Intracranial Blood Flow in Insulin Coma

The cause of the coma and other neurologic manifestations which occur during insulin hypoglycemia has been a subject of some controversy among investigators in this field. The most striking and consistent effect of hypoglycemia on the brain is a diminished difference between the oxygen content of blood entering the skull (arterial) and that of blood leaving through the internal jugular veins.1Some investigators2have attributed this low arteriovenous difference during insulin hypoglycemia to a diminution in the oxygen uptake of the brain, while others have suggested that it may be due to an increased blood flow to the brain.3After continuously recording the velocity of blood flow through the internal jugular vein with the Gibbs thermoelectric blood flow recorder4in 2 cases, Loman and Myerson concluded that the volume flow of blood through the brain is slightly diminished during insulin hypoglycemia.5On the other hand,