Tympanic temperature reflects intracranial temperature changes in humans

The purpose of the study was to identify extracranial locations in which temperature changes in humans reflect those of intracranial temperature in a reliable and repeatable way. This was achieved by subjecting 14 non-anaesthetized patients after neurosurgery to face fanning while intracranial and extracranial temperatures were continuously measured. In all patients the cranium was closed and the group included both febrile and non-febrile as well as hyperthermic and normothermic patients. The patients' faces were fanned for 20-30 min, with a small fan at an air speed of 3.25 m s(-1). This gave intracranial temperature changes measured in the subdural space (T-sd) that were highly and significantly correlated (r = 0.91, P < 0.05, n = 14) with changes in tympanic temperatures (T-ty). A low, statistically insignificant correlation (r = 0.40, P > 0.05, n = 12) was found between T-sd and oesophageal temperatures. In conclusion, intracranial temperature changes, induced by face fanning, were reliably reflected by the changes in T-ty.