Auditory nerve-brain stem evoked potentials and EEG during severe hypoglycemia.

To investigate the effects of severe hypoglycemia on the ability of the brain to generate electrical activity, the EEG and auditory nerve-brain stem evoked potentials (ABP) were recorded before and during the development of insulin-induced hypoglycemia in rats (ABP only) and cats (ABP and EEG). No significant ABP changes were seen in rats in which the average blood glucose levels had reached 0.38 mmol/l (= 7 mg%). In cats, even though the EEG was depressed, no ABP latency changes and only slightly significant amplitude changes were seen in animals in which the average blood glucose level was 0.8 mmol/l. In both animals blood glucose levels were below 1.66 mmol/l for an average duration of 90 min. Therefore, even though it has been shown that the brain structures involved in generation of the ABP have higher metabolic rates, they seem to be resistant to deviations from homeostasis such as hypoglycemia.