Spina bifida occulta: is it a predictor of underlying spinal cord abnormality in patients with lower urinary tract dysfunction?

OBJECT The purpose of this study was to evaluate the importance of spina bifida occulta in radiographs of children with lower urinary tract or bowel dysfunction. METHODS The authors prospectively investigated the presence of spinal cord abnormalities in 176 patients with functional urinary and bowel problems: 88 children with radiographic evidence of spina bifida occulta (SBO) and 88 age-and sex-matched controls. Each group included 46 boys and 42 girls (age range 5-14 years). Nocturnal enuresis, isolated diurnal enuresis, enuresis during both day and night, urinary tract infection, urinary frequency, encopresis, intractable constipation, and vesicoureteral reflux were assessed in all patients. Magnetic resonance (MR) images were obtained in all patients and evaluated for spinal cord abnormalities. Sacral ratios (SRs) were calculated on the basis of plain radiographs. RESULTS There was no statistically significant difference between the 2 groups on any of the clinical measures. The most common sites of SBO on radiographs were the S-1 (47%) and L-5 and S-1 (25%). The mean SRs (+/-standard deviations) in the SBO and control groups, respectively, were 0.64+/-0.45 and 0.68+/-0.51 (no statistically significant difference). Sacral agenesis was found in 17 children (7 in the SBO group and 10 in the control group, p=0.44). Abnormal MR imaging findings were observed in 9 children (10.22%) in the SBO group and 3 (3.4%) in the control group. Abnormalities included tethered spinal cord in 5 children, syringomyelia in 4, and club-shaped conus in 2. No significant association was found between the presence of SBO and spinal cord abnormalities identified on MR images (p=0.13, paired t-test). CONCLUSIONS Among children with functional bowel and urinary problems, there was no statistically significant difference in the prevalence of abnormal spinal MR imaging findings in those with radiographic SBO and an age- and sex-matched control group. Spina bifida occulta was not shown to be a reliable indicator of spinal cord structural abnormalities. Its probable role as a finding associated with spinal cord dysfunction remains unclear.