Deep medullary vein thrombosis (DMVT) is an increasingly recognized etiology of neonatal brain injury, but remains poorly understood. Our study aimed to assess the association between MRI severity and neurodevelopmental impairment (NDI) in neonates with DMVT, and develop a novel MRI grading system that might inform clinical outcomes. We retrospectively reviewed relevant charts from infants admitted to our tertiary care hospital between January 1990 to March 2023, and evaluated clinical characteristics, MRI features, and neurodevelopmental assessments of this cohort. We developed and validated a simple MRI grading system based on injury severity, categorizing lesions into mild, moderate, or severe groups. Of the 63 neonates with a diagnosis of DMVT, 41 had moderate or severe MRI lesions
those patients were 24-fold more likely to experience NDI compared to those with mild injury (adjusted OR 24.3, 95% CI 4.7-180.2, p<
0.001). Of the 52 infants with follow-up data, 40.4% developed NDI
MRI severity was the strongest predictor of impaired outcomes, independent of clinical factors including gestational age, Apgar score and seizures at presentation. Our findings suggest that this pragmatic MRI grading scheme may offer clinicians and researchers a valuable classification and prognostication tool.