Acute encephalopathy with biphasic seizures and late restricted diffusion on MRI in a Japanese child living in the USA

Abstract

We report an 18‐month‐old Japanese female living in the USA whose clinical course and radiographic findings were consistent with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). She was initially diagnosed with complex febrile seizures. However, on day 3 of admission, she had a cluster of complex partial seizures and the onset of a global developmental regression. In contrast to the normal magnetic resonance image of the brain obtained on admission, subsequent imaging demonstrated transient subcortical diffusion‐weighted abnormalities in the white matter of the bilateral posterosuperior frontal, parietal, temporal, and occipital regions, with sparing of the perirolandic area. One year later, her developmental delay, although improved, persisted and she continued to experience sporadic seizures while being treated with topiramate monotherapy. Repeat imaging showed diffuse, poorly defined, increased T2 signals in the white matter of the posterosuperior frontal, parietal, temporal and occipital regions and diffuse cerebral volume loss. Previous reports of AESD have been limited to children aged under 4 years living in Japan. With the identification of this case, it is important that all physicians, not only those in Japan, who care for children with febrile seizures be aware of AESD and its associated neurological morbidity.

Analysis of Multiple B-Value Diffusion-Weighted Imaging in Pediatric Acute Encephalopathy

“…The exact mechanisms underlying the link between the diffusion parameters above (D s , D f , and f s ) and tissue microstructure remain largely unknown; however, one of the most accepted assumptions is that D s and D f provide intracellular and extracellular ADCs respectively, and thus f s indicates the fraction of intracellular volume [19]. Non-inflammatory brain edema and decrease in the size of extracellular space owing to cell (especially astrocyte) swelling have been pointed out in acute encephalopathy [29], [30], which may in this respect increase f s .…”

Deaths Associated with Pandemic (H1N1) 2009 among Children, Japan, 2009–2010

“…Children with acute encephalopathy or encephalitis associated with pandemic (H1N1) 2009 have been reported outside Japan ( 20 – 23 ), but most survived with no or mild neurologic sequelae. Most children with acute encephalopathy, such as acute necrotizing encephalopathy ( 25 ) and acute encephalopathy with biphasic seizures and late reduced diffusion ( 26 ), were of Japanese or east Asian descent. Children in Japan are presumed to have an underlying genetic predisposition for development of acute encephalopathy ( 26 ).…”

“…Most children with acute encephalopathy, such as acute necrotizing encephalopathy ( 25 ) and acute encephalopathy with biphasic seizures and late reduced diffusion ( 26 ), were of Japanese or east Asian descent. Children in Japan are presumed to have an underlying genetic predisposition for development of acute encephalopathy ( 26 ). The median age of children who died of encephalopathy (62 months) was older than that of patients with encephalopathy associated with seasonal influenza (median 2–3 years) ( 19 , 27 ).…”

Differences of Clinical Manifestations According to the Patterns of Brain Lesions in Acute Encephalopathy with Reduced Diffusion in the Bilateral Hemispheres

“…4 It is interesting that all reported cases of children with AESD have been of in those of East Asian descent. 5 At present, the precise clinical characteristics of AESD are not fully understood. For example, it is uncertain whether a biphasic clinical course is always observed in children with AESD.…”