When to Get a CT Scan After a Head Injury

When to Get a CT Scan After a Head Injury: Key Insights

A CT scan is a safe, painless imaging test and is often used as an initial emergency department assessment after a head injury to check for any significant damage and assess injury severity. So, when should you get a CT scan after a head injury? It depends on your symptoms.

Here, we’ll take a look at the signs that you need a CT scan after a head injury, how CT scans work and what to expect during your scan. We’ll also explore other imaging options for head trauma.

What is a head injury?

A head injury can happen in everyday situations. For example, a pedestrian may fall and hit their head, a cyclist struck on the head after a fall could be seriously injured, or a driver may suffer a high speed injury. In some cases, these accidents can lead to traumatic brain injuries and neurological disorders.

A head injury can also cause a temporary brain injury called a concussion. This happens when a blow to the head causes shaking of the brain tissue and consequently interferes with brain function. This is usually a mild traumatic brain injury and most people recover within a month.

However, severe head injuries can cause longer-lasting effects and neurological conditions.

Signs you need a CT scan after a head injury

If you show signs of a basal skull fracture, you should seek immediate medical attention. Visit your nearest emergency department or trauma unit and have an urgent CT head scan for a primary investigation. The signs of a basal skull fracture include:

blood or clear fluid leaking from your ears or nose
bruising behind the ears
bruising around the eyes
loss of hearing

You should also have an immediate CT scan of your head after a head injury if you experience signs such as:

you become very confused
you vomit more than once
you have seizures after your head trauma (post traumatic seizures)
you show signs of weakness or numbness in any part of your body
your skull is cracked open or appears deformed (depressed skull fracture).

If you have sustained a head injury but do not display any of the above symptoms, you should still seek medical attention if you have experienced a loss of consciousness for any amount of time, changes in blood pressure, you feel drowsy, or struggle to keep your eyes open.

You should also seek medical attention if you have certain risk factors, such as being aged over 65 or taking blood-thinning medication (anticoagulant treatment).

In addition, you should have a head CT scan if you have worsening symptoms or develop concussion symptoms, such as persistent headaches and confusion. Other concussion symptoms include any focal neurological deficit — this means a change caused by damage to a specific part of the brain.

These changes include memory problems, mood changes, dizziness, balance problems, vision changes and sensitivity to light or noise. These changes can get worse over time if a secondary brain injury develops after the initial head injury.

If you sustained your injury during a road traffic accident or a fall of more than one metre (5 steps on a staircase), you should seek medical attention even if you do not develop significant symptoms or seem to have only superficial injuries. A doctor will carry out an initial assessment to determine if you need a head CT scan or have other injuries.

CT scans for post concussion syndrome

If you develop a concussion due to a head injury, you may have mild but persistent symptoms for weeks or months later. This is called post-concussion syndrome — the symptoms are the same as concussion symptoms but milder.

If you did not have a CT scan within hours after the injury and then develop post-concussion syndrome, your doctor may recommend that you have a CT scan.

How CT scans work

CT scans use X-rays, a type of ionising radiation, as well as computer processing. Together, this technology creates detailed images of the inside of your body.

During a CT scan, you will be asked to lie down on a patient table. The table will be slid through a large ring, which is part of the CT scanner. The ring contains X-ray generators and X-ray detectors.

The X-ray generators pass beams of X-rays into your body. Some X-rays are absorbed by your tissues while others pass straight through and are picked up by the X-ray detectors.

Signals from the X-ray detectors are sent to a computer, where they are processed to form a 2D image of part of your body. Multiple 2D images are collected to form a detailed 3D image of tissues in your body.

CT imaging of the head produces high-resolution images of the top part of your central nervous system, that is, your brain and cervical spine as well as blood vessels that supply it and any blood clots that have formed.

Consequently, a CT head scan may be requested by health professionals for risk assessment after they have performed a neurological exam to investigate a head injury.

Other imaging options for head trauma

CT scans are usually the first option to investigate head injuries, especially within the first few hours of sustaining the injury.

However, an MRI (magnetic resonance imaging) scan may be used later to investigate ongoing symptoms or, once your condition is stable, to assess the extent of damage caused.

An MRI scan of the head can help detect conditions that may be missed on a CT head scan, such as a diffuse axonal injury.

What to expect during your CT scan

Some CT scans are performed using a contrast agent to improve the clarity of the images. If you are having a contrast agent, you will need to fast; your care team will advise you for how long.

You will need to remove all metal items before having your scan. This includes jewellery, hair accessories, body piercings and removable medical devices, as well as clothing with metal zippers, buttons and clasps. You will be provided with a hospital gown to change into if needed.

A CT head scan usually takes 10–15 minutes to complete. If you have a contrast agent, you will need to remain at the scanning facility for up to 30 minutes after your scan to check that you do not develop an allergic reaction to the contrast agent – this is rare and usually mild.

Find out if you need a CT scan

If you have recently had a head injury and are concerned about ongoing symptoms, you can see one of our experienced Vista Health GPs, who can refer you for a private CT scan if needed.