Default mode network hypometabolism in epileptic encephalopathies with CSWS

Area of Science:

• Neuroscience
• Pediatric Neurology
• Medical Imaging

Background:

• Previous studies on cerebral metabolism in continuous spike-waves during sleep (CSWS) used healthy adults as controls, limiting analysis of age-related brain changes.
• This study focuses on the acute phase of CSWS in children, comparing their brain metabolism to age-matched pseudo-controls.

Purpose of the Study:

• To investigate metabolic and connectivity changes in the brain during the acute phase of cryptogenic CSWS in children.
• To compare brain metabolism in children with CSWS to pediatric pseudo-controls, accounting for physiological age-related metabolic variations.

Main Methods:

• [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) was used on 17 awake children with cryptogenic CSWS.
• Voxel-based analyses and pathophysiological interaction methods were employed to assess metabolic changes and functional connectivity.
• Comparison was made with 18 pediatric pseudo-controls with non-CSWS focal cryptogenic epilepsy and normal FDG-PET results.

Main Results:

• CSWS patients exhibited bilateral perisylvian hypermetabolism and hypometabolism in the prefrontal cortex, precuneus, posterior cingulate cortex, and parahippocampal gyri.
• No significant changes in thalamic metabolism were observed.
• Altered functional connectivity was detected between hypermetabolic and hypometabolic regions in CSWS patients.

Conclusions:

• The study reveals hypometabolism in default mode network (DMN) nodes in awake CSWS patients, potentially due to sustained remote inhibition from epileptic foci.
• This hypometabolism may contribute to the cognitive and behavioral deficits seen in CSWS epileptic encephalopathies.
• The absence of thalamic metabolic changes supports a primary cortical involvement in the genesis of CSWS.