Perivascular abnormalities in pediatric encephalopathy with fulminant brain edema

Acute encephalopathy with acute brain swelling (ABS) is a recently proposed disease of unknown etiology, characterized by rapid progression to whole-brain swelling. To our knowledge, we reported the first case of a patient with acute encephalopathy with ABS wherein brain magnetic resonance imaging (MRI) abnormalities were noted prior to the diffuse brain swelling onset.

An 11-year-old boy was admitted to our unit owing to prolonged disturbance of consciousness following febrile status epilepticus. At the initial visit, the vital signs were within the normal range, except for the body temperature and consciousness level (Glasgow Coma Scale 6; E1V1M4). The initial laboratory results showed elevated inflammatory marker levels and mild hyponatremia. Cerebrospinal fluid analysis revealed albuminocytologic dissociation, whereas the myelin basic protein level was not elevated. Electroencephalography showed diffuse, high-amplitude slow waves. No abnormalities were detected on the initial brain computed tomography (CT) scan. However, at 11 h after the seizure onset, diffuse hyperintense lesions were observed throughout the cerebrum on T2-weighted brain MRI. The patient was diagnosed with acute encephalopathy and received methylprednisolone-pulse therapy (1 g) with high-dose gamma globulin (1 g/kg) administration. At 14 h after the seizure onset, the patient was declared brain-dead; the brain CT findings revealed whole-brain swelling and herniation.

Our findings were suggestive of a perivascular pathophysiology and may be used for subtyping acute encephalopathy. In cases where such findings are observed, subsequent development of severe diffuse brain swelling should be considered.