A 66 year old male with a past medical history of type 2 diabetes presents to the emergency department for head injury. He was the restrained driver when he swerved his car to avoid a child that ran into the street to retrieve a ball. He was driving approximately 15 mph in his neighborhood and swerved onto grass. He hit his head on the driver side window and complains of a headache. He was able to ambulate out of the vehicle and denies loss of consciousness, vomiting, or use of blood thinners. Vital signs are normal. On exam, he is neurologically intact and has ecchymosis to the left forehead. Which of the following is appropriate justification to obtain head imaging according to the Canadian CT Head Rule?
A: Dangerous mechanism
B: Headache
C: Patient age
D: Rule does not apply to this patient
Answer: Rule does not apply to this patient
The Canadian CT Head Rule is a widely used clinical decision tool that emergency physicians frequently utilize to screen for significant head injuries. In the external validation trial, it was found to be 100% sensitive in detecting both clinically important brain injuries and injuries that required neurosurgical intervention. This patient does not meet the inclusion criteria for its use. If he did meet the inclusion criteria, his age would be an appropriate justification of head imaging as a high risk criteria. Headache is not part of the decision tool. His injury also does not meet the medium risk dangerous mechanism.
MDCalc states, “Patients with minimal head injury (i.e., no history of loss of consciousness, amnesia, and confusion) generally do not need a CT scan. For example, patients over 65 years old may not need a CT scan just based on their age if they do not have the history mentioned above. When a patient fails the CCHR, use clinical judgment on whether a CT scan is necessary.”
| Canadian CT Head Rule | |
| Inclusion Criteria | Exclusion Criteria |
| Head injury with GCS 13-15 and at least one of the following: | Age < 16 years |
| Loss of consciousness | Use of blood thinners |
| Amnesia to head injury event | Seizure after injury |
| Witnessed disorientation | |
References:
Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357(9266):1391-1396. doi:10.1016/s0140-6736(00)04561-x
https://www.mdcalc.com/calc/608/canadian-ct-head-injury-trauma-rule
