Correlation of EEG with neuropsychological status in children with epilepsy.
OBJECTIVE
To determine correlations of the EEG frequency spectrum with neuropsychological status in children with idiopathic epilepsy.


METHODS
Forty-six children ages 8-18 years old with idiopathic epilepsy were retrospectively identified and analyzed for correlations between EEG spectra and neuropsychological status using multivariate linear regression. In addition, the theta/beta ratio, which has been suggested as a clinically useful EEG marker of attention-deficit hyperactivity disorder (ADHD), and an EEG spike count were calculated for each subject.


RESULTS
Neuropsychological status was highly correlated with posterior alpha (8-15 Hz) EEG activity in a complex way, with both positive and negative correlations at lower and higher alpha frequency sub-bands for each cognitive task in a pattern that depends on the specific cognitive task. In addition, the theta/beta ratio was a specific but insensitive indicator of ADHD status in children with epilepsy; most children both with and without epilepsy have normal theta/beta ratios. The spike count showed no correlations with neuropsychological status.


CONCLUSIONS
(1) The alpha rhythm may have at least two sub-bands which serve different purposes. (2) The theta/beta ratio is not a sensitive indicator of ADHD status in children with epilepsy. (3) The EEG frequency spectrum correlates more robustly with neuropsychological status than spike count analysis in children with idiopathic epilepsy.


CONCLUSIONS
(1) The role of posterior alpha rhythms in cognition is complex and can be overlooked if EEG spectral resolution is too coarse or if neuropsychological status is assessed too narrowly. (2) ADHD in children with idiopathic epilepsy may involve different mechanisms from those in children without epilepsy. (3) Reliable correlations with neuropsychological status require longer EEG samples when using spike count analysis than when using frequency spectra.
Department of Neurology, University of Wisconsin, Madison, WI, USA. Electronic address: hsu@neurology.wic.edu.
David A
DA
Hsu
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Katherine
K
Rayer
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Daren C
DC
Jackson
Department of Neurology, Johns Hopkins University, Baltimore, MD, USA.
Carl E
CE
Stafstrom
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Murielle
M
Hsu
Department of Pediatrics, University of Wisconsin, Madison, WI, USA.
Peter A
PA
Ferrazzano
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Kevin
K
Dabbs
Department of Neurology, Mayo Clinic, Rochester, MN, USA.
Gregory A
GA
Worrell
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Jana E
JE
Jones
Department of Neurology, University of Wisconsin, Madison, WI, USA.
Bruce P
BP
Hermann
D000293:Adolescent; D000513:Alpha Rhythm / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D002648:Child; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies
Alpha rhythm; IQ; Neuropsychological status; Quantitative EEG; Spike count; Theta/beta ratio