Normative data for the subjective visual vertical test during centrifugation.

BACKGROUND The otoliths act as gravito-inertial force sensors and contribute to the perception of spatial orientation. The perception of gravitational vertical can be assessed by asking a subject to adjust a light bar to the vertical. Prior to clinical use of the SVV (subjective visual vertical) test, normative data and test-retest reliability must be established. PURPOSE To obtain normative data and d etermine the test-retest reliability for the SVV test performed in static and dynamic test conditions. RESEARCH DESIGN A descriptive design was used to obtain normative data. STUDY SAMPLE Twenty-four young adults with no history of neurological disease, middle-ear pathology, open or closed head injury, cervical injury, or audiovestibular disorder participated in the study. DATA COLLECTION AND ANALYSIS The SVV angle was measured in the static position and in three dynamic conditions: (1) on-axis clockwise (CW) rotation, (2) off-axis CW rotation of right ear, and (3) off-axis CW rotation of left ear. RESULTS In young healthy individuals, the SVV was <2° for static and on-axis rotation, and shifted up to 11° during unilateral centrifugation. Test-retest reliability of the SVV was good for all test conditions. CONCLUSIONS The normative data obtained in this study may be useful in identifying patients with chronic utricular dysfunction. We recommend the use of difference angles (on-axis SVV - off-axis SVV) to remove baseline bias and decrease the variability of the SVV angles for the off-axis conditions.