To determine whether unenhanced CT alone could be sufficient for the screening of patients admitted with a suspicion of secondary headache in an emergency center.

A feasibility study including consecutive patients admitted to our emergency department for acute non-traumatic headache, in whom a brain CT was required by the emergency physician, was conducted over a 3-month period of time. Patients with a suspicion of intracranial pathology, which can only be depicted by i.v. images (arterial dissection, venous thrombosis, or postoperative complication) were recorded but excluded from analysis. All patients underwent both unenhanced and i.v. enhanced cerebral CT, including CT angiography. Unenhanced CTs were reviewed by two radiologists, blinded to the clinical data, to the radiological reports and to the i.v. enhanced images. Unenhanced CT were sorted by the radiologists into three groups: (1) normal CT, (2) benign finding that could explain headache without need of injection of contrast media, (3) evidence of an intracranial pathology, requiring further imaging. Results were compared to i.v. enhanced CT images.

A brain CT was required in 105 patients (34 males, 71 females) during the study period, 74 (70%) of them met our inclusion criteria. Fifty-nine (80%) were sorted in group 1 (normal), four (5%) in group 2, 11 (15%) in group 3. No further finding that could explain acute headache was found on i.v. CT images in patients of group 1 or 2. A significant pathology was confirmed by i.v. CT in all patients of group 3.

This feasibility study suggests that a normal unenhanced CT might be sufficient to exclude the cause of headache in the initial screening of a selected group of patients admitted with cephalalgia. It compels researchers to perform further prospective studies to confirm the current data on a larger amount of patients.