A subdural haematoma is a serious brain condition that is often caused by a head injury. Blood collects between the skull and the surface of the brain.
Symptoms of a subdural haematoma can include:
Symptoms can appear quickly or may develop over time depending on the type of subdural haematoma (see below).
A subdural haematoma occurs when a blood vessel in the space between the skull and the brain (the subdural space) is ruptured. Blood escapes from the ruptured blood vessel, leading to the formation of a blood clot (haematoma), which places pressure on the brain and may cause brain damage.
Types of subdural haematoma
A subdural haematoma can be:
acute – the haematoma forms immediately after the initial injury
subacute - the haematoma forms up to a week after the initial injury
chronic – the haematoma forms over a period of two to three weeks after the initial injury
These are discussed in more detail below.
Acute subdural haematoma
Acute subdural haematomas are the most serious type of subdural haematoma. They usually occur after severe, high-impact head injuries, often caused by motor vehicle accidents, falls and physical assaults.
An acute subdural haematoma is a medical emergency that requires immediate admission to a hospital. Surgery is usually required to remove the haematoma.
Subacute subdural haematoma
Subacute subdural haematomas are less common, and often harder to detect, than other types of subdural haematoma.
The signs and symptoms can appear days, or even weeks, after an injury and will be similar to those of an acute subdural haematoma.
Chronic subdural haematoma
Chronic subdural haematomas are more commonly seen in older people. It is thought they occur because the natural ageing process makes the brain more vulnerable to injury in some people.
This means that even a minor injury can cause bleeding inside the subdural space (in around half of all cases, the injury is so minor that the person cannot remember it).
The symptoms of a chronic subdural haematoma often develop several weeks after the initial injury, because our brain usually shrinks as we get older, creating more subdural space for the haematoma to expand into before it causes any noticeable symptoms.
Chronic subdural haematomas may also be regarded as a medical emergency. Surgery is usually required.
Acute subdural haematoma carries a high risk of death. Age is an important factor that affects a person’s outlook. For example, people who are:
under 40 years old have a 20% risk of dying
40 to 80 years old have a 65% risk of dying
80 years old or over have an 88% risk of dying
People who survive an acute subdural haematoma usually take a long time to recover from the effects of the haematoma. The recovery time will depend on the severity of the haematoma. There can also sometimes be permanent physical and mental disabilities.
Less information is available about subacute subdural haematomas as they are less common. However, the outlook for a subacute subdural haematoma is often better than for an acute subdural haematoma.
The outlook for a chronic subdural haematoma is also much better than the outlook for acute subdural haematoma. However, the condition still carries a moderately high risk of death. An estimated 1 in 20 people will die within the first 30 days after having surgery to treat a chronic subdural haematoma.
This CT scan shows a haematoma bulding up on the right side of the skull
Major trauma services
Patients with multiple serious injuries may need to be transferred to a major trauma centre.
Symptoms of subdural haematoma
The symptoms of an acute subdural haematoma may develop rapidly after a severe head injury. Symptoms of a chronic subdural haematoma can develop within two to three weeks after a minor head injury.
Symptoms of a subdural haematoma include:
nausea (feeling sick)
personality changes – such as being unusually aggressive or having rapid mood changes
decreased levels of consciousness – such as finding it difficult to keep your eyes open
speech problems – e.g. slurring words or difficulty saying words
impaired vision or double vision
paralysis on one side of the body
loss of consciousness
When to seek emergency medical treatment
Always seek emergency medical treatment after a significant head injury. You should go immediately to the accident and emergency (A&E) department of your nearest hospital, or dial 999 to request an ambulance.
A severe head injury could be the result of a fall, violent assault or motor vehicle accident.
