Cobalt-55 positron emission tomography in late-onset epileptic seizures after thrombo-embolic middle cerebral artery infarction

The pathogenesis of late-onset epileptic seizures after thrombo-embolic cer ebral infarction is poorly understood. Our previous positron emission tomog raphic (PET) studies with O-15 have demonstrated that post-apoplectic epile psy is associated with more severe brain ischemia, but we were unable to de termine if this was the cause or the consequence of the seizures. Using cob alt-55 (Co-55) as PET tracer we can now distinguish recur rent, recent infa rction in patients with a previous old infarct in the same vascular territo ry. In seven out of twelve patients with post-apoplectic seizures an increa sed uptake of Co-55 was observed in the border area and in two of them also within the old infarct core. In the control group, composed of eight seizu re-free patients with also an old infarct involving the cortical territory of the middle cerebral artery, no increase in Co-55 uptake was observed on PET examination. The present study indicates that in a significant number o f patients late-onset epilepsy is the clinical expression of recurrent stro kes, occurring in the same vascular territory. (C) 2000 Elsevier Science B. V. All rights reserved.