[Study of cerebral metabolism and blood flow in partial complex epilepsy and status epilepticus in man using positron...

Positron Emission Tomography (PET) with the oxygen-15 steady state inhalation technique was used to provide quantitative values of regional cerebral blood flow (CBF), oxygen consumption (CMRO2) and oxygen extraction ratio (OER) in 25 patients with partial complex seizures during the interictal state, in 1 patient with recurrent temporal seizures and in 3 patients whose EEGs were characterized by periodic lateralized epileptiform discharges (PLEDs). Interictal scans showed temporal zone(s) of hypoperfusion and hypometabolism in 80% of patients with normal X-ray CT Scan. In all cases, ictal scans revealed a focal or multifocal increase in CBF and CMRO2. The localization of the most affected regions correlated well with the spatial distribution of the EEG abnormalities. Comparison of the different values of CBF, CMRO2 and OER showed that the increase in perfusion always exceeded that of oxygen consumption and hence was accompanied by a significant decrease in OER, the latter was always the most prominent in the region of the focus determined by serial EEG recordings. The observed imbalance between blood flow and oxidative glucose metabolism could suggest an impairment of O2 utilization by the mitochondria in the epilepticus focus during seizures or status epilepticus.