Failure of localized head cooling to reduce brain temperature in adult humans.

Non-invasive brain temperature measurements using proton magnetic resonance spectroscopy were used to test the hypothesis that localized head cooling would reduce brain temperature in 10 normal adult humans. Temperature reductions of the head surface to 15.8+/-3.5 degrees C did not reduce brain temperature measured in the superficial cortex (36.8+/-0.5 degrees C) or thalamus (36.6+/-0.7 degrees C), as compared to measurements obtained with a head surface temperature of 34.7+/-1.6 degrees C (37.0+/-0.6 degrees C and 36.6+/-0.4 degrees C, respectively). There was no change in the temperature gradient from the superficial to deep brain locations in the presence or absence of head cooling, and brain temperature did not decrease as a function of the duration of head cooling for periods up to 50 min. There was no correlation between the scalp surface (range: 10-38 degrees C) and brain temperature at either the deep or superficial locations.