This study was an observational cross-sectional case-control study performed on 19 consecutive patients with typical CAE on valproate therapy, 11 newly diagnosed CAE patients not receiving AEDs, and 30 healthy control subjects (HCS) matching patients’ age, sex, and educational level. Patients and HCS were selected from the epilepsy clinic in the Neurology and Psychiatry Center, Tanta University Hospitals, from the period 1 April 2017 to 31 March 2019. Typical CAE was diagnosed according to the revised criteria of the International League Against Epilepsy (ILAE) 2017 for absence epilepsy [8].
Exclusion criteria comprised of children with atypical absence epilepsy, intellectual disabilities, developmental delay, premorbid psychiatric problems, neuro-metabolic disorders, or those receiving drugs with a negative impact on cognition.
The study was approved by the local Ethical Research Committee of the Faculty of Medicine, Tanta University Hospitals. Informed consent was obtained from all subjects’ guardians before participation in the study and any potential risks were clarified to them.
All participants were subjected to medical history taking, neurological examination, routine laboratory tests, measurement of serum valproic acid (in treated patients’ group), and blood level of ammonia. They were also submitted to simultaneous long-term EEG monitoring and cognitive assessment. Long-term EEG for 2 h was done in the morning by two different epileptologists with experience of more than 15 years in EEG analysis. Comparison between both raters showed no interrater variability. Provocative tests like post hyperventilation and photic stimulation were used.
The mean IISL was calculated and correlated with the cognitive assessment results. EEG was visually rated by two different epileptologists. The number of spike-wave in 2 h was calculated and divided on 120 where the mean spike per minute was estimated for every case.
The EEG was performed using the Nihon Kohden EEG system (model EEG-1200, 64 channels, Japan) regarding the American Clinical Neurophysiology Society guidelines [9].
The IQ was measured by the Arabic validated version of Stanford Binet Intelligence Scale 5th ed. [10], and the cognitive functions were evaluated by applying the computerized version 0.14 of The Psychology Experiment Building Language (PEBL) and PEBL Test Battery [11]. We assessed the executive planning/set-shifting by the Wisconsin Card Sorting Test [12], the problem-solving by Tower of London test [13], the attention/response inhibition by Stroop test, the processing speed by Trail Making Test, the fine motor speed by finger tapping test, the complex motor control by pursuit rotor task, the working memory by Corsi’s Block Tapping Test [11], and the language/verbal fluency by the Arabic version of the Controlled Oral Word Association Test (COWAT) [14].
All the psychometric tests were done in a single session by the psychiatrist in the morning after performing the specified laboratory investigation. Each psychometric test is explained in detail in the Arabic language to each participant before starting to apply the test battery.
A psychiatric evaluation was done using the Arabic translation of the Kiddie Schedule of Affective Disorders and Schizophrenia (K-SADS) [15]. The emotional and behavioral problems were assessed by using an Arabic validated form of the Child Behavior Checklist (CBCL) that was fulfilled by the guardians and scored by a computerized software system (Assessment Data Manager-version 9.1) [16].
Statistical presentation and analysis were conducted using the Statistical Program for Social Science (SPSS) Version 20.0, IBM, Armonk, NY, USA. Quantitative data were expressed as mean ± standard deviation (SD), and qualitative data were expressed as frequency and percentage. Chi-square (χ2) and ANOVA tests were also used.