Genitourinary Function
The bladder performs two functions: storage and elimination of urine. Performance of those functions depends on anatomic and physiologic integrity and neurologic conditions affect the latter. Congenital neural tube defects, such as myelomeningocele, spinal dysraphism, and tethered cord lesions, are the most common causes of neurogenic bladder in children. However, SCI and diseases (stroke, myelopathies, tumors, etc.) also can cause acquired dysfunction, with significant long-term consequences (Lucas 2019).
Pediatric SCI-related neurogenic dysfunction of the urinary tract differs from the adult type in the fact that it affects a developing organ. Normal voiding in newborns is largely reflexive with some input from the cerebral cortex. Detrusor and sphincter functions remain uncoordinated through the first several years of life (Yeung et al. 1995). As children grow, the brainstem takes more control of the pontine micturition center (Blaivas 1982). In SCI/D (spinal cord injury/dysfunction) related paralysis, the lower urinary tract dysfunction characteristics depend on the type of neurologic injury, specifically, upper and lower motor neuron type, with a small percentage having a mixed pattern (i.e., conus medularis). The upper motor neuron pattern SCI/D-related urinary tract dysfunction, a consequence of injury to the spinal cord itself, is characterized by over-active detrusor/detrusor hyperreflexia, detrusor-sphincter dyssynergia, decreased bladder compliance, and increased detrusor pressures, leading to the risk of developing vesicoureteral reflux. In this instance, the bladder acts under reflex control; as the bladder fills, the sacral micturition reflex triggers an involuntary contraction leading to bladder evacuation, clinically expressed as incontinence. Because the lesion is below the pontine micturition center (thus eliminating its’ control), there is loss of coordinated detrusor/sphincter relaxation; instead, there are intermittent contractions of the external sphincter during a detrusor contraction which can result in high intra-vesical voiding pressures, ultimately leading to upper urinary tract dysfunction and renal deterioration if not addressed. The lower motor neuron type urinary tract dysfunction, characteristic to injuries to cauda equina/nerve roots leads to a flaccid bladder which prevents emptying; external sphincter may be flaccid and incontinence can occur with any increase in intra-abdominal pressure (such as when coughing or straining). The internal sphincter tone may be intact because the sympathetic innervation originates above the conus medullaris, and this may contribute to incomplete emptying.
Most common complications of lower motor neuron type urinary tract dysfunction are recurrent UTIs related to bladder stasis and injury to the bladder wall because of distension. The small number of mixed injury bladder patterns are type A, where the detrusor is rendered flaccid, there is hypertonic external urinary sphincter and incontinence is uncommon; and type B pattern characterized by spastic bladder due to a disinhibited detrusor nucleus, a flaccid external urinary sphincter with resulting incontinence. Development of pyelonephritis and nephrolithiasis can occur in both upper motor neuron and lower motor neuron types of urinary tract dysfunction.
Goals of treatment change in the pediatric SCI as they advance through life. While preservation of kidney and bladder function remain the most important goals throughout life, social continence becomes essential as the child grows beyond the potty-training period, followed by achieving independence from caregivers. Achieving low-pressure urinary storage associated with bladder continence and efficient and complete emptying with normal pressures and minimizing the number of infections become mainstay of day-to-day bladder management.
Discussion
Given the low incidence of pediatric SCI/D (Blaivas 1982), it is quite expected that we only found seven observational studies, one post-test, and two case reports looking at individuals with pediatric-onset SCI. Due to the heterogeneity of the presentation of the findings and the small sample size of most studies identified from the literature, conclusions regarding the prevalence of bladder dysfunctions in children with SCI/D cannot be drawn. In a larger-scale study involving 216 adults with pediatric-onset SCI, the majority (74%) of participants reported experiencing at least one UTI in the past year (Vogel et al. 2002b). Etiology-wise, most study participants suffered motor vehicle accidents, either being in the vehicle during accident or as pedestrians struck by cars; some studies included participants with birth injuries (Burke 1974; Chao & Mayo 1994; Fanciullacci et al. 1988; Generao et al. 2004), domestic accidents (Fanciullacci et al. 1988), gunshot wounds (Chao & Mayo 1994; Generao et al. 2004), iatrogenic causes (Fanciullacci et al. 1988; Generao et al. 2004), transverse myelitis (Chao & Mayo 1994; Tanaka et al. 2006).