A number of risk factors make a person more vulnerable to a minor head injury resulting in a chronic subdural haematoma.
being 65 years old or over
having a previous history of brain surgery
having a condition that makes you bleed more easily, such ashaemophilia, or having a condition that makes your blood more prone to clotting, such as thrombophilia
taking anticoagulant medication to prevent blood clots, such as warfarin or aspirin
Symptoms that could suggest people in these groups may have developed a subdural haematoma include:
previous loss of consciousness (passing out)
not remembering events that occur before or after the injury
changes in behaviour, such as irritability, being easily distracted or having no interest in the outside world
If you or someone in your care has any of the above signs, symptoms or risk factors, you or they should go to the nearest hospital’s accident and emergency (A&E) department to seek immediate medical attention.
Causes of subdural haematoma
A subdural haematoma is most often caused by a head injury that tears a blood vessel in the space between the skull and the brain (the subdural space).
Blood escapes from the ruptured blood vessel, leading to the formation of a blood clot (haematoma), which places pressure on the brain and may cause brain damage.
As the bleeding continues, the subdural haematoma will grow, taking up more room inside the skull. The haematoma may press on the brain, leading to a build-up of pressure inside the skull. This is referred to as intracranial hypertension.
As the pressure increases, it is thought to have a harmful effect on the cells of the brain. This causes the brain tissue to swell, leading to a further increase in pressure. The increased pressure squashes the brain against the wall of the skull, resulting in symptoms such as headaches, confusion and muddled speech.
Left untreated, a subdural haematoma may damage your brainstem. The brainstem is the part of the brain that helps to regulate many of the body’s vital functions, such as consciousness and breathing. Therefore, brainstem damage can sometimes result in coma and possibly death.
In most cases, subdural haematomas develop after a head injury causes a large amount of blood to escape from a torn blood vessel.
Acute subdural haematomas
The most common cause of acute subdural haematoma is probably the brain being subjected to an "acceleration-deceleration force". This is when the skull and the brain inside the skull are propelled in one direction with great force (acceleration) before coming to a sudden stop (deceleration).
The most common ways that the brain can be subjected to this type of injury are:
motor vehicle accidents
These types of injury can damage the brain in three main ways:
they can cause tearing of the veins that carry blood from the brain to the heart and lungs
they can damage the arteries that provide the brain with oxygen-rich blood
they damage the tissue of the brain, resulting in bleeding
As well as the direct damage caused by the pressure of the haematoma on the brain, the damage to the blood vessels inside the brain can disrupt the blood flow to the brain. This can often result in secondary brain damage, which is more severe than the damage caused by the initial injury.
Chronic subdural haematomas
The fact that most people’s brains tend to shrink to a certain extent as they grow older is thought to play an important part in the development of a chronic subdural haematoma.
This shrinkage places the veins that carry blood out of the brain under increased tension, much like a rubber band that has stretched to its maximum extent. The increase in tension makes the veins much more vulnerable to damage, so that even a minor injury can result in the veins tearing.
Unlike acute haematomas, these tears are usually minor, causing low levels of bleeding. However, over the course of several weeks, the amount of blood gradually builds up and a haematoma develops.
A number of factors may increase your risk of developing a chronic subdural haematoma. These are discussed below.
Over half of all cases of chronic subdural haematoma affect people aged over 60. The chance of developing one increases with age.
This is mainly because as a person gets older, their brain reduces in size, creating a larger subdural space (more space between the brain and the skull).
Drinking too much alcohol can shrink the brain over a period of time, which can result in a larger subdural space being created.
Taking anticoagulant medicines can increase the risk of developing a subdural haematoma. Anticoagulants are often used to treat or prevent conditions that are caused by the blood clotting too quickly, such as deep vein thrombosis (DVT) and heart attacks.
Anticoagulant medicines, such as warfarin and heparin, work by slowing down the body’s blood clotting process. This can prevent a bleed in the subdural space from clotting quickly enough, so you'll bleed for longer than usual into the subdural space.
A seizure occurs when the normal electrical activity of the brain is disrupted, which can cause the brain and body to behave strangely, such as losing conciousness or shaking uncontrollably.
