Long-term video-EEG recordings following transient unilateral middle cerebral and common carotid artery occlusion in Long–Evans rats

The mechanisms of injured brain that establish poststroke seizures and epilepsy are not well understood, largely because animal modeling of these phenomena has had limited development. We studied the electrobehavioral properties of 2.5-month-old male Long–Evans rats by video-electroencephalogram (EEG) recordings during the 6 months following sham operation or lesioning by transient unilateral middle cerebral artery (MCA) and common carotid artery (CCA) occlusion (MCA/CCAO). The main findings of this study were: (1) control animals demonstrated interictal focal or restricted bilateral 7–8 Hz spike–wave discharges (SWDs) lasting 1–2 s without behavioral change and ictal generalized 7–8 Hz SWDs (absence seizures), which were prolonged, frequent, and associated with motor arrest of the animal; (2) lesioned animals demonstrated cortical infarction associated with interictal SWDs similar to controls, except that focal discharges were more numerous relative to bilateral discharges, and ictal SWDs, which were of shorter duration and less frequent than those of controls; (3) lesioned animals demonstrated decreased hemispheric and regional spectral power at ∼ 7 and 15 Hz compared with controls, directly related to the reduced occurrence of ictal SWDs; and (4) lesioning did not independently generate either focal or generalized epileptic seizures. These studies demonstrate distinct electrobehavioral properties of Long–Evans rats lesioned by MCA/CCAO as juveniles and monitored by video-EEG recordings during young adulthood but fail to provide evidence of poststroke seizures or epilepsy.