Population-wise, the papers looked at individuals who sustained SCI between the ages of 0 and 18 years (Generao et al. 2004). The mean time post-injury was 46 months (Chao & Mayo 1994) to 28 years (Patki et al. 2006). Topics of examination consisted of bladder management method (Burke 1974; Chao & Mayo 1994; Fanciullacci et al. 1988; Generao et al. 2004; Patki et al. 2006; Tanaka et al. 2006), and continence (Fanciullacci et al. 1988; Patki et al. 2006; Tanaka et al. 2006; Vogel et al. 2002b), urodynamic studies (UDS; with or without video and cystography) (Chao & Mayo 1994; Fanciullacci et al. 1988; Generao et al. 2004; Patki et al. 2006; Tanaka et al. 2006), upper tract health, as established by renal ultrasound (Chao & Mayo 1994; Generao et al. 2004; Patki et al. 2006; Tanaka et al. 2006) and/or intravenous pyelogram (Burke 1974; Chao & Mayo 1994; Fanciullacci et al. 1988), medical complications like infections (Burke 1974; Fanciullacci et al. 1988; Patki et al. 2006; Vogel et al. 2002b), renal insufficiency (Burke 1974; Patki et al. 2006; Tanaka et al. 2006), lithiasis (Burke 1974; Vogel et al. 2002b), and need for subsequent surgical interventions, like sphincterotomies/stent placement, urinary diversions and bladder augmentation, nephrectomies, etc.
Surprisingly, the severity and level of neurologic injury were not necessarily predictive of urodynamic findings. Detrusor pressures and activity did explain changes in bladder capacity, compliance, and cystometric appearance at times of follow-up (Patki et al. 2006)
Burke et al. (1974) looked at 29 children who sustained C1 to below T12 SCI under the age of 13 years; 26 of them had urologic follow-up. Among the 20 children who were less than 10 years after injury, 17 had normal upper tracts, 15 were using reflex voiding, 10 were having infected urine, and 1 already had a nephrostomy in the single residual kidney he had. In the 6 individuals that suffered the neurologic injury more than 10 years prior to data collection, only 1 had intravenous pyelogram (which was normal), 1 emptied his bladder by reflexive void, 4 had indwelling catheters (urethral or suprapubic) and 1 had bilateral cutaneous ureterostomy.
Fanciullaci et al. (1988) reported on 18 children with SCI seen 1972-1985 in 1 unit in Italy. Participants were first assessed 2-18 months post-injury, and follow-up assessment was done in 14 children 7.7 years post-injury on average, to evaluate results of the conservative management of the neurogenic bladder. Authors noted that the initial indwelling catheter was removed within 4 months in 14 of the participants. In the initial urologic follow-up, the upper urinary tract was normal in 13 patients; slight dilatation and vesicoureteral reflux was noted in 2 each, and renal stone in 1 patient; UTI was deemed present in 15/18 patients, but 13 of the 15 were noted to be asymptomatic bacteriuria. 15/18 underwent UDS which showed over-active detrusor in 12 children. In the 14 children that were evaluated 2-16 years post-injury, the upper urinary tract was deemed normal in 8/11 patients; 1 child was found to have a slight dilatation of the upper tract; vesicoureteral reflux was found in 2 children (with normal intravenous pyelogram) and UTI was present in 7/14 patients, with 5/7 noted to be asymptomatic bacteriuria.
