Purpose or Case Report: A preterm male infant born at 28+2 weeks from twin pregnancy was admitted to Neonatal Intensive Care Unit post urgent cesarean section for placental abruption. Postnatal echocardiogram confirmed multiple cardiac abnormalities including double outlet right ventricle with D-transposition of great arteries, requiring an arterial switch operation. His hospital course was complicated by seizure with previous documentation of left grade 1 germinal matrix hemorrhage and multifocal thromboembolic stroke on brain MRI. At 2 months of life, he required a chest tube insertion during which he had a cardiac arrest requiring venoarterial extracorporeal membrane oxygenation (ECMO).

Head US at 2 hours post-cannulation showed new bilateral symmetrical linear hyperechoic abnormalities in the periventricular supratentorial regions predominantly in the watershed areas, extending peripherally reaching the cortices. Similar new hyperechoic linear foci were seen in the right thalamus. While the clinical diagnosis at this time included watershed infarcts, the pattern of hyperechogenicity with dirty shadowing suggested air emboli, less likely hemorrhage or calcifications.

Follow-up head US at 5 hours post-cannulation was arranged which showed near-complete resolution of the previously seen bilateral parenchymal hyperechoic abnormalities. Thus, we concluded resolving cerebral intravascular air emboli secondary to recent ECMO cannulation, rather than watershed infarcts. No evidence of new evolving infarct nor intracranial hemorrhage was noted.

The patient unfortunately sustained a fulminant septic shock and end-organ injuries despite maximum medical therapies. His family elected to withdraw all life-sustaining therapies the day after his head US.

Systemic air embolism is a rare but potentially fatal complication of ECMO. Rapid recognition is important for reducing morbidity and mortality. Head ultrasound is usually the first brain imaging study performed in neonates for screening. Bilateral periventricular increased echogenicity can be seen in a wide range of different pathologies, including but not limited to periventricular leukomalacia, infarcts, hemorrhages and neonatal encephalitis. This case report highlights important sonographic features distinguishing intracranial air embolism from other confounding diagnosis.
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