Canadian Computed Tomography (CT) Head Rule Study

Inclusion Criteria:

Consecutive adult patients presenting to one of the study hospital EDs after sustaining acute minor head injury will be enrolled into the study. Eligibility as an 'acute minor head injury' case will be determined by the patient having all of the following characteristics upon arrival in the ED.

1. Blunt trauma to the head resulting in witnessed loss of consciousness, definite amnesia, or witnessed disorientation, no matter how brief; this may be determined from the patient or from the report of a witness (the patient will be asked specific questions: 'do you remember the accident?', 'how did you get to the hospital?', 'have you talked to me before?').
2. Initial ED GCS score of 13 or greater as ascertained by the attending physician (e.g. opens eyes spontaneously, obeys commands, but speech may include only comprehensible but inappropriate words).
3. Injury within the past 24 hours.

Exclusion Criteria:

1. less than 16 years,
2. 'minimal' head injury i.e. no loss of consciousness, amnesia, or disorientation,
3. no clear history of trauma as the primary event (for example primary seizure or syncope),
4. GCS score of less than 13,
5. head injury occurred more than 24 hours previously,
6. obvious penetrating skull injury or depressed fracture,
7. acute focal neurological deficit (motor or cranial nerve) that cannot be ascribed to an extracerebral cause, for example, traumatic mydriasis or peripheral neuropathy,
8. have suffered a seizure prior to assessment in the ED,
9. a bleeding disorder or current use of oral anticoagulants,125 or
10. returned for reassessment of the same head injury