Hypothalamic dysthermia in persons with brain damage

Brain injury causing dysthermia has appeared to be not uncommon in institutionalized people with mental retardation. We sought to determine the characteristics and risks of patients of one institution. Of 1100 residents surveyed over 10 years 92 were reported to have unexplained high or low body temperatures, and 48 were monitored. Core temperatures were taken by non-invasive thermometers recording continuously for 24 h. Results were related to clinical conditions and aetiologies of mental retardation. Twenty-one per cent of the residents monitored showed hyperthermia, often related to prenatal metabolic or chromosomal abnormalities. Forty-two per cent had hypothermia, related to other causes of brain injury. Seventy-five per cent had abnormal patterns, including flat or exaggerated rhythms, reversed day-night cycle, unusual fluctuations, or sleep phase delay. Sixty-two per cent of 21 deaths to date have occurred in hypothermic patients. Occasional discrepancies between history of dysthermia and monitored results are best explained by fluctuations of temperature control over several days, probably due to changes in timing of hypothalamic rhythmicity. This could be better delineated by longer periods of monitoring.