Subdural Hematoma

Basics

Description

  • Classification of subdural hematoma (SDH):
    • Acute: Diagnosis within the 1st 2 d
    • Subacute: Diagnosis 3 d–2 wk
    • Chronic: Diagnosis after 2 wk
  • CT description:
    • Rarely crosses midline
    • Does cross suture lines
    • Inner margins are often seen to be irregular
  • Acute:
    • Most commonly due to acceleration–deceleration forces and less commonly from direct trauma
    • Sagittal movement of the head causes stretch of parasagittal bridging veins
    • Other bleeding sites include:
      • Laceration of dura
      • Venous sinus injury
      • Cortical arteries
      • Nontraumatic injuries: Intracerebral aneurysm rupture, arteriovenous malformation, coagulation disorder, arterial HTN, drug or alcohol abuse
  • Chronic:
    • Encapsulated hematoma most likely caused by repeated small hemorrhages of bridging veins

Etiology

  • Acute:
    • Most common type of intracranial hematoma (66–70%)
    • Up to 60% of patients with ASDH are on anticoagulants and 40% of CSDH
    • Occurs most commonly at cerebral complexities > falx cerebri > tentorium cerebelli
    • Peak incidence 31–47 yr, 2nd peak >75 yr
    • Represents 26–63% of blunt head injury
    • Motor vehicle crash (MVC) is the most common cause overall
    • Falls and assault more commonly result in isolated SDH (72%) than do MVCs (24%)
    • Elderly patients and those with seizure disorders are at increased risk
    • Mortality is related to presenting signs and symptoms as well as comorbidities:
      • Mortality is 50% for age >70
      • <1/2 present as simple extra-axial collection (22% mortality rate)
      • ∼40% of patients will have complicated SDH: Parenchymal laceration or intracerebral hematoma (mortality rate >50%)
      • 3rd group associated with contusion (30% mortality rate with functional recovery of 20%)
  • Coagulopathy: INR >2 increases risk of bleed ×2, INR >3 is associated with larger initial volume and increased expansion
  • Atraumatic can occur with AV malformation rupture, meningiomas, dural metastasis
  • Chronic:
    • Most common in babies or elderly with atrophy:
      • Associated with infarction in underlying brain
  • 75% of patients are >50
  • <50% have history of head trauma
  • 50% are alcoholic
  • Epilepsy and shunting procedures

Pediatric Considerations

  • May occur secondary to trauma at birth
  • Nonaccidental trauma more common

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