Border zone ("watershed area") cerebral ischemia.

Twenty subjects showing clinical and electroencephalographic patterns of the so-called "diffuse cortical ischemic syndrome with an extraterritorial (border zone) predilection," as described by Gastaut and Naquet (1965) and Gastaut et al. (1971) were studied. This syndrome occurs in elderly patients presenting a sudden disturbance of consciousness of various degree, neurological deficits, and epileptic seizures consisting of focal motor attacks and epilepsia partialis continua. Periodic lateralized epileptiform discharges were recorded. They could be bilateral or more often predominated over one hemisphere, usually in the parieto-temporo-occipital areas. The various pathological factors are discussed. Four main types of abnormalities, sometimes combined, seem to be important for the occurrence of this syndrome: generalized underperfusion, hypertension, embolic processes and sometimes metabolic factors (alcohol, anoxic anoxia, electrolyte imbalance or nonketotic hyperglycemia) and, particularly, in the presence of pre-existing cerebral infarcts, either symptomatic or asymptomatic.