Detailed characteristics of acute encephalopathy with biphasic seizures and late reduced diffusion: 18-year data of a single-center consecutive cohort

Abstract

Objective: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a syndrome characterized by biphasic seizures with impaired consciousness. AESD is rare outside Asia, and consecutive cohort studies are therefore scarce. Herein, we aimed to describe the detailed characteristics of AESD, including clinical course, electroencephalogram data, laboratory data, imaging findings, treatment, and outcomes. Methods:We reviewed the clinical database and medical charts of 43 consecutive pediatric patients (<18 years old) who developed AESD between October 1, 2002, and September 30, 2019. Results: We found that AESD occurred even though patients did not develop prolonged seizures. A comparison between the two groups (first seizure duration <30 min and first seizure duration ≥30 min) revealed three main findings: first, patients with AESD who had shorter seizures had better prognosis than those with prolonged seizures; second, patients with AESD who had shorter seizures tended to have earlier occurrence of a second seizure; and third, high signal intensity on diffusion-weighted magnetic resonance imaging was observed mainly in frontal areas, not diffusely, in patients with shorter seizures, and in a broader area in patients with prolonged seizures. Conclusions: Our description of the detailed clinical picture of AESD may add new insight into its pathophysiology.

Pediatric Encephalopathy and Complex Febrile Seizures

“…Patients usually survive the acute episode, but neurological sequelae can be serious. 3,5,8 The early clinical differentiation of AESD and FSE with a prolonged waking time can be challenging.…”

“…While the mortality rate for AESD is reported to be low in Japan (<5%), a wide spectrum of adverse neurodevelopmental outcomes have been described. 3,5,8 In all, 28% to 45% of patients have a good recovery, 40% to 50% experience mild deficits, and 5% to 45% severe sequelae. 3,5,8 Poor outcomes include motor and/or cognitive impairment as well as refractory epilepsy.…”

“…3,5,8 In all, 28% to 45% of patients have a good recovery, 40% to 50% experience mild deficits, and 5% to 45% severe sequelae. 3,5,8 Poor outcomes include motor and/or cognitive impairment as well as refractory epilepsy. PEE has been reported to occur 2 to 39 months after AESD and often involves multiple seizure types which are difficult to control.…”

“… 3 , 4 The median age of presentation is 15 to 19 months of age, with a female predominance and generally low mortality but high morbidity rate. 3 , 5 While there are rare case reports internationally, there is only a single case reported in the United States 6 and no cases reported in Canada. It remains unclear whether the disorder is underrecognized or truly uncommon in North America, but these cases suggest that AESD can occur outside Japan and in children of various ethnicities.…”

Predicting the Onset of Acute Encephalopathy With Biphasic Seizures and Late Reduced Diffusion by Using Early Laboratory Data

“…Some patients with FS experience prolonged seizures and impaired consciousness for several hours. However, some patients with AESD develop early seizures shorter than 30 min (median: 4 min; approximately 20% of patients) ( 6 ) or completely recover their consciousness after early seizures (~20% of patients) ( 7 ).…”