Normalization of periictal bihemispheric cerebral perfusion in temporal lobe epilepsy

Under normal circumstances, cerebral blood flow (CBF), between the two hemispheres is coupled in a direct (i.e. positive slope), linear fashion. However, in temporal lobe epilepsy, the relationship between the two temporal cortices, during the interictal and postictal periods, is the inverse of normal (i.e. correlation is with negative slope and linear). Long-term combined temporal lobe thermal diffusion flowmetry (TDF) subdural regional cerebral blood flow and electroencephalographic (EEG) recording was performed to test the hypothesis that, during the 10 min periictal period (i.e. 5 min before and 5 min following clinical seizure onset), the cerebral perfusion relationship between epileptic and nonepileptic cortex returns to normal (i.e. becomes direct, with positive slope, and linear). A consecutive series of 13 patients with complex partial epilepsy was studied. During continuous monitoring of clinical phenomenology in time sequence with subdural CBF/EEG, the 10 min periictal period was characterized by a direct, linear correlation between epileptic and nonepileptic temporal cortical blood flow (r=0.302, d.f.=85, t=2.921, P<0.01). The fact that this pertubation in the CBF relationship between the bilateral temporal cortices begins prior to and continues for 5 min following clinical and subdural EEG seizure onset raises the interesting possibility that normalization of periictal bilateral cerebral perfusion may be associated with temporal lobe epileptogenesis.