Amid a prolonged heatwave, warnings are plentiful against heat-related illnesses, ear infections, and conjunctivitis associated with water activities.

However, people, especially older adults, should also be cautious of cerebral infarction, which occurs when blood vessels in the brain become blocked, experts say.

While cerebral hemorrhage is more common during seasonal changes when temperatures fluctuate greatly, cerebral infarction tends to increase in the summer due to the heat. When the weather is hot, dehydration causes water to leave the body, making blood vessels more susceptible to blockage.

“When the temperature rises, the body releases large amounts of moisture through sweat to lower its temperature. During this process, blood viscosity increases, and the likelihood of blood clots forming also rises,” said Dr. Kim Hyun-gon, director of the Department of Neurosurgery at Bundang Jesaeng Hospital. “As blood vessels expand to lower body temperature, blood pressure and blood flow speed decrease, slowing blood circulation, which can also lead to cerebral infarction.”

During the summer, blood vessels expand to lower body temperature, which slows blood flow and reduces blood supply to brain cells. Additionally, dehydration reduces the body's water content, increasing blood viscosity and making blood clots more likely to form. These clots, commonly known as “blood clots,” can travel through the bloodstream and block blood vessels in the brain, resulting in cerebral infarction, Kim explained.

“Those with pre-existing conditions, such as hypertension, diabetes, arrhythmia, or a family history of stroke, should be particularly vigilant during the summer. Additionally, sudden exposure to high temperatures after being in an air-conditioned environment can cause the sympathetic nervous system to overactivate, leading to vasoconstriction and increasing the risk of stroke,” Dr. Kim noted.

To prevent heatstroke, it is essential to stay hydrated and avoid extreme temperature fluctuations. For high-risk individuals, careful health management is essential.

“A stroke is a cerebrovascular disease in which blood vessels supplying blood to the brain become blocked or ruptured, damaging cells that receive blood flow and causing various neurological deficits in the brain. When a stroke occurs, symptoms, including headache, paralysis, speech disorders, and loss of consciousness, may appear, and patients may suffer lifelong disabilities as sequelae, so prevention is crucial,” he advised.

To prevent strokes during the summer, it is important to regulate body temperature. During the hot daytime hours, avoid outdoor activities. In air-conditioned indoor spaces, set the temperature appropriately to prevent body temperature from dropping too low, and ventilate regularly to circulate the indoor air. Additionally, people should drink plenty of water, avoid excessive alcohol consumption and smoking, and consume sufficient amounts of water-rich foods such as vegetables and fruits.

To prevent cerebrovascular diseases, maintaining a healthy diet, engaging in regular exercise, quitting smoking, managing stress, and controlling blood pressure and blood sugar levels are all crucial. If sudden symptoms, such as one-sided paralysis or language disorders, occur, it is vital to visit the emergency room immediately.