Computed tomography for non-traumatic headache in the emergency department and the impact of follow-up testing on altering the initial diagnosis.

The purpose of this study was twofold: (1) to determine the incidence of positive computed tomography (CT) findings in patients presenting to the emergency department (ED) with non-traumatic headache at our institution and (2) to examine follow-up exams, including lumbar puncture, non-enhanced CT, CT angiogram, CT venogram, and magnetic resonance imaging (MRI), to see how often the use of further testing changes the diagnosis. With IRB approval, 865 patients were identified through ED requisitions for CT head with the indication of headache during the calendar year 2011. Exclusion criteria included head trauma, prior intracranial surgery, focal neurologic symptoms, and known intracranial mass. CT results were divided into three categories: P0, P1, and P2. Negative studies were graded as P0. Positive studies were subdivided into clinically insignificant or P1 and clinically significant or P2. Clinically significant was defined as requiring medical treatment. Subsequently, the electronic medical records and picture archiving and communication system (PACS) were reviewed to determine the incidence of follow-up exams, including lumbar puncture or imaging. The secondary tests were divided into the same P0, P1, and P2 categories. There were 254 positive studies: P1 clinically insignificant (27.1 %, 235/865) and P2 clinically significant (2.2 %, 19/865). Of 257 follow-up exams performed, the majority were lumbar punctures (36.0 %) or CT angiograms (29.5 %). In 19/257 exams or 7.4 %, the additional testing changed the clinically insignificant (P0/P1) diagnosis to a significant (P2) result. At our institution, there was a 2.2 % incidence of significant positive CT findings in patients presenting to the ED with non-traumatic headache. Follow-up testing was variable and resulted in a 7.4 % increase in the severity of diagnosis compared to the initial negative CT scan.