Abstract Body: Introduction: Neonatal deep medullary vein (DMVT) is an increasingly recognized etiology of brain injury in term and preterm infants. However, long-term outcomes remain poorly described, and the prognostic significance of the radiographic findings is uncertain.

Methods: We extracted demographics and clinical variables for all infants with DMVT at our institution from 2007 to 2023. MRIs were scored as mild if there was isolated DMVT with no or only punctate parenchymal injury; moderate if there was DMVT with focal, unilateral ischemic or hemorrhagic injury, and severe if there was bilateral, confluent ischemic or hemorrhagic injury. The primary outcome was the presence of moderate-to-severe neurodevelopmental impairment (NDI), defined as a composite of any of the following at 2 years of age a) score < 70 on Bayley II/III/IV cognitive/language; cerebral palsy with GMFCS > 1; or profound vision or hearing impairment. We preformed univariate and multivariate logistic regression to evaluate whether moderate-to-severe initial imaging was associated with the likelihood of developing NDI.

Results: 64 infants had DMVT, of whom 30/64 (47%) were preterm. The median age of presentation was 2.5 days (1-8), and presenting symptoms included seizures (29/64, 45%), encephalopathy (24/64, 38%), respiratory distress (21/64, 33%), and abnormal tone (15/64, 23%). Neonatal comorbidities included congenital cardiac disease (14/64, 22%) and infection (12/64, 19%), but concurrent cerebral venous sinus (3/64, 5%) or systemic (5/64, 8%) thromboses were rare. Most infants had moderate (21/64, 33%) or severe (20/64, 31%) injury on initial MRI. Of 27 infants with follow up imaging at a median of 5.5 (4-19) days after the initial scan, only 3 had radiographic worsening. Most (54/64, 85%) survived to discharge. In the univariate analysis, the odds of NDI were 7-fold higher for moderate/severe MRI patients (OR: 8.182, 95% CI: 2.018 - 55.647, p=0.0092). Patients with moderate or severe initial MRI had 5-fold higher odds of developing NDI compared to those with mild MRI, after adjusting for confounding factors (OR: 6.356, 95% CI: 1.423 - 45.358, p=0.0283).

Conclusions: While mortality after symptomatic DMVT is low, nearly half of survivors will develop moderate to severe neurodevelopmental impairment by 2 years of age. Moderate-to-severe injury on initial MRI is associated with a 5-fold higher odds of developing moderate to severe neurodevelopmental impairment at 2 years of age.