Reversible brain cell damage due to hypoglycemia in a patient with insulinoma.

A case of an insulinoma with hypoglycemic attacks accompanied by episodes of unconsciousness in a 57-year-old woman is described. During the hypoglycemic spells the level of adenylate kinase (AK) in the cerebrospinal fluid (CSF) was elevated 6-fold above the normalized level obtained later from the patient being in a normoglycemic condition. CSF-AK was previously found to be a sensitive marker of subtle brain cell damage due to hypoxia. The increased efflux of AK into CSF during the insulinoma-induced hypoglycemia was most probably the result of a brain cell injury caused by shortage of glycolytic fuel.