Investigators at Children’s Memorial Hospital/Northwestern University School of Medicine Epilepsy Center, Chicago, and Kangbuk Samsung Hospital, Seoul, Korea examined the relationship of cognitive proficiency (CP) to general intellectual ability (GA) and seizure focus by retrospective chart review of 90 children (aged 6-18 years) with epilepsy, video-EEG recording, MRI, and neuropsychological testing (WISC-IV). Cognitive Proficiency Index (CPI) scores based on the WISC-IV Working Memory (WM) and Processing Speed (PS) indices were significantly lower than the General Ability Index (GAI) scores, comprising the WISC-IV Verbal Comprehension (VC) and Perceptual Reasoning (PR) indices. GAI>CPI differences were significantly greater in the right than left lateralized seizure group and also greater for the frontal than temporal group. CP was selectively compromised in those with seizures lateralized to the right hemisphere or localized to the frontal lobe. Right lateralization and frontal localization independently impact CP. GAI>CPI differences were significantly greater in the right-lateralized group than the generalized group and in the frontal-localized group than the generalized group. Deficits in CP are a defining neurocognitive characteristic of pediatric epilepsy in individuals with both focal and generalized onset, but especially when seizures originate from a primary epileptogenic focus within the right hemisphere or the frontal lobe. 
COMMENT. Children with epilepsy lateralized to the right hemisphere or localized to the right frontal lobe are at increased risk of cognitive deficits involving working memory and processing speed. Working memory maintains short-term information, and processing speed determines the amount of information that can be used and accommodated in working memory. Cognitive proficiency contributes to cognitive aptitude in learning and problem solving. A general availability of psychological services should add to the proficiency of epilepsy management in the clinic.