4. Categorization of Acute Encephalopathy, and MR Imaging Findings

Jun-ichi Takanashi, Hiroko Tada¹⁾
Department of Pediatrics, Kameda Medical Center, Segawa Neurological Clinic for Children¹⁾

Abstract
　　Acute encephalopathy, including influenza-associated encephalopathy, is divided into at least six types : Reye syndrome, acute necrotizing encephalopathy（ANE）; hemorrhagic shock and encephalopathy syndrome ; clinically mild encephalitis/encephalopathy with a reversible splenial lesion（MERS）; encephalopathy with acute brain swelling ; and a recently reported acute encephalopathy syndrome characterized by biphasic seizures and late reduced diffusion（AESD）. ANE and AESD are the most common forms of encephalopathy in Japanese infants. MRI is accepted as a more sensitive technique than CT for the diagnosis of encephalitis/encephalopathy ; diffusion weighted images are particularly useful for detecting early changes in the brain. In this issue, we review the clinical and radiological features in patients with ANE, AESD, and MERS.

Keywords： Acute encephalopathy, Acute necrotizing encephalopathy (ANE), Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), Clinically mild encephalitis / encephalopathy with a reversible splenial lesion (MERS)