What are the causes of post-stroke (cerebrovascular accident) fever?

From the Guidelines

Fever after a stroke is a medical emergency that requires immediate attention, and the first step is to identify and treat the underlying cause, which is often an infection such as pneumonia, urinary tract infection, or infected IV lines, as hyperthermia is associated with poor neurological outcome and increased mortality 1.

Key Considerations

• Fever is common after a stroke, occurring in approximately one third of patients, and is associated with poor neurological outcome and increased mortality 1.
• The underlying cause of fever should be identified and treated promptly, with antibiotics started empirically after appropriate cultures are obtained if infection is suspected 1.
• Acetaminophen (Tylenol) is the preferred antipyretic at doses of 650-1000mg every 4-6 hours (maximum 4g daily) to reduce temperature, although its effectiveness in reducing fever in stroke patients is modest 1.
• Physical cooling methods like cooling blankets may be used for persistent high fevers, and temperature should be maintained below 37.5°C (99.5°F) to prevent hyperthermia and its associated negative effects on brain injury and outcomes 1.

Infection Management

• Pneumonia and urinary tract infections are common causes of fever after a stroke, and antibiotics should be tailored to the likely source of infection 1.
• For pneumonia, options include ceftriaxone 1-2g IV daily plus azithromycin 500mg daily; for UTI, ceftriaxone 1-2g IV daily or ciprofloxacin 400mg IV twice daily 1.
• Regular monitoring of vital signs, neurological status, and infection markers is essential to ensure prompt detection and treatment of infections 1.

Outcome Improvement

• Fever management is critical because each 1°C increase in body temperature can increase the metabolic rate by 10-13%, increasing oxygen demands in already compromised brain tissue 1.
• Maintaining normothermia or lowering an acutely elevated body temperature has been hypothesized to improve the prognosis of patients with stroke, although the evidence is not yet conclusive 1.

From the Research

Fever Post Stroke

• Fever is a common complication in patients hospitalized for stroke, with approximately 50% of patients developing fever 2.
• High body temperature is significantly correlated to initial stroke severity, lesion size, mortality, and neurologic outcome 2.
• Fever occurring after stroke is associated with poor outcomes, and oral antipyretics are only marginally effective in lowering elevated body temperature in this population 2.

Treatment of Fever Post Stroke

• Nonpharmacologic approaches to cooling have been more effective in achieving normothermia, but whether stroke outcomes can be improved remains unclear 2.
• A 4-step standard operating procedure for the treatment of fever in patients with acute stroke has been shown to be effective in reducing fever duration and achieving normothermia 3.
• The use of paracetamol, metamizole, and calf compress can lead to significant reduction in body temperature, and infusion of cooled saline solution can be used in patients who do not respond to these applications 3.

Infections and Fever Post Stroke

• Post-stroke infections, such as pneumonia and urinary tract infections, are common complications and contribute to mortality in stroke patients 4, 5.
• Hyperthermia following stroke is associated with neuronal damage and worse outcomes, and post-stroke immunosuppression and activation of inflammatory mediators can cause infections 4.
• Early antibiotic therapy may reduce the rate of post-stroke infections and fever spikes, but does not improve functional outcome or reduce mortality and morbidity 4.

Antibiotic Treatment

• Amoxicillin-clavulanic acid has been shown to be effective in treating febrile urinary tract infections in children under five years old, with superior short-term therapeutic efficacy compared to ceftriaxone sodium 6.
• The use of antibiotics, such as ceftriaxone, levofloxacin, penicillin, and minocycline, has been studied in the context of post-stroke infections, but the benefits of prophylactic antibiotic therapy are unclear 4.