A person with a severe head injury should always be seen in an A&E department.
The healthcare professionals treating you will first make sure you're in a stable condition, before asking some questions to help with the diagnosis and treatment of your injury.
If a friend or relative has come with you to hospital, they may be asked to describe what happened if you can't remember.
The CT scan produces a detailed image of the inside of your head and shows whether there's any bleeding or swelling in your brain.
Depending on your scan results, you may be allowed to go home.
But you'll usually be kept in hospital for a short period of time to make sure your injury hasn't caused any serious problems.
The healthcare professionals treating you will assess your condition using the Glasgow Coma Scale (GCS).
The GCS is often used to assess the severity of damage to the brain.
It scores you on:
Your score for each is added up to give a total.
A slightly different version of the GCS is used for children under 5 years of age.
Depending on your GCS score, head injuries are classed as:
A score of 15 (the highest possible score) means you know who and where you are, can speak and move when asked to, and your eyes are open.
Someone with a score of 3 (the lowest possible score) will be in a coma, an unconscious state where a person is unresponsive and can't be woken. Their chances of survival will be small.
Based on your assessment, you may be allowed to go home, or you may be referred for further testing and treatment in hospital.
You may also need to have follow-up appointments at your local neurological centre or head injury clinic.
After a severe head injury, you'll only be allowed to go home if the results of your CT scan show that you don't have a brain injury and the person in charge of your care (a neurosurgeon or an A&E consultant) thinks you have a low risk of developing one.
You'll need someone to take you home because you won't be allowed to drive until you have completely recovered.
If possible, you'll also need someone to stay with you for the first 24 hours after your injury to keep an eye out for problems.
Before leaving hospital, you'll be advised about what to do and what not to do in the weeks after your injury.
You may need to be admitted to hospital for observation after a severe head injury.
This may be because:
Find out how a severe head injury is treated for more information about what happens when you're admitted to hospital.