if sphincteric incompetence is treated without regard for any detrusor malfunction. PATIENT ASSESSMENT

History General features of relevance comprise mobility, intelligence, and social factors, plus the nature and effectiveness of any bowel management. The urologic features include:

116

• continuous dribbling, particularly if exacerbated by coughing, crying, or standing, is almost pathognomonic of some degree of sphincteric incompetence. Note, however, that provoked hyperreflexia sometimes may simulate sphincteric incompetence. • a discrete, spontaneous, urinary stream is typical of contractile bladder and, if interrupted, is indicative of detrusor-sphincter dyssynergia. • urinary infections, especially if febrile, are strongly suggestive of upper renal tract complications, actual or impending. Examination

• Bladder distension is indicative of outflow obstruction, while an expressible bladder is pathognomonic both of neuropathy and of some measure of sphincteric incompetence. • An inexpressible bladder implies either sphincteric competence or one permanently empty by reason of gross sphincteric incompetence. • Neurologic examination is limitable to the lowermost sacral segments, ie, me presence or absence of conus reflexes and similarly of sensory or motor sparing. Neonatal Assessment

Bladder expressibility is demonstrable neonatally and so also conus reflexes and sensory sparing as judged by general arousal to perianal pinprick. No matter how slight the neurologic deficit, neuropathic bladder is certain if the bladder is expressible or conus reflexes are negative or if there is no sensory sparing. By contrast, bladder function may prove to be normal if the bladder is inexpressible and conus reflexes are positive and there is sensory sparing. Investigations Imaging studies. Ultrasonography of me urinary tracts, with estimation of residual urine where practicable and relevant, represents bom the best means of initial assessment and of subsequent follow-up, with the frequency of examinations for the latter purpose determined by what is known of bladder malfunction and, hence, the perceived risk of upper renal tract complications. Among other imaging studies, DMSA scintigraphy is of value in patients wim vesico-ureteric reflux or febrile urinary infections, whereas cystography, to confirm or exclude vesico-ureteric reflux or bladder outflow obstruction, is best combined wim simultaneous urodynamic examination. Urodynamics. Principal indications for this examination are to: • identify the "unsafe" bladder neonatally

A.M.K. RICKWOOD

• determine the cause(s) of secondary upper urinary tract complications • plan treatment for incontinence • (more arguably) provide routine assessment of the risk of upper tract complications throughout childhood. In conducting the study, practical considerations are: • It is best performed by the clinician also responsible for the patient's management. • It should, if at all possible, be combined with simultaneous cystography • Slow filling is utilized, aiming to reach expected bladder capacity over not less than 20 minutes. • The presence or absence of sphincteric incompetence should be assessed periodically during filling by maneuvers raising intraabdominal pressure (standing, coughing, application of suprapubic pressure). • In me presence of gross sphincteric incompetence it may be necessary to occlude the bladder neck by a Foley balloon catheter to fill the bladder to expected capacity.

MANAGEMENT Basic Considerations

Because of the very variable nature of neuropathic bladder dysfunction, no single form of treatment can ever be expected to be a universal panacea. Successful management calls for a flexible approach based on the following principles: • Maintenance of renal function always is the principal concern and, in practice, means that bladder outflow obstruction always calls for active treatment, by medical or surgical elimination or by CISC: whenever there is conflict between the interest of maintaining renal function and of securing continence, the former always takes precedence. • Management must relate to the nature of the bladder dysfunction in any individual case and, because mis is frequently complex, memods of treatment may need to be used in combination. • Those forms of treatment (usually medical) that are reversible are routinely preferable, in the first instance, to those (usually surgical) that are not. • Because a major objective is self-management, or, at worst, minimal dependence on others, treatment must be realistically geared to the patient's overall physical and intellectual abilities. The implications of this last principle are evident enough in terms of gender and already have been alluded to in respect of intellect, dexterity, and deformity. Three further features, however, deserve a little elaboration: Age. Ideally, continence should be achieved by school age, but this commonly is impracticable, espe-

