Continuous monitoring of post mortem temperature changes in the human brain

Abstract

Recent developments in neurochemistry research on the post mortem human brain require a detailed understanding of the post mortem changes in the human brain, including the correlation between time related temperature changes and alterations in biochemical parameters. As an initial step towards our deeper insight into the intricate relationships between post mortem time, temperature and neurochemical processes, in the present study we set out to monitor continuously temperature changes in the post mortem human brain in eight cadavers for a period of up to 24 h after death under 'standard' clinical conditions at a neurosurgery clinic. A main objective of the study was to find a simple and reliable mathematical formula, requiring only time and an easily obtainable body temperature measurement parameter, with the help of which the superficial and deep brain temperatures can be obtained without invasive interactions. With a portable thermoprobe data logger system superficial (4 cm from skull surface) and deep (8 cm) brain temperatures, the temperature of the liver and that of the forehead skin, as well as the ambient temperature of the room were measured at regular time intervals (every 1 or 5 min). Various mathematical models were fitted to the data in order to create a simple model capable to predict brain temperatures from easily accessible measurements, such as that of the forehead skin. On the basis of the tested models we propose that with simple polynomial equations the deep and superficial brain temperatures can be described reliably as T (br4) ( degrees C)=T (fh)-0.001t (3)+0.0541t (2)-1.0622t+7.5933 and T (br8) ( degrees C)=T (fh)-0.0003t (3)+0.0201t (2)-0.619t+7.9036, respectively, where T (br4) is the superficial (4 cm) brain temperature, T (br8) is the deep (8 cm) brain temperature, T (fh) is the forehead temperature and t is the time from death. These measurements can, in combination with further neurochemical studies, contribute to our better understanding of the human brain's time- and temperature-related post mortem biochemical changes.