Fever And Stroke: Is There A Link?

Fever is a common complication after a stroke, with between 40% and 60% of patients experiencing a rise in body temperature. Fever is associated with a worse prognosis, with patients exhibiting a higher risk of death and more severe neurological deficits. The underlying mechanism for this is the heightened inflammatory response induced by the elevated temperature, which increases the permeability of the blood-brain barrier, leading to cerebral edema and neuronal death.

In the INTREPID study, an international research team led by Dr. David Greer found that stroke patients treated proactively with a temperature control device experienced half as much fever as those treated reactively. However, after three months, the treatment did not significantly improve functional or cognitive outcomes.

Fever is a common complication after a stroke

Fever is a common complication following a stroke, with between 40% and 60% of patients experiencing a raised temperature. In fact, one source suggests that approximately 50% of patients hospitalised for stroke develop a fever.

Fever after a stroke is often caused by infections, such as pneumonia, urinary tract infections, and viral infections. In some cases, the infection may have been acquired before the stroke. However, fever can also be endogenous, caused by immune system activation or the effects of the brain lesion on thermoregulatory centres. This type of fever is often difficult to distinguish from infection-induced fever and is typically resistant to antibiotic and antipyretic treatment.

Fever after a stroke is associated with poorer outcomes, including increased mortality and greater disability. This is because fever causes a heightened inflammatory response, which makes the blood-brain barrier more permeable to immune cells, leading to cerebral edema and neuronal death. It also increases the production of free radicals, promoting glutamate release and excitotoxicity.

The American Heart Association recommends that normothermia (a body temperature of below 37.6°C) should be the standard of care for patients who have had a stroke. Acetaminophen is the primary treatment for fever in these patients, although ibuprofen is sometimes used despite concerns about an increased risk of bleeding. Physical cooling measures, such as ice packs and fans, are also used, but there is limited evidence for their effectiveness.

Fever after a stroke is often caused by infection

Fever after a stroke is common and is often caused by infection. In fact, between 40% and 61% of patients who experience a stroke develop a fever.

Infection is the cause of fever in most cases after a stroke. A study of 119 patients hospitalized after an ischemic stroke found that 25% of these patients had a fever within 24 hours of experiencing stroke symptoms, and 32% had a body temperature higher than 37.5°C within 48 hours. The probable causes of fever within 48 hours after an ischemic stroke included pneumococci, streptococci, Escherichia coli, enterococci, parainfluenza virus, and influenza virus type A. The authors concluded that most fevers (83%) could be explained by infectious or chemical aspiration pneumonia.

In addition to infection, there are other causes of fever after a stroke. In severe stroke, massive tissue necrosis can elevate body temperature. The presence of blood in the brain can also cause a noninfectious fever. Within hours after a hemorrhage, lysis of blood cells leads to the accumulation of free blood constituents like hemoglobin and hemoglobin degradation products such as heme, which have been shown to induce fever in animal studies.

Fever after a stroke is associated with poor outcomes. Patients with a fever are far more likely to die within the first 10 days after a stroke than those with lower temperatures. Fever occurring after a stroke has been linked to larger lesion size, higher mortality, and worse neurological outcomes.

Fever is associated with a more severe neurological deficit on admission

Fever is a common occurrence in patients with stroke, with between 40% and 61% of stroke patients developing a fever. Fever occurring after stroke is associated with poor outcomes, including severe neurological deficit and a poor outcome.

Several studies have found that fever is associated with a more severe neurological deficit on admission. One study found that fever was associated with a more severe deficit on admission independent from age, vascular diseases and risk factors. Another study found that fever was negatively associated with a good outcome.

Fever can be caused by infection or by the stroke itself. In one study, the probable cause of fever within 48 hours after stroke included infective or chemical aspiration pneumonia, other respiratory tract infection, urinary tract infection, viral infections, or insufficiently defined causes. In about half of the infected patients, the infection was probably acquired before the stroke.

Fever can also be caused by non-infectious factors, such as the presence of blood in the brain. Within hours after a haemorrhage, lysis of blood cells leads to the accumulation of free blood constituents like haemoglobin, which can cause a febrile response.

The distinction between infectious and non-infectious fever is important because standard antipyretics are ineffective against non-infectious fever. The timing of fever can indicate its origin: if pre-existing infection is excluded, early fever in stroke patients can indicate a neurological origin.

Fever prevention in stroke patients is feasible and effective

Fever prevention in stroke patients can be achieved through a combination of physical cooling measures and the administration of antipyretics. Physical cooling measures include ice packs, air and water circulating blankets, water circulating pads, and iced saline administration. However, physical cooling measures should only be used in conjunction with antipyretics to avoid shivering, which increases oxygen use and metabolic demand.

Antipyretics, such as acetaminophen, are the first line of therapy for fever prevention in stroke patients. It is important to note that intravenous administration of acetaminophen requires close monitoring as it can cause hypotension.

The INTREPID study, a randomized controlled trial of temperature modulation in critically ill cerebrovascular patients, found that stroke patients treated proactively experienced half as much fever on average as those treated reactively after a fever occurred. This demonstrates that fever prevention in stroke patients is both feasible and effective.

Fever prevention in stroke patients does not improve functional or cognitive outcomes

Fever is a common occurrence after strokes, and higher temperatures have been linked to worse outcomes. Approximately 40% to 60% of patients hospitalized for stroke develop a fever, and those patients are more likely to die within the first 10 days after a stroke than those with lower temperatures. Clinical data supports that body temperatures higher than 37.5°C are significantly correlated with poor outcomes.

The INTREPID study was the largest randomized clinical trial of temperature modulation in critically ill cerebrovascular patients, involving 677 patients across 43 international sites. The researchers used a temperature control device that regulates patients' temperatures through an automated closed system using tightly adherent pads with water running through them. The team monitored patient temperatures and shivering hourly.

While fever prevention was found to be feasible and effective in the ICU setting, the study is now focused on investigating whether fever prevention improves functional outcomes in patients who have a higher likelihood of developing a fever to enhance patient recovery and quality of life.

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