117

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

cially for those patients with gross sphincteric incompetence requiring surgical correction. Even currently, incontinence can result in special rather than mainstream education, although this is usually avoidable if education authorities can be assured that there is likely to be a solution before secondary school age. It also is desirable that the treatment adopted should be one that the patient can practice independently at as young an age as possible: CISC by a second party, for example, is quite acceptable for a 5 year old, much less so for a 10 year old, and positively undesirable for a teenager. Mobility. Definition of "adequate" functional bladder capacity hinges largely on mobility. When good (and which, in the average British house, usually includes ability to negotiate stairs), a capacity ensuring dryness for 2 hours is "adequate" if not ideal. For the patient wheelchair bound, by contrast, a capacity achieving dryness for at least 4 hours is desirable and certainly never less than 3. Balance. Perurethral CISC, in calling for use of both hands, requires balance without support and which, in patients with a high neurologic level or a major spinal deformity, often is lacking. Some such patients, however, are able to catheterize an abdominal Mitrofanoff stoma using only 1 hand. Management in Relation to Bladder Dysfunction

As previously described, CISC has become the almost universal means of achieving both "empty" and "void at will" and also of treating any bladder outflow obstruction. The occasional exceptions come within 3 categories: • Those with incomplete cord lesions and achieving spontaneous continence, although a proportion of these, with appreciable residual urine, find CISC helpful in maximizing effective bladder capacity, if not always as the sole means of voiding, then 2 or 3 times a day. • Those with an artificial urinary sphincter and able to void adequately, with a small amount or nonexistent residual urine, by abdominal straining (less than 50% in the author's series). • Those with a large residual urine but unable to practice perurethral CISC because of an incomplete cord lesion, with intact urethral sensation, and unwilling to contemplate a Mitrofanoff stoma. During the mid 1970s a vogue existed for treating neuropathic outflow obstruction by alpha-blockade. 28 Because the results were inconsistent, this form of treatment soon became superceeded by CISe. However, for patients as outlined above and who have static sphincteric obstruction (as opposed to detrusor-sphincteric dyssynergia) alpha-blockade remains worth a trial and is sometimes (though unpredictably) dramatically effective both in eliminating residual urine and in improving continence.

Clean Intermittent Self-Catheterization

Despite remaining the most important advance in the management of neuropathic bladder, only some 10% to 20% of patients became continent by this means alone29 (ie, spontaneously have adequate functional capacity) and, among those fortunate to do so, a proportion experience new or further upper renal tract complications (ie, have adequate functional capacity but at the expense of excessive intravesical pressure). Consequently, the majority of patients require treatment over and above CISC, and a sizeable minority require treatments in combination, typically one to improve detrusor function and another to enhance sphincteric competence. For current purposes, however, treatment is described under individual aspects of dysfunction. Treatment of Detrusor Hyperreflexia

Anticholinergics have long been used to treat hyperreflexia and, until the recent introduction of tolterodine, the most useful agent has been oxybutynin. The almost invariable urodynamic response to oxybutynin is one not always sufficient for clinical purposes. To an appreciable extent the response is dose related, and in cases in which enhanced dosage (5 mg three times daily at 10 years of age to 10 mg twice daily at 15 years of age) is required without engendering side effects, the agent may be administered intravesically during the course of CISC. In a few cases, standard dosage appears to be more effective given intravesically than orally, whereas in others who are continent on normal dosage but experiencing side effects, this means of delivery also is appropriate. The recently introduced single daily dose slow-release preparation (Ditropan XL, 5 mg daily) represents a useful advance for some patients but currently is licensed for use only in those 12 years of age or older. Tolterodine is advanced with fewer side effects than oxybutynin and may be used as an alternative agent for that reason. On the basis of early experience, it is, among patients in general, no superior in treating hyperreflexia, although some individual patients have found it so. Augmentation cystoplasty represents a last resort when medication proves to be ineffective, although only rarely is this procedure required to treat hyperreflexia alone (as opposed to a combination of hyperreflexia and noncompliance ). Detrusor Noncompliance

Although agents with a direct inhibitory effect on smooth muscle (imipramine, oxybutynin) have been used to treat noncompliance,3o rarely, if ever, has there been any useful response, and the management of this phenomenon remains purely surgical (ie, augmentation cystoplasty).

