Neocortical and Mesial Temporal Sleep Spindles Are Reduced in Children with Focal Epilepsy and Developmental Delay

Background/Purpose: Drug-resistant focal epilepsy in children is often accompanied by developmental delay. Recent analyses of intracranial EEG have highlighted the importance of local components of sleep in mesial temporal structures and the neocortex for permanent acquisition of new skills and knowledge. It is, however, poorly understood how epileptic activity interferes with normal psychomotor development. We hypothesized that sleep spindles in the neocortex and in mesial temporal structures are reduced in children with focal epilepsy and developmental delay.

Methods: Intracranial EEG, recorded with depth electrodes or subdural grid electrodes, was retrospectively analyzed in consecutive patients with drug-resistant focal epilepsy. Children with severe developmental delay (group 1) were compared with subjects with mild or no developmental delay (group 2). A representative 30-minute interval of NREM sleep was selected for analysis. Sleep spindles were visually identified in a referential montage. Post-implantation MRI was reviewed to identify contacts located in the neocortex and in mesial temporal regions.

Results: A total of 16 patients (age 2–12 years) were included and intracranial EEG from 740 electrode contacts was analyzed. The median rate of sleep spindles was lower in children with epilepsy and severe developmental delay (group 1, n = 8 patients) than in patients with mild or no developmental delay (group 2, n = 8 patients; p < 0.05). A reduction of spindles was found both for the neocortex (p < 0.05) and for mesial temporal structures (p < 0.05), and both inside the seizure onset zone (SOZ; p < 0.05) and in non-SOZ contacts (p < 0.05).

Conclusion: In children with drug-resistant focal epilepsy, developmental delay was associated with a reduction of neocortical and mesial temporal sleep spindles. This suggests that disruption of local sleep in both regions might contribute to developmental delay. Future analyses of intracranial sleep microstructure could provide further insights into the underlying mechanisms.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
13 November 2023