Hypoglycemia-Induced Changes in the Electroencephalogram

Abstract

Hypoglycemia is defined by an abnormally low blood glucose level. The condition develops when rates of glucose entry into the systematic circulation are reduced relative to the glucose uptake by the tissues. A cardinal manifestation of hypoglycemia arises from inadequate supply of glucose to the brain, where glucose is the primary metabolic fuel. The brain is one of the first organs to be affected by hypoglycemia. Shortage of glucose in the brain, or neuroglycopenia, results in a gradual loss of cognitive functions causing slower reaction time, blurred speech, loss of consciousness, seizures, and ultimately death, as the hypoglycemia progresses. The electrical activity in the brain represents the metabolic state of the brain cells and can be measured by electroencephalography (EEG). An association between hypoglycemia and changes in the EEG has been demonstrated, although blood glucose levels alone do not seem to predict neuroglycopenia. This review provides an overview of the current literature regarding changes in the EEG during episodes of low blood glucose.

Electroencephalographic alterations in a mare with presumed intermittent neuroglycopenia caused by severe hypoglycaemia‐associated with nonislet cell tumour

“…As the hypoglycaemia worsened, abnormal electrical activity became generalised, progressing to overt ictal electric activity accompanied by manifestation of seizures. The electrical activity pattern presented in this mare was similar to that described for humans with progressive, severe hypoglycaemia (Blaabjerg and Juhl ).…”

“…In diabetic humans with post insulin hypoglycaemia, electrical changes in EEG are typically noted when blood glucose is around 40 mg/dL (2.2 mmol/L) (Sejling et al . ; Blaabjerg and Juhl ). Infants with severe neonatal hypoglycaemia present severe seizures when the blood glucose is below 36 mg/dL (2 mmol/L) (Burns et al .…”

“…; Sejling et al . , ; Blaabjerg and Juhl ; Rubega and Sparacino ).The glycaemic threshold for EEG changes has been studied in diabetic humans with post insulin hypoglycaemia and infants with neonatal hypoglycaemia, and it is reported to vary among individuals. In diabetic humans with post insulin hypoglycaemia, electrical changes in EEG are typically noted when blood glucose is around 40 mg/dL (2.2 mmol/L) (Sejling et al .…”

“…The EEG recordings in humans and animals during hypoglycaemia show characteristic patterns with early changes, such as decreased frequency band for alpha (8–13 Hz) and beta (13–30 Hz) activities, large delta (>0 to <4 Hz) waves, progressing to spike and bursting (Florez et al . ; Blaabjerg and Juhl ). Most studies evaluating hypoglycaemia as a proxy for neuroglycopenia have been conducted in human diabetic patients subjected to recurrent episodes of hypoglycaemia following insulin treatment, where initial mild cognitive dysfunction quickly progresses to seizures or collapse associated with severe hypoglycaemia (Sejling et al .…”

“…; Sejling et al . , ; Blaabjerg and Juhl ; Rubega and Sparacino ). To our knowledge, EEG patterns during hypoglycaemia in adult horses have not been reported.…”