Fever Control in Neurocritical Care

Abstract

Fever is a frequent and clinically significant challenge in neurocritical care, associated with worsened outcomes in patients with acute brain injury. This review synthesizes current evidence on epidemiology, pathophysiology, risk factors, clinical features, diagnostic strategies, and management of fever in neurocritical settings, with an emphasis on recent advances and guideline-based recommendations. The article addresses the impact of fever on neuronal injury, explores the mechanistic underpinnings of temperature-related secondary brain damage, and highlights practical implications for intensive care management, aiming to optimize neurologic recovery and minimize complications.

Introduction

Fever, defined as a core body temperature exceeding 38°C, is a common occurrence in patients admitted to neurocritical care units (NCCUs). Its prevalence in this population is driven by the combination of central thermoregulatory dysfunction, infectious and non-infectious etiologies, and invasive interventions. Fever in the context of acute brain injury has been consistently linked to poorer neurologic outcomes, increased length of stay, and higher mortality rates. The management of fever in neurocritical care thus represents an area of paramount clinical importance, requiring a nuanced understanding of its underlying mechanisms, systemic effects, and evidence-based intervention strategies.

Epidemiology / Disease Burden

Fever occurs in up to 70% of patients with severe traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH), and ischemic stroke treated in NCCUs. Both infectious and non-infectious causes contribute significantly to the fever burden, with non-infectious or "central fever" accounting for a substantial proportion, particularly in the early phase post-injury. Epidemiological studies demonstrate that persistent fever, rather than short-lived hyperthermia, is associated with adverse neurologic sequelae. The disease burden is further amplified by the increased risk of secondary complications, such as seizures, increased intracranial pressure (ICP), and metabolic dysfunction, significantly impacting patient morbidity and resource utilization.

Pathophysiology

The pathophysiology of fever in neurocritical care is multifactorial. Brain injury disrupts central thermoregulation, particularly within the hypothalamus, leading to impaired homeostatic control. Release of endogenous pyrogens (e.g., interleukin-1, interleukin-6, tumor necrosis factor-α) in response to tissue injury or infection increases the hypothalamic set-point, resulting in systemic fever. Hyperthermia exacerbates neuronal injury through multiple mechanisms: it increases cerebral metabolic demand, augments excitotoxicity, promotes blood-brain barrier disruption, and enhances the inflammatory cascade. These effects create a vicious cycle of secondary brain injury, underscoring the urgency of prompt fever control in susceptible patients.

Risk Factors

Risk factors for fever in neurocritical care patients include the severity and location of brain injury, mechanical ventilation, invasive monitoring devices (e.g., external ventricular drains), immunosuppression, and the presence of systemic infections such as pneumonia or urinary tract infections. Central fever is particularly prevalent in cases of hypothalamic involvement, diffuse axonal injury, or extensive cortical damage. Patient-specific factors such as advanced age, diabetes, and prior use of immunomodulatory therapy may further predispose to both infectious and non-infectious fever.

Clinical Features

Clinically, fever in the neurocritical care population may manifest with or without systemic signs of infection. Central fever is often characterized by a lack of infectious source, persistent elevation of core temperature, and poor response to antipyretics. Associated features include tachycardia, diaphoresis, and hemodynamic instability. In patients with impaired consciousness, fever may be the only overt sign of underlying infection or neurologic deterioration, necessitating vigilant temperature monitoring and prompt evaluation.

Diagnosis

Diagnosis of fever in the neurocritical setting involves a thorough assessment to distinguish infectious from non-infectious etiologies. Workup includes serial temperature measurements, blood cultures, imaging studies (e.g., chest X-ray, brain CT/MRI), and analysis of cerebrospinal fluid when indicated. Biomarkers such as procalcitonin and C-reactive protein may aid in the identification of underlying infection but are not definitive. Differentiating central fever from infectious fever remains a clinical challenge; criteria include exclusion of infection, temporal relationship to brain injury, and response to temperature-lowering interventions.

Treatment & Management

The cornerstone of fever management in neurocritical care is the rapid identification and treatment of infectious causes, coupled with aggressive temperature control. Strategies include pharmacologic antipyretic agents (acetaminophen, non-steroidal anti-inflammatory drugs), external cooling devices (cooling blankets, surface or intravascular cooling catheters), and supportive measures such as fluid resuscitation and optimization of hemodynamics. In refractory cases, endovascular cooling may be considered. Non-pharmacologic interventions, including environmental temperature control and targeted temperature management (TTM), are increasingly employed, particularly in patients with severe TBI or post-cardiac arrest syndrome. The goal is typically to maintain normothermia (36–37.5°C) or prevent fever spikes, as hypothermia carries its own risks.

Recent Advances / Emerging Therapies

Recent advances in fever control focus on precision temperature management and personalized protocols. The development of advanced surface and intravascular cooling devices has improved the speed and precision of temperature regulation. Emerging therapies include selective brain cooling, transnasal evaporative cooling, and the use of novel pharmacologic agents targeting the inflammatory cascade. Clinical trials are ongoing to delineate the optimal target temperature and duration of therapy in various neurocritical populations. Artificial intelligence-driven monitoring systems and closed-loop feedback mechanisms are being explored to enhance real-time temperature control and reduce adverse events.

Guideline Recommendations

Current guidelines from the Neurocritical Care Society, American Heart Association/American Stroke Association, and other authoritative bodies recommend prompt investigation and management of fever in patients with acute brain injury. Normothermia is endorsed as the target range, with aggressive fever control advised for patients with TBI, SAH, ICH, and ischemic stroke. The use of pharmacologic and non-pharmacologic interventions should be tailored to patient-specific risk profiles, with close monitoring for complications such as shivering, electrolyte disturbances, and overshoot hypothermia. Multidisciplinary care and protocol-driven approaches are emphasized to ensure standardized, evidence-based management.

Conclusion

Fever control remains a critical aspect of neurocritical care, directly influencing neurologic outcomes in patients with acute brain injury. While significant progress has been made in understanding the pathophysiology and management of fever, ongoing research is needed to refine treatment protocols and integrate emerging technologies into clinical practice. Adherence to guideline recommendations, vigilant monitoring, and individualized care strategies are essential to optimize patient outcomes and mitigate the risks associated with fever in the neurocritical population.