The first systematic documentation of dynamic cerebral vascular changes associated with focal seizures was made by Penfield in the thirties. In recent years in vivo imaging techniques, principally single photon emission computed tomography (SPECT), have been used to study regional cerebral blood flow (rCBF) in patients with focal epilepsy. The main finding has been of focal hypoperfusion, the location in the brain differing according to the site of the focus. The incidence and clinical associations of this finding have varied, and few large studies have been carried out. Until the development of the blood flow tracer HMPAO (hexamethylpropyleneamine oxime) there was no practical way to study regional cerebral blood flow during or soon after seizures. When the present work was started no studies existed, although several have appeared during its course. Only complex partial seizures of temporal lobe origin have been systematically studied
