Subdural hematoma

In the case of a chronic subdural hematoma, however, the blood seeps in only slowly. It can be caused by even minor injuries. The symptoms depend on whether the subdural hemorrhage is acute or chronic. Treatment usually consists of an operation in which a neurosurgeon removes the bruise. Embolization can also be carried out in which the blood vessels supplying the tumour are closed off.

What is a subdural hematoma?

A subdural hematoma is a hemorrhage between two meninges – the dura mater and the arachnoid membrane. Both consist of connective tissue. They surround and protect the brain. The term subdural hematoma can be derived as follows: “sub” means “under”, “dural” stands for the dura mater and a hematoma is a bruise. Other medical names for subdural hematoma are subdural hemorrhage or subdural hematoma.

Experts differentiate between acute, subacute and chronic subdural hematoma, depending on the time course. Symptoms may set in quickly or only within a few days or weeks. The cause of acute subdural hematoma is usually a serious accident, for example in road traffic. Sometimes even minor injuries, so-called minor trauma, are enough to trigger chronic subdural hemorrhage. Bleeding occurs when blood vessels (veins) in the so-called subdural space are injured. This gap is only created artificially when blood seeps into it and it widens. It is not normally visible because the two meninges lie close together.

An acute subdural hematoma becomes noticeable within hours or a few days through headaches, nausea, vomiting and impaired consciousness. Chronic subdural hematoma, on the other hand, develops gradually and the symptoms often only become apparent after several weeks. Pressure in the head, tiredness, concentration problems or confusion are possible signs.

Subdural hematoma – frequency and age

The frequency of acute subdural hematoma cannot be precisely quantified. However, bleeding can occur in principle in any person who is subjected to massive violence to the head and causes injury. Examples include serious traffic accidents involving cars and bicycles as well as sports and leisure accidents. And these happen all over the world every day, including in Switzerland. They can affect people of any age. But as a rule, younger people behave more riskily in traffic, during sport and leisure activities.

Chronic subdural hemorrhage occurs in the western world with a frequency of 1 to 5.3 per 100,000 inhabitants per year. It often affects older people. Sometimes just bumping your head against an object is enough to trigger the bleeding. People suffering from alcoholism also have an increased risk.

Subdural hematoma: causes and risk factors

The causes of acute subdural hematoma are usually severe head injuries. They can be caused by the following situations, for example:

• Accidents in road traffic (e.g. car, bicycle, e-bike, e-scooter), during sport, leisure activities or at work
• Falls on the head, for example from a great height
• Violence to the head, for example in a fight or brawl
• Child abuse: The bleeding can be caused by shaking trauma

In the case of chronic subdural hematoma, even minor injuries are sufficient to trigger the oozing hemorrhage. Those affected often do not even remember the triggering event if it happened several weeks ago.

Causes and risk factors can be

• Old age – senior citizens are more likely to suffer a subdural hematoma
• Alcohol abuse
• Slight fall on the head
• Hitting your head against a wall, open cupboard door or pulled out drawer
• Diabetes mellitus
• Blood-thinning medication – taking anticoagulants promotes subdural hemorrhage
• Medical interventions, e.g. loss of cerebrospinal fluid after spinal punctures or overdrainage in the case of a horizontal cerebrospinal fluid shunt system

Sometimes the subdural hemorrhage occurs spontaneously and no cause can be found.

Subdural hematoma – how it develops

The dura mater and the arachnoid are traversed by numerous vessels. A head injury can cause the vessel wall to tear. Blood from the veins in the subdural space then enters the gap between the two meninges. It widens and only now does the subdural space become recognizable on images of the brain. It is not normally visible because the two meninges lie very close together.

The hematoma can grow quickly or slowly (acute or chronic form). The haematoma displaces the brain tissue and increases the pressure in the brain. This can cause brain damage that cannot be reversed. Doctors must therefore usually treat the subdural hemorrhage quickly.

Symptoms: Subdural hematoma is noticeable immediately or after weeks

A distinction is made between different forms of subdural hematoma depending on the time course and onset of symptoms.

• Acute subdural hematoma: Symptoms begin within minutes, hours or three days at the latest.
• Subacute subdural hematoma: The symptoms develop within three weeks of the triggering event.
• Chronic subdural hematoma: Symptoms do not appear until three weeks to several months after the head injury.

The symptoms of a subdural hematoma are different in the acute and chronic forms. They can also vary in severity. It is always important to seek medical advice in the event of a head injury or to call the emergency medical service on 144 immediately.

Acute subdural hematoma: symptoms

Acute subdural hematoma develops rapidly within a few minutes, hours or up to three days after an accident. The symptoms are due to the increased intracranial pressure when the hematoma spreads. The brain tissue is displaced and the brain cannot expand due to the bony skull. It is “squeezed together”.

These signs are possible, for example:

• Headache
• Nausea, vomiting
• Dilation and no reaction of the pupil on the side of the bleeding, sometimes also on both sides
• Hemiplegia on the other side of the body
• Impaired consciousness, coma

Chronic subdural hematoma: symptoms

Chronic subdural hematoma, on the other hand, develops gradually within several weeks of the head injury. At the beginning there is only a small hemorrhage. The blood then seeps steadily into the subdural space and the haematoma continues to enlarge. A minor injury, such as a slight bump to the head on an object, is often enough to cause a subdural hematoma. Many people can no longer remember the event that triggered it because it happened so long ago.

