Hyperthermia induced pathophysiology of the central nervous system.

This review is focused on the pathophysiology of the central nervous system (CNS) associated with mild-to-moderate hyperthermia (body temperature > 37 degrees C but <40 degrees C) induced thermal stress in Human cases as well as whole body hyperthermia (WBH) in animal studies. Pathological changes can be observed in the nerve cells and glial cells in Humans following mild-to-moderate thermal exposure. On the other hand, morphological changes in the axons, nerve cells, glial cells and vascular endothelium is seen at the cellular and the molecular levels in rats subjected to heat exposure at 38 degrees C for 4 h (body temperature > 40 degrees C but <42 degrees C). This effect depends on the age of the animals and their prior thermal experiences. Taken together, heat stress induced hyperthermia, once believed to be non-toxic in the mammalian CNS, do produce specific alterations in the CNS that may have long-term behavioural, physiological and neuropathological consequences. The probable mechanism(s) underlying hyperthermia induced brain pathology is discussed.