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BACKGROUND: Children 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 MRI findings of a fatty filum terminale (FF) and/or low lying cord (LLC) was identified. Utilizing long-term follow-up data, positive and negative predictors for achieving urinary continence following tethered cord release (TCR) were determined.

METHODS: A retrospective chart review of pediatric patients with a diagnosis of tethered cord who underwent TCR from 1995-2005 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 one year follow-up, and who were old enough to have continence status assessed (age > 6 years). Patients with other associated forms of spinal dysraphism (lipomeningeocele, 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. In the evaluation of urodynamic studies, results were categorized by 3 blinded urologists into one of 6 different urodynamic patterns including normal, high pressure voiding, detrusor over-activity, detrusor under-activity, hypocontractile with abnormal compliance, and neurogenic (poor compliance, detrusor sphincter dyssynergia and/or increased leak point pressure).

RESULTS: 147 patients with FF and/or LLC that underwent TCR were reviewed. 51 patients were excluded because of other associated spinal dysraphism (15/51 patients) and anorectal malformations or genitourinary anomalies (36/51 patients). 59 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 CIC. Statistical analysis revealed that age of untethering, type of cutaneous lesion, level of conus, presence of hydronephrosis, and high grade VUR were not independent predictors of continence. In patients with a cutaneous lesion that were asymptomatic, 15/15 remained continent post TCR (p<.05). In patients that were old enough to assess continence pre TCR, 14/25 patients were continent pre TCR and 11/25 were incontinent. Of the 14 that were continent pre TCR, all remained continent post TCR (p<.05). Of the 11 that were incontinent pre TCR, 5 (45%) eventually became continent post TCR. Assessment of urodynamic data revealed that neither pre nor post TCR urodynamics predicted continence status.

CONCLUSIONS: Isolated 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 need for further urologic follow-up requires further examination.