A blow to the head
If you are reading this at three in the morning with a child in your arms, start with the red box. The rest can wait until tomorrow. And no, you do not have to keep them awake: that is a myth, and what you should be doing is something else.
This page is written differently from the other seven, because whoever is looking for it almost never has time. So the urgent part comes first and the explanation afterwards.
When to go to the emergency department now
After a blow to the head, any one of these signs means going in straight away, without waiting to see whether it passes:
- Loss of consciousness, even if it lasted only seconds.
- Repeated vomiting — more than once, or vomiting that keeps coming hours later.
- A headache that keeps getting worse instead of better.
- Unusual drowsiness or confusion: hard to wake, not recognising people, saying strange things, disorientated.
- A seizure.
- Weakness, pins and needles, trouble speaking, double vision, pupils of different sizes, loss of balance.
- Blood or clear fluid coming from the nose or the ear.
- Bruising behind the ear or around both eyes that appears hours later.
In a baby under one year old, also: irritability that nothing settles, refusing feeds, a large soft swelling on the head, or any fall from more than a metre. With the youngest, the threshold for going in should be far lower.
In an older person, or in anyone taking anticoagulants or antiplatelet drugs, go in even if the blow was mild and even if they feel fine. This is the group in whom a trivial injury can bleed.
If none of the above is present, this is very probably a blow without serious consequences, and what is called for is watching at home over the first twenty-four to forty-eight hours.
The myth about not letting them sleep
It is the most widespread belief about head injury, and it is false. You do not have to keep someone awake after a blow to the head. Sleep makes nothing worse, whereas lack of sleep makes the headache, the irritability and the confusion worse — and those are exactly the symptoms you want to be able to judge.
What you should do is different: check every so often, over the first few hours, that the person wakes normally. Not keeping them awake: checking that they can be woken. If you call them and they respond normally, let them sleep.
If someone is hard to wake, or is confused on waking, that is a reason to go in.
What a concussion is
It is a temporary disturbance of how the brain works, caused by a blow, with no injury visible on the scans. It causes headache, feeling dazed, nausea, sensitivity to light and noise, difficulty concentrating, irritability and disturbed sleep.
Two things worth knowing:
You do not have to lose consciousness to have a concussion. In fact, most people do not. That idea leads to a great many concussions being underestimated.
A normal CT scan does not mean nothing happened. Concussion is a clinical diagnosis. The CT scan looks for bleeding and fractures; a normal CT is exactly what is expected in a concussion, and it does not invalidate the symptoms.
How long it takes to pass
Here there is a badly calibrated expectation that makes a lot of people suffer. The best prospective study, with 594 participants, measured this:
- At 14 days, 45 per cent had recovered.
- At 4 weeks, 77 per cent.
- At 8 weeks, 96 per cent.
In other words: fewer than half recover within two weeks. Still having a headache and trouble concentrating at ten days does not mean something is wrong: it means recovery is going the way recovery goes. Recovery tends to be somewhat slower in women.
During that time, current practice is not complete rest in a darkened room, which has been abandoned. It is relative rest for the first few days and then a gradual return to activity, stopping short of provoking symptoms. The return to contact sport is done in stages, and always after the return to school or work.
Chronic subdural haematoma
It deserves a section of its own, because it is the scenario people do not expect.
In older people, and above all in those taking anticoagulants, a mild blow — sometimes one they do not even remember — can cause slow bleeding between the brain and its coverings. That bleeding builds up over weeks and only then starts to produce symptoms: a persistent headache, progressive confusion, changes in personality, unsteadiness when walking, weakness down one side.
It gets mistaken for dementia, for a stroke, or for "old age". And it has a simple, highly effective treatment once it is recognised.
So if an older person changes in the weeks or months after a blow — even a minor one, even a month later — tell the doctor. Even if the blow seemed insignificant at the time.
What you will hear that is not true
"Do not let them sleep." False, and counterproductive. The right thing is to check that they wake properly.
"They did not black out, so it was nothing." False. Most concussions happen without any loss of consciousness.
"The CT was clear, so nothing happened." A CT scan rules out bleeding; it does not rule out concussion.
"You will be fine in a week." Only 45 per cent recover within two weeks.
"It stopped hurting, so they can play again." The absence of pain is not the criterion for going back to contact sport. The return is gradual and staged, because a second blow during the vulnerable period is far more dangerous than the first.
"A mild blow never bleeds." In older people and in those on anticoagulants, it can. That is exactly the mechanism of chronic subdural haematoma.
What will happen at the appointment
You will be asked about the mechanism — from what height, against what, whether there was any loss of consciousness, whether the moment is remembered — and they will assess level of consciousness, the pupils, strength and balance, and check the scalp for wounds and depressions.
A CT scan is not always requested, and that is correct: there are validated decision rules that identify who benefits and avoid unnecessary radiation, especially in children. If one is not requested, it is reasonable to ask which criteria were used, but it is not in itself an oversight.
If you are sent home, you will be given warning signs to watch for. Ask for them in writing.
Questions worth writing down before you go
- What exactly do I have to watch for, and for how many hours?
- Is a CT scan needed in this case? Why, or why not?
- When can they go back to school, to work, to sport?
- Which medicines can they take for the headache, and which not?
- If they take anticoagulants, does anything need to be done differently?
- When should they come back to be checked?
The questions people ask most
How long should you stay awake after a head injury?
You should not: that advice is a myth. Nobody needs to be kept awake because of a blow to the head. What you should do is check every so often, over the first few hours, that the person wakes normally and responds properly. If they are hard to wake, or confused on waking, go to the emergency department.
How long after a head injury can symptoms appear?
Concussion symptoms can appear or intensify over the first twenty-four to forty-eight hours. Acute bleeding usually shows itself within the first few hours. And chronic subdural haematoma, typical of older people, can take weeks to produce symptoms. That is why the period of close watching is one to two days, but any change over the following weeks also deserves a consultation.
How long does a concussion last?
Less time than people fear, but more than they are usually told. At fourteen days, 45 per cent of patients had recovered; at four weeks, 77 per cent; at eight weeks, 96 per cent. Still having symptoms at ten days does not mean something is wrong.
Is vomiting after a head injury normal?
A single vomit immediately after the blow can happen, especially in children. What is not normal is vomiting repeatedly, or starting to vomit hours later: that is a reason to go in without waiting.
When is a head injury serious in a child?
The threshold is lower than in an adult, above all under one year old. Go in for a fall from more than a metre, loss of consciousness, repeated vomiting, irritability that will not settle, unusual drowsiness, a large soft swelling, or any change in how the child normally behaves. If you are in doubt with a baby, go.
What is a chronic subdural haematoma?
It is slow bleeding between the brain and its coverings, building up over weeks after an injury that was often mild. It is typical of older people and of people on anticoagulants. It causes progressive confusion, headache, changes in personality or difficulty walking, and it gets mistaken for dementia. It has effective treatment once it is recognised.
What can you take for a headache after a head injury?
In the first few hours it is better to avoid anti-inflammatories and aspirin, because they can encourage bleeding, and to use paracetamol if something is needed. But this is worth confirming with the doctor who assesses the case, especially if the person takes anticoagulants.
When can you go back to playing sport?
After the symptoms have resolved, and following a gradual staged return that starts with light activity and ends with contact. You never go back to contact on the same day. The reason is that a second blow during the recovery period is far more dangerous than the first.