Nonepileptic cortical cerebral blood flow and temporal lobe epileptogenicity

Long-term combined electrocorticographic (ECoG) and surface cerebral blood flow (CBF) monitoring was performed to test the hypothesis that human temporal lobe epileptogenicity (i.e. seizure frequency) depends on perfusion of nonepileptic cortex. ECoG and CBF data were continuously recorded from homotopic regions of nonepileptic and epileptic temporal lobes. During the 2-h peri-ictal and 5-min pre- and post-ictal periods, seizure frequency was a positive linear function of nonepileptic CBF (r=0.599, df=48, P<0.01; r=0.794, df=130, P<0.01 and r=0.610, df=1040, P<0.01; respectively). As nonepileptic CBF increased, seizure frequency increased. The results support the hypothesis that human temporal lobe epileptogenicity (i.e. seizure frequency) depends on perfusion of nonepileptic cortex. Increasing nonepileptic CBF is associated with increased seizure frequency. It is theorized that this may be due to redistribution of CBF from epileptic to nonepileptic cortex, consistent with the vascular steal hypothesis of epileptogenicity. Future therapeutic strategies designed to reduce nonepileptic cortical perfusion should produce reduction in temporal lobe epileptogenicity. Copyright (C) 1999 Elsevier Science Ireland Ltd.