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Chronic Subdural Hematoma

Last updated Dec. 9, 2019

Approved by: Maulik P. Purohit MD MPH

James Heilman, MD

MRI showing large left sided frontal parietal subdural hematoma with associated midline shift.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Chronic Intracranial Subdural Haematoma
  • Chronic Subdural Hemorrhage

What is Chronic Subdural Hematoma? (Definition/Background Information)

  • Chronic Subdural Hematoma is collection of blood (hematoma) between the layers of coverings of the brain. It is also known as Chronic Subdural Hemorrhage
  • The brain is made up of three layers that protect it from being damaged. These coverings are called dura, arachnoid, and pia matter. This 3-layered membrane covering tightly holds the brain, preventing it from unintended movements or from being affected by harmful substances
  • The space between the:
    • Skull and dura mater is called the epidural space
    • Dura and arachnoid mater is called the subdural space
    • Arachnoid and pia mater is called the subarachnoid space             
  • In Chronic Subdural Hematoma, blood (in liquid state) accumulates in the subdural space and causes altered mental status (such as drowsiness and confusion), headache, paralysis, and other symptoms
  • It is most commonly seen in elderly adults, generally in men. Chronic Subdural Hematoma is caused by a trivial trauma; half the time the individual may not be even aware of trauma to their head
  • The prognosis is good with early surgical intervention, though it also depends on factors such as age of the individual, associated illnesses, presenting signs and symptoms, and other factors

Who gets Chronic Subdural Hematoma? (Age and Sex Distribution)

  • Chronic Subdural Hematoma usually occurs in individuals who are 60 years or older; the frequency increasing with increasing age. In rare cases, it can occur in other age groups too
  • It is slightly more common in males than females
  • It can affect individuals of all races and ethnicities
  • It is seen worldwide; there is no geographical restriction

What are the Risk Factors for Chronic Subdural Hematoma? (Predisposing Factors)

The risk factors of Chronic Subdural Hematoma include:

  • The elderly individuals are at risk, because the brain shrinks (atrophies) with advancing age and the veins too become fragile. Due to these reasons, the brain moves a bit more freely within the skull (unlike younger individuals) and veins can tear with minimal trauma
  • Generally, males have a higher risk, probably due to the reason that they may be more exposed to injuries
  • Apart from age, a direct or indirect head injury is the most important risk factor
  • Seizures (fits)
  • Alcohol abuse increases the risk, due to alcohol-induced brain atrophy and associated defective blood clotting mechanisms. Also, alcohol abuse is more likely to cause falls and injury
  • Shunts placed in the head may drain more cerebrospinal fluid and result in decreased intracranial pressure (pressure within the head), placing an individual at a higher risk for Chronic Subdural Hematoma
  • The use of blood-thinning medications, such as warfarin and aspirin, prescribed for prophylactic heart diseases
  • Hemodialysis
  • Tendency to bleed in conditions such as inherited hemophilia or liver failure

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Chronic Subdural Hematoma? (Etiology)

  • Chronic Subdural Hematoma occurs due to a trauma, which may be mild. The trauma is usually minimal and 50% of the individuals may not be aware of the same
  • Atrophy of the brain with advancing age can cause the brain to move a little more freely within the skull. The bridging veins (that have become fragile with age) tear as a result of movement of the brain during trauma. These factors can result in a slow accumulation of blood in the subdural space over several days and weeks
  • The trauma can also be an indirect injury to the head. In this type of injury, there is no direct impact to the head, rather just a movement, such as occurring due to a fall or sudden jerking action, which can slightly move the brain move and cause the veins to tear
  • One of the two outcomes happens to the collected blood. If the bleed is small, it gets reabsorbed. If the bleed is large, a thin layer is formed around the bleed
  • On top of this new layer, new blood vessels are formed. These new blood vessels bleed more easily, resulting in slow expansion of the hematoma. The slowly expanding hematoma compresses the brain tissue and causes the related signs and symptoms
  • In some situations, the arachnoid layer (layer of meninges deeper to the dura) is torn and cerebrospinal fluid along with blood accumulates, increasing the intracranial pressure. This results in a lack of blood flow (ischemia), ultimately leading to brain cell death

What are the Signs and Symptoms of Chronic Subdural Hematoma?

