What is the management approach for a patient with a subdural hematoma, considering symptoms, anticoagulant therapy, and potential increased intracranial pressure?

Management of Subdural Hematoma

For subdural hematoma management, immediately assess for surgical indications (thickness >5mm with midline shift >5mm, neurological deterioration, or signs of herniation), reverse any anticoagulation emergently, maintain systolic blood pressure ≥100 mmHg and cerebral perfusion pressure 60-70 mmHg, and proceed with urgent surgical evacuation if symptomatic or conservative management with close neurological monitoring every 4 hours if small and asymptomatic. 1, 2, 3

Immediate Assessment and Stabilization

Diagnostic Imaging

• Obtain non-contrast head CT scan to characterize hematoma size, location, mass effect, and midline shift 1
• Evaluate specifically for compression of basal cisterns, ventricular effacement, or midline shift >5mm as indicators of increased intracranial pressure 1
• MRI with contrast may be considered only if spontaneous intracranial hypotension is suspected as underlying cause 1

Critical Hemodynamic Parameters

• Maintain systolic blood pressure ≥100 mmHg (ideally 100-150 mmHg) and mean arterial pressure 80-110 mmHg to ensure adequate cerebral perfusion 2, 3
• Target cerebral perfusion pressure (CPP) 60-70 mmHg if ICP monitoring is established (CPP = MAP - ICP) 1, 2, 3
• Hypotension (SBP <90-100 mmHg) is strongly associated with poor outcomes and must be avoided at all costs 3

Anticoagulation Assessment and Reversal

• Immediately verify anticoagulant or antiplatelet use, as these dramatically increase hematoma expansion risk 1, 2
• For patients on vitamin K antagonists (VKA) with INR ≥2.0: administer four-factor prothrombin complex concentrate immediately, followed by intravenous vitamin K to prevent later INR increase 4
• For patients on DOACs (dabigatran, apixaban, edoxaban, rivaroxaban): administer specific antidote immediately; if unavailable, use (activated) prothrombin complex concentrate instead 4
• For dabigatran specifically, hemodialysis can be considered for drug removal 4
• For unfractionated or low-molecular-weight heparin: administer intravenous protamine sulfate 4
• For antiplatelet therapy (aspirin, clopidogrel, ticagrelor, prasugrel): do NOT use platelet transfusions, as RCT data suggest worse outcomes in ICH patients receiving antiplatelet therapy who are treated with platelet infusion 4
• Target parameters before neurosurgery: platelet count >50,000/mm³, PT/aPTT <1.5 times normal control 2

Surgical Indications (Urgent Neurosurgical Consultation Required)

Immediate surgical evacuation is indicated for: 1, 2

• Subdural hematoma thickness >5mm with midline shift >5mm
• Development of altered consciousness or new/worsening focal neurological deficits
• Signs of cerebral herniation or severe intracranial hypertension
• Any symptomatic subdural hematoma causing neurological deterioration

Risk factors for delayed hematoma enlargement requiring surgery include: 5

• Large initial hematoma volume (independent predictor, OR 1.094)
• Degree of midline shift on initial CT (independent predictor, OR 1.433)
• Approximately 35% of initially nonoperative acute subdural hematomas may require delayed evacuation, with median time of 17 days after trauma

Conservative Management (Small, Asymptomatic Hematomas)

Monitoring Protocol

• Close neurological monitoring with serial examinations at least every 4 hours initially is the cornerstone of management 1, 3
• Maintain euvolemia to optimize cerebral perfusion 1
• Consider repeat imaging at 4-6 weeks to ensure resolution or stability 1
• 30-40% of subdural hematomas expand in first 12-36 hours, manifesting as neurological deterioration 3

ICP Monitoring Indications

• ICP monitoring is NOT routinely indicated for small subdural hematoma with normal neurological exam and no mass effect 1
• Consider ICP monitoring if: neurological surveillance is not feasible, hemodynamic instability is present, compressed basal cisterns or other severity signs exist on imaging, or after surgical evacuation with any of the following: preoperative GCS motor response ≤5, preoperative anisocoria or bilateral mydriasis, preoperative hemodynamic instability, brain midline shift >5mm, intraoperative cerebral edema, or postoperative appearance of new intracranial lesions 1, 3

