High Body Temperature: A Stroke Trigger?

Extreme temperatures, both hot and cold, have been found to increase the risk of stroke mortality. In addition, high temperatures can cause heat-related issues such as dehydration and heat stroke, which can also increase stroke risk. A study of eight large cities in China found that both cold and hot temperatures were associated with an increased risk of stroke mortality, with the effects of cold temperatures lasting longer than those of hot temperatures. Another study found that approximately 50% of patients hospitalized for stroke develop a fever, which is associated with poor outcomes.

High temperatures can cause heat stroke and dehydration, which increases stroke risk

High Temperatures, Heat Stroke, Dehydration, and Stroke Risk

High temperatures can cause heat stroke and dehydration, which increases the risk of stroke.

Heat stroke is a form of hyperthermia, a condition in which the body temperature rises above the normal range due to excessive heat exposure or physical exertion. Heat stroke occurs when the body's thermoregulatory mechanisms are overwhelmed and unable to cool down, resulting in a rapid increase in body temperature. Dehydration is a significant risk factor for heat stroke as it impairs the body's ability to dissipate heat through sweating and can lead to a dangerous elevation in body temperature.

According to a study by Renjie Chen et al., both high and low temperatures are linked to an increased risk of stroke mortality. The study analyzed data from eight large cities in China and found that hot temperatures had more immediate effects, while the effects of low temperatures lasted longer, up to two weeks. This suggests that extreme temperatures, in general, can impact stroke risk and mortality.

Additionally, high temperatures can lead to dehydration, which is a known risk factor for stroke. Dehydration causes a reduction in blood volume, which can lead to thickened blood and an increased risk of blood clots. These clots can block blood flow to the brain, resulting in a stroke. Dehydration can also affect blood pressure and heart function, further increasing the risk of stroke.

Furthermore, high temperatures and heat stroke can cause physiological changes that contribute to stroke risk. For example, during heat stroke, the body diverts blood flow away from the core to the periphery in an attempt to cool down. This can lead to reduced blood flow to the brain, increasing the risk of ischemic stroke. Additionally, the stress of extreme heat can trigger an inflammatory response, which has been linked to an increased risk of stroke.

In summary, high temperatures can cause heat stroke and dehydration, both of which are associated with an increased risk of stroke. The impact of temperature on stroke risk is complex and influenced by various factors, including geographical location, individual health status, and the presence of other risk factors. It is important to be aware of the potential risks associated with extreme temperatures and take appropriate precautions to stay hydrated and maintain a healthy body temperature.

High body temperature is correlated with initial stroke severity, lesion size, mortality, and neurological outcome

High body temperature is significantly correlated with initial stroke severity, lesion size, mortality, and neurological outcome. Fever occurring after a stroke is associated with poor outcomes. Experimental studies on animals show that a rise in body temperature after induced cerebral ischemia produces more extensive brain damage, and that hyperthermic ischemic rats tend to remain unresponsive and die soon after ischemia.

In humans, a study of 400 stroke patients found that stroke severity, as measured by the National Institutes of Health Stroke Scale, was positively associated with peak body temperature within 48 hours of stroke onset. Another study found that between 40% and 61% of patients hospitalized for stroke develop a fever, and those patients with a fever are far more likely to die within the first 10 days after a stroke than those with lower temperatures.

In addition, high body temperature causes the transformation of ischemic penumbra into infarction, increases blood-brain barrier breakdown, and increases apoptosis and the inflammatory response.

High temperatures can increase the risk of stroke mortality

The impact of temperature on health may be more noticeable in developing countries, where air conditioning is less used. Additionally, high temperatures can lead to dehydration and heat stroke, which can further increase the risk of stroke.

The exact reasons for the association between temperature and stroke mortality are complex and not yet fully understood. One possible explanation is that cold temperatures may lead to vasoconstriction, diverting blood flow away from the brain and increasing blood pressure. High temperatures, on the other hand, can cause an increase in heart rate, vasodilation, and sweating, reducing blood supply to the brain.

