Subdural haematoma

A subdural haematoma is a collection of blood between the brain and the dura, the tough membrane that covers it. The blood does not spill into brain tissue; it gathers on top of the brain, beneath the membrane, and presses on it from outside. The skull cannot expand, so even a moderate amount of blood eventually stops the brain working properly. There is one thing worth taking away from this page, and it is not about the blow: nobody misses a severe head injury, but in an older person a haematoma can grow weeks after a fall they have already forgotten about, and then it gets mistaken for old age.

Two different illnesses under one name

An acute haematoma follows a serious injury: a road accident, a fall from height, a heavy blow. The blood builds up quickly, within hours, and the person visibly deteriorates over the first day or two. Nothing here is subtle, and the only question is how quickly an ambulance was called.

A chronic haematoma works differently, and it is the one that usually goes unrecognised. The bleeding is slow, from thin veins running from the surface of the brain to the membrane. Blood collects over weeks, thins out and turns into a slowly enlarging pocket of fluid. Anything from two weeks to several months passes between the injury and the first complaints, and by then nobody connects the two. What is more, the knock may have been trivial: catching your head on a door frame, stepping off a stool badly, a sharp jolt on a bus. The person often has no memory of it at all and tells the doctor, quite honestly, that they have not banged their head.

Why it happens mainly to older people

With age the brain shrinks a little, and more free space opens up between it and its coverings. The veins crossing that space are left stretched, like cables strung over a gap, and they tear with far less force than they would in a young person. The free space matters in a second way too: there is room for blood to collect, so it causes no symptoms for a long while, because nothing is yet squeezed. By the time the complaints appear, the haematoma is already large.

The risk is markedly higher in anyone taking medicines that thin the blood, whether anticoagulants or antiplatelet drugs. They are prescribed for atrial fibrillation, after a heart attack, after a valve replacement, after a stent, and the people taking them are usually well past seventy. Add frequent falls, heavy drinking, clotting disorders and previous brain surgery, and you have a portrait of the typical patient with a chronic haematoma.

What relatives see and put down to age

A chronic haematoma almost never announces itself dramatically. It shows up as gradual change that is easy to explain away as something else:

• a headache lasting for days and creeping upwards in severity, often worse in the morning;
• drowsiness and listlessness: more and more time spent in bed, harder to rouse;
• confusion, forgetfulness, repeated questions, losing the thread of a conversation;
• a change in character: irritability, apathy, withdrawal, behaviour that is out of keeping;
• unsteadiness on the feet, more frequent falls, a feeling that the legs will not obey;
• weakness or clumsiness in one arm or leg, usually on the same side of the body;
• slurred speech, difficulty finding words, trouble swallowing;
• double or blurred vision, nausea and, less often, loss of bladder control.

All of it looks very much like dementia, depression or simply getting old, and that is exactly how families usually explain it. The difference comes down to one thing, and it is decisive: dementia worsens over years, a haematoma over weeks. If an older person has changed in the space of a month or six weeks, if they are noticeably sleepier, more muddled or less steady than they were last Christmas or last summer, that is not ageing and it is a reason to have a scan of the head. A chronic haematoma belongs on the short list of causes of confusion in an older person that can be reversed: take the blood away and the person comes back.

When a head injury needs an ambulance

Call an ambulance (112 is the single emergency number across Europe) if any of these follow a blow to the head:

• loss of consciousness, especially if the person does not come round or is hard to wake;
• vomiting, particularly more than once;
• a headache that keeps building and is not relieved by painkillers;
• a seizure;
• slurred speech, weakness or numbness in an arm, a leg or one side of the face;
• pupils of unequal size;
• increasing confusion, odd behaviour, failing to recognise familiar people;
• clear fluid or blood coming from the nose or ear, bruising behind the ears or around both eyes without a direct blow to the eye.

The lucid interval deserves its own warning. It goes like this: the person felt awful after the blow, then clearly improved, talking, joking, refusing to see anyone, and an hour or several hours later starts to fade again. That middle stretch of improvement does not mean they got away with it. It means blood is collecting and is about to compress the brain. Deterioration after a period of clarity is an ambulance call, with nothing to debate.

