A bucket of static vestibular function

Abstract

Validation of a bedside test to measure the monocular and binocular subjective visual vertical (SVV). Monocular and binocular measurements of the SVV were made in 30 healthy subjects (mean age 46.1 +/- 16.4 years) and 30 patients with acute peripheral or central vestibular lesions (mean age 51.3 +/- 17.1 years). The established method uses a hemispheric dome (adjustment of a bar to the vertical without spatial orientation clues in a motor-driven, hemispheric dome randomly covered with colored dots). It was compared to a simple, self-made bucket method, in which the subject estimates true verticality by attempting to properly align a straight line visible on the bottom of a bucket that is rotated at random by the examiner. Comparative measurements of the whole group (n = 60) showed no difference in the distribution of monocular or binocular SVV values while using the hemispheric dome or the bucket method. Intertest reliability was 89% for monocular and 90% for binocular SVV measurements. Intratest reliability of the bucket method in 10 repetitions was 92% for binocular and monocular SVV determinations. With the bucket method, the range of absolute deviations of SVV values from true verticality in healthy subjects was 1.1 +/- 0.7 degrees for monocular and 0.9 +/- 0.7 degrees for binocular measurements (mean +/- SD). There was no significant effect of age or gender. The bucket method is an easily performed and reliable bedside test for determining monocular and binocular subjective visual vertical. The bucket can be modified within 1 hour and costs less than $5.