Management of Increased Intracranial Pressure

Osmotherapy

• Use mannitol 20% at 250 mOsm dose (0.25 to 2 g/kg body weight as 15-25% solution), infused over 15-20 minutes (or 30-60 minutes per FDA labeling) for threatened intracranial hypertension or signs of brain herniation 4, 2, 3, 6
• Maximum effect occurs at 10-15 minutes, lasting 2-4 hours 3
• Alternatively, hypertonic saline (3%) can be used 4
• Monitor fluid, sodium, and chloride balance with osmotherapy 3
• Target serum osmolality 300-310 mOsmol/kg 4

Additional Measures

• Profound sedation, analgesia, intubation, and controlled mechanical ventilation with target PaCO2 of 35-40 mmHg 4, 2
• Do NOT use prolonged hypocapnia to treat intracranial hypertension 3
• Head elevation (though no RCT evidence exists for this measure) 4
• Maintain PaO₂ 60-100 mmHg 2

Blood Pressure Management During ICP Crisis

• Use rapid-onset, short-duration antihypertensive agents (e.g., IV nicardipine) to facilitate smooth titration and sustained blood pressure control 3
• Avoid large blood pressure variability—smooth, sustained control improves functional outcomes 3
• Avoid aggressive blood pressure lowering (SBP <130 mmHg) in spontaneous ICH as this is potentially harmful 4, 3

Surgical Technique and Perioperative Management

Intraoperative Considerations

• Fronto-parieto-temporo-occipital craniectomy with diameter of at least 12 cm, durotomy, and enlargement duroplasty 4
• Removing ischemic brain tissue is not recommended; however, concomitant intracranial bleeding/hematoma can be evacuated 4
• ICP monitor placement is recommended 4
• Maintain systolic blood pressure >100 mmHg or mean arterial pressure >80 mmHg during all interventions 2

Postoperative Management

• ICP and CPP monitoring, treatment of intracranial hypertension (>40% of patients develop postoperative intracranial hypertension after evacuation) 4, 3
• Control CT after 24 hours or earlier if signs of intracranial hypertension are present 4
• Monitor for hematoma re-accumulation with serial neurological exams and consider repeat CT at 24 hours, especially in anticoagulated patients 2
• Thromboembolic prophylaxis with subcutaneous low-dose heparin, low molecular weight heparin, or heparinoids from the second postoperative day, after consulting neurosurgeon 4
• Early mobilization and rehabilitation should be initiated once patient is awake, extubated, and without signs of significant intracranial hypertension 4

Critical Pitfalls to Avoid

• Never allow systolic blood pressure to drop below 90-100 mmHg—this is the most preventable cause of secondary brain injury 3
• Do not delay surgery in symptomatic patients with mass effect while awaiting "optimal" timing 2
• Do not underestimate small hematomas in anticoagulated elderly patients—they expand rapidly 2, 5
• Do not target CPP >70 mmHg routinely—increases complications (respiratory distress syndrome) without neurological benefit 3
• Do not use platelet transfusions for antiplatelet-associated ICH—RCT data show worse outcomes 4
• Do not perform non-emergent extracranial surgery in the presence of intracranial hypertension 2
• Avoid large blood pressure fluctuations and peaks—smooth control is essential 3

Prognostic Factors

• The extent of primary underlying brain injury is more important than the subdural clot itself in dictating outcome 7
• Ability to control ICP is more critical to outcome than absolute timing of subdural blood removal, though earlier surgery shows trends toward improved outcomes 7
• Mortality rate for acute subdural hematoma in severely head-injured patients (GCS 3-7) is approximately 66%, with 19% functional recovery 7
• Poor prognostic factors include: age >65 years, admission GCS score of 3-4, postoperative ICP >45 mmHg, motorcycle accident as mechanism 7
• Spontaneous resolution of acute subdural hematoma can occur in rare occasions, though vast majority >10mm thickness require immediate surgical evacuation 8