Explicit diagnostic criteria for transient ischemic attacks to differentiate it from migraine with aura.

Background The diagnosis of transient ischemic attacks is fraught with problems. The inter-observer agreement has repeatedly been shown to be low even in a neurological setting, and the specificity of the diagnosis is modest to low, reflected in a poor separation of transient ischemic attacks and mimics, particularly migraine with aura with its varied symptomatology. In other disease areas, explicit diagnostic criteria have improved sensitivity and specificity of diagnoses. We therefore present novel explicit diagnostic criteria for transient ischemic attacks tested for sensitivity and for specificity against migraine with aura. Methods The proposed criteria were developed using the format of the international headache classification. We drew upon the existing literature about clinical characteristics and diagnosis of migraine with aura and transient ischemic attacks. We tested the criteria for sensitivity in a prospectively-collected material of 120 patients with transient ischemic attacks diagnosed before we developed the criteria using extensive semi-structured interview forms in the acute phase after admission. Eligible patients had focal brain or retinal ischemia with resolution of symptoms within 24 hours without presence of new infarction on magnetic resonance imaging with diffusion weighted imaging (n=112) or computed tomography (n=8). These criteria were also tested for specificity against a Danish (n=1390) and a Russian (n=152) material of patients with migraine with aura diagnosed according to the International Classification of Headache Disorders edition 3 (beta). Results The sensitivity of the proposed criteria was 99% in patients with transient ischemic attacks. The specificity was 95% in the Danish material of patients with migraine with aura and 96% in the Russian material. Conclusions Proposed explicit diagnostic criteria for transient ischemic attacks showed both high specificity and sensitivity. They are likely to improve the emergency room diagnosis of transient ischemic attacks. Further testing in unselected materials referred to transient ischemic attacks clinics was beyond the scope of the present study but is recommended for future study.