Mobile phone app Vs bucket test as a subjective visual vertical test: a validation study.

BACKGROUND: The SVV tests the ability of a person to perceive the gravitational vertical. A tilt in SVV indicates vestibular imbalance in the roll plane, and thus injuries to the utricle or its connecting nerves. A validated bedside method (et, al., 2009, 72(19):1689-1692, Neurol, Zwergal) is the bucket method, in which the subject estimates the true vertical by attempting to properly align a straight line visible on the bottom of a bucket that is rotated at random by the examiner. In our study, the subjects need to align the plumb line on the Visual Vertical iOS app to the vertical direction. METHODS: Measurements of the SVV were made in 22 healthy subjects (16 females and 6 males). Each subject conducted 10 iterations of bucket test and 10 iterations of iOS app test. The reliability and validity of the iOS app was analyzed by SPSS21. RESULTS: Cronbach's α for the plumb line method was 0.976, and the iOS app was 0.978. Statistical comparison of SVV values measured by the iOS app and the bucket method showed no significant difference in distribution (Mann Whitney U test U = 0.944). CONCLUSION: The Visual Vertical iOS app is an effective and accessible substitute to the plumb line for the measurement of the validated bucket test.

Nuevo método para evaluar el Test Subjetivo Vertical / New method for assessing Subjective Visual Vertical Test

Introducción: La prueba Visual Subjetiva Vertical (SVV por sus siglas en inglés) corresponde a una prueba de bajo costo y complejidad que permite el estudio de la función vestibular "estática". En el año 2009 se valida la Prueba del Balde con igual confianza, sensibilidad y especificidad, que la prueba de domo. Sin embargo, diversos factores impresionan disminuir su precisión. Objetivo: Proponer un nuevo método utilizando un programa computacional y una interfaz pantalla-paciente, que permita disminuir la influencia de variables y aumentar la precisión de la evaluación. Material y método: En 43 voluntarios sin historia de patología vestibular y en 32 pacientes con patología vestibular se compararon los resultados de la aplicación de SVV en dos modalidades: prueba del balde tradicionalyuna prueba computarizada propuesta en el presente artículo. Resultados: En nuestro estudio el SVV con balde muestra 57% de sensibilidad y 90% de especificidad, mientras el SVV digital tiene 74% de sensibilidad y 93% de especificidad, el cual también presentó significativamente una menor desviación estándar. Conclusión: En suma, el SVV computarizado arroja un resultado más preciso que SVV con balde, con mejor utilidad clínica al tener mayor de discriminación con mejores perfiles de sensibilidad/especificidad.

Background: Subjective Visual Vertical Test (SVV) is a low-cost and simple evaluation that allows the physician to study the static vestibular function of a patient. In 2009 the Bucket Test was validated as a high confidence, sensitivity and specificity comparable to the hemispheric dome testing device. Although, its result can be affected by multiple variables. Aim: To propose a new method to evaluate SVV using a computer software interface, that allows a reduction ofvariables therefore increasing its precision. Material and method: In a sample of 43 volunteers with no previous history of vestibular pathologies and 32 patients with diagnosed vestibular pathologies we compared the results of 2 different modules of SVV testing: a traditional bucket test and a computerized test proposed in the present article. Results: Bucket test SVV for this research showed a sensitivity of 57% and a specificity of 90%, meanwhile Computerized SVV had a sensitivity of 74% and a specificity of 93%, which also presented a significant smaller standard deviation. Conclusion: In summary, digital SVV testing grants more accurate result in comparison to the Bucket Test, with a better clinical performance due to an improved discriminatory capacity with better Sensitivity/Specificity profiles.