Brain temperature regulation in poor-grade subarachnoid hemorrhage patients - A multimodal neuromonitoring study

Elevated body temperature (T-core) is associated with poor outcome after subarachnoid hemorrhage (SAH). Brain temperature (T-brain) is usually higher than T-core. However, the implication of this difference (T-delta) remains unclear. We aimed to study factors associated with higher T-delta and its association with outcome. We included 46 SAH patients undergoing multimodal neuromonitoring, for a total of 7879 h of averaged data of T-core, T-brain, cerebral blood flow, cerebral perfusion pressure, intracranial pressure and cerebral metabolism (CMD). Three-months good functional outcome was defined as modified Rankin Scale <= 2. T-brain was tightly correlated with T-core (r = 0.948, p < 0.01), and was higher in 73.7% of neuromonitoring time (T-delta +0.18 degrees C, IQR -0.01 - 0.37 degrees C). A higher T-delta was associated with better metabolic state, indicated by lower CMD-glutamate (p = 0.003) and CMD-lactate (p < 0.001), and lower risk of mitochondrial dysfunction (MD) (OR = 0.2, p < 0.001). During MD, T-delta was significantly lower (0 degrees C, IQR -0.2 - 0.1; p < 0.001). A higher T-delta was associated with improved outcome (OR = 7.7, p = 0.002). Our study suggests that T-brain is associated with brain metabolic activity and exceeds T-core when mitochondrial function is preserved. Further studies are needed to understand how T-delta may serve as a surrogate marker for brain function and predict clinical course and outcome after SAH.

Automated summary

Elevated brain temperature (T-brain) exceeding core body temperature is associated with better metabolic state and improved outcome, suggesting that ΔT may serve as a surrogate marker for brain function and predict clinical course and outcome after subarachnoid hemorrhage (SAH).