DEFENSIVE Stroke Scale: Novel Diagnostic Tool for Predicting Posterior Circulation Infarction in the Emergency Department

Background: Dizziness is the most common posterior circulation symptom; however, diagnosing a posterior circulation infarction is difficult due to a lack of typical symptoms. We aimed to investigate the frequency of misdiagnosis of a posterior circulation infarction in patients who presented with dizziness and to develop a new stroke scale that increased the diagnostic accuracy for stroke among these subjects. Methods: We retrospectively analyzed consecutive data from subjects hospitalized with ischemic stroke who presented with dizziness (the developmental phase). Based on these results, we created a novel stroke scale, which was used as a diagnostic procedure in the prospective validation phase. We compared the rate of misdiagnosis of ischemic stroke between phases. Results: During the development phase, 115 subjects were hospitalized for ischemic stroke accompanied by dizziness. Six ischemic stroke subjects were not properly diagnosed (6/115, 5.2%). We created the new DisEquilibrium, Floating sEnsation, Non-Specific dizziness, Imbalance, and VErtigo (DEFENSIVE) stroke scale to prevent underdiagnosis of a posterior circulation infarction. During the validation phase, 949 subjects with dizziness were examined with the DEFENSIVE stroke scale; among these subjects, 100 were hospitalized for ischemic stroke accompanied by dizziness. No subject with ischemic stroke was overlooked. The new DEFENSIVE stroke scale had a sensitivity of 100% and decreased the rate of improper diagnosis of stroke (5.2% versus 0%; P = .022). Conclusions: Our new stroke recognition instrument for a posterior circulation infarction presenting with dizziness and related symptoms (the DEFENSIVE stroke scale) is easy to administer and has good diagnostic accuracy.