The Canadian CT Head Rule (CCHR) can be used to help determine if a person who has had a minor head injury should have a CT scan. This can help improve the efficiency of resource utilization without compromising patient care. The authors are from multiple Canadian Universities and Emergency Departments.


Criteria for minor head injury:

(1) initial Glasgow coma score 13 to 15 (I believe this is as determined by the physician in the Emergency Department)

(2) one or more of the following:

(2a) witnessed loss of consciousness

(2b) definite amnesia

(2c) witnessed disorientation


Exclusion criteria:

(1) age < 16 years of age

(2) current anticoagulation therapy

(3) bleeding disorder

(4) Glasgow coma score < 13

(5) obvious open-skull fracture


The endpoints were either a need for neurological intervention and/or clinically important brain injury detected on CT scan.



Need for neurological intervention

death within 7 days from head injury; need for craniotomy, elevation of skull fracture, intracranial pressure monitoring, or intubation due to head injury within 7 days of injury.

Clinically important brain injury

any acute brain injury found on CT scan which would require hospitalization and/or neurological followup.


Rule: A CT scan is done if one or more medium and/or high risk factors are present.


Medium risk (for brain injury identified on CT scan)

(1) amnesia for events before impact > 30 minutes

(2) dangerous mechanism



• A dangerous mechanism includes (1) pedestrian struck by motor vehicle, (2) occupant ejected from motor vehicle, (3) fall from a height > 3 feet, or (4) fall down stairs > 5 steps


High risk (for need of neurological intervention):

(1) GCS score < 15 at 2 hours after injury

(2) suspected open or depressed skull fracture

(3) any sign of basal skull fracture

(4) >= 2 vomiting episodes

(5) age >= 65 years



• Signs of basal skull fracture includes (1) hemotympanum, (2) "raccoon" eyes, (3) CSF otorrhea or rhinorrhea, or (4) Battle's sign

• raccoon eyes = periorbital ecchymosis

• Battle's sign = discoloration in the line of the posterior auricular artery, with ecchymosis first appearing near the tip of the mastoid process



• Using both high and medium risk criteria to detect clinically important brain injury: sensitivity 98.4%, specificity 49.6%, proportion of patients with CT ordered 54.3%.

• Using the high risk criteria to identifying patients requiring neurological intervention: sensitivity 100%, specificity 68.7%, proportion of patients with CT ordered 32.2%.


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