How should I assess and manage a patient with a suspected subdural hematoma, including imaging, stabilization, anticoagulation reversal, intracranial pressure control, seizure prophylaxis, and criteria for surgical evacuation?

Management of Subdural Hematoma

Immediate Assessment and Stabilization

Obtain a non-contrast head CT scan immediately to characterize hematoma thickness, midline shift, mass effect, and compression of basal cisterns—this determines whether surgical evacuation is needed. 1

Critical Hemodynamic Targets

• Maintain systolic blood pressure ≥100 mmHg or mean arterial pressure ≥80 mmHg at all times—hypotension below this threshold is the most preventable cause of secondary brain injury and strongly associated with poor outcomes 1, 2
• Target cerebral perfusion pressure (CPP) 60-70 mmHg if ICP monitoring is established (CPP = MAP - ICP) 3, 1
• Never target CPP >70 mmHg routinely—this increases respiratory complications fivefold without improving neurological outcomes 3
• CPP >90 mmHg worsens outcomes due to vasogenic cerebral edema 2

Neurological Evaluation

• Document Glasgow Coma Scale motor score, pupil examination (check for anisocoria or bilateral mydriasis), and any focal neurological deficits 3, 2
• Assess for signs of herniation or intracranial hypertension including compressed basal cisterns, ventricular effacement, or midline shift >5mm 1

Anticoagulation Reversal

Reverse anticoagulation immediately upon diagnosis—do not delay for surgical planning. 1

Specific Reversal Protocols

• Vitamin K antagonists (warfarin) with INR ≥2.0: Administer four-factor prothrombin complex concentrate immediately, followed by intravenous vitamin K 1
• DOACs (dabigatran, apixaban, rivaroxaban, edoxaban): Administer specific antidote immediately; if unavailable, use (activated) prothrombin complex concentrate 1
• Dabigatran specifically: Consider hemodialysis for drug removal 1
• Unfractionated or low-molecular-weight heparin: Administer intravenous protamine sulfate 1
• Antiplatelet therapy (aspirin, clopidogrel, ticagrelor, prasugrel): Do NOT use platelet transfusions—RCT data demonstrate worse outcomes in ICH patients on antiplatelet therapy who receive platelet infusion 1

Surgical Indications

Immediate surgical evacuation is indicated for any of the following: 1, 4

• Subdural hematoma thickness >10mm OR midline shift >5mm (regardless of GCS score) 4, 5
• Development of altered consciousness or GCS decline ≥2 points from injury to admission 4, 6
• New or worsening focal neurological deficits 1
• Asymmetric or fixed and dilated pupils 4
• Signs of cerebral herniation or severe intracranial hypertension 1
• ICP >20 mmHg in comatose patients (GCS <9) even with hematoma <10mm and shift <5mm 4

Surgical Technique

• Perform craniotomy or craniectomy (preferred over burr holes) with fronto-parieto-temporo-occipital approach, diameter ≥12 cm, with durotomy and duraplasty 1, 4, 5
• Place ICP monitor intraoperatively 1
• Do not remove ischemic brain tissue, but evacuate concomitant intracranial bleeding 1
• Perform surgery as soon as possible once indicated—timing matters for outcomes 4

Conservative Management

Conservative management is appropriate for subdural hematomas <10mm thick with midline shift <5mm in patients with GCS 11-15 and no focal deficits. 6, 7

Monitoring Requirements

• Serial neurological examinations at least every 4 hours initially 1, 8
• Maintain euvolemia to optimize cerebral perfusion 1, 8
• 30-40% of subdural hematomas expand in the first 12-36 hours—watch for neurological deterioration 1
• Repeat imaging at 4-6 weeks to ensure resolution or stability 1, 8

When to Avoid Conservative Management

• Patients with GCS decline between prehospital and admission assessment require surgery even with small hematomas 6
• Presence of compressed basal cisterns or other severity signs on imaging 3
• Inability to perform reliable neurological surveillance 3

ICP Monitoring Indications

Place ICP monitor in the following scenarios: 3, 2

• All comatose patients (GCS ≤8) with subdural hematoma 4, 2
• Post-evacuation if any of these criteria present: preoperative GCS motor ≤5, preoperative anisocoria/bilateral mydriasis, preoperative hemodynamic instability, compressed basal cisterns or midline shift >5mm, intraoperative cerebral edema, or postoperative new intracranial lesions 3
• Use intraparenchymal probes rather than ventricular drains—better risk-benefit profile with lower infection rates (2.5% vs 10%) and hemorrhage risk (0-1% vs 2-4%) 3, 2

Management of Elevated ICP

For threatened herniation or intracranial hypertension, administer mannitol 20% at 0.25-2 g/kg as 15-25% solution over 15-20 minutes. 1

• Maximum effect occurs at 10-15 minutes, lasting 2-4 hours 1
• Alternatively, use hypertonic saline 3% 1
• Target serum osmolality 300-310 mOsmol/kg 1
• Monitor fluid, sodium, and chloride balance closely 1
• In cerebral herniation, temporary hypocapnia (PaCO2 35-40 mmHg) may be used while awaiting emergency surgery 2

Critical Pitfalls to Avoid

• Never allow systolic blood pressure <90-100 mmHg—this is the single most preventable cause of secondary brain injury 1
• Do not delay surgery in symptomatic patients while awaiting "optimal" timing—outcomes worsen with delay 4
• Do not underestimate small hematomas in anticoagulated or elderly patients—they expand rapidly 1
• Do not administer long-lasting sedatives or paralytics before neurosurgical evaluation—this masks clinical deterioration 6
• Do not use platelet transfusions for antiplatelet-associated subdural hematoma—RCT evidence shows harm 1
• Avoid administering dexamethasone routinely—significant side effects outweigh uncertain benefits 9