What are the criteria for probable evacuation in patients with a subdural hematoma?

Criteria for Subdural Hematoma Evacuation

Surgical evacuation is indicated for acute subdural hematomas with thickness >5 mm or midline shift >5 mm, regardless of Glasgow Coma Scale score. 1, 2

Primary Indications for Surgical Evacuation

Radiographic Criteria

• Hematoma thickness >5-10 mm 1, 2
• Midline shift >5 mm 1, 2, 3
• Compressed basal cisterns 4
• Presence of other intracranial lesions 4

Clinical Criteria

• Comatose patient (GCS <9) with any significant SDH 2
• Decline in GCS score by ≥2 points between injury and hospital admission 2
• Presence of asymmetric or fixed/dilated pupils 2
• Intracranial pressure (ICP) exceeding 20 mmHg 2
• Preoperative Glasgow Coma Scale motor response ≤5 4
• Preoperative anisocoria or bilateral mydriasis 4
• Preoperative hemodynamic instability 4

Surgical Approach Considerations

Type of Procedure

• Craniotomy with or without bone flap removal and duraplasty is recommended for comatose patients 2
• Decompressive craniectomy should be considered for:
  • Patients with coma
  • Large hematomas
  • Significant midline shift
  • Elevated ICP refractory to medical management 1
  • Fronto-parieto-temporo-occipital craniectomy up to midline with diameter ≥12 cm is recommended for decompressive hemicraniectomy 1

Timing of Surgery

• Surgical evacuation should be performed as soon as possible when indicated 2
• Surgery within 8 hours of hemorrhage may improve outcomes 4

Special Considerations

Anticoagulation Management

• Immediate reversal of anticoagulation is critical before surgical intervention 1
• Prothrombin complex concentrate is preferred over fresh frozen plasma for reversal 1
• Vitamin K should be administered in combination with reversal agents 1

Postoperative Monitoring

• ICP monitoring is recommended after evacuation if any of these criteria are present:
  • Preoperative GCS motor response ≤5
  • Preoperative anisocoria or bilateral mydriasis
  • Preoperative hemodynamic instability
  • Preoperative severity signs on imaging
  • Intraoperative cerebral edema
  • Postoperative appearance of new intracranial lesions 4

Cerebral Perfusion Pressure Management

• Maintain cerebral perfusion pressure between 60-70 mmHg 4, 1
• Avoid CPP >70 mmHg routinely as it may increase risk of respiratory distress syndrome 4
• Avoid CPP <60 mmHg as it is associated with poor outcomes 4

Prognostic Factors

• Worse outcomes are associated with:
  • Larger hematoma volume
  • Lower initial GCS score
  • Presence of intraventricular hemorrhage 1
  • Age >60 years 1

Pitfalls to Avoid

• Attempting to control ICP via ventricular catheter insertion alone without hematoma evacuation is insufficient and potentially harmful 4
• Delaying surgery when indicated increases mortality risk
• Failing to reverse coagulopathy before surgical intervention
• Setting CPP targets too high (>90 mmHg) can worsen neurological outcomes due to aggravation of vasogenic cerebral edema 4
• Overlooking the need for ICP monitoring in patients with high-risk features after hematoma evacuation 4

By following these evidence-based criteria for subdural hematoma evacuation, clinicians can optimize patient outcomes while minimizing unnecessary surgical interventions.