Venous-significant intracranial hemorrhage in neonatal HIE treated with therapeutic hypothermia: imaging phenotypes, diagnostic pitfalls, and prognostic implications.

In the therapeutic hypothermia era, intracranial hemorrhage is increasingly detected in term and near-term neonates with hypoxic-ischemic encephalopathy (HIE), yet its clinical significance remains heterogeneous and is often oversimplified. This review uses a pattern-based approach for venous system-related intracranial hemorrhage in neonatal HIE, with particular emphasis on cerebral sinovenous thrombosis (CSVT) and hemorrhagic venous infarction. Magnetic resonance imaging plays a central role in etiologic assessment, with diffusion-weighted imaging and susceptibility-weighted imaging providing the core parenchymal and hemorrhagic information, while MR venography is most informative when imaging features raise suspicion for venous involvement. Imaging phenotypes that should prompt venous reconsideration include hemorrhagic parenchymal lesions crossing arterial territories and intraventricular hemorrhage accompanied by unilateral thalamic or deep parenchymal hemorrhage. Common pitfalls in neonatal MR venography interpretation-particularly flow-related artifacts-are also highlighted, emphasizing the importance of parenchymal-venographic concordance in avoiding both over- and underdiagnosis of CSVT. Mechanistically, hypoxia-reperfusion injury, endothelial activation, venous stasis, and developmental hemostatic vulnerability may create a milieu in which thrombosis and hemorrhage coexist. Available evidence suggests that long-term outcomes are driven more by associated venous-related parenchymal injury than by small-volume hemorrhage alone, underscoring the importance of pattern-guided imaging interpretation and follow-up.