The magnetic activity distribution in the brain before and after carotid endarterectomy

INTRODUCTION It is well known that cerebrovascular lesions of the brain are the source of neuronal dysfunctions, which produce focal slow wave activity (1-6 Hz), that can be localized by magnetoencephalography (MEG) (Gallen et al. 1992, Vieth 1990, Vieth et al. 1992, ). This slow wave activity has not only been observed with structural lesions (infarctions) but also with transient ischemic attacks (Vieth 1990, Vieth et al. 1992, Rieke et al. 1993). Recently we could demonstrate (Grummich et al. 1993, Vieth et al. 1993) that also focal beta wave activity (12.5-30 Hz) is associated with these lesions. In this study we wanted to investigate by the MEG the influence of the blood supply on the brain activity.