I tried measuring 'Brain Temperature'. Brain temperature rhythm and mortality

📖 Literature Information and Abstract Translation

A daily temperature rhythm in the human brain predicts survival after brain injury

📕Rzechorzek, Nina M., et al. "A daily temperature rhythm in the human brain predicts survival after brain injury." Brain 145.6 (2022): 2031-2048. https://doi.org/10.1093/brain/awab466
🔗 DOI, PubMed, Google Scholar 🌲MORE⤴ >>> Connected Papers
※ What is Connected Papers? >>> note.

[Background/Objective] Patients receive interventions to achieve a "normal" brain temperature. Because neuronal function is highly sensitive to temperature, the brain should be isothermal, but observations from patients and primates suggest significant spatiotemporal fluctuations. We aimed to determine the clinical validity of brain temperature in patients by clarifying how much the brain temperature of healthy adults changes.

[Methods] We retrospectively screened data from all patients enrolled in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) High Resolution Intensive Care Unit Sub-Study. Only patients who underwent direct brain temperature measurement and were not receiving targeted temperature management were included. To interpret the patient analysis, 40 healthy adults (20 men, 20 women, aged 20-40) were prospectively recruited to undergo brain temperature measurement using magnetic resonance spectroscopy. Participants were scanned in the morning, afternoon, and late at night.

✅ How to measure brain temperature
■ Traumatic brain injury patients
・Data collected directly from the brain (retrospective)
・Consisted of 109 out of 134 eligible patients screened
・Admitted directly to the intensive care unit or after surgical intervention for mass lesions
・Brain temperature measured directly via an instrument inserted into the brain parenchyma through a dedicated bolt placed via a burr hole (Integra Neurosciences)
■ Healthy individuals
・Data inferred using a calculation formula from MRI (prospective recruitment)
・40 eligible participants (20 women) recruited for scanning
・Mechanism is described in the main text (it's complex...)

[Results]
■ Brain temperature has a circadian rhythm
Brain temperature in patients (n = 114) ranged from 32.6 to 42.3°C, with the mean brain temperature (38.5 ± 0.8°C) exceeding body temperature (37.5 ± 0.5°C, P < 0.0001). Of the 100 patients included in the brain temperature rhythm analysis, 25 showed a diurnal rhythm, and the amplitude of brain temperature decreased in older patients (P = 0.018).

■ Brain temperature by region and time of day
Brain temperature in healthy subjects ranged from 36.1 to 40.9°C, with the mean brain temperature (38.5 ± 0.4°C) exceeding oral temperature (36.0 ± 0.5°C), and was 0.36°C higher in women in the luteal phase compared to women in the follicular phase and men (P = 0.0006 and P < 0.0001, respectively). Brain temperature increased with age, particularly in deep brain regions (0.6°C over 20 years, P = 0.0002). The thalamus had the highest temperature, with a spatial variation of 2.41 ± 0.46°C. Brain temperature changed depending on the time of day, particularly in deep regions (0.86°C, P = 0.0001), and was lowest at night.

■ Brain temperature rhythm and mortality in traumatic brain injury patients
From healthy data, we constructed HEATWAVE—a 4D map of human brain temperature. When we validated the clinical validity of HEATWAVE in patients, we found that the probability of death in the intensive care unit was 21 times higher in the absence of a daily brain temperature rhythm (P = 0.016). However, we found that a higher mean brain temperature was associated with higher survival (P = 0.035), and that aging by 10 years or more increased the probability of death by 11 times (P = 0.0002).

[Conclusion] We found that human brain temperature is higher and fluctuates more significantly than previously thought, depending on age, sex, menstrual cycle, brain region, and time of day. This has significant implications for temperature monitoring and management, and the daily brain temperature rhythm has emerged as one of the strongest single predictors of survival after brain injury. We concluded that it is not the absolute brain temperature, but the daily rhythmic brain temperature fluctuation, that is one way to distinguish human brain physiology from pathophysiology.

🌱 So What?: What did I find interesting?

I felt the impact of this study was incredible.
I thought that the fact that brain recovery and death differ based on changes in brain temperature is a very direct monitoring method, and since they have devised a method that can be inferred via MRI, it has become a value that can be measured by anyone using a non-invasive method.
From a rehabilitation perspective, I feel there are two major potential applications.

■ It seems to affect not just mortality but also rehabilitation effects
・For example, just as cerebral blood flow and brain activity measured by fMRI are related to functional recovery after a stroke, a hypothesis can be formed that the level and rhythm state of brain temperature are related to functional recovery.
・If an algorithm is built that can be automatically calculated from MRIs taken in routine clinical practice, it could become one of the important biomarkers for prognosis prediction.

■ Brain temperature seems easy to intervene in
・This might sound foolish, but would an ice pack lower brain temperature?
・If control is possible there, for example, what would happen if we artificially created a brain temperature rhythm after a brain injury (like performing cardiac massage)?
・If that leads to changes in mortality after brain injury or changes in rehabilitation effects, that would be a super important matter!

"Keep your head cool and your feet warm."
Feet tend to get cold, so they should be warmed; the head tends to get hot, so it should be cooled.
This study asks us:
“Is that really the case...?”
The important thing might not be just cooling, but creating a rhythm.

Signs of heading downhill appear at the peak,
and the stirrings of something new arise at the extreme of decline.
Hong Zicheng, "Caigentan"

○●━━━━━━━━━━━・・・‥ ‥ ‥ ‥
High-quality rehabilitation medicine-related English paper reading 'ARI: ARI'
From here♪
↓↓↓

‥ ‥ ‥ ‥・・・━━━━━━━━━━━●○

#️⃣ #PhysicalTherapy #ClinicalResearch #Research #Rehabilitation #EnglishPaper #LiteratureReading #EnglishLiteratureReading #Evidence #Science #DailyUpdate #RecentLearning