SUSPECTED ACUTE ENCEPHALOPATHY WITH SYMMETRICAL ABNORMAL SIGNAL AREASIN THE BASAL GANGLIA, THALAMUS, MIDBRAIN AND PENS DIAGNOSED BY MAGNETIC-RESONANCE-IMAGING

A 4-year-old boy was admitted with disturbed consciousness following a convulsion. He developed bilateral pyramidal tract signs and showed a decerebrate posture, Laboratory findings revealed severe liver dysfun ction and disseminated intravascular coagulation. On the eighth day ei ght in hospital he developed parkinsonism. However, 5 months from onse t he had recovered almost completely. Brain CT on admission showed low density areas in the basal ganglia, thalamus, midbrain and pens. A T2 -weighted scan in magnetic resonance imaging (MRI) showed almost symme trical high signal intensities in both basal ganglia (including putame n, caudate nucleus, globus pallidus), external capsule, internal capsu le, thalamus, midbrain, pens and white matter of the peribasal ganglia ; but a T1-weighted scan showed low signal intensities in the same reg ions during all phases. Therefore hemorrhagic lesions or the presence of thalamic methemoglobin were excluded. It was considered that the pa thogenesis may be cytotoxic cellular edema due to cytotoxic agents or acute metabolic factors. Clinical presentation, laboratory findings an d radiological findings were most suggestive of acute necrotizing ence phalopathy. As differential diagnoses, acute disseminated encephalomye litis and brainstem encephalitis were considered.