Patients who go to the emergency department (ED) with seizures often undergo neuroimaging, usually CT scans. Such imaging in adults presenting with new onset ('index') seizures leads to a change in care for 9-17% of patients, but it's unclear if such changes are made following imaging in the ED for seizures in adults with known seizure disorders ('non-index' seizures).

Epilepsia 

In an Epilepsia study of 822 ED visits for non-index seizures, neuroimaging was performed in nearly half of all patients. Of these, 3% of imaging tests led to an acute change in patient management, 2% after excluding false positive scans.

Acute head trauma, prolonged alteration of consciousness, and a focal neurological examination at presentation were associated with an increased yield of ED neuroimaging. Without any of these three clinical factors, the true positive yield of neuroimaging was zero.

ED Neuroimaging

The findings support a more conservative use of ED neuroimaging for non-index seizures, based on clinical factors at the time of presentation. They reviewed 822 consecutive ED visits for nonindex seizures at the Oregon Health & Science University and the VA Portland Health Care System.

For each visit, they abstracted details of the clinical presentation, whether neuroimaging was obtained, the results of neuroimaging, and the results of previous neuroimaging studies, when available.

They determined whether ED neuroimaging led to an acute change in patient management (yield). Clinical factors associated with obtaining ED neuroimaging, and with the yield of neuroimaging, were evaluated by multivariate logistic regression.

A majority (78%) of ED seizure visits were for nonindex seizures. Neuroimaging was obtained in 381 of 822 nonindex seizure visits (46%). Of these, 11 imaging studies (3%) led to an acute change in patient management, 8 (2%) after excluding false?positive scans. Acute head trauma, prolonged alteration of consciousness, and a focal neurologic examination at presentation were associated with an increased yield of ED neuroimaging. Absent any of these 3 clinical factors the true positive yield of neuroimaging was zero.

ED neuroimaging was performed in nearly half of all patients presenting with nonindex seizures. A more conservative use of ED neuroimaging for nonindex seizures, based on clinical factors at presentation, could decrease imaging frequency with minimal loss of yield.