A stroke occurs when blood flow to a part of the brain is interrupted, depriving brain cells of oxygen and nutrients and leading to cell damage or death. Following a stroke, the body can experience various complications, with fever being a significant concern. Understanding why fever occurs and how it is managed is important for recovery.
Why Fever is a Concern After Stroke
An elevated body temperature following a stroke poses a serious threat to the already compromised brain. Even a slight increase in temperature can worsen the initial injury, leading to secondary brain injury. This occurs when weakened brain tissue becomes more vulnerable to further damage. For every 1°C increase in temperature, the odds of poor outcomes and short-term mortality may increase by 2.2, particularly within the first 24 hours after an ischemic stroke.
Fever increases the brain’s metabolic demand, requiring more oxygen and glucose from an already limited blood supply. This heightened demand in compromised tissue can extend the area of brain damage. Hyperthermia can exacerbate neuronal injury, leading to increased blood-brain barrier breakdown, heightened inflammatory responses, and potentially more extensive cell death.
The relationship between increased temperature and poor outcomes is consistently observed across various types of brain injuries, including ischemic and hemorrhagic strokes. The timing of fever also appears to matter, with elevated temperatures in the first 24 hours after stroke onset being strongly associated with larger infarct volumes and poorer neurological outcomes.
Common Causes of Fever After Stroke
Fever in stroke patients can arise from several sources, with infections being the most frequent cause. Stroke-associated pneumonia (SAP) is a common respiratory infection, occurring in 7% to 22% of stroke patients. This often results from dysphagia, or difficulty swallowing, which can lead to aspiration—inhaling food or liquids into the lungs. Immobility following a stroke also contributes to the risk of pneumonia due to reduced lung expansion and impaired clearance of secretions.
Urinary tract infections (UTIs) are another common infection, with incidence rates ranging from 1% to 24% within the first week to month after a stroke. Stroke patients are more susceptible to UTIs due to factors such as bladder dysfunction and the increased use of urinary catheters. These infections can prolong hospital stays. Other infections like skin infections or sepsis can also occur, often linked to prolonged immobility or medical interventions.
Beyond infections, some fevers after a stroke are non-infectious, termed “central fever” or “neurogenic fever.” This type of fever results directly from damage to the brain’s temperature-regulating centers, primarily the hypothalamus. Central fever is characterized by a rapid onset of high temperature, often with significant fluctuations, and typically does not respond well to standard antipyretic medications. It is more commonly seen in cases of severe stroke and is diagnosed after ruling out infectious causes through detailed investigations.
Treatment and Monitoring Approaches
Managing fever in stroke patients involves careful monitoring and a multi-pronged approach to treatment. Regular temperature monitoring is a standard practice, with guidelines suggesting measurements at least every four hours in the hospital, and more frequently in the emergency department. This helps identify fever early, as prompt intervention can be beneficial.
Pharmacological treatments often include antipyretic medications like acetaminophen (paracetamol). Major stroke guidelines recommend treating fevers above 37.5°C with paracetamol. While acetaminophen can effectively reduce body temperature, its effect on long-term functional outcomes in stroke patients has shown mixed results in studies.
In cases of severe or persistent fever, non-pharmacological cooling methods may be employed. These can include external cooling techniques such as cooling blankets or cool compresses. Ice packs may be placed on the groin, armpits, and neck to facilitate heat loss. Physical cooling methods are often used in conjunction with antipyretics to prevent shivering, which can counteract cooling efforts by generating more heat. Treating the underlying cause of the fever, such as administering antibiotics for bacterial infections, is paramount for effective management.
Preventing Fever and Its Effects
Proactive measures are implemented to reduce the risk of fever and its detrimental effects in stroke patients. Infection control practices are foundational, including strict hand hygiene among healthcare providers and proper care of medical devices like urinary catheters. Limiting unnecessary catheterization or using antiseptic-coated catheters can reduce the risk of catheter-associated UTIs.
Early mobilization and rehabilitation are encouraged, often beginning as soon as 24 hours after the stroke, once the patient is stable. This helps prevent complications associated with immobility, such as pneumonia and deep vein thrombosis.
Swallowing assessments are routinely performed to identify dysphagia, a common post-stroke complication that significantly increases the risk of aspiration pneumonia. Based on these assessments, diet modifications, such as thickened liquids or pureed foods, and specific feeding techniques are implemented to prevent aspiration. In some cases, a nasogastric tube or percutaneous endoscopic gastrostomy (PEG) may be necessary for safe nutrition and hydration. Adequate hydration is also maintained, often through intravenous fluids initially, to prevent dehydration and complications.