Rationale:
Electrical Status Epilepticus in Sleep (ESES) is a syndrome characterized by marked activation of epileptiform discharges in sleep associated with neurocognitive regression. The spike-wave index (SWI) in non-rapid eye movement (NREM) sleep is widely used to diagnose ESES. The exact cut-off for the SWI varies in the literature from >25% to >85%. The role of awake and sleep electroencephalography (EEG) features in the diagnosis of ESES is not fully studied. Our study sought to determine awake and sleep EEG features as markers of neurocognitive impairment in children with ESES.
Methods:
Twenty-three patients with ESES ranging in age from four to sixteen years (mean age 11.2 years) underwent a comprehensive neuropsychological evaluation within six months of EEG monitoring. Neuropsychological functioning was measured across IQ, verbal memory, language (i.e.g,fluency, expressive vocabulary, rapid naming), fine motor, and psychosocial functioning with age-appropriate standardized measures. EEG was reviewed for background, focal slowing, sleep features, and SWI. Correlations and t-tests were conducted to determine the associations among EEG variables and how they are related to neuropsychological functioning.
Results:
Among those with and without an abnormal background or focal slowing, there were no differences in spindle duration, spindle frequency in hertz (SHz), frequency of spindles/30 minutes (SF), or SWI. Abnormal spindle was significantly higher for spindle duration, SF, and SWI. Among linear EEG variables, spindle duration correlated with FHz (r = .527, p=.01).
Youth with ESES who had an abnormal background and abnormal spindles had significantly worse IQ and verbal fluency. Each was also associated with worse performance on other skills including expressive vocabulary and fine motor (abnormal background), and processing speed, language, memory, and parent ratings of executive functioning (abnormal spindles). Presence of focal slowing was not associated with any neuropsychological performance differences. SF directly correlated with IQ, working memory, processing speed, language, and memory. Spindle duration, SHz, and SWI did not correlate with neuropsychological functioning.
Conclusions:
EEG awake and sleep features were explored to determine their relationship to traditional SWI metrics and neuropsychological functioning in ESES. Given the strong and specific correlations of abnormal background, abnormal spindles, and SF with neuropsychological functioning, these metrics may be more sensitive markers of ESES than SWI.
Funding: None