DO SEIZURES CAUSE NEURONAL DAMAGE - A MRI STUDY IN NEWLY-DIAGNOSED AND CHRONIC EPILEPSY

IT is a matter of dispute whether or not recurrent epileptic seizures cause neuronal damage in the human brain. We approached this question by measuring the volumes of the amygdala, hippocampus and parahippocam pal gyrus with magnetic resonance imaging in 15 controls, 13 unmedicat ed patients with newly diagnosed epilepsy and 16 patients with chronic drug-refractory epilepsy. In all patients, the seizure origin was in the temporal lobe region and the seizure aetiology was unknown. Newly diagnosed epilepsy patients with seizure lateralization on the left ha d right-left difference (p < 0.01) and right/left ratio (p < 0.05) com pared with controls. Patients with chronic epilepsy and lateralization on the left had increased hippocampal right-left difference (p < 0.05 ) and right/left ratio (p < 0.05) compared with controls. In this pati ent group, the volume of the left hippocampus was 16% smaller than in controls (p < 0.01). The rostral portion of the parahippocampal gyrus was 12% smaller than in controls (p < 0.01). In chronic epilepsy patie nts with lateralization on the right, we found a statistically non-sig nificant decrease (13%) in the right hippocampal volume compared with controls. In this patient group, the amygdaloid right-left difference (p < 0.05) and right/left ratio (p < 0.05) were decreased compared wit h controls. The present cross-sectional study provides evidence that m ild hippocampal damage is already present in the early stages of epile psy. Hippocampal damage is more severe in patients with a long history of recurrent generalized seizures. In the present study population, t his damage was more obvious if the seizure lateralization was on the l eft. In chronic epilepsy the amygdala and parahippocampal gyrus are al so damaged. These findings support the idea that epileptic seizures ma y cause damage in the human temporal lobe.