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Canadian CT Head Rule (CCHR)

Canadian CT Head Rule (Stiell 2001)

Decides whether a non-contrast head CT is warranted after a minor head injury (Glasgow Coma Scale 13-15) using five high-risk and two medium-risk criteria. Any single criterion present means the rule recommends imaging.

Also searched as: head injury · trauma · decision rule · GCS · emergency · tbi

Glasgow Coma Scale score below 15 at 2 hours after the injury

High-risk criterion: its presence predicts need for neurosurgical intervention.

Suspected open or depressed skull fracture

High-risk criterion: its presence predicts need for neurosurgical intervention.

Any sign of basal skull fracture (hemotympanum, raccoon eyes, CSF otorrhea or rhinorrhea, Battle sign)

High-risk criterion: its presence predicts need for neurosurgical intervention.

Two or more episodes of vomiting

High-risk criterion: its presence predicts need for neurosurgical intervention.

Age 65 years or older

High-risk criterion: its presence predicts need for neurosurgical intervention.

Retrograde amnesia to the event lasting more than 30 minutes

Medium-risk criterion: its presence predicts clinically important brain injury on CT.

Dangerous mechanism (pedestrian struck by a motor vehicle, occupant ejected from a motor vehicle, fall from more than 3 feet or more than 5 stairs)

Medium-risk criterion: its presence predicts clinically important brain injury on CT.

Information
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  • Answer all seven criteria (present or absent) to apply the rule. The rule applies only to minor head injury: age 16 or older, GCS 13-15, with witnessed loss of consciousness, amnesia, or disorientation.

How this tool works

The Canadian CT Head Rule was derived and validated in adults (age 16 or older) with minor head injury - blunt trauma with witnessed loss of consciousness, definite amnesia, or witnessed disorientation and a GCS score of 13 to 15. Five high-risk criteria were chosen for 100% sensitivity for injuries requiring neurosurgical intervention, and two medium-risk criteria extend sensitivity for clinically important brain injury found on CT. The rule is not validated for patients under 16, patients with a GCS below 13, those on anticoagulation or with a bleeding disorder, or those with an obvious open skull fracture or a seizure after the injury; such patients generally warrant imaging on clinical grounds.

References

Implemented from the cited published sources. Educational use only; confirm against current guidelines before clinical use.

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