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(Extra-axial Haematoma; Subdural Haemorrhage; SDH)


A hematoma is a collection of blood. A subdural hematoma (SDH) happens in the space between the covering of brain (the dura) and the brain. This pool of blood can put pressure on the brain.


SDH is most often caused by a head injury. This may be due to traumas such as car accidents, assault, and falls.

Head Injury
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Risk Factors

Taking blood thinning medicine raises the risk of SDH.


The blood may pool quickly or take some time to build up. This will affect how fast symptoms happen. The SDH may be:

  • Acute—symptoms appear soon after the injury
  • Subacute—symptoms appear a few days after the injury
  • Chronic—bleeding is slower and symptoms only appear weeks after the injury

After a head injury, a SDH may cause:

  • Loss of consciousness
  • Bruising around the head or eyes
  • Vision problems
  • Speech difficulties
  • Headache

Seek medical care right away if you have any of these symptoms after a head injury.


Your doctor will ask about your symptoms and health history. A physical exam will be done. You may also be referred to a specialist for more testing.

Pictures may be taken of the brain and the structures around it. This can be done with:

Your brain function may be assessed. This can be done with:

  • Neurological exam
  • Neuropsychological testing

You may have blood tests.


Talk with your doctor about the best plan for you. Treatment will depend on the size and severity of the SDH. It will also be based on your specific symptoms.

Here are some treatment methods:

Watch and Wait

A minor injury with little or no symptoms may not need treatment. Your doctor may simply ask that you watch for any new symptoms. It can take days and weeks for some symptoms to happen.


Steroids may be given to lower brain swelling.


Surgery may be needed to ease pressure on the brain. Examples are:

  • A small hole may be made in the scalp and skull. It will allow the blood clot to drain.
  • A section of the skull may be removed. This is called a craniotomy .


To help lower your chance of a head injury:

  • Reduce the risk of a fall or injury. Safeguard your home and workplace.
  • Wear proper helmets when playing sports and riding a bike or motorcycle.
  • Use a seat belt while traveling in car.


American Academy of Otolaryngology—Head and Neck Surgery 

Brain Injury Association of America 


Brain Injury Canada 

Ontario Brain Injury Association 


Servadei F, Compagnone C, Sahuguillo J. The role of surgery in traumatic brain injury. Curr Opin Crit Care. 2007;13(2):163-168.

Subdural hematoma. EBSCO DynaMed Plus website. Available at:  . Updated September 13, 2017. Accessed June 25, 2018.

Subdural haematoma. Patient UK website. Available at: Updated September 24, 2017. Accessed June 25, 2018.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 05/2018
  • Update Date: 06/25/2018