The signs and symptoms of Chronic Subdural Hematoma include:

  • The most common presentation is altered mental state including confusion, drowsiness, delirium, etc.
  • Other common symptoms may include:
    • Headache
    • Focal neurological deficits: These include weakness, numbness, paralysis, slurring of speech, visual defects, difficulty in speaking, etc. These deficits can be transient (appear and disappear) in some individuals
    • Fits (seizures)
    • Balancing difficulties may cause further falls and worsen the condition
    • Nausea and vomiting
    • Memory associated signs and symptoms          
  • Loss of consciousness and coma may develop eventually, if Chronic Subdural Hematoma is not promptly treated

How is Chronic Subdural Hematoma Diagnosed?

The following procedures may be used to diagnose Chronic Subdural Hematoma:

  • Thorough evaluation of the individual’s medical history and a complete physical examination
  • During history taking the physician may want to know the following:
    • When the symptoms began and whether they are becoming worse
    • List of prescription (warfarin, aspirin, etc.) and over-the-counter medications currently being taken
    • About one’s personal and family history of stroke, falls, walking problems, stress, associated medical illnesses, etc.            
  • A neurologist and neurosurgeon consultation is often necessary, as they are the experts in dealing with head injury
  • A high index of suspicion is required to diagnose Chronic Subdural Hematoma, because other brain diseases, such as depression and dementia, may present similar signs and symptoms
  • Computed tomography (CT scan) of the head is the first preferred diagnostic test. It varies in density (CT image) and may extend over a large portion of the surface of brain. If the diagnosis is still indecisive, then a CT scan with contrast and/or a magnetic resonance imaging (MRI) scan of brain may be required
  • Other appropriate tests may be required for associated medical illnesses, if any present

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Chronic Subdural Hematoma?

The possible complications of Chronic Subdural Hematoma include:

  • If the condition is not promptly treated, the symptoms may persist permanently and slowly worsen over time. Symptoms, such as headaches, memory and concentration problems, paralysis, speech problems, and others, may persist
  • Post-operative complications, such as re-accumulation of blood (hematoma), fits (seizures), etc., can occur

If Chronic Subdural Hematoma progresses quickly, then the brain matter may herniate (moves down into the spinal cord opening) and cause coma and possibly death.

How is Chronic Subdural Hematoma Treated?

The treatment options of Chronic Subdural Hematoma include:

  • If the bleed is small and if the neurological function does not deteriorate, the individual can be observed without surgical therapy. But such individuals should be carefully monitored in a hospital setting; frequent examinations and imaging may be performed, as necessary
  • Other individuals may be first treated with twist drill trephination (by surgically creating a hole in the skull). The procedure is usually done by the bedside
  • If the individual is not responding, then either a burr hole craniotomy or an open craniotomy, may be done

The healthcare provider will recommend the best treatment options based upon each individual’s specific health circumstances.

How can Chronic Subdural Hematoma be Prevented?

Prevention of head injury and falls in elderly is very important because even trivial head injuries can cause Chronic Subdural Hematoma. The following measures can help prevent falls:

  • Guardrails
  • Adequate lighting
  • Medication assessment
  • Friendly bathroom fixtures and floor
  • Family support
  • The use of assistive devices, such as cane and walker

Elderly individuals presenting with altered mental status should be thoroughly assessed for the development of Chronic Subdural Hematoma.

What is the Prognosis of Chronic Subdural Hematoma? (Outcomes/Resolutions)

  • Nearly 90% of the individuals regain their lost function and improve, if the hematoma is evacuated promptly
  • Undiagnosed or untreated individuals with Chronic Subdural Hematoma may notice a slow decline of day-to-day function. This could potentially cause death, if the condition remains untreated.

Additional and Relevant Useful Information for Chronic Subdural Hematoma:

  • According to current studies, it has been documented that acute subdural hematoma has a high death rate incidence

The following article link will help you understand acute subdural hematoma:


What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 17, 2015
Last updated: Dec. 9, 2019