Context
Absence seizures (AS) are generalized non-motor seizures met in various epilepsy syndromes, the
most frequent being childhood absence epilepsy (CAE). Clinically, absence seizures (AS) are
characterized by brief episodes of impaired consciousness, loss of awareness, and stereotyped
movements, with episodes lasting about 10 seconds and occurring frequently throughout the day.
Although the prognosis for CAE is generally favorable, recent research indicates that these seizures
are not benign: deficits in executive functions, attention, and memory are common, and there is an
increased risk for comorbidities such as ADHD and anxiety disorders. Consciousness impairment is a
key feature of AS and disturbances in cortical-subcortical networks, like the Default Mode Network
(DMN), the frontal cortex, and the thalamus are believed to be the root of such impairment. This
study aims to further explore the electrophysiological differences associated with varying levels of
consciousness impairment in children with CAE.
Methods
Using the software Brainstorm, we extracted 23 epochs from as many absences recorded from 11
patients. With Brainstorm, we then performed EEG power spectra analyses of the 23 epochs. The
comparison between the two patient cohorts' EEG power - with and without word recollection - was
carried out using non-parametric statistical methods. Using the software RStudio, we ran a Fisher’s
test on epochs grouped by our two main variables: word input moment during AS and word
recollection, to verify whether variables are significantly associated or not.
Results
From power spectral analysis, we found that the “without word recollection” group has a mainly pre-
central concentration of high EEG power at word presentation. The “with word recollection” group
shows the opposite, i.e. a focus of high EEG power in the post-central region at word presentation.
The non-parametrical statistic test performed on the 23 EEG epochs belonging to our two cohorts
(word recollection = 9; no word recollection = 14) showed no significant difference (p-value > 0.05) in
power at frequencies of interest (3-4 Hz). Fisher’s exact test showed that there is not a significant
association (OR 1.11; 95% CI 0.14-9.94; p-value = 1) between our two variables.
Conclusion
We found that absence seizures with impaired consciousness show greater EEG power with a frontal
predominance, but no statistically significant difference in EEG power between spared and impaired
consciousness.