Comparative Literature Analysis of Peripheral Vestibular Function Assessment Tools

Objective Purpose: One main function of the peripheral vestibular system\u27s semicircular canals is to stabilize images on a target during head movements through the important vestibula-ocular reflex (VOR) in order to maintain clear vision. Abnormal VOR response results in fast, compensatory, catch­ up saccadic eye movements suggesting dysfunction in the semicircular canals. Several functional assessment tools have been developed since the twentieth century to measure the VOR response and saccadic eye movement, and some are still widely used currently, such as the caloric test, rotary chair test, bedside head impulse test (bHIT), scleral search coil technique, and video head impulse test (vHIT). However, with advancing technology and evidence-based medicine, what was traditionally used lack validity and reliability or clinical applicability. This paper aims to 1. evaluate each of the five assessment tools individually in describing its historical use, set-up parameters, benefits, and limitations, and 2. to compare current literature on the validity of the newest vHIT assessment tool against the other four, age-tested peripheral vestibular function assessment tools. Methods: A comparative literature analysis was performed, using a computerized literature search from Medline, CINAHL, PubMed, Google Scholar, and PEDro. Studies describing search words such as vestibular system, peripheral vestibular function, semicircular canal, VOR, saccades, assessment tools, caloric test, rotary chair test, bedside head impulse test (bHIT), scleral search coil technique, and video head impulse test (vHIT) were included. Human subjects and English language restrictions were imposed. 27 studies, textbooks and manuscripts were included. Results: In the current literature, the newest vHIT assessment tool was consistently found to provide accurate and objective data in identifying peripheral vestibular dysfunction of the semicircular canals, in both middle-aged and older healthy controls, as well as in patients in an acute and non-acute peripheral vestibular disease stage. In comparison to the other four assessment tools, the vHIT was also found to be portable, simple, affordable, quick, non­ invasive, and clinically easy-to-use. Conclusion: The findings of the comparative literature search suggest the newest assessment tool, the vHIT, can be considered the best available reference standard for an assessment tool in identifying peripheral vestibular dysfunction of the semicircular canals, based on its validity, reliability and widespread clinical applicability. Further clinical research is needed to determine if the theoretical comparisons are true