118

A.M.K. RICKWOOD

Sphincteric Incompetence Of all the factors limiting functional capacity of the neuropathic bladder, this is most difficult to treat. Marginal degrees of sphincteric incompetence may respond to an alpha-adrenergic agonist (imipramine, phenylpropanolamine, or, best, ephedrine), and such agents can be administered in conjunction with oxybutynin in cases in which there is coexistent hyperreflexia. More major degrees of sphincteric incompetence always call for surgical treatment. Limitations of Nonsurgical Treatment As is evident, limitations relate principally to detrusor noncompliance and sphincteric incompetence. To an appreciable extent, the likelihood, or otherwise, of nonsurgical measures being effective can be determined without recourse to urodynamics. Those with positive conus reflexes fare well, if not on CISC alone then in combination with oxybutynin, and in author's series, 93% of such cases have wholly reliable continence, and only 10% of them have undergone augmentation cystoplasty. Among those with negative conus reflexes, measurement of residual urine is advantageous. Where this is large, exceeding expected functional capacity for age, CISC will almost certainly achieve continence, although augmentation cystoplasty still may be required in the event of detrusor noncompliance. Conversely, a small residual amount of urine «25% expected bladder capacity) is nearly always indicative of gross sphincteric incompetence requiring surgical treatment. In patients with residual urine volumes between those extremes, the urodynamic findings are wholly unpredictable, and they may, for example, discover that capacity is limited by hyperreflexia rather than by noncompliance or sphincteric incompetence, or if there is sphincteric incompetence, this is no more than modest, and may respond to ephedrine. Nonetheless, the results of nonsurgical measures in patients with negative conus reflexes are generally disappointing with only 23% of the author's patients so managed reliably continent. Management Neonatally and During Infancy Although the upper renal tracts are the immediate concern during this period, especially because it is one of

relatively high risk, any active treatment should, if at all possible, avoid compromising later continence. There is general agreement that neonates identified as having an "unsafe" bladder should be commenced on intermittent catheterization,31,32 and some would advocate this measure in all cases given the frequency with which "safe" bladders become "unsafe" during infancy.21 It also may be advantageous to administer oxybutynin if there is marked detrusor hyperreflexia. If an expectant rather than a proactive approach is adopted for those with "safe" bladders, close surveillance is evidently advisable with ultrasonography at 4-month intervals and with videourodynamic reassessment in the event of any deterioration found on such examinations or of febrile urinary infection. On occasion, upper renal complications occur despite intermittent catheterization or existing complications fail to resolve on this treatment, circumstances best managed by a temporizing cutaneous vesicostomy.33 Endoscopic sphincterotomy34 represents an alternative policy for male infants with a competent bladder neck (contractile bladder). Management of the Severely Disabled Some form of continent urinary diversion may be offered to those having severe physical disabilities but retaining the motivation, dexterity, and balance necessary for intermittent catheterization of an abdominal stoma. For those not enjoying these advantages, less ambitious management, limited to protecting the upper renal tracts and securing dryness with a minimum dependence on others, is more appropriate. A penile urinary appliance is suitable for most boys (although sometimes not until puberty), but an endoscopic sphincterotomy should be performed as a prophylactic measure if there is any element of bladder outflow obstruction. An indwelling urethral catheter, if properly handled, may be used for long-term management of girlS.35 Where such measures fail, or are considered socially unacceptable, a conduit urinary diversion may be offered to patients of either sex.

REFERENCES I. Guttman L: Paraplegia 17:6-14,1979 2. Sharrard WJW, Zachary RB, Lorber J, et al: A controlled trial of immediate and delayed elosure of spina bifida cystica. Arch Dis Child 38:18-30, 1963 3. Eckstein HB, Cooper DGW, Howard AR: Causes of death in children with myelomeningocele or hydrocephalus. Arch Dis Child 42:163-167, 1967 4, Smith ED: Spina Bifida and the Total Care of Myelomeningocele. Springfield, Charles C Thomas, 1965 5. Middleton A W ,Hendren HM: Ileal conduits at the Massachusetts General Hospital from 1955-1970. J Urol 115:591-595, 1976

6. Lapides J, Dlokno AC, Silber SJ, et al: Clean intermittent selfcatheterisation in the treatment of urinary tract disease. J Urol 107:458461, 1972 7. McGuire EJ, Woodside JR, Borden TA, et al: Prognostic value of urodynamic testing in myelomeningocele patients. J Urol 126:205-209, 1981 8. Rickwood AMK, Thomas DG, Philp NH, et al: Assessment of congenital neuropathic bladder by combined urodynamic and radiological studies. Br J Urol 52:502-511, 1982 9. Mundy AR, Shah PJR, Borzyskowski M, et al: Sphincter behaviour in myelomenngocele Br J Urol 57:647-651, 1985

