Predictors of urinary continence following tethered cord release in children with occult spinal dysraphism

Abstract

ObjectiveChildren with occult spinal dysraphism represent a wide spectrum of patients. Previous studies assessing urologic outcomes have in part been deficient due to the inability to appropriately categorize these patients and gather long-term follow-up data. In this study, a uniform set of patients that had occult spinal dysraphism with magnetic resonance imaging findings of a fatty filum terminale (FF) and/or low-lying cord (LLC) was identified. Utilizing long-term follow-up data, predictors for achieving urinary continence following tethered cord release (TCR) were determined. MethodsA retrospective chart review of pediatric patients with a diagnosis of tethered cord who underwent TCR from 1995 to 2005 was performed. Analysis was limited to patients who had primary TCR by one of two neurosurgeons within our multidisciplinary spina bifida clinic, who had greater than 1-year follow-up, and who were old enough to have continence status assessed (age > 6 years unless definitively toilet trained earlier). Patients with other associated forms of spinal dysraphism (lipomyelomeningeocele, spinal lipomas, sacral agenesis), anorectal malformations, and genitourinary anomalies were excluded. Pre- and post-TCR urodynamics, radiographic studies, functional orthopedic status, and urologic outcomes were assessed. Urodynamic results were categorized by three blinded urologists into one of three urodynamic patterns: (1) normal, (2) indeterminate, and (3) high risk. ResultsA total of 147 patients with FF and/or LLC that underwent TCR were reviewed. 51 patients were excluded because of another associated spinal dysraphism (15/51 patients) or an anorectal/genitourinary anomaly (36/51 patients). Fifty-nine of the remaining 96 patients had adequate long-term follow-up data to be included in the study. 20 patients were asymptomatic at the time of TCR while 39 presented with orthopedic and/or urologic symptoms. The average age at surgery was 59.3 months (range 2–277 months) with an average follow-up of 7.0 years (range 1–16 years). At latest follow-up, 47 (80%) patients were continent while 12 (20%) were either incontinent or utilizing clean intermittent catheterization (CIC). Statistical analysis revealed that age of untethering, type of cutaneous lesion, level of conus, presence of hydronephrosis, and high-grade vesicoureteral reflux (VUR) were not independent predictors of continence. In patients with a cutaneous lesion who were asymptomatic, 19/20 obtained continence post-TCR (*p = 0.036). In patients who were old enough to assess continence pre-TCR, 14/25 patients were continent pre-TCR and 11/25 were incontinent. Of the 14 who were continent pre-TCR, all remained continent post-TCR (*p = 0.002). Of the 11 who were incontinent pre-TCR, five (45%) eventually became continent post-TCR. Assessment of urodynamic data revealed that neither pre- nor post-TCR urodynamics predicted continence status. ConclusionIsolated cutaneous lesions and preoperative continence status are positive predictors for post-TCR continence. While pre- and post-TCR urodynamics do not predict continence status, their utility in preoperative work-up, monitoring for retethering, and long-term urologic follow-up requires further examination.