EFFECT OF SEIZURES ON CEREBRAL BLOOD-FLOW MEASURED WITH O-15-H2O AND POSITRON EMISSION TOMOGRAPHY

To study quantitative alterations in regional cerebral blood flow (rCB F) accompanying seizures, and to assess the utility of ictal activatio n PET scanning as a noninvasive clinical tool for localization of epil eptogenic foci, we used pentylenetetrazole (PTZ) to induce seizures du ring O-15-water positron emission tomography (PET) CBF measurement in 15 patients with uncontrolled complex partial seizures (CPS) who had b een referred for surgical evaluation. Continuous EEG monitoring was pe rformed during the PET scans. After baseline scans were obtained, each patient was injected with 150-300 mg PTZ. Two patients had generalize d tonic-clonic seizures (GTCs). CBF increases were asymmetrical. Two p atients (in 1 the seizure occurred spontaneously, without PTZ injectio n) who had CPS had bitemporal 70-80% increases in CBF. Thalamic CBF in creased during both CPS and GTCS. Five patients had an increase in foc al EEG interictal abnormality, accompanied by focal flow decreases in 3. PTZ injection not accompanied by clinical seizures did not increase CBF. Partial seizures may be associated with bilateral increases in C BF, and subcortical gray regions are involved in ictal activation.