How should persistent unexplained fever be evaluated and managed in an adult patient with a midbrain contusion after traumatic brain injury?

Management of Persistent Unexplained Fever in Midbrain Contusion Patients

Initiate controlled normothermia immediately using automated feedback-controlled temperature management devices targeting 36.0-37.5°C, as antipyretic medications alone are insufficient for effective temperature control in brain injury patients with central fever. 1

Immediate Temperature Control Strategy

Begin automated feedback-controlled temperature management without delay while investigating fever source, as fever duration correlates with worse neurological outcomes regardless of etiology. 1 The key principle is that treatment should not be delayed while searching for the source—act immediately. 1, 2

Target Parameters

• Core temperature: 36.0-37.5°C 3, 1
• Temperature variation: ≤±0.5°C per hour and ≤1°C per 24-hour period 3, 1
• Continue throughout the acute phase while the brain remains at risk of secondary injury 3, 1

Why Automated Devices Are Essential

Midbrain contusions specifically predispose to neurogenic fever through thermoregulatory center disruption. 3 Antipyretics (acetaminophen, NSAIDs) have limited efficacy in severe TBI and should only serve as adjuncts during induction, not primary therapy. 3, 1 Studies demonstrate that induced normothermia via intravascular cooling reduces fever burden from 10.6% to 1.6% and significantly decreases intracranial hypertension. 4

Parallel Diagnostic Workup

While initiating temperature control, simultaneously investigate infectious causes:

Mandatory Initial Studies

• Chest radiograph for all ICU patients with new fever 1, 2
• At least two sets of blood cultures (60 mL total) to identify bacteremia 1, 2
• CT imaging if recent surgery to exclude surgical site infections 1, 2
• Lumbar puncture if mental status changes are unexplained and not contraindicated 1

Critical Context

Up to 50% of fever in neurocritical care patients is non-infectious in origin, but this should never delay treatment. 1 Neurogenic fever occurs in 4-37% of TBI survivors and is essentially a diagnosis of exclusion. 5

Pathophysiological Rationale for Aggressive Management

Fever in midbrain contusions is particularly dangerous because:

• Increases brain metabolic rate, cerebral blood flow, and intracranial pressure 3, 1
• Enhances neurotransmitter release and free radical production 1
• Aggravates excitotoxicity, inflammation, and apoptosis 1
• Brain temperature can be up to 2°C higher than systemic temperature and varies independently based on pathology 3

Temperature Monitoring Approach

Use central temperature monitoring (bladder catheter, esophageal thermistor, or pulmonary artery catheter) rather than peripheral sites. 3, 2 Continuous monitoring is preferable to intermittent measurements for precise control. 3, 2

Duration of Treatment

Continue controlled normothermia for as long as the brain remains at risk of secondary injury, particularly in patients with:

• Seizures or high seizure risk 3, 1
• Impending herniation or obliterated basal cisterns 3
• Significant mass effect requiring tier 1-2 ICP management 1

Common Pitfalls to Avoid

• Relying solely on antipyretics is insufficient for temperature control in severe TBI 3, 1
• Delaying treatment while investigating fever source worsens outcomes 1, 2
• Discontinuing temperature control too early while the brain remains vulnerable 3, 1
• Using peripheral temperature monitoring instead of central monitoring leads to inaccurate assessment 3, 2

Role of Pharmacological Adjuncts

Acetaminophen or NSAIDs may be used as adjunctive therapy during the induction phase, with daily dosages up to 6000 mg of acetaminophen showing modest temperature-lowering effects. 1 However, these should never be the primary management strategy. 3, 1