PP1411 - Novel Paradigm to Assess Motion Perception in Children

Abstract:
While vestibular reflexive testing is heavily researched, there are few studies analyzing vestibular perception and nothing to-date on motion perception in children. While reflexes are fully developed in school-aged children, it is currently not known if children perceive motion similar to adults. This study adapted an adult psychophysics protocol for school-aged children and collected data on 10 healthy children and 10 healthy adults. Participants were rotated at various velocities and rotational amplitudes and asked to provide a measure of their spatial orientation and their perceived speed. Preliminary analyses show remarkably similar perception between groups.

Summary:
Vestibular disorders are experienced in 0.45% of children with higher prevalence observed in those with congenital hearing loss (O’Reilly et al., 2010). Children are commonly assessed for vestibular disorders through modified reflex testing, such as rotary chair assessments or vestibular evoked myogenic potentials (Janky & Rodriguez, 2018). However, reflexes may not correlate with patient symptoms and functional impact of a vestibular lesion on a child may not be understood. There is a need to broaden testing for childhood vestibular disorders as this group is more likely to experience delayed gross motor skills (Janky & Rodriguez, 2018).

The use of vestibular psychophysics can provide a subjective rating of perception to either threshold level stimuli (Gelfand, 2017) or suprathreshold stimuli (Benson & Brown, 1992). This study assesses if pediatric vestibular perception at suprathreshold levels can be measured, and how these measurements compare to adult vestibular perception.

Twenty participants with normal hearing and balance completed the study. Exclusion factors included neurological disorders, vestibular disorders, and history of greater than one concussion. Ten adults aged 18-30 years and ten children aged 5-10 years comprised the control and experimental groups respectively.

A Micromedical Technologies System 2000 rotary chair was used to present stimuli using a sinusoidal harmonic acceleration (SHA) paradigm of one cycle in the yaw plane. Ten different conditions were completed with stimulus frequencies between 0.08-0.64 Hz and peak velocities between 30–90 deg/sec. Both control and experimental groups provided magnitude estimates of their speed and estimates of their spatial orientation after each rotation using a protocol modified for children. In the original adult protocol, magnitude estimates of speed were made using a visual analog scale from 0-100 and spatial orientation estimates were made using a 360 degree circle where participants marked how far they rotated. In the modified pediatric protocol, magnitude estimates of speed were made on a five point scale that included animals that increased in speed, specifically a snail, turtle, dog, horse, and cheetah. The spatial orientation measure was modified to be a circle divided into four parts, each represented by a picture in the room. The animal/item scales were designed for children to easily understand and pilot tested prior to the study.

Statistical analysis of vestibular perception includes descriptive statistics completed on SPSS including averages of mean responses across stimulus conditions for the two groups. Animal/item data was transformed into ordinal numbers with a 1-5 range for animal speeds and a 1-4 range for item spatial orientation. A repeated measure analysis of variance (ANOVA) is used to assess the variance between the means of the two groups.

Initial results indicate children understood the test paradigm and the modified animal/item aspects held their attention. Measures of vestibular perception were similar between children and the adult groups. Limitations included large steps sizes between items and animals which decreased precision. These limitations will need to be addressed in future studies.

This session will be intermediate reviewing fundamentals of pediatric vestibular testing while emphasizing new approaches to vestibular perception testing.