Abstract Body: Introduction. Dizziness is a common reason patients visit the emergency department (ED). Stroke-dizziness diagnosed in the ED is typically due to cerebellar or brainstem lesions which might only have subtle signs of central vestibular dysfunction. Stroke after the ED visit is infrequent but could have been missed at the index visit. In attempts to reduce missed stroke, efforts have focused on implementing the use of vestibular evaluations. However, lacking are details about the strokes in the follow-up period. Imaging details might inform the likelihood that the strokes could have been identified with a vestibular evaluation or were directly related to the index dizziness visit.

Methods. We conducted a retrospective cohort study from January 2016 to December 2020 across 13 EDs within a large integrated healthcare system in Southern California. We identified all adults with a stroke hospitalization (primary discharge diagnosis of I60-I64) in the 30 days following discharge home from the ED after a primary dizziness visit, excluding those with DNR/hospice status, trauma, or index stroke diagnosis. We abstracted stroke characteristics from the available imaging studies and reports.

Results. From a total of 77,315 index ED dizziness visits discharged home, we identified 92 (0.12%) patients with stroke hospitalization in the subsequent 30 days. Median age was 59 years (IQR,44-71) and 62% were female. The imaging studies identified an infarct in 69 (75%), hemorrhage in 17(18%), and no lesion in 5(5%) (imaging results not available in 1). In the 91 patients with available imaging results, stroke lesions were present in the anterior fossa in 55% (50 of 91) and the posterior fossa in 41% (37 of 91; 23 cerebellar, 14 brainstem). In 69 patients with imaging results available for measurement, the maximal lesion diameter was a median of 2.1 cm (IQR,0.9-4.0) [anterior fossa: 2.3 cm (IQR, 1.1-4.0); posterior fossa: 2.1 cm (IQR, 0.9-4.0)].

Conclusions. We found that most strokes diagnosed after ED dizziness visits were due to small lesions in the anterior fossa. These findings suggest that a large proportion of subsequent strokes are unlikely to be identified on vestibular evaluations and/or may not be directly related to the previously dizziness visit.