Head CT scans in the ED: Essential or exploited?

Many patients who present to the emergency department with dizziness and syncope receive head CT, but how many actually benefit?

The authors of a study published in the January 2015 issue of the American Journal of Roentgenology attempted to answer that question, as well as determine the clinical factors that might predict abnormal findings on head CT.

Dizziness is the reason for approximately 3.3% of all ED visits in the U.S. and responsible for 1.9% of all ED admissions, yet considerable confusion exists around clinical guidelines, the authors note. For instance, head CT is not recommended unless loss of consciousness is expected not to be syncope; and CT in uncomplicated syncope should be avoided unless physical or historical features of CNS dysfunction are present.

To answer their questions, the authors retrospectively reviewed consecutive patients who presented to the ED of the Kaiser Foundation Hospital in Honolulu complaining of dizziness, syncope or near-syncope between July 1, 2012, and December 31, 2012 and received head CT (489 patients).

Just 7.1% of patients who reported dizziness (253) and 6.4% of those with syncope and near syncope (236) showed abnormal results. Although the diagnostic yield was low, it included a number of potentially life-threatening conditions: intracranial hemorrhage, intracranial masses, possible acute infarct, hydrocephalus and skull fractures. Slightly more than 55% of the patients with syncope and acutely abnormal findings on CT were admitted to hospital; and near 40% of syncope patients with acutely abnormal CT findings were admitted.

Using binary stepwise logistic regression, the authors reported that 93.3% of the 489 patients had no acutely abnormal head CT findings. Furthermore, of the factors analyzed for the correlation of abnormal CT findings, three were found to be clinically significant (although using them within the regression model did not increase accuracy):

1. focal neural deficit
2. age greater than 60 years
3. acute head trauma

The authors acknowledged the difficulty ED physicians have in triaging patients presenting with dizziness and syncope and called for the construction of an imaging algorithm to aid ED physician in selecting patients with dizziness or syncope for imaging.

“Our results suggest that most patients presenting to the ED with syncope or dizziness may not benefit from head CT unless they are older, have a focal neurologic deficit or have a history of recent head trauma,” the authors concluded.