LAUSR

### Public Health Concern Dizziness and vertigo are responsible for an estimated 4.4 million emergency department (ED) visits in the United States each year and account for 4% of chief symptoms in the ED.1 Strokes are the underlying cause of ≈3% to 5% of such visits (130 000–220 000).2 These visits are associated with a high cost, estimated now to exceed $10 billion per year in the United States.3 This results from neuroimaging obtained in roughly half the patients1 and admissions for nearly 20%.4 ED physicians worldwide rank vertigo a top priority for developing better diagnostic tools.5 An evidence-based, cost-effective approach to diagnosing acute dizziness and vertigo is needed. ### Diagnostic Errors Improving diagnosis is recognized by the National Academy of Medicine as a public health priority.6 Nearly 10% of strokes are misdiagnosed at first medical contact.7 Of the ≈130 000 to 220 000 patients with stroke presenting with vertigo or dizziness to the ED, it is estimated that perhaps 45 000 to 75 000 are initially missed,3 with misdiagnosis disproportionately affecting the young (age<50), women, and minorities.8,9 A population-based cohort study found that patients discharged from the ED said to have benign dizziness are at 50-fold increased risk of a stroke hospitalization in the 7 days postdischarge relative to propensity score-matched controls.10 Another population-based registry showed that 90% of isolated posterior circulation transient ischemic attacks (TIAs), half presenting isolated vertigo symptoms, were not recognized at first medical contact.11 Overall, dizziness and vertigo are the symptoms most tightly linked to missed stroke.7,9 Given their low sensitivity (7%–16%),12 computed tomography (CT) scans are of little use for identifying acute ischemic strokes,13 particularly in the posterior fossa.12 Despite this, nearly 50% of US ED patient presenting dizziness are imaged by CT, and <3% by magnetic …