Chronic subdural hematomas often cause no symptoms for a long time. Then they only set in slowly, are initially mild and many do not associate their symptoms with a head injury that occurred some time ago.

These signs may indicate a chronic subdural hematoma:

• Headache
• Feeling of pressure in the head
• Dizziness
• cognitive disorders and loss of intellectual abilities: e.g. disorders of perception, attention, memory, thinking and memory
• Psychomotor slowdown: facial expressions, running, walking, speaking (e.g. word-finding disorders)
• Change of character and personality
• Weakness in the arms and legs
• Paralysis
• Sensory disturbances
• epileptic seizures
• Consciousness reduction

Diagnosis of subdural hematoma

The diagnosis of a subural hematoma always begins with a medical history interview. In the case of an acute subdural hematoma following a serious accident, the affected person is often unable to provide information themselves – in this case, relatives or witnesses to the accident are required.

For example, we ask the following questions:

• What are your symptoms? z. e.g. headache, pressure in the head?
• How long have they existed? Hours, days, weeks?
• Where are they located? Right, left or both sides of the body?
• How pronounced are they?
• Have the symptoms started acutely or have they increased continuously over the last few days and weeks?
• Do you have any known underlying diseases?
• Was there a triggering event that you can remember? Have you had an accident recently or a long time ago? Which one exactly and what happened?
• Do you drink alcohol? If yes: Since when and how much?
• Are you taking any medications? If yes: Which and since when?

Based on the symptoms described and an accident with a head injury, we can often already make an assessment as to whether it could be a subdural hematoma. It is also important to rule out other causes for the symptoms. Examples include dementia or a stroke, which are associated with symptoms similar to those of a chronic subdural hematoma.

This is usually followed by a physical examination, during which we listen to the heart and lungs and carefully palpate the body. The neurological examination provides further information in the diagnosis of a subdural hematoma. We test the function of the brain and nerves. For example, reflexes, movements, gait, coordination and memory are significant.

Finally, imaging techniques are used to visualize bleeding in the brain. This also provides information about the shape, location and extent of the hematoma. It is also possible to see whether the hemorrhage is recent or old and whether there are hematomas and injuries elsewhere in the brain.

The most important radiological imaging procedures are

• Computed tomography (CT): An X-ray examination in which the radiologist produces high-resolution cross-sectional images of the head and brain. Sometimes they also use a contrast agent. An acute subdural hemorrhage usually appears crescent-shaped on CT and has an increased optical density compared to the cerebral cortex. In the case of chronic bleeding, the opposite is true – the optical density is reduced.
• Magnetic resonance imaging (MRI = magnetic resonance imaging): Radiology specialists use strong magnetic waves and take images of the brain “slice by slice”. MRI is a good way of detecting bleeding that is more than four weeks old.

Subdural hematoma: prevention, early detection, prognosis

There are no special measures for the prevention and early detection of a subdural hematoma. However, accidents on the road, in sport, during leisure activities or at work are often the cause of a serious head injury. Violence to the head by others can also trigger a subdural hemorrhage. Some tips:

• Protect your head with a high-quality helmet when you ride your bike, e-scooter or e-bike. When riding a motorcycle or scooter, a helmet is compulsory in many countries anyway. In the event of a fall or collision with another vehicle, your head is better protected.
• Always drive defensively on the road, not aggressively – even if you are in the right and have the right of way. This often prevents serious collisions with head injuries.
• If you work on construction sites, you should consistently comply with the various safety precautions. Helmets are usually a must. Some people work at greater heights and there is a risk of falling. Objects could also fall on your head on a construction site.
• Some sports are risky, even for the head. Make sure you wear good protective equipment, for example when skiing, snowboarding, skating, climbing, boxing or alpine mountaineering.
• Do not get involved in fights and brawls. It is better to seek a conversation or distance yourself if conflicts arise. A heavy blow with a fist or a kick to the head can be very dangerous.

In the event of an accident with a head injury, a rapid examination by a doctor or emergency doctor is always necessary. You should also seek medical advice for supposedly minor injuries, for example if you have bumped your head. This is especially true for older people and people suffering from alcoholism. Sometimes the injury is not as harmless as it seems. And if you have any unusual symptoms, it is always advisable to see your doctor quickly anyway.

Course and prognosis of subdural hematoma

The course and prognosis depend on the type and size of the subdural hematoma. In general, the sooner treatment begins, the better the prognosis. Without therapy, a large hemorrhage in the brain can always become life-threatening.

An acute subdural hematoma is usually more serious and must be treated immediately – otherwise the prognosis is unfavorable. In most cases, however, those affected not only have a subdural hemorrhage, but also other brain injuries following an accident. This also influences the prognosis. Depending on the extent and size of the hemorrhage, the mortality rate is between 30 and 80 percent.

The course and prognosis are more favorable for small, chronic subdural hematomas. If it is diagnosed in time and treated adequately, there is a high probability that you will make a full recovery. This is all the more true the younger a person is. However, elderly people who also suffer from other illnesses often suffer from subdural hemorrhage.

Subdural hematoma: treatment must usually begin quickly

An acute subdural hematoma is always an emergency – treatment must therefore begin immediately in order to improve the chances of survival. Those affected must seek treatment in a hospital.