Correlation of Changes in Blood Flow and Acid-Base Changes in the Brain during Induced Epileptic Seizures

Abstract

Although it is well known that epileptic seizures of whatever type are accompanied by a pronounced increase in cerebral blood flow (CBF), the mechanisms have remained unclarified. A majority of workers have assumed that the coupling factor is an increase in the extracellular H⁺ activity, secondary to glycolytic production of lactic acid. There has been the problem, though, that the increase in CBF is of rapid onset and that at least three groups of workers have found that the pH, as measured on the surface of the brain, may increase transiently during the epileptic discharge (2, 5, 7). Recently, these results were confirmed (6). However, these workers concluded that the alkaline surface response was due to a H⁺ barrier in the pia-arachnoid membrane, and that the extracellular fluid proper was acidified. The evidence for this was that tissue pH, calculated from ^PCO₂ and tissue bicarbonate content, declined after onset of seizure discharge.