vHIT Testing of Vertical Semicircular Canals With Goggles Yield Different Results Depending on Which Canal Plane Being Tested

Louise Wittmeyer Cedervall; Måns Magnusson; Mikael Karlberg; Per-Anders Fransson; Anastasia Nyström; Fredrik Tjernström

doi:10.3389/fneur.2021.692196

vHIT Testing of Vertical Semicircular Canals With Goggles Yield Different Results Depending on Which Canal Plane Being Tested

Front Neurol. 2021 Jul 27:12:692196. doi: 10.3389/fneur.2021.692196. eCollection 2021.

Authors

Louise Wittmeyer Cedervall¹, Måns Magnusson¹, Mikael Karlberg¹, Per-Anders Fransson¹, Anastasia Nyström¹, Fredrik Tjernström¹

Affiliation

¹ Department of Otorhinolaryngology, Head and Neck Surgery, Clinical Sciences, Lund Skåne University Hospital Lund, Lund, Sweden.

Abstract

Objective: The use of goggles to assess vertical semicircular canal function has become a standard method in vestibular testing, both in clinic and in research, but there are different methods and apparatus in use. The aim of this study was to determine what the cause of the systematic differences is between gain values in testing of the vertical semicircular canals with two different video head impulse test (vHIT) equipment in subjects with normal vestibular function. Study Design: Retrospective analysis of gain values on patients with clinically deemed normal vestibular function (absence of a corrective eye saccade), tested with either Interacoustics or Otometrics system. Prospective testing of subjects with normal vestibular function with the camera records the eye movements of both eyes. Finally, 3D sensors were placed on different positions on the goggles measuring the actual vertical movement in the different semicircular planes. Results: In the clinical cohorts, the gain depended on which side and semicircular canal was tested (p < 0.001). In the prospective design, the combination between the stimulated side, semicircular canal, and position of the recording device (right/left eye) highly influenced the derived gain (p < 0.001). The different parts of the goggles also moved differently in a vertical direction during vertical semicircular canal testing. Conclusion: The gain values when testing the function of the vertical semicircular canals seem to depend upon which eye is recorded and which semicircular plane is tested and suggests caution when interpreting and comparing results when different systems are used both clinically as well as in research. The results also imply that further research and development are needed to obtain accurate vertical semicircular canal testing, in regard to both methodology and equipment design.

Keywords: LARP; RALP; gain values; interacoustics; otometrics; vertical semicircular canals; vertical vHIT.