In emergency departments, the use of computed tomography increased day by day. But its value in the diagnosis of neurological changes in patients with a severe headache is still controversial. Therefore in this meta-analysis, the author justified the diagnostic role of CT in patients with a severe headache.  

Subjects with acute severe headache, normal noncontrast head computed tomography (NCCT), and normal neurological examination may still have cervical arterial dissection, subarachnoid haemorrhage, reversible cerebral vasoconstriction syndrome (RCVS), or cerebral venous thrombosis (CVT). Computed tomography angiography (CTA) is employed frequently in the emergency department for assessing this, but its combined value is uncertain.

The data was collected retrospectively on the CTA diagnostic yield among subjects with acute severe headache, normal NCCT, and normal neurological examination who obtained added CTA in the acute phase. The identified data of this study combined with those from the literature and conducted a meta-analysis.

A total of 641 patients after literature search and 88 patients from the present analysis were selected. Fifty-four out of 729 patients exhibited vascular abnormality on CTA. Abnormalities comprised RCVS, aneurysms, CVT, arterial dissection, ischemia, and Moyamoya syndrome. As the maximum of the aneurysms were incidental findings, only 12 cases showed a clear association between the headache and CTA findings. The number needed to scan to determine an abnormality was 14, and 61 for an abnormality except for an aneurysm.

Diagnostic yield of CTA among patients with acute headache, normal NCCT, and normal neurological examination is weak, but because of the potential therapeutic outcomes, its application might be sustained in the emergency setting. Further analyses are required for confirming these results and cost-effectiveness.