The Canadian CT Head Rule
Abstract & Commentary
Source: Stiell IG, et al. The Canadian CT head rule for patients with minor head injury. Lancet. 2001;357:1391-1396.
The Canadian CT head injury group made up of emergency medicine leaders has focused on the usefulness of computed tomography (CT) in identifying potentially severe, trauma-induced intracranial hematomas that require neurosurgical intervention. They cite that emergency departments in the United States perform an estimated 270,000 annual CTs in head injuries with a total cost of $135-216 million dollars. Canada has varying records of using CT for acute head trauma in large different hospitals but their present numbers considerably vary among the different institutions.
Ten Canadian community and teaching institutions enrolled consecutive adult patients who arrived at their emergency departments after sustaining minor head injury. Accepted patients had received blunt head trauma, brief losses of consciousness (LOC), definite amnesia or disorientation, but all amounting to 13-15 Glasgow Coma Scale (GCS) ratings at onset, (15 GCS ratings = no severe abnormalities, but patients with < 13 GCS at any time always had CT scans). The time window for waiting to reach the hospital and enter the evaluations lasted for 24 hours following the trauma.
A total of 2078 high-risk patients fulfilled the above criteria for GCS score and received immediate CT scans associated with the injuries in the CT Head Rule. Stiell and colleagues define the CT Head Rule as follows: high-risk factors (for neurological intervention) include: GCS score < 15 at 2 hours after injury; suspected open or depressed skull fracture; any sign of basal skull fracture (hemotympanum "racoon" eyes, cerebrospinal fluid otorrhea/rhinorrhea, Battle’s sign); vomiting ³ 2 episodes; age ³ 65 years. Medium risk factors (for brain injury on CT) include: amnesia before impact > 30 min; and dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height > 3 feet or 5 stairs). They defined minor head injury as witnessed loss of consciousness, definite amnesia, or witnessed disorientation in patients with a GCS score of 13-15.
Stiell et al indicate that any 1 of the above 5 high-risk factors have the potential for requiring neurosurgical intervention, a fact indicator that CT is imperative. Most American hospitals presently would also perform the medium risk CT, but minor risks rarely need a CT for management.
Commentary
This report provides statistically strong indications for obtaining CT scans as quickly as possible for trauma patients who suffer a high symptomatic risk of progressive injury or death unless surgical treatment is supplied. As is true in the United States, medium-risk patients who arrive at small hospitals having no CT scanners should be sent promptly to more comprehensive institutions with a strong trauma service that is active a full 24 hours a day! Most such patients who need CTs within 24 hours post-trauma should be in the hands of alert doctors to act if worsening appears. —Fred Plum
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