The threshold for getting checked is lower than people think

Anyone taking blood-thinning medicine should be seen by a doctor even after a mild bang on the head, and even if they feel completely well. That is the single most useful rule on this page. On these drugs, bleeding that would stop by itself in someone else carries on, and a scan in the first few hours is far cheaper than an operation a week later. The same applies to older people after any fall involving the head, to people with clotting disorders, and to anyone who had been drinking when the injury happened: alcohol masks precisely the signs used to judge how serious things are.

Nobody should stop an anticoagulant on their own initiative, either before or after an injury. The risk of clots and stroke after an unsupervised withdrawal is entirely real. That decision belongs to a doctor, who has both the drugs that reverse the blood-thinning effect and the judgement about when treatment can safely start again.

In babies a subdural haematoma is rare but calls for particular care. Worrying signs are a bulging fontanelle, a head circumference growing unusually fast, vomiting, floppiness, seizures and refusing feeds. If those appear with no clear account of an injury, the baby needs to be seen urgently. The causes in infants vary, and sorting them out is a job for a specialist, not for parents reading online.

How it is found and what happens next

The diagnosis is made on a scan. A CT scan of the head is usually enough; it takes a few minutes and shows blood well. In a chronic haematoma, where the blood has already thinned and shows up less clearly on CT, an MRI scan helps. No blood test or examination replaces the picture, so there is no point talking a doctor out of one, just as there is no point demanding one after a trivial knock with not a single warning sign.

From there, two paths are possible. A small haematoma that barely presses on the brain and causes no symptoms is sometimes simply watched: the scan is repeated after a while, the blood-thinning medicines are reviewed, the person is kept under observation. Some of these collections clear on their own.

If the haematoma is large or the symptoms are getting worse, the blood is removed surgically. In a chronic haematoma, where the contents are liquid, a small operation is usually enough: one or two burr holes are made in the skull, the collection is washed out and a fine drain is left in place for a day or two. An acute haematoma with a solid clot needs a larger operation with a section of skull opened. In some centres, chronic haematomas are additionally treated by blocking the artery that supplies the membrane from the inside, to make refilling less likely. Improvement after the blood is removed is often quick: within days the mind clears and walking steadies.

Recovery and what to expect afterwards

The outcome depends above all on how quickly the haematoma was found and what state the person was in on arrival. Where a chronic haematoma is treated in good time, older people frequently return to their previous life in full, and relatives are startled to find that the dementia has gone. An acute haematoma after a severe injury is far more dangerous and can leave lasting consequences: weakness in the limbs, speech problems, difficulty with memory and attention, changes in personality and sometimes epileptic seizures.

Three things are worth knowing in advance. First, a chronic haematoma can refill, and this is not unusual, so if the old complaints come back the answer is to see a doctor rather than wait. Second, recovery runs for months, and fatigue, headaches and slowed thinking during that period are normal; sessions with a physiotherapist, a speech and language therapist and a psychologist all help. Third, it is worth tackling the cause of the falls: check eyesight and hearing, review with a doctor any medicines that cause dizziness, clear slippery rugs and trailing cables out of the house, improve the lighting and fit grab rails. Dull measures, but they cut the chance of a second haematoma more than any tablet does.

Online consultation

An acute head injury is not something to work through online: the signs listed above need an ambulance, not a message thread. A remote appointment still has several clear uses here. A doctor can help decide whether a particular knock on the head needs an examination and a scan today, especially where the person takes blood-thinning medicine and has no sense of how much that changes things. They can go through the changes in an older relative with the family and say whether this looks like gradual dementia or like something that has come on too fast and warrants a scan. They can put an existing report into plain words. And they can help plan recovery after surgery: what timescales to expect, when to return to physical activity, how to raise restarting the anticoagulant with the treating team, and what to change at home so the fall does not happen again.

This material is for information only and does not replace medical advice.