Furthermore, high temperatures are associated with worse endothelial function and can increase blood viscosity and cholesterol levels, which can contribute to microvascular thrombosis and stroke. The impact of temperature on stroke risk may also vary depending on geographic and meteorological characteristics, as well as individual risk factors such as age, gender, and pre-existing health conditions.

While the study provides valuable insights, it is important to note that it has some limitations. The analysis used 24-hour average outdoor temperatures, which may underestimate the effects of shorter periods of extreme temperatures. Additionally, people tend to spend more time indoors during extreme weather, which could also impact the results. Further research is needed to fully understand the complex relationship between temperature and stroke risk.

High temperatures can cause vasodilation and sweating, reducing blood supply to the brain

A study by Chen et al. found that both cold and hot temperatures were associated with an increased risk of stroke mortality in China. The study examined the effects of temperature on daily stroke mortality in eight Chinese cities, finding that the adverse effects of hot temperatures were more immediate, while the effects of cold temperatures lasted longer.

Another study by Renjie Chen et al. showed that approximately 50% of patients hospitalized for stroke develop a fever. The study also found that high body temperature is significantly correlated with initial stroke severity, lesion size, mortality, and neurological outcome.

Extreme temperatures and high humidity can increase the risk of heat-related issues such as dehydration and heat stroke. These weather conditions can also increase the risk of stroke for some people.

Additionally, a study by Ström et al. found that body temperature elevation within 48 hours of stroke onset is common and associated with neurological status at admission. The study hypothesized that the initial elevation of body temperature may be due to local effects on cerebral thermoregulatory centers or stimulation of the immune system caused by necrosis.

Furthermore, high temperatures can lead to an increase in heart rate, vasodilation, and sweating, which can reduce blood supply to the brain. This reduction in blood flow can potentially trigger a stroke, especially in individuals who are already at risk.

In summary, while high temperatures can cause vasodilation and sweating, reducing blood supply to the brain, it is important to note that both high and low temperatures have been associated with an increased risk of stroke and stroke mortality. The underlying mechanisms involve the impact of temperature on the body's thermoregulatory responses, cardiovascular system, and immune function.

High temperatures can increase the likelihood of microvascular thrombosis and stroke

The impact of temperature on health is more easily identified in developing countries, where air conditioning is less used. A study of eight large cities in China found that both cold and hot temperatures were associated with an increased risk of stroke mortality. The study included almost 48 million urban residents, and during the study period, there were 127,750 stroke deaths. The annual mean temperature ranged from 8.2°C in Shenyang to 23.7°C in Hong Kong, capturing the temperature variations in China.

The effects of high temperatures on stroke risk are more immediate, while the effects of low temperatures can last for more than two weeks. The pooled relative risks of extreme cold and cold temperatures over lags of 0-14 days were 1.39 and 1.11, respectively, compared to the 25th percentile of temperature. In contrast, the relative risks of stroke mortality over lags of 0-3 days were 1.06 for extreme hot temperatures and 1.14 for hot temperatures, compared to the 75th percentile.

The exact reasons for the observational differences between hot and cold temperatures are difficult to determine, but may involve differences in study populations, geographic and meteorological characteristics, periods of the study, and healthcare systems. Additionally, study designs and analytical strategies may contribute to the inconsistency between results. Most previous studies assumed a linear association between temperature and stroke risk, without considering the possibility of nonlinear relationships.

High temperatures can lead to an increased risk of stroke through several mechanisms. Firstly, the body needs to increase heat diffusion via thermoregulatory means such as elevating heart rates, vasodilation, and sweating. As a result, blood supply to the brain may be reduced, and existing ischemia may be aggravated. Dehydration on hot days may also increase blood viscosity and cholesterol levels, which can, in turn, increase the likelihood of microvascular thrombosis and subsequent stroke.

Furthermore, high temperatures are associated with worse endothelial function, which can impact blood vessels and blood flow. Endothelial dysfunction can lead to a prothrombotic state, increasing the risk of blood clots and stroke. Additionally, high temperatures can cause hemo-concentration, which can also contribute to the increased incidence of ischemic stroke in individuals predisposed to stroke.

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