Complex relations between body temperature, tPA action, and stroke outcome
In “Elevated body temperature in ischemic stroke associated with neurological improvement”, Khanevski et al1 supply another set of information toward the understanding of the pathophysiology and optimal management of body temperature (BT) in the early phase of stroke. The authors are highly appreciated for their whole contribution to the knowledge on this issue. A prominent finding of the current study is that higher body temperature in the first 3 hours of ischemic stroke promotes early neurological improvement, with a strong relation between these two characteristics in proximal MCA occlusion patients. This association was found for both thrombolyzed and non‐thrombolyzed patients (I assume that none was treated with mechanical thrombectomy, which is questionable, by the way). The results are consistent with selected other data suggesting that tPA action might be temperature‐dependent.2 On the other hand, BT after stroke is rarely higher than 37°C, peaks as late as 1.5 to 2 days after the onset, and higher BT in the early phase of stroke was associated with poorer outcome (as measured by modified Rankin scale) in many studies.4 Trials to decrease BT below 36.5°C pharmacologically early after stroke have not altered the functional outcome despite its effective reduction.5
The authors of the paper1 conclude that there might be a time‐dependent association between BT and stroke outcome, which seems indisputable. However, the lack of simple and repeatable relation between BT and stroke outcome or between antipyretic therapy and outcome across different studies might also be associated with many problems other than the time of BT measurement or the time of intervention to alter BP. Some of these potential mechanisms and other relevant considerations are provided below.
Furthermore, studies on the associations between body temperatures, brain temperatures, and neurological outcomes, in relation to the aforementioned factors, such as the recent one released by Khanevski et al,1 will help to design new stroke BT interventional trials more precisely.