Chao et al. (1994) looked at 40 children with SCI receiving urological care; Initial bladder management was done by reflex voiding (with acceptable voiding pressures <40 cm H2O) in 11 of the participants; the rest of 29 emptied their bladder by intermittent catheterization, utilizing anticholinergic drugs to address higher than 40 cm H2O voiding pressures, presence of detrusor-sphincter dyssynergia and/or having moderate to severe bladder trabeculations. First UDS showed that all 22 patients with cervical injury had over-active detrusor; 8 were reflexively voiding and 14 emptied their bladder by intermittent catheterization; in the thoracic injured category, 11 patients had over-active detrusor and two were areflexic; among them, 2 were reflexively voiding and 11 were using intermittent catheterization; in the 5 individuals with lumbar spine injury, bladder management was by reflexive void in 2 and intermittent catheterization in 3 and UDS showed that all of them had areflexic bladders. 28/40 participants were followed for more than 1 year undergoing bladder management assessment and video UDS; 11/19 patients with cervical injury, 5/6 with thoracic injury and 1/3 with lumbar injury were emptying the bladder using intermittent catheterization/anticholinergic drugs at this follow up; video fluoroscopy during UDS showed the bladder wall to be smooth in 43%, mildly trabeculated in 50% of participants, and markedly trabeculated in 7%. Five patients had a change from a smooth bladder wall to mild trabeculation (four cervical injuries and one thoracic injury). Four patients had a change from a trabeculated bladder wall to a smooth wall (three cervical injuries and one thoracic injury) at six months follow-up after institution of intracranial pressure and anticholinergic therapy. One patient had a grade 2/5 vesicoureteral reflux, which resolved on intermittent catheterization/anticholinergics. The authors noted that neurogenic management treatment failure was related to non-compliance with catheterization or pharmacologic regimen.
Unlike the studies discussed previously, Vogel and colleagues (2002b) work assessed the consequences of pediatric SCI/D-related neurogenic bladder by interviewing 216 adults with pediatric-onset SCI using a structured questionnaire. Mean number of UTI’s/year was reported to be 3.9 and occurred in 74% of individuals; those experiencing more UTIs had lower International Standards for Neurological Classification of Spinal Cord Injury motor scores and were less likely to have AIS D grade injury. In addition, a history of severe UTIs and urinary stones were associated with lower motor scores, higher injury level, and Functional Independence Measure scores. Those who reported having orchitis and epididymitis tended to be older, injured for a longer period of time, and reported having had severe UTIs. Bladder incontinence was reported by 25% of participants, more common in those using external catheters; UTIs were more common in individuals managing bladder with all types of catheters. Severe UTIs, orchitis, and epididymitis were not associated with any specific type of bladder program, but stones were more common in individuals using indwelling catheters.
Generao et al. (2004) performed a retrospective review of 42 pediatric patients who had been living with SCD-related paralysis for a minimum of 1 year. Assessed outcomes were bladder management, continence, medication, UTI occurrence, upper urinary tract health (US), and video-UDS in the context of safe bladder capacity (defined as pressure-specific volume of 40 cm water or less. 40/42 children were managing the bladder using intermittent catheterization and 37 were taking anticholinergic medications. Upper tract exploration showed no vesicoureteral reflux, hydronephrosis, or renal parenchymal scarring. Bladder capacity was less than expected in 80% of cervical injuries (but increasing with time); it was less than expected in 58% of thoracic injuries (and only 76% were found to progress as expected with time) and was less than expected in 50% of lumbar injuries. Early bladder management with intermittent catheterization and anticholinergic drug usage was considered to prevent hydronephrosis, scarring, reflux, and bladder trabeculation, improve continence and decrease rates of infection. In addition, thoracic injuries were found to have the most variable bladder pattern.
Patki et al. (2006) conducted a retrospective review of urological follow-up in 10 adults with pediatric-onset SC The group was divided into Neurogenic Detrusor Overactivity with or without Detrusor Sphincter Dyssynergia and a-contractile detrusor with or without low bladder compliance, based on initial UDS studies. It was found that patients with Neurogenic Detrusor Overactivity and Detrusor Sphincter Dyssynergia were at higher risk of developing complications. In addition, those who opt for reflex voiding and SPC were more likely to experience multiple problems requiring hospitalizations and interventions. The authors also noted that over time, most participants required changes to optimize urological management.
