A subdural hematoma is a collection of blood between the dura mater (the outer covering of the brain) and the arachnoid membrane.
It usually occurs when bridging veins that drain blood from the brain surface are torn — often due to head trauma or rapid acceleration-deceleration injury.
Subdural hematomas can be acute, subacute, or chronic, depending on how quickly the bleeding develops.
They are common in elderly patients, those on blood thinners, or individuals with brain atrophy.
Prompt diagnosis and treatment are crucial to prevent irreversible brain injury or death.
Types of Subdural Hematoma
1. Acute SDH
Develops within hours after a head injury — often from severe trauma.
Causes rapid neurological decline and requires urgent surgical intervention.
2. Subacute SDH
Appears days to weeks after the injury, with symptoms that progress gradually as the hematoma enlarges.
3. Chronic SDH
Develops over weeks to months, typically from minor or unnoticed trauma.
Fragile veins bleed slowly, especially in elderly patients or those on anticoagulant therapy.
Symptoms
Symptoms depend on the size and speed of bleeding but often include:
- Headache (persistent or worsening)
- Confusion, drowsiness, or personality changes
- Weakness or numbness on one side of the body
- Difficulty walking or imbalance
- Speech disturbances
- Seizures in some cases
- Nausea, vomiting, or visual changes
In acute SDH, rapid deterioration of consciousness and unequal pupils may indicate brain herniation — a life-threatening emergency.
Diagnosis
The main diagnostic tool is a non-contrast CT scan of the head, which typically shows a crescent-shaped (concave) hyperdense area spreading over the brain surface.
CT also identifies associated brain swelling, midline shift, or fractures.
MRI can help evaluate chronic or mixed-age hematomas and differentiate them from other conditions.
Serial imaging may be needed to monitor hematoma evolution in conservatively managed patients.
Treatment Options
1. Emergency Surgical Evacuation
Indicated for acute or large subdural hematomas with neurological deficits or significant mass effect.
- Craniotomy: A bone flap is opened to remove the clot and control bleeding.
- Burr hole drainage: Often used for chronic SDH — a minimally invasive method to evacuate liquefied blood and relieve pressure.
Surgery aims to restore brain function, reduce intracranial pressure, and prevent secondary injury.
2. Conservative (Non-Surgical) Management
Small, stable hematomas without neurological symptoms may be treated with close monitoring, head elevation, and serial CT scans.
Anticoagulant or antiplatelet medications are temporarily stopped under medical supervision.
If the hematoma enlarges or symptoms worsen, urgent surgery is performed.
3. Recurrence Management
Chronic subdural hematoma may recur in up to 20% of cases.
Re-operation or use of closed drainage systems reduces recurrence risk.
Recent studies support the use of minimally invasive endoscopic evacuation or embolization of the middle meningeal artery in recurrent cases.
Recovery & Follow-Up
Hospital stay varies from a few days to two weeks, depending on severity and neurological status.
Most patients improve rapidly after surgery, though elderly or comorbid individuals may require longer rehabilitation.
Follow-up CT or MRI ensures complete resolution.
Rehabilitation focuses on motor recovery, balance training, and cognitive therapy when necessary.
In chronic SDH, outcomes are generally excellent with timely treatment.
Prognosis
Prognosis depends on the patient’s age, initial neurological condition, and timing of surgery.
- Acute SDH carries higher mortality and requires immediate neurosurgical care.
- Chronic SDH has a good prognosis, with most patients achieving full recovery.
Prevention includes controlling risk factors such as anticoagulant use, alcohol abuse, and fall hazards in the elderly.
When to Seek Medical Attention
Seek immediate help if you or a loved one experiences:
- Head trauma followed by confusion, headache, or drowsiness
- Progressive weakness or slurred speech
- Repeated vomiting or unequal pupils
Early evaluation by a neurosurgeon can be life-saving.