Head CT after concussion?
Firstly, evidence of concussion does not show up on standard brain imaging.
If a brain scan of some sort is ordered, the physician is likely looking for evidence that the injury might be more than a concussion. But why might a physician suspect that the injury is more than a concussion?
When might a Head CT be ordered?
The Emergency Physician may use the PECARN Pediatric Head Injury/Trauma Algorithm for determining whether a Head CT is indicated or not.
PECARN stands for Pediatric Emergency Care Applied Research Network.
The goal is to use head CT tests for those people that would benefit from them, that is, those people that are likely to need some sort of medical intervention like neurosurgery.
The other goal is to avoid using head CT scans on people who are low risk of needing hospital admission and medical intervention. This is because a CT scan uses X-rays which is an ionizing radiation. One head CT scan can be the equivalent of 100 chest X-rays of radiation exposure. There is a small increased risk of cancer later in life when people are exposed to ionizing radiation, but this depends on the total amount of radiation exposure.. This is why clinical prediction rules like the PECARN Rule are developed and tested.
So here’s a summary of the PECARN Rule for determining if a Head CT is indicated for children aged 2 – 18 years old.
Step 1:
Answering ‘yes’ to any of the first 3 categories during the hospital assessment suggests a high risk (4.3%) that the child has a Clinically Important Traumatic Brain Injury, and a Head CT is indicated.
1) GCS (Glasgow Coma Score) score less than 15
- a score of 15 means the person
a) obeys commands fully
b) is alert and oriented
c) has spontaneous eye opening
2) Signs of basilar skull fracture
Palpable skull fracture
Bloody eardrum
CSF leaking from nose (CSF is Cerebrospinal Fluid)
CSF leaking from ear
Late signs (up to 24 hours after injury): raccoon eyes or bruising behind the ears.
3) Abnormal Mental Status
Agitation
Somnolence
Repetitive questioning
Slow response to verbal questioning
Step 2:
Answering ‘yes’ to any of the next 4 categories may result in a Head CT being ordered, or it may be decided that more observation while in hospital is most appropriate before making a definitive decision about the Head CT.
4) Loss of Consciousness (LOC)
But does not include LOC less than 5 seconds associated with low-risk mechanisms for
head trauma.
5) Severe Mechanism of Injury
Fall from 5 feet or higher
Head struck by high impact object
Motor vehicle collision with patient ejection from vehicle, or death of another passenger, or a rollover.
Pedestrian or cyclist without helmet struck by a motorized vehicle.
6) Any Vomiting
7) Severe Headache
If none of the 7 from the above are present then the Risk of severe Traumatic Brain Injury: is less than 0.05% and CT is not indicated according to the PECARN Rule.
The main point here is that not everyone will need a brain scan in hospital because abnormalities will not be visible on standard brain scans when it comes to concussion. The scan is used to assess for other injuries that are more serious in nature and that may require hospitalization and medical intervention.