HYPERTHERMIA COMPLICATES MIDDLE CEREBRAL-ARTERY OCCLUSION INDUCED BY AN INTRALUMINAL FILAMENT

The present experiments were designed to study under what circumstance s middle cerebral artery (MCA) occlusion by an intraluminal filament t echnique leads to hyperthermia and what the mechanisms are. We found t hat permanent MCA occlusion by this technique lead to a rise in body ( core) temperature to 39.0-39.5 degrees C during the first 2-4 h, and t o sustained hyperthermia thereafter (38.5-39.0 degrees C). After 2 h o f transient MCA occlusion hyperthermia could only be avoided if anesth esia (with control of temperature) was maintained for 2 h of ischemia and 1 h of recirculation or, in unanesthetized animals, if external co oling was maintained for 2 h of ischemia and 2 h of recirculation. Con trol of temperature only during ischemia did not prevent a postischemi c rise in temperature. One hour of MCA occlusion had less effect on bo dy temperature. Results are presented which suggest that the hyperther mia observed is due to an interference, by the intraluminal filament, of circulation to hypothalamic centers regulating body temperature. It is speculated that the hyperthermia induced may blunt or obliterate t he effect of drugs, normally considered to ameliorate brain damage due to focal ischemia.