Can subdural hematomas cause hypothermia?

Subdural Hematomas and Hypothermia

Subdural hematomas do not cause hypothermia; rather, therapeutic hypothermia may be used in specific cases of traumatic brain injury including subdural hematomas to control intracranial pressure. 1

Relationship Between Subdural Hematomas and Body Temperature

Subdural hematomas are a type of traumatic brain injury that can lead to increased intracranial pressure (ICP) and secondary brain damage. However, the current evidence does not support that subdural hematomas themselves cause hypothermia. Instead, the relationship between temperature and subdural hematomas is primarily therapeutic in nature.

Temperature Management in Traumatic Brain Injury

Temperature management is considered a key aspect of managing ICP in patients with traumatic brain injury, including those with subdural hematomas. The most recent guidelines recommend:

• Controlled normothermia (36.0-37.5°C) is recommended for Tier 1 and Tier 2 management of increased ICP 1
• Mild hypothermia (35.0-36.0°C) is only considered as a Tier 3 intervention for refractory intracranial hypertension 1
• Early application of measures to reduce heat loss and maintain normothermia is strongly recommended in trauma patients (Grade 1C) 1

Therapeutic Hypothermia in Subdural Hematoma Management

While subdural hematomas don't cause hypothermia, therapeutic hypothermia has been studied as a potential treatment for patients with subdural hematomas:

• Laboratory studies in rat models showed that mild (34°C) and moderate (32°C) hypothermia reduced brain edema formation beneath acute subdural hematomas 2
• Preoperative-induced mild hypothermia (33°C) may reduce neuronal damage in acute subdural hematoma models 3
• Combined mild hypothermia (35°C) with alkalizing agents showed significant reduction in brain water content and infarction volume in experimental models 4

However, clinical translation has been disappointing:

• A multicenter randomized clinical trial of hypothermia (33°C for 48h) for patients requiring evacuation of subdural hematoma was terminated early due to futility, with no statistically significant difference in functional outcomes between hypothermia and normothermia groups 5

Current Recommendations for Temperature Management

The current evidence-based approach to temperature management in patients with subdural hematomas includes:

1. Maintain normothermia (36.0-37.5°C) as the primary goal 1
2. Treat fever (core temperature >38.0°C) promptly, especially in the acute phase of TBI 1
3. Consider mild hypothermia (35.0-36.0°C) only as a Tier 3 intervention for refractory intracranial hypertension 1
4. If hypothermia is applied in TBI patients, it should:
   • Be initiated within the first 3 hours following injury
   • Be maintained for at least 48 hours
   • Include a 24-hour rewarming period
   • Maintain cerebral perfusion pressure >50 mmHg 1

Important Caveats and Pitfalls

• Hypothermia itself carries significant risks including coagulopathy, with a 1°C drop in temperature associated with a 10% drop in coagulation factor function 1
• Body temperatures below 34°C compromise blood coagulation 1
• Patients with subdural hematomas often require surgical intervention, and hypothermia-induced coagulopathy can increase bleeding risk
• Other potential complications include hypotension, hypovolemia, electrolyte disorders, insulin resistance, and increased infection risk 1

In conclusion, while therapeutic hypothermia has been studied as a potential treatment for subdural hematomas in specific circumstances, subdural hematomas themselves do not cause hypothermia. Current guidelines recommend maintaining normothermia in most cases of traumatic brain injury, with hypothermia reserved only for specific situations of refractory intracranial hypertension.