From the Guidelines
Computed Tomography (CT) head scans are indicated for patients with head trauma who have a Glasgow Coma Scale (GCS) less than 15, suspected open or depressed skull fracture, signs of basal skull fracture, post-traumatic seizure, focal neurological deficit, or more than one episode of vomiting, as well as for non-traumatic presentations including sudden severe headache, new onset seizures, altered mental status, focal neurological deficits, suspected stroke, persistent headache with concerning features, and signs of increased intracranial pressure, according to the most recent guidelines 1. The indications for CT head scans in the United Kingdom and according to Advanced Trauma Life Support (ATLS) guidelines can be broken down into several key categories, including:
- Head trauma patients with a GCS less than 15, suspected open or depressed skull fracture, signs of basal skull fracture, post-traumatic seizure, focal neurological deficit, or more than one episode of vomiting
- Non-traumatic presentations, such as:
- Sudden severe headache
- New onset seizures
- Altered mental status
- Focal neurological deficits
- Suspected stroke
- Persistent headache with concerning features
- Signs of increased intracranial pressure These guidelines are supported by recent studies, including a 2021 update on acr appropriateness criteria for head trauma, which recommends CT head scans for patients with head trauma who have a normal CT but with an abnormal neurologic examination (eg, GCS <15) 1. It's worth noting that there is some controversy about the necessity of routine repeat CT in the presence of a normal initial CT and in the absence of neurologic deterioration, with some guidelines recommending against it 1. However, the most recent and highest quality study suggests that CT head scans are highly sensitive for the detection of findings that may require neurosurgical intervention in the acute phase 1. In terms of specific patient populations, such as those with coagulopathy, the evidence suggests that the risk of delayed traumatic intracranial hemorrhage (ICH) is low, even on anticoagulant or antiplatelet medication, and does not merit routine observation and repeat CT 1. Overall, the indications for CT head scans are guided by the need to identify potentially life-threatening conditions while balancing radiation exposure risks and resource utilization, with the most recent guidelines prioritizing the use of CT head scans for patients with head trauma and non-traumatic presentations who are at high risk of adverse outcomes 1.
From the Research
Indications for CT Head Scans
- The Canadian CT Head Rule suggests that CT head scans are indicated for patients with minor head injuries who have certain high-risk factors, including failure to reach a Glasgow Coma Scale (GCS) score of 15 within 2 hours, suspected open skull fracture, any sign of basal skull fracture, vomiting more than 2 episodes, or age over 65 years 2.
- The study also identified medium-risk factors, such as amnesia before impact more than 30 minutes and dangerous mechanism of injury, which can help identify patients who may benefit from a CT head scan 2.
- Another study found that patients with minor head trauma who have high-risk criteria, such as vomiting or suspected skull fracture, should undergo initial CT scan, even if they have a GCS score of 15 3.
- The Advanced Trauma Life Support (ATLS) guidelines recommend CT head scans for patients with severe head injuries, defined as a GCS score of 8 or less, as well as for patients with mild to moderate head injuries who have certain risk factors, such as age over 65, anticoagulant use, or evidence of basal skull fracture 4.
- A study on older adult patients with minor head injury found that CT head scans may be avoided if the patient does not have high-risk mechanisms of injury, vomiting, witnessed loss of consciousness, or anterograde amnesia 5.
CT Head Scans in the United Kingdom
- There is no specific evidence provided on the indications for CT head scans in the United Kingdom.
- However, the ATLS guidelines, which are widely adopted in the UK, recommend CT head scans for patients with severe head injuries and for patients with mild to moderate head injuries who have certain risk factors 4.
Repeat CT Head Scans
- A study found that routine repeat CT head scans are not necessary for patients with mild to moderate head injuries, but may be beneficial for patients with severe head injuries or those who have undergone neurosurgical intervention 6.
- Another study found that patients with a GCS score of 8 or less may benefit from routine repeat CT head scans, as the results may lead to intervention without neurologic change 4.