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![[Sunwoo Yong-nyeo YouTube]](https://wimg.heraldcorp.com/news/cms/2026/10/02/news-p.v1.20261002.1ae16f986dcd4fcc9fad0bbc387f85ed_P1.png)
Actor Sunwoo Yong-nyeo has said that after suffering a cerebral infarction, she was left with a lingering aftereffect: her ankle no longer sweats properly. Stroke can alter not only the strength and sensation in the limbs but also autonomic functions such as perspiration and body-temperature regulation.
Sunwoo recently visited a charcoal sauna in Wonju, Gangwon Province, and shared the experience on her YouTube channel. "The cerebral infarction affected my ankle area," she said. "So my ankle does not sweat. Where it does not hurt, it does not feel hot — but where it is uncomfortable, it stings and burns."
She has spoken about charcoal saunas before, noting that "where circulation is good, sweat pours out, but only the places that hurt do not sweat."
Cerebral infarction occurs when a blocked blood vessel cuts off blood supply to brain tissue, causing damage. Depending on which area of the brain is affected and which neural pathways are involved, aftereffects can include impaired movement, sensation, and sweating in the arms or legs.
Reduced sweating on one side after stroke is linked to autonomic dysfunction — research confirms the pattern persists for months
Sweat is not simply produced by the skin on its own. When body temperature rises, the brain and autonomic nervous system send signals to the sweat glands, which release perspiration; as it evaporates, it draws heat away from the body.
When a stroke damages the neural networks involved in this regulatory process, sweat secretion can change. Autonomic dysfunction after stroke has been associated with problems regulating blood pressure and heart rate, as well as sensations of coldness in one arm or leg and asymmetric sweating between the two sides of the body.
Research measuring sweat responses in cerebral infarction patients has confirmed that asymmetric perspiration between the two sides of the body can appear after stroke. In some cases, the change persisted not only through the acute phase but for several months or longer.
More recent studies have also reported that sensations of coldness and abnormal sweating in paralyzed limbs after stroke appear to be related to changes in autonomic — particularly sympathetic — nervous system regulation.
Sunwoo's description of her ankle not sweating can be understood in the context of these post-stroke autonomic changes. However, the specific area of reduced sweating cannot be used on its own to pinpoint the exact location of the brain damage from the infarction.
A charcoal sauna is not an MRI — stinging or dryness in the heat does not diagnose disease
Sunwoo described the charcoal sauna as "like an MRI," saying that areas of discomfort neither sweat nor feel hot but instead sting.
In a high-temperature environment, the skin's blood vessels dilate and sweat production increases, which can make unusual sensations more noticeable than usual. For someone who has experienced changes in sensation or autonomic function after a stroke, the same heat stimulus may feel different depending on the part of the body.
The fact that a particular area stings or sweats less in the heat does not mean that area has poor circulation or an underlying condition.
An MRI uses magnetic fields and radio waves to produce images of internal structures — the brain, spinal cord, joints, and organs. It operates on an entirely different principle from detecting problem areas through the degree of sweating or heat sensation.
There is also insufficient evidence that charcoal saunas or conventional saunas treat the aftereffects of cerebral infarction. Observational research has found that frequent sauna users have a lower risk of stroke than non-users, but that does not mean sauna use treats stroke or prevents recurrence.
For the motor and sensory impairments that remain after stroke, rehabilitation tailored to the individual patient's condition is the standard approach. The American Stroke Association recommends rehabilitation to restore muscle strength, gait, balance, and daily functioning as a core part of stroke recovery.
Blood pressure can drop in high heat — older adults and stroke survivors should limit their time inside
In a sauna or charcoal sauna, the high temperature causes the skin's blood vessels to dilate and triggers heavy sweating, which can lower blood pressure. Significant fluid loss can also lead to dehydration.
Recent research analyzing heat exposure from hot baths and saunas found that peripheral vasodilation and fluid loss can cause low blood pressure, fainting, and heat-related illness. Older adults and those with cardiovascular conditions need to be particularly careful.
People taking blood pressure medication may experience dizziness if they stand up suddenly after leaving a hot environment. Sauna research has also reported that the combination of dehydration, low blood pressure, and alcohol consumption can significantly increase risk.
Stroke survivors who use a charcoal sauna or conventional sauna should monitor how their body feels rather than staying inside for extended periods, and should drink plenty of water. If dizziness, palpitations, nausea, or a severe headache develops, they should leave the hot space immediately.
If new neurological symptoms appear — sudden drooping on one side of the face, sudden weakness in one arm or leg, or slurred speech — this is not a situation to rest through inside a sauna. Delayed treatment allows brain damage to worsen, so emergency medical care must be sought immediately.
Changes in sweating in specific areas after a cerebral infarction, as Sunwoo described, are among the aftereffects that can genuinely occur. There is an important distinction between noticing changes in the body in a hot environment and using those changes as a diagnostic tool. After a cerebral infarction, consistently monitoring remaining aftereffects and continuing rehabilitation and recurrence prevention are what matter most.
rainbow@heraldcorp.com
