extradural vs subdural hematoma

2 min read 16-03-2025

Introduction:

Head injuries are a serious concern, and two types of bleeding within the skull—extradural hematoma (EDH) and subdural hematoma (SDH)—represent life-threatening complications. While both involve bleeding in the brain, their locations, causes, and clinical presentations differ significantly. This article will delve into the key distinctions between EDH and SDH, highlighting their causes, symptoms, diagnosis, and treatment. Understanding these differences is crucial for prompt diagnosis and appropriate management, leading to improved patient outcomes.

What is an Extradural Hematoma (EDH)?

An extradural hematoma (EDH) is a collection of blood that forms between the skull and the dura mater—the tough outer layer of the brain's protective membranes. EDHs are usually caused by a rupture of the middle meningeal artery, often due to a temporal bone fracture. This artery is located just outside the dura mater, making it vulnerable to damage during impacts to the head.

Causes of EDH:

Head trauma: The most common cause is blunt force trauma to the head, such as a fall or a motor vehicle accident.
Skull fracture: Often associated with a fracture of the temporal bone.

Symptoms of EDH:

The classic presentation of EDH involves a lucid interval—a period of consciousness after the initial injury—followed by a rapid deterioration in neurological status. Symptoms can include:

Loss of consciousness
Severe headache
Nausea and vomiting
Neurological deficits (e.g., weakness, paralysis)
Seizures

What is a Subdural Hematoma (SDH)?

A subdural hematoma (SDH) is a collection of blood that forms between the dura mater and the arachnoid mater—the middle layer of the brain's protective membranes. SDHs are typically caused by the rupture of bridging veins that cross the subdural space. These veins are more susceptible to tearing due to their relatively fragile nature.

Causes of SDH:

Head trauma: A common cause, ranging from mild to severe.
Shaken baby syndrome: A significant cause in infants.
Spontaneous rupture: Can occur in individuals with bleeding disorders or on anticoagulants.

Symptoms of SDH:

Symptoms of SDH can be more insidious than those of EDH, with a slower onset of neurological deterioration. They may include:

Headache
Drowsiness
Confusion
Nausea and vomiting
Focal neurological deficits

Key Differences Between EDH and SDH:

Feature	Extradural Hematoma (EDH)	Subdural Hematoma (SDH)
Location	Between the skull and dura mater	Between the dura mater and arachnoid mater
Source of bleed	Middle meningeal artery (usually)	Bridging veins
Onset of symptoms	Often rapid, with a lucid interval	Can be gradual or acute
Appearance on CT scan	Lens-shaped, biconvex collection of blood	Crescent-shaped collection of blood
Risk factors	Significant head trauma, temporal bone fracture	Head trauma, bleeding disorders, anticoagulant use

Diagnosis and Treatment of EDH and SDH:

Both EDH and SDH are typically diagnosed using computed tomography (CT) scans of the brain. Treatment focuses on relieving the pressure on the brain and stopping the bleeding. This often involves surgical intervention, such as craniotomy to evacuate the hematoma. The urgency of surgery depends on the size and location of the hematoma, as well as the patient's neurological status.

Conclusion:

EDH and SDH are serious conditions requiring prompt medical attention. While both involve intracranial bleeding, their underlying causes, clinical presentations, and imaging characteristics differ. Recognizing these differences is vital for accurate diagnosis, timely intervention, and ultimately, improved patient outcomes. Prompt medical evaluation is critical for anyone who sustains head trauma, especially if they experience any of the symptoms mentioned above. Early diagnosis and treatment are essential for minimizing long-term neurological damage.