Using rapid-sequence MRI scans to compare ventricular and intracranial volumes in shunted and non-shunted children with myelomeningocele: a retrospective observational cohort study

PURPOSE: Hydrocephalus is a common complication of myelomeningocele (MMC), typically managed with a ventriculoperitoneal shunt (VPS). Despite clinical relevance, there remains a paucity of studies quantitatively comparing intracranial and ventricular volumes in shunted versus non-shunted MMC patients. This study aims to determine whether significant volumetric differences exist between these groups. METHODS: Ninety-one MRIs from 19 MMC patients (13 shunted, 6 non-shunted), aged 0-3 years, were retrospectively analyzed. Volumes were obtained from rapid-sequence MRIs using automatic segmentation with manual correction. Outcomes included ventricular volume, intracranial volume, and ventricle-to-intracranial volume (ventricle/ICV) ratio. Analyses included nonparametric tests, mixed-effects models, bootstrap resampling, permutation testing, and robust regression. RESULTS: At baseline, shunted patients exhibited larger intracranial volumes (644.3 vs 403.5 mL; p = 0.020) but not ventricular volumes (82.2 vs 34.2 mL; p = 0.072) compared to non-shunted patients. Although the ventricle-to-intracranial volume ratio was significantly higher in shunted patients under 50 days of age (p = 0.026), this difference was no longer significant after adjusting for head circumference and prematurity (p = 0.144). Sensitivity analyses confirmed differences in the neonatal period (p = 0.013), but not in infancy or toddlerhood. Effect-size analyses demonstrated a large difference within 50 days (Hedges' g = 1.268) that diminished thereafter (g = 0.452). CONCLUSION: Shunted MMC patients demonstrated larger intracranial volumes and higher ventricle/ICV ratios in the neonatal period, but these differences diminished after 50 days. Early ventricular enlargement in this cohort's shunted patients appears robust yet transient, with no sustained volumetric differences between shunted and non-shunted patients later in development.