Exactly why seizures increase the risk of developing a chronic subdural haematoma is unclear. It may be that the abnormal electrical activity during a seizure makes the brain more vulnerable to damage.
Ventriculoperitoneal (VP) shunt
A ventriculoperitoneal (VP) shunt is a thin tube that is implanted in the brain to drain away any excess fluid to another part of the body. VP shunts are used to treat a condition called hydrocephalus.
Occasionally, a VP shunt can overdrain, which can cause a chronic subdural haematoma.
Burr holes are usually the preferred treatment option for most chronic subdural haematoma cases. The process involves making tiny holes in the skull to allow the neurosurgeon to drain the blood from the subdural haematoma. The haematoma is drained through a flexible rubber tube fed through the burr holes.
Burr hole surgery is sometimes carried out under local anaesthetic, which means that the area is numbed, so you will not feel any pain, although you will be awake during the procedure.
Small tubes may be temporally left inside the burr holes for a few days to help drain away any blood and debris from the site of the surgery. Research results published in 2009 reported that using drainage tubes reduces the risk of complications.
After the procedure, the burr holes can be closed using either stitches or staples. Most people are well enough to leave hospital within three to nine days.
Complications of burr hole surgery include:
excessive bleeding at the site of the surgery
Symptoms that occurred before surgery may persist after surgery – for example:
hemiparesis – muscle weakness on one side of the body
dysphasia – problems with certain brain functions that affect talking and understanding others
Recurrence of the haematoma occurs in an estimated one in 10 cases and may require further surgery to correct.
Recovering from subdural haematoma
In some cases, a subdural haematoma can cause damage to the brain that requires further care and recovery time.
If this is the case, you may need further treatment from a neuro-rehabilitation team. This team may include physiotherapists, speech therapists and occupational therapists, who will help you to regain your ability to move, speak and live independently.
It can take a year or more to recover from a severe subdural haematoma. It is also important to remember that there may be some permanent damage, such as changes to your moods and concentration, or memory problems and weakness in your limbs.
Getting back to normal
Recovery after having a subdural haematoma will vary depending on how severe it is. One person may make a good recovery while another may be left with a disability or even end up in a vegetative state(function unconsciously).
After being discharged from hospital, it may take some time before you begin to feel normal again.
The length of time it takes to completely recover from a subdural haematoma will vary from person to person.
You may feel ready to return to work a few weeks after leaving hospital. But before you do, you may have to meet with your medical team at your outpatient's appointment. This may be some time after you are discharged.
While you are recovering, it is important to take things easy and not to do too much too soon. Make time every day to completely rest your brain from any kind of distraction, such as the radio or television.
Speak to your specialist for advice before flying. Depending on the severity of your subdural haematoma they may advise you not to fly for a period of time after treatment to avoid aggravating symptoms.
As everyone’s recovery will be different, it is a good idea to seek further information about the possible effects and rehabilitation techniques. A number of charities and organisations may be able to help including:
Headway (the brain injury association) – see below
BASIC (Brain and Spinal Injury Centre)
Brain & Spine Foundation
Headway is a charity that provides help and support to people affected by head injuries.
advise you about other sources of support
help you find local rehabilitation services
give you support and advice if you experience problems
You can use the Headway website to search for local Headway services. They offer a wide range of services, including rehabilitation programmes, carer support, social re-integration, community outreach and respite care (when short-term support is provided for someone who needs care, for example to give the usual carers a break).
Headway cannot give medical advice or a diagnosis. For this, see your GP or call Direct on 0845 46 47.
People who have a serious brain injury, such as a subdural haematoma, are not allowed to drive. They have a legal obligation to inform the Driver and Vehicle Licensing Agency (DVLA) and their insurance company about the injury.
It is likely that the DVLA will withdraw your licence for six months or a year. After that time you can reapply for your licence, depending on your recovery.
If you have a seizure during your recovery from surgery, you will have to spend a year without having any further seizures before you will be allowed to drive a car or a motorcycle. It will take longer before you are allowed to drive a heavy goods vehicle.