PP1512 - Normal Aging and vHIT: Influence of Gain Method and Role of Saccades

POSTERS

Location: Halls A1-A2

Instructional Level: Intermediate

Poster Presenter(s)

CO

Clara Orsini

Student
University of Montréal
University of Montreal

Disclosure(s): No financial or nonfinancial relationships to disclose.

Contributor (Not Presenting)(s)

JD

Jonathan Dion

Disclosure(s): No financial or nonfinancial relationships to disclose.
AC

Assan Mary Cédras

Disclosure(s): No financial or nonfinancial relationships to disclose.
AP

Antonio Sam Pierre

Disclosure(s): No financial or nonfinancial relationships to disclose.
FC

François Champoux

Professor
University of Montreal
Montreal, Quebec, Canada

Disclosure(s): No financial or nonfinancial relationships to disclose.
MM

Maxime Maheu

Professor
University of Montreal

Disclosure(s): No financial or nonfinancial relationships to disclose.

Abstract: This project evaluate the effect of age on the different gain calculation methods currently used clinically (area under the curve and instantaneous gain) and the different saccade parameters in vHIT. This will be useful as gain is crucial to assess VOR's function.

Summary:

Rationale/Purpose. Vestibular-ocular reflex (VOR) allows to maintain image stability in foveal position during head movement by moving the eyes at the same velocity, but in opposite direction of the head. The vHIT quantifies VOR’s function, by calculating a ratio between head and eye movements (gain) and determining presence of rapid eye movements (saccades). There’s currently various equipment, each using a different methods to calculate gain (area under the curve, instantaneous gain). As this parameter is crucial to assess VOR’s function and that previous studies suggest an influence of age and saccades, it is of great importance to determine how normal aging influence these parameters. The aim of this study is to measure the effect of age on different gain methods (area under the curve, instantaneous gain) and saccade parameters (frequency, latency, velocity) in the video head impulse test (vHIT).
Methods. 24 young adults (mean age 24.6 ± 3.4) and 24 elderly (mean age 69.3 ± 4.0) were recruited and performed the HIMP using vHIT (ICS Impulse, Otometrics). The data were exported, and each trial was reviewed using a custom Matlab script (Matlab, 2019a). The gain was computed using two common methods (Area under the desaccaded curve, Instantaneous gain at 40, 60, 80ms). First saccade was manually identified by an experienced user and Matlab script computed saccade frequency, amplitude and latency.
Results & Conclusions. No significant difference was observed between groups for both gain methods. However, older adults showed saccades with significant higher frequency, higher amplitude and shorter latencies, as opposed to younger adults. Age had no significant influence for both gain calculation methods. However, significant differences were observed for all saccades parameters. Clinically, this suggests that both methods could be used to assess gain in young and elderly patients. Moreover, saccades could be an early clinical sign of age on high velocity VOR function.

Learning Objectives:

Demonstrate that the method used has no significant impact on the vHIT gain value, regardless of patients age.