Objective: To describe the association between a unilateral mid-temporal rh
ythmic theta discharge ('psychomotor variant of Gibbs') with neuroimaging-d
emonstrated underlying mass lesion.
Methods: Standard routine awake and scalp electroencephalography, continuou
s video-EEG monitoring and magnetic resonance brain imaging were employed i
n the diagnostic work-up of a 9-year-old boy with a severe behavioural dist
urbance and episodic outbursts of aggression.
Results: EEG showed a unilateral mid-temporal rhythmic discharge which was
continuous in drowsiness and which remained confined to the right hemispher
e. MRI showed a lesion in the temporal horn of the right lateral ventricle
displacing superiorly the white matter stem of the right temporal lobe.
Conclusion: A rhythmic mid-temporal theta discharge, commonly regarded as a
benign EEG variant, may, in some patients, reflect underlying structural p
athology. Neuroimaging should be considered particularly when this EEG patt
ern remains confined to one hemisphere. (C) 2001 Elsevier Science ireland L
td. All rights reserved.