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Risk Factors and Presentation of Symptomatic Retethering in Occult Spinal Dysraphism
Brendan T. Frainey, BS, Elizabeth B. Yerkes, MD, Vani S. Menon, MD, Edward M. Gong, MD, Theresa A. Meyer, MS, RN, CPN, Robin M. Bowman, MD, David G. McLone, MD, PhD, Earl Y. Cheng, MD. Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.
BACKGROUND: Occult spinal dysraphism occurs along a spectrum of radiographic and functional severity. Practice patterns vary nationally in terms of indications for tethered cord release (TCR) in children with fatty filum (FF) and/or low lying conus medullaris (LLC). Part of the counseling process includes projected risk of deterioration with retethering years after the initial TCR. We review outcomes and incidence of retethering in children undergoing TCR for FF/LLC at our institution.
METHODS: All children undergoing TCR for FF/LLC at our institution between 1995 and 2005 were identified and all outpatient data, radiographic and urodynamic studies, and surgical records were retrospectively reviewed. The study cohort included only children who had primary TCR and longitudinal care through our Spina Bifida multidisciplinary clinic. Those with concomitant spinal cord anomalies were excluded. At least one year of post-TCR follow-up was required. Three subgroups (asymptomatic, symptomatic and VATER) were compared for incidence of retethering. The study was IRB-approved. Subgroup analysis based upon numerous clinical parameters was performed.
RESULTS: 147 children were identified as the team cohort. After exclusion criteria were applied, 98 children had primary TCR (41 FF, 4 LLC, 53 FF/LLC) and the required follow-up. Of the “asymptomatic” group presenting only with a skin lesion, 0 of 26 (0%) had retethering during mean follow-up of 6.7 (1.3-15.2) years. Of the “symptomatic” group with initial presentation of incontinence, UTI or orthopedic symptoms, 2 of 41 (4.9%) had re-tethering during mean follow-up of 6.4 (1.1-16.3) years. Of the “VATER” group, with or without anorectal malformation, 1 of 31 (3.23%) had retethering during mean follow-up of 7.9 (1.6-17.2) years. The overall incidence of retethering was 3.1% over follow-up of mean 6.9 (1.3-17.2) years. No statistically significant features or contributing factors were found on subgroup analysis. Of those who retethered, 2 had a FF/LLC and 1 had a FF only. Symptoms of retethering included failure to toilet train (n=1), new onset incontinence (n=2) and orthopedic change (n=2). Both of the patients with urodynamic data available for review had changes from baseline consistent with their symptoms and with retethering. Repeat TCR occurred at mean 5.4 years (range 5.1-6). No patient had more than 2 TCR. After TCR, the two patients from the symptomatic group remained incontinent and the child from the VATER group became dry.
CONCLUSIONS: In our experience the risk of retethering after TCR for FF/LLC, regardless of initial presentation, is less than 5%. No children who presented with only a cutaneous lesion and FF/LLC had symptomatic re-tethering. Symptoms and recovery varied in this small group of retethered children. Signs and symptoms of retethering should be discussed with patient and family at each team visit to allow prompt evaluation and management.
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