As Summer begins in Chennai, heat-related illnesses are becoming a significant public health concern. Among them, heat stroke stands out as a life-threatening emergency affecting the brain and nervous system. From the neurological standpoint, heat stroke results from failure of the body’s thermoregulatory mechanisms causing cerebral damage.

Heat stroke occurs when the body’s core temperature rises above 40°C (104°F), overwhelming its ability to dissipate heat. Under normal circumstances, the hypothalamus — the brain’s temperature-regulating center, maintains equilibrium through sweating and vasodilation. However, during extreme heat exposure, dehydration, or prolonged physical exertion, these mechanisms fail. The result is a cascade of cellular injury, systemic inflammation, and neurological dysfunction.

The consequences of heat related medical conditions range  from mild muscle cramps to severe complications such as altered mental status, , rhabdomyolysis and acute kidney injury. Heat stroke can lead to altered mental status. Patients may initially present with confusion, irritability, or disorientation. As the condition progresses, symptoms can escalate to  seizures, coma and death.

From a pathophysiological perspective, elevated temperatures disrupt neuronal integrity. Proteins undergo structural breakdown, the blood-brain barrier becomes more permeable, and cerebral edema may develop. In severe cases, this can lead to long-term complications such as memory impairment, motor deficits, or persistent vegetative state. The cerebellum, particularly Purkinje cells, is highly sensitive to heat injury, which explains why survivors may exhibit coordination and balance issues.

Certain populations are more vulnerable to get heat stroke. Elderly individuals, children, and those with chronic neurological conditions are at higher risk. Certain common medications such as anticholinergics, antipsychotics, and antidepressants can impair sweating and thermoregulation, further increasing susceptibility. Additionally, patients with prior strokes or neurodegenerative diseases may have abnormal autonomic responses, making them susceptible to heat stress. Another important factor is people taking less water during the summer leading to dehydration and adding to the existing risk. People who exercise excessively in heat also are higher risk. Environmental and occupational factors also play a critical role. Outdoor workers, athletes, and individuals in poorly ventilated environments are particularly at risk. Hydration status, clothing, and acclimatization also influence individual risk profiles.

Recognizing early warning signs can be lifesaving. Symptoms such as intense headache, dizziness, nausea, and excessive fatigue should not be ignored. A key distinguishing feature is the absence of sweating in many cases of classic heat stroke, although exertional heat stroke may still present with profuse sweating. Skin may feel hot and dry, pulse becomes rapid, and breathing may be shallow. Immediate management is based  on rapid cooling and supportive care. This includes moving the patient to a shaded or air-conditioned environment, removing excess clothing, and initiating active cooling measures such as cold water immersion, ice packs, or evaporative cooling techniques. Intravenous fluids are often required to correct dehydration and maintain circulation. Importantly, delays in cooling are directly associated with worse neurological outcomes. If there is associated kidney Injury, multidisciplinary team management including neurologist, nephrologist and intensivist is necessary.

 As summer is intensifying in cities, prevention remains the most effective strategy. Public awareness campaigns, workplace safety regulations, and community level interventions are needed. Simple measures like adequate hydration, avoiding peak sun hours, wearing light clothing, and ensuring proper ventilation can reduce the risk of heat stroke. Vulnerable individuals should be closely monitored during heat waves, and caregivers must remain vigilant for early signs of distress.