The “headline” you’ll see from this article is that the Canadian Head CT Rule outperforms the New Orleans Criteria for radiographic imaging in minor head trauma. Specifically, it outperforms it in this prospective, observational cohort from several hospitals in Tunisia, consecutive patients with blunt trauma to the head and at least one symptom secondary to the head trauma.
The most striking thing about this article, however, remains the gruesome number of false positives generated by each of these head CT decision rules. While, obviously, the intent is to capture all the cases requiring neurosurgical intervention, the New Orleans Criteria could not rule out potential need for neurosurgical intervention in 1,180 out of 1,582. When the theoretical purpose of these rules is to prevent “scanning everyone”, we’re not getting much bang for our buck. The Canadian Head CT Rule was better – but still indicated a need for scan in 656 out of 1,582.
While the article focuses mostly on the need for neurosurgical intervention in GCS 15 patients, it’s interesting to see their “secondary outcomes” which did not need “intervention”. Only 34 total patients in their cohort required intervention – while they found 133 skull fractures, 41 subdurals, 45 epidurals, 69 subarachnoids/hemorrhagic contusions, and 1 case of pneumocephalus. The Canadian rule would have missed 11 of the 218 “clinically significant” findings, for a sensitivity of 95%. The article does not specific precisely which types of findings were missed, but, clearly, many of those may be argued to be not significant. Unfortunately, deriving a better rule based on a more liberal definition of “clinical significance” is likely to result in more missed interventions – but it’s still probably worth trying.
“Prediction Value of the Canadian CT Head Rule and the New Orleans Criteria for Positive Head CT Scan and Acute Neurosurgical Procedures in Minor Head Trauma: A Multicenter External Validation Study”
http://www.ncbi.nlm.nih.gov/pubmed/22251188