Abstracts

Rationale: “Epileptic encephalopathies” (EEs) are a group of epilepsies in which the epileptic activity contributes to poor outcomes in terms of seizure control and cognitive and behavioral impairment1,2. Despite the importance, little is known about its pathophysiological mechanisms, in particular the pathological changes in structural neuronal networks. The aim of this study is to evaluate the presence and distribution of gray (GM) and white matter (WM) atrophy in children with EE. Methods: We included 21 consecutive pediatric patients with diagnosis of EE, according to ILAE criteria, followed at the Child Neurology epilepsy service of UNICAMP and 36 age and sex-matched controls. Cerebral T1-weithed volumetric images of patients and controls were acquired in a 3 Tesla MRI. Voxel based morphometry (VBM) was used to evaluate GM and WM volume with CAT12/SPM12 software (Statistical Parametric Mapping - Welcome Department of Cognitive Neurology). (Two-sample T-test, covariated for age and sex, p < 0.001, minimum of 100 contiguous voxels). Results: There was no difference of age or sex distribution between patients and controls (patients: mean age 12.8 years (range 5.5-17.9), 28% women; controls: mean age 13.4 (range 7.9-17.9), 36% women). Mean age of seizure onset was 35 months (range 2-132). According to the electro-clinical data, 12 patients (57%) had borderline syndromes, 3 (14%) myoclonic astatic epilepsy, 2 (10%) Lennox-Gastaut syndrome, 2 (10%) genetic epilepsy with febrile seizures plus, 1 (5%) Dravet syndrome and 1 (5%) EE with continuous spike-and-wave during sleep. Patients presented a diffuse network of GM and WM atrophy, including mainly areas in bilateral cerebellum, thalamus, caudate and putamen, bilateral insula, left cingulate gyrus, and bilateral associative areas of frontal and parietal lobes.  WM atrophy had a discrete predominance in the left hemisphere. Patients with EE did not present any areas of increased GM or WM volume. Conclusions: Our results show areas of GM and WM atrophy localized in the both hemispheres of patients with EE, including mainly subcortical regions and associative areas, with a discrete predominance of WM damage in the left hemisphere. The causes of these possible structural changes in children with epileptic encephalopathy remain unknown. Most importantly, it is possible that these networks of GM and WM abnormalities might contribute to the cognitive and behavior impairment of these children.References: [1] Fisher RS, Acevedo C, Arzimanoglou A, et al. A practical clinical definition of epilepsy. Epilepsia 2014; 55(4), 475-482; [2] Capovilla G, Wolf P, Beccaria F, Avanzini G. Epileptic encephalopathies: The history of the concept of epileptic encephalopaty. Epilepsia 2013; 54(S 8): 2–5. Funding: CAPES - Coordination for the Improvement of Higher Education Personnel