Utility and Interrater Reliability of Video Urodynamics in Patients with an Isolated Fibrolipoma of Filum Terminale
Shane Forest Batie, MD, Caitlin T. Coco, MD, Bruno P. Braga, MD, Yvonne Chan, MD, Irina Stanasel, MD, Micah A. Jacobs, MD, Craig A. Peters, MD, Linda A. Baker, MD, Bruce J. Schlomer, MD.
University of Texas Southwestern, Dallas, TX, USA.
Background: Pediatric patients with an isolated fibrolipoma of filum terminale (IFFT) but otherwise normal spinal cord are often referred for bladder evaluation with video urodynamics (VUDS). VUDS interpretation is subjective and can be difficult, especially in young children. These patients may undergo a detethering surgery if there is concern for symptomatic tethered cord or risk of developing this. We hypothesized that VUDS in children with IFFT would have limited clinical utility and poor interrater reliability.
Methods: Patients seen in our clinic with IFFT who underwent VUDS for from 2009-2021 were retrospectively reviewed for demographics, clinical characteristics , and whether VUDS impacted the decision for or against detethering. 6 pediatric urologists who were blinded to patient clinical characteristics except age, gender, estimated bladder capacity, and presence of IFFT reviewed the VUDS. Reviewers were asked about capacity, compliance, EMG activity, leakage, voiding, and appearance of fluoroscopic images. They classified each study as normal, reassuring for normal, concerning for abnormal, or abnormal. Fisher's exact test was used to compare groups. Gwet's first order agreement coefficient (AC1) with 95% CI was used to assess interrater reliability.
Results: 48 patients (25F:23M) were identified. Median age at initial evaluation was 2.8yrs (IQR:1.5-6.8). 24 (50%) patients underwent a detethering surgery. 16 (33%) were toilet trained at initial evaluation, 13 (27%) were toilet trained during follow-up. Of those not toilet trained at last follow-up, 14 (29%) were younger than 3 years of age, and 5 (10%) over age 3. There was no difference in toilet training between those undergoing detethering or not (p=0.7). VUDS at initial evaluation were interpreted by the treating urologist as normal in 4 (8%), reassuring for normal in 39 (81%), or concerning for abnormal in 5 (10%). Based on neurosurgery clinic and operative notes, VUDS made no apparent change in management in 38 patients (79%), prompted detethering in 3 (6%), and avoided detethering in 7 (15%) patients. Interrater reliability for VUDS interpretation ranged from fair to very good depending on the question (Table 1). Fair agreement (AC1=0.27) was seen for overall categorizing of urodynamic findings.
Conclusion: VUDS affected the decision for or against detethering surgery in about 20% of our cohort. Toilet training outcomes were similar between those who did and did not have detethering. Interpretation of VUDS had fair interrater reliability for assigning normal versus abnormal bladder function. VUDS interpretation has limitations in determining normal versus abnormal bladder function in children with IFFT; this should be understood by parents and physicians.
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