Active conductive head cooling of normal and infarcted brain: A magnetic resonance spectroscopy imaging study

Diprose, William K; Morgan, Catherine A.; Wang, Michael T.M.; Diprose, James P.; Lin, Joanne C.; Sheriff, Sulaiman; Campbell, Doug; Barber, P Alan

doi:10.1177/0271678x221107988

Cited by 8 publications

(15 citation statements)

References 40 publications

(78 reference statements)

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“…The authors, therefore, cannot disregard the effects that a reduced brain temperature may have had, although these effects are currently unknown. Diprose et al (2022) used a powerful cooling system to reduce the temperature of the head; therefore, any decrease in brain temperature in the current study is likely to have been smaller in magnitude in comparison. The increase in the duration of the protocol from cooling presents a further added confounding effect, and future research could extend these findings by focussing on dynamic reductions in skin temperature (de Dear et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia

Gordon

Tillin

Diss

et al. 2023

Experimental Physiology

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New Findings What is the central question of this study?Hyperthermia reduces the human capacity to produce muscular force, which is associated with decreased neural drive: does mitigating a reduction in neural drive by altering localised thermal sensation help to preserve voluntary force output? What is the main finding and its importance?Altering thermal sensation by cooling and heating the head independent of core temperature did not change neural drive or benefit voluntary force production. Head cooling did slow the rate of rise in core temperature during heating, which may have practical applications in passive settings. Abstract This study investigated altered local head and neck thermal sensation on maximal and rapid torque production during voluntary contractions. Nine participants completed four visits in two environmental conditions: at rectal temperatures ∼39.5°C in hot (HOT; ∼50°C, ∼39% relative humidity) and ∼37°C in thermoneutral (NEU; ∼22°C, ∼46% relative humidity) conditions. Local thermal sensation was manipulated by heating in thermoneutral conditions and cooling in hot conditions. Evoked twitches and octets were delivered at rest. Maximum voluntary torque (MVT), normalised surface electromyography (EMG) and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions of the knee extensors. Rate of torque development (RTD) and EMG were measured during rapid voluntary contractions. MVT (P = 0.463) and RTD (P = 0.061) were similar between environmental conditions despite reduced VA (−6%; P = 0.047) and EMG at MVT (−31%; P = 0.019). EMG in the rapid voluntary contractions was also lower in HOT versus NEU during the initial 100 ms (−24%; P = 0.035) and 150 ms (−26%; P = 0.035). Evoked twitch (+70%; P < 0.001) and octet (+27%; P < 0.001) RTD during the initial 50 ms were greater in the HOT compared to NEU conditions, in addition to a faster relaxation rate of the muscle (−33%; P < 0.001). In conclusion, hyperthermia reduced neural drive without affecting voluntary torque, likely due to the compensatory effects of improved intrinsic contractile function and faster contraction and relaxation rates of the knee extensors. Changes in local thermal perception of the head and neck whilst hyperthermic or normothermic did not affect voluntary torque.

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Section: Discussionmentioning

confidence: 99%

Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia

Gordon

Tillin

Diss

et al. 2023

Experimental Physiology

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“…Experiment 4 tested active conductive head cooling based on Tolerability and efficacy of non-invasive head COOLing in normal and HypopErfused brain: A magnetic resonance stuDy (COOLHEAD-1) with scalp temperature set to 5 °C. 7 The time-varying temperature within the 3 D model was solved using COMSOL and the mean temperatures of each of the regions was computed at each time-step. A 2 D section view of the temperature distribution across the brain at the end of the simulation was also generated.…”

Section: Methodsmentioning

confidence: 99%

Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study

Diprose,

Rao,

Ghate

et al. 2023

J Cereb Blood Flow Metab

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In ischemic stroke, selectively cooling the ischemic penumbra might lead to neuroprotection while avoiding systemic complications. Because penumbral tissue has reduced cerebral blood flow and in vivo brain temperature measurement remains challenging, the effect of different methods of therapeutic hypothermia on penumbral temperature are unknown. We used the COMSOL Multiphysics® software to model a range of cases of therapeutic hypothermia in ischemic stroke. Four ischemic stroke models were developed with ischemic core and/or penumbra volumes between 33–300 mL. Four experiments were performed on each model, including no cooling, and intraarterial, intravenous, and active conductive head cooling. The steady-state temperature of the non-ischemic brain, ischemic penumbra, and ischemic core without cooling was 37.3 °C, 37.5–37.8 °C, and 38.9–39.4 °C respectively. Intraarterial, intravenous and active conductive head cooling reduced non-ischemic brain temperature by 4.3 °C, 2.1 °C, and 0.7–0.8 °C respectively. Intraarterial, intravenous and head cooling reduced the temperature of the ischemic penumbra by 3.9–4.3 °C, 1.9–2.1 °C, and 1.2–3.4 °C respectively. Active conductive head cooling was the only method to selectively reduce penumbral temperature. Clinical studies that measure brain temperature in ischemic stroke patients undergoing therapeutic hypothermia are required to validate these hypothesis-generating findings.

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“…Diprose et al . recently developed a cooling cap that called WElkins Temperature Regulation System, 2 nd Gen.[ 22 ] After wearing this cooling cap for 80 min, the mean brain temperature was reduced by 0.9°C ± 0.7°C, while the core body temperature only decreased by 0.3°C ± 0.1°C. These two methods have significantly improved the efficacy of surface brain cooling.…”

Section: Surface Brain Coolingmentioning

confidence: 99%

Research progress of selective brain cooling methods in the prehospital care for stroke patients: A narrative review

Ji¹,

Chen²,

An³

et al. 2023

Brain Circ

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Over the past four decades, therapeutic hypothermia (TH) has long been suggested as a promising neuroprotective treatment of acute ischemic stroke (AIS). Much attention has focus on keeping the hypothermic benefits and removing side effects of systemic hypothermia. In the past few years, the advent of intravenous thrombolysis and endovascular thrombectomy has taken us into a reperfusion era of AIS treatment. With recent research emphasizing ways to plus neuroprotective treatments to reperfusion therapy, the spotlight is now shifting toward the study of how selective brain hypothermia can offset the drawbacks of systemic hypothermia and be applied in prehospital condition. This mini-review summarizes current brain cooling methods that can be used for inducing selective hypothermia in prehospital care. It will guide the future development of selective cooling methods, extend the application of TH in prehospital care, and provide insights into the prospects of selective hypothermia in AIS.

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Active conductive head cooling of normal and infarcted brain: A magnetic resonance spectroscopy imaging study

Cited by 8 publications

References 40 publications

Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia

Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia

Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study

Research progress of selective brain cooling methods in the prehospital care for stroke patients: A narrative review

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