The application of subjective visual vertical in balance system disorders

According to the guidelines approved by international scientific associations, the assessment of the vestibular system and its rehabilitation is carried out by audiologists. The subjective visual vertical (SVV) test, while simply done, is an appropriate test for assessment of otolithic system. This review study has tried to introduce the application of SVV test in different disorder of the vestibular system based on the clinical research in various resources.
We searched the subject of SVV in various databases from 1900 up to 2017. We used keywords of subjective visual vertical and SVV. 110 papers were found and 78 of them were selected. The application of SVV in balance system diseases was reviewed based on these original articles and three related text books.
The SVV test in the Pusher syndrome, migraine and the chronic phase of Meniere's disease did not statistically differentiate between two groups of normal and abnormal people. However, the SVV deviation in individuals with pusher syndrome was higher than normal subjects. In Parkinson's disease, vestibular neuritis, vestibular schwannoma, Pisa syndrome, benign paroxysmal positional vertigo, aging, hydrocephalus, chronic neck pains, acute phase of Meniere's disease and multiple sclerosis, the SVV test was able to separate normal subjects from abnormal subjects. The method and procedure for performing the SVV test will have a significant impact on the test result. Therefore, it is necessary to standardize the method of performing the SVV test for each particular disease.