The Relationship between Sleep-Activated Interictal Epileptiform Discharges and Intelligence in Children

ABSTRACT.

This study investigates the relationship between interictal epileptiform discharges (IEDs) during sleep in children with benign rolandic epilepsy (BRE) and cognitive test scores as measured by the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) with the hypothesis that, as IEDs increase, cognitive test scores decrease. Studies have shown that generalized seizures and status epilepticus can negatively impact cognition (Dodrill 2004), that children with epilepsy have lower cognitive function on average than children without epilepsy and that children with epilepsy and abnormal electroencephalograms (EEGs) have lower cognitive function than children with epilepsy and normal EEGs (Bailet et al. 2000). Studies have also indicated that as IEDs decrease, neurocognitive test scores increase (Baglietto et al. 2001). The current study evaluated sleep-activated IEDs in children with the specific syndrome of benign rolandic epilepsy based on the frequency of IEDs in sleep in relation to cognitive test scores. Neuropsychological test scores from the WISC-IV were gathered along with the number of spikes per minute detected in EEG recordings. Statistical analysis revealed a negative correlation between spike frequency and both processing speed and coding scores, though the relationship did not reach statistical significance. This study concludes that there may be correlations between increased spike density and cognitive test scores, or there might be other factors impacting cognition in BRE, but a larger sample is needed to further investigate. In addition, it is possible that a negative result in the present study represents good news, that the number of IEDs in BRE does not harm the brain by negatively impacting cognition.

KEY WORDS.:

• Benign rolandic epilepsy (BRE)
• electrical status epilepticus of sleep (ESES)
• interictal epileptiform discharges (IEDs)
• neuropsychology