What is the management of a patient with a subdural hematoma?

Management of Subdural Hematoma

Surgical evacuation is indicated for acute subdural hematomas with thickness >5 mm and midline shift >5 mm, and this should be performed urgently to reduce mortality and improve functional outcomes. 1

Initial Assessment and Stabilization

Airway and Ventilation Management

• Secure the airway immediately with tracheal intubation and mechanical ventilation, monitoring end-tidal CO₂ from the pre-hospital period onward. 1, 2, 3
• Maintain PaCO₂ within normal range—avoid hypocapnia as it causes cerebral vasoconstriction and increases risk of brain ischemia. 1, 2, 3
• End-tidal CO₂ monitoring confirms correct tube placement and guides ventilation targets. 1, 3

Hemodynamic Resuscitation

• Maintain systolic blood pressure >110 mmHg using vasopressors (phenylephrine or norepinephrine) without delay. 3
• Even a single episode of hypotension (SBP <90 mmHg) significantly worsens neurological outcomes. 3
• Use continuous infusions of sedatives rather than boluses to prevent hemodynamic instability. 1, 3

Neurological Assessment

• Perform complete neurological evaluation using Glasgow Coma Scale (GCS), pupillary examination, and focal neurological deficits. 2
• Verify anticoagulant or antiplatelet use immediately, as these medications increase hematoma expansion risk. 2

Imaging

• Obtain urgent non-contrast CT scan to characterize size, location, and mass effect of the hematoma. 2, 3
• Use inframillimetric reconstructions with thickness >1mm, visualized with double window (CNS and bone). 3

Surgical Indications

Acute Subdural Hematoma

The following criteria mandate surgical evacuation: 1, 2

• Hematoma thickness >5 mm with midline shift >5 mm
• Any symptomatic subdural hematoma regardless of size
• GCS ≤8 with significant mass effect
• Progressive neurological deterioration

Timing of Surgery

• While earlier surgery shows trends toward improved outcomes, the extent of underlying brain injury is more critical than absolute timing. 4
• Emergency decompressive craniotomy in the emergency room may be performed when operating room availability is delayed, particularly for patients with GCS 3-4 and anisocoria. 5
• No patient with initial subdural hematoma ≤3 mm required surgery, although 11% enlarged to maximum 10 mm. 6

Surgical Technique Options

• Standard craniotomy with hematoma evacuation remains the first-line surgical approach. 1
• For select patients with acute subdural hematoma who are GCS ≥13, hematoma thickness ≥7 mm, moderate deficits without progression, and no need for immediate evacuation, twist-drill craniostomy with pressure-controlled fibrinolytic irrigation achieved 90% independence (mRS 0-3) versus 56.7% with craniotomy. 7

Post-Operative Management

ICP Monitoring Indications

Monitor ICP after subdural hematoma evacuation if ANY of the following are present: 1

• Preoperative GCS motor response ≤5
• Preoperative anisocoria or bilateral mydriasis
• Preoperative hemodynamic instability
• Preoperative severity signs on imaging (compressed basal cisterns, midline shift >5 mm, other intracranial lesions)
• Intraoperative cerebral edema
• Postoperative appearance of new intracranial lesions

The rationale is strong: 50-70% of patients develop postoperative intracerebral hematoma, and >40% will have uncontrollable intracranial hypertension. 1

ICP and CPP Targets

• Maintain cerebral perfusion pressure (CPP) between 60-70 mmHg. 1
• CPP <60 mmHg is associated with poor outcomes. 1
• CPP >70 mmHg increases respiratory distress syndrome risk 5-fold without improving neurological outcomes. 1
• CPP >90 mmHg worsens outcomes due to aggravation of vasogenic cerebral edema. 1

Management of Intracranial Hypertension

For threatened intracranial hypertension or signs of brain herniation: 1

• Use mannitol 20% or hypertonic saline at 250 mOsm dose, infused over 15-20 minutes after controlling secondary brain insults. 1
• External ventricular drainage may be performed for persisting intracranial hypertension despite sedation and correction of secondary insults. 1, 2

Decompressive Craniectomy

• Consider decompressive craniectomy for refractory intracranial hypertension in multidisciplinary discussion, particularly in patients <65-70 years. 1, 2
• Large temporal craniectomy (>100 cm²) with enlarged dura mater plasty is the standard technique. 1
• Good outcomes (GOS 4-5 at 6 months) occurred in 40-57% after unilateral craniectomy versus 28-32% in controls. 1

Postoperative Monitoring

• Monitor for complications including seizures, infection, and hematoma expansion. 2
• Subdural drain placement during surgery may reduce recurrence rates. 2
• Maintain euvolemia and avoid hypovolemia to optimize cerebral perfusion. 2

Conservative Management

Indications for Non-Operative Management

Conservative management may be considered when ALL of the following are present: 2

• No signs of intracranial hypertension
• No neurological deterioration
• Small hematoma with minimal mass effect
• Specifically, hematomas ≤3 mm never required surgery in one large series, though 11% enlarged. 6

Monitoring Strategy

• Close neurological observation with serial GCS, pupillary exams, and focal deficit assessments. 2
• Repeat imaging for patients with risk factors for expansion: larger initial size, concurrent subarachnoid hemorrhage, hypertension, convexity location, and midline shift. 6
• An 8.5 mm initial subdural hematoma size threshold best predicted need for surgical intervention (AUC 0.81). 6

Adjunctive Medical Therapies

• Dexamethasone should be used with caution in selected patients given side effects. 8
• Tranexamic acid may be utilized as adjunct to surgery, but more randomized trials are needed. 8
• Middle meningeal artery embolization shows interesting results but risks (intracerebral hemorrhage, stroke, vasospasm) are not well-studied. 8

Special Populations

Elderly Patients

• Require careful monitoring as small hematomas can expand rapidly, especially in those on anticoagulants. 2
• Elderly patients are prone to poor surgical outcomes and complications. 8

Subacute Subdural Hematoma

• Same surgical thresholds apply (thickness >5 mm, midline shift >5 mm). 2
• Conservative management appropriate for small hematomas without mass effect or neurological deterioration. 2

Critical Pitfalls to Avoid

• Delaying surgical intervention in symptomatic patients leads to neurological deterioration and poorer outcomes. 2
• Using sedation boluses instead of continuous infusions causes hemodynamic instability. 3
• Allowing hypocapnia, which induces cerebral vasoconstriction and brain ischemia. 2, 3
• Permitting even single episodes of hypotension (SBP <90 mmHg), which markedly worsens prognosis. 3
• Delaying transfer to neurosurgical center for "stabilization" in facilities without neurosurgery. 3

Prognostic Factors

The following factors predict worse outcomes: 4

• Age >65 years
• Admission GCS 3-4
• Postoperative ICP >45 mmHg
• Motorcycle accident mechanism

The extent of primary underlying brain injury is more important than the subdural clot itself in dictating outcome; therefore, aggressive ICP control is more critical than absolute timing of clot removal. 4