What type of brain injury is characterized by bleeding between the dura and the skull?

Epidural Hematoma: Bleeding Between the Dura and Skull

An epidural hematoma is the type of brain injury characterized by bleeding between the dura mater and the skull. 1 This potentially life-threatening condition typically occurs following traumatic brain injury and requires prompt diagnosis and management to prevent serious neurological complications.

Pathophysiology and Mechanism

Epidural hematomas typically result from:

• Traumatic injury causing skull fracture (most common)
• Laceration of the middle meningeal artery (primary source of bleeding) 2
• Blood accumulation in the potential space between the dura and inner table of the skull
• Rapid expansion due to arterial pressure, causing progressive mass effect

Clinical Presentation

The classic presentation includes:

• Initial trauma followed by a "lucid interval" before neurological deterioration
• Progressively worsening headache
• Altered level of consciousness
• Pupillary dilation (often ipsilateral to the hematoma)
• Hemiparesis (often contralateral to the hematoma) 2
• Rapid neurological deterioration if untreated

Diagnostic Imaging

CT scan is the gold standard for diagnosis of epidural hematoma:

• Appears as a hyperdense, biconvex (lens-shaped) collection
• Does not cross suture lines (unlike subdural hematomas)
• May show associated skull fracture
• May demonstrate midline shift and mass effect 1

MRI can provide additional information but is typically not the first-line imaging modality in the acute setting due to time constraints 3.

Management

Management depends on the size of the hematoma, clinical status, and progression:

1. Surgical Management:

   • Emergency craniotomy and evacuation is indicated for:
     • Symptomatic patients
     • Hematomas >30 mL
     • Midline shift >5 mm
     • Thickness >15 mm
     • Progressive neurological deterioration 1

2. Conservative Management:

   • May be considered for small, asymptomatic hematomas
   • Requires close neurological monitoring and serial imaging
   • Spontaneous resolution can occur in rare cases, particularly in pediatric patients 4

Prognosis

Prognosis depends on:

• Time to treatment (critical factor)
• Glasgow Coma Scale score at presentation
• Pupillary abnormalities
• Age
• Associated brain injuries

Early diagnosis and prompt surgical intervention significantly improve outcomes 1.

Special Considerations

• Vertex epidural hematomas: Rare variant that may be missed on axial CT; coronal and sagittal reconstructions are essential 2
• Bilateral epidural hematomas: Extremely rare but life-threatening; may require simultaneous bilateral craniotomies 5
• Non-traumatic epidural hematomas: Can occur in patients with certain medical conditions like sickle cell disease 6

Prevention of Secondary Injury

In patients with epidural hematoma and traumatic brain injury:

• Maintain MAP ≥80 mmHg to ensure adequate cerebral perfusion 7
• Prevent hypoxemia and maintain normocapnia
• Control intracranial pressure if elevated
• Avoid hyperthermia

Early recognition and management of epidural hematomas are crucial to prevent the potentially fatal complication of transtentorial herniation and subsequent brainstem compression.