Acute encephalopathy with callosal, subcortical and thalamic lesions

Acute encephalopathy is classified into multiple syndromes, such as acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) and acute necrotizing encephalopathy (ANE), characterized radiologically by lesions in the cerebral subcortical white matter, splenium of the corpus callosum and bilateral thalami, respectively. We described a previously healthy 8-year-old boy who had febrile and biphasic seizures, and encephalopathy. MRI showed abnormal signal intensity in the corpus callosum on day 2 and cerebral subcortical white matter and bilateral thalamic lesions on day 8. This is the first case of acute encephalopathy in which callosal, subcortical and thalamic lesions co-existed. The clinical course of this case was typical for AESD, atypical for MERS, and different from that of ANE. Neurology Asia 2015; 20(1) : 85 – 89 Address correspondence to: Yukifumi Monden, Department of Pediatrics, Jichi Medical University, Department of Pediatrics, Jichi Medical University; 3311-1 Yakushiji, Shimotsuke city, Tochigi, Japan. Tel: +81-285-58-7710, Fax: +81-285-44-8329, Email: [email protected] INTRODUCTION Acute encephalopathy is classified into many syndromes, based on clinical and MRI findings. Among these syndromes, acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common in Japan, followed by clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) and acute necrotizing encephalopathy (ANE). Each of these syndromes shows distinct clinical and radiological features (Table 1). However, MRI findings are variable among cases. For example, a severe case of AESD showed cerebral swelling on day 1, which is atypical for AESD. Another case of acute encephalopathy had bilateral thalamic lesions on day 3 and cerebral subcortical white matter lesions on day 10, findings characteristic of ANE and AESD, respectively. Here, we report on a child with AESD whose MRI findings had features overlapping those of MERS and ANE.