NEUROPATHIC BLADDER: CONSERVATIVE MANAGEMENT

10. Reiner I, 10nes M, Donnell SC, et al: Normal micturition in myelomeningocele patients. Arch Dis Child 67:640-641, 1992 II. Williams MPL, Katz Z, Escala 1M, et al: Peripheral neurology as a predictor of bladder dysfunction in congenital neuropathic bladder. Br J Urol 62:51-53, 1988 12. Lonton AP: Location of the myelomeningocele and its relationship to subsequent physical and intellectual abilities in children with myelomeningocele and hydrocephalus. Zeitschrift fur Kinderchirugie 22:51-57, 1977 13. Rickwood AMK, Hodgson J, Lonton AP, et al: Medical and surgical complications in adolescent and young adult patients with spina bifida. Health Trends 16:91-95, 1984 14. Duhamel B: From mermaid to anal imperforation: The syndrome of caudal regression. Arch Dis Child 36:152-155, 1961 15. Williams DI, Nixon HH: Agenesis of the sacrum. Surg Gynecol Obstet 105:84-88, 1957 16. Treble NS, Owen R, Rickwood AMK: Classification of congenial anomalies of the sacrum. Acta Orthopaedica Scandinavia 1988; 59:412416 17. Thomas DG, Smallwood R, Graham D: Urodynamic observations following spinal trauma Br J Urol 47: 161-165, 1975 18. Weston PMS, Robinson LQ, Williams S, et al: Poor compliance in early filling in the neuropathic bladder. Br J Urol 63:28-31, 1989 19. Bors E, Comarr AE: Neurological Urology Karger, Basle, 1971 20. Keshtgar AS, Rickwood AMK: Urological consequences of incomplete cord lesions in patients with myelomeningocele. Br 1 Urol 82:258-260, 1998 21. Kroovand RL, Bell W, Hart LJ, et al: The effect of back closure on detrusor function in neonates with myelomeningocele. 1 Urol 144: 423-425, 1990 22. Wilcock AR, Emery lL: Deformities of the renal tract in children with myelomeningocele and hydrocephalus compared with those children showing no such deformities. Br 1 Urol 42:152-157, 1970 23. 10hnston JH, Kathel B: The obstructed neurogenic bladder in the newborn. Br 1 Urol 43:206-210, 1971

119

24. Cass AS: Urinary tract complications in myelomeningocele patients. 1 UroI1l5:102-104, 1976 25. Light K, van Blerk PIP: Causes of renal deterioration in patients with myelomeningocele. Br 1 Urol 49:257-260, 1977 26. Rickwood AMK, Thomas DG: The upper renal tracts in adolescents and young adults with myelomeningocele. Zeitschrift fur Kinderchirurgie 39: 104-106, 1984 27. Webb Rl, Griffiths Cl, Neal DE: Ambulatory monitoring in neuropathic bladder dysfunction. Neurourology and Urodynamics 10: 419-420, 1991 28. Mobley DF: Phenoxybenzamine in the management of neurogenic vesical dysfunction. 1 Urol 116:737-740, 1976 29. Rickwood AMK, Arnold Al: Current management of childhood neuropathic bladder: Review of 156 cases. Zeitschrift fur Kinderchirurgie 45:238-241, 1990 30. Raezer DM, Benson GS, Wein Al, et al: The functional approach to the management of the pediatric neuropathic bladder: A clinical study. 1 Urol 117:649-653, 1977 31. Geraniotis E, Koff SA, Enn'le B: Prophylactic use of clean intermittent self-catheterisation in the treatment of infants and young children with myelomeningocele and neurogenic bladder. 1 Urol 139: 85-86, 1988 32. 10seph DB, Bauer SB, Colodny AH, et al: Clean intermittent catheterisation of infants with neurogenic bladder. Paediatrics 84:7882, 1989 33. Snyder HM, Kalichman MA, Charney E, et al: Vesicostomy for neurogenic bladder with spina blfida: Follow up. 1 Urol 130:924-926, 1983 34. Koontz WW, Vernon-Smith Ml: Transurethral external sphincterotomy in boys with myelomeningocele. 1 Urol 117:500501,1977 35. Rickwood AMK, Philp NH, Thomas DG: Long-term indwelling catheterisation for congenital neuropathic bladder. Arch Dis Child 58:310-314, 1983