What is the indication for a Computed Tomography (CT) scan for a concussion?

From the Guidelines

A Computed Tomography (CT) scan is indicated for a concussion in patients with high-risk factors, such as altered mental status, signs of basilar skull fracture, or significant mechanism of injury.

Indications for CT Scan

• High-risk factors for clinically important traumatic brain injury (TBI) by PECARN criteria, including:
  • Altered mental status
  • Signs of basilar skull fracture
  • Significant mechanism of injury
• Moderate or severe acute blunt head trauma (GCS 13), excluding suspected abusive head trauma 1
• Subacute blunt head trauma with cognitive or neurologic signs, where CT head without IV contrast or MRI head without IV contrast may be appropriate 1

Considerations for CT Scan

• The risk of clinically important intracranial injury in high-risk patients is estimated at approximately 4.3% to 4.4% 1
• CT has the advantage of rapid acquisition and excellent sensitivity for acute intracranial hemorrhage and fractures 1
• Careful clinical observation or CT head without IV contrast may be appropriate for the initial imaging of children with minor acute blunt head trauma and intermediate risk for clinically important brain injury per PECARN criteria 1

From the Research

Indications for Computed Tomography (CT) Scan in Concussion

The following are indications for a CT scan in patients with a concussion:

• High-risk factors such as 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
• Medium-risk factors such as amnesia before impact more than 30 minutes and dangerous mechanism of injury 2
• Loss of consciousness (LOC) or altered mentation, although these are not sensitive indicators for selecting patients for CT scanning 3
• Skull fractures or superficial craniofacial injury, although these have poor negative predictive value 3
• Mechanism of injury, such as a high-risk mechanism, despite normal neurologic status in the field and at hospital screening 3

Clinical Decision Rules

Clinical decision rules, such as the Canadian CT Head Rule, can be used to determine the need for a CT scan in patients with minor head injuries 2, 4

• The Canadian CT Head Rule consists of five high-risk factors and two medium-risk factors, and has a sensitivity of 100% and specificity of 48-77% 2, 4
• The use of clinical decision rules can help reduce the number of unnecessary CT scans performed 4

Special Considerations in Children

In children, especially those under 3 years of age, the indications for a CT scan may be different due to the risks of radiation exposure 5, 6

• The fear of malpractice litigation is a common reason for requesting a CT scan in children with minor head trauma, even if it may not be necessary 6
• A liberal policy of CT scanning may be warranted for pediatric patients with a high-risk mechanism of injury, despite normal neurologic status 3