Finally, Tanaka et al. (2006) retrospectively examined the long-term urological outcomes in 22 children affected by transverse myelitis, as well as the correlation between bladder dysfunction and lower limbs spasticity and ambulatory status in addition to neurologic level of injury. Lower limb spasticity was documented in 14/22 (61%) and, while none of the children were ambulatory immediately post-onset of neurologic deficit, 9/22 (41%) became ambulatory during the follow-up period. At follow-up, 86% of children reported persistent bladder dysfunction. Bladder management was done by intermittent catheterization in 73% and 64% was using anticholinergic medications. Three were still incontinent despite adequate bladder management and 1 had the incontinence resolved by undergoing intra-detrusor onabotulinumtoxin type A injections. 6/22 were able to void volitionally, 2 of them having incomplete cervical injuries and maintaining continence (one using anticholinergic medication) and 4 of them having incomplete lumbar injuries, with only 2/4 maintaining continence. All patients with complete injury remained on intermittent catheterization. UDS were completed in 17 at follow-up, an average of 2.2 years after disease onset; detrusor over-activity was present in 10 patients (59%), Detrusor Sphincter Dyssynergia in 7 (41%), low compliance in 8 (47%) and detrusor leak point pressure greater than 40 cm water in 2 (12%). Upper tract was evaluated in 19/22 individuals using renal ultrasound and cystography for vesicoureteral reflux; 26% had upper tract changes (hydronephrosis in 3, reflux in 1, and hydronephrosis and reflux in 1). Chronic renal insufficiency developed in only 1 individual that did not have adequate urologic care for the initial 2.7 years post-injury, developed hydronephrosis and vesicoureteral reflux despite having a complete thoracic injury with no lower limb spasticity; the bladder was found to have low compliance and, despite treatment with intermittent catheterization and anticholinergics, patient needed to undergo augmentation cystoplasty and bilateral ureteral reimplantation to address the complications. 6 individuals that subsequently underwent upper tract and UDS evaluation started intermittent catheterization in the first 9 months post-injury, and another 10 in the first 2.3 years post-injury and were considered early intermittent catheterization users; none of the early catheterization users developed low bladder compliance of upper pathologic tract changes, as opposed to 7 of 10 patients in the delayed catheterization group exhibiting low bladder compliance and 4 of 10 having upper tract changes at follow up.
Conclusion
Major shortcomings of the literature pertaining to management and consequences of neurogenic upper and lower urinary tract dysfunction in children with SCI/D-related paralysis is the retrospective, observational case studies reporting type. That is because high-quality evidence regarding management and follow-up does not exist in the literature (Averbeck & Madersbacher, 2015). There is no standardization of intervention or even follow-up. The approach is not scientifically rigorous but clinically driven and there are no controls. Sometimes, even the definition of terms is variable (e.g., bladder compliance).
With that said, given the fact that pediatric SCI/D is extremely rare, learning from robust case series is the first step toward building knowledge. The reviewed papers consistently point to the lack of predictive value of neurological injury category on bladder function and management. To that point, it does appear that thoracic injuries are less likely to be predictable when it comes to the type and subsequent management of neurologic bladder dysfunction. The ideal urological treatment needs to be individualized and tailored to suit a specific patient’s medical and social needs and both needs are changing as the child grows. Changes in bladder management required at later stage in injury and variation of renal deterioration with different bladder managements make a strong case for regular and long-term follow-up of the pediatric SCI population. Ongoing long-term comprehensive assessment utilizing imaging (renal ultrasound and scan, computed tomography scan, cystometrogram, cystoscopy) and functional (video-urodynamics, creatinine clearance, glomerular filtration rate, cystatin C, radio-isotope studies etc.) tools to assess both upper and lower tracts is strongly recommended for management guidance in the ever-growing and evolving genitourinary system. Preservation of renal function is the most important objective of any long-term treatment plan in children with SCI/D-related neurogenic bladder dysfunction. Early assessment of the bladder function in this population and ongoing treatment compliance monitoring appears to play a major role in preventing long-term medical complications. Asymptomatic bacteriuria and recurrent infections are frequent, especially in the instrumented bladder and prophylactic antibiotic usage is not well supported. There is a great need for developing prospective, controlled studies looking at effect of specific interventions on renal function preservation and prevention of bladder pathologic changes.
