Subjective Visual Vertical Evaluation by a Smartphone-based Test-Taking the Phone Out of the Bucket.

Abstract

To measure the subjective visual vertical (SVV) in patients suffering from peripheral vestibular disorders versus controls, using a smartphone-based test designed to simulate the bucket test, in order to validate it as an available tool for the clinician. Prospective cohort study. Academic tertiary medical center. Forty-five adult patients were recruited to the study, 25 had vestibular disorders, and 20 did not (controls). All patients underwent conventional bucket-SVV (b-SVV) and smartphone-based SVV (s-SVV) testing. Correlation and agreement of b-SVV and s-SVV scores in patients with peripheral vestibular disorders compared to controls. SVV score in the vestibular disorders group was significantly higher compared to controls in both testing methods (p < 0.001 for b-SVV and p = 0.01 for s-SVV, effect size d = 1.7 for both testing methods). Intragroup correlation was excellent within the study group. Spearman's rank correlation coefficient between b-SVV and s-SVV was 0.902 (p = 0.01). Agreement measurements suggested a greater sensitivity for the b-SVV test, showing a mean difference of 1.088 degree (SD ± 1.77); directionality, however, was preserved. The smartphone-based test is a valid, simple, and efficient in-office screening tool for assisting in the diagnosis of vestibular disorders.