This study is designed to investigate the effects of The Otolith Labs bone conduction
device (BCD) on the vestibular system. In the context of this trial, the BCD was designed
and developed to reduce the effects of external stimulation of the vestibular system. The
eventual intended use of the device is for people who have vestibular disorders (e.g.
Vestibular Migraine, Meniere's Disease) who may benefit from a device that can provide a
normalizing response to an abnormal vestibular neural signal.
To better understand the functioning principles of the BCD, the investigators want to
conduct standard clinical testing using a rotary chair, specifically
Step velocity testing (SVT) with the chair rotating and vision denied
Optokinetic testing (OKT) with the chair stationary and visual field moving
Published studies have demonstrated that a reduction in the vestibulo-ocular reflex (VOR)
time constants during optokinetic and velocity step testing is correlated with improved
motion sickness symptoms. The investigators aim to determine if the BCD similarly reduces
the VOR time constant. A reduction in time constant has been shown to be strongly
correlated with a reduced time constant of integration in the central velocity storage (a
long time constant very strongly correlates with motion sensitivity and with the severity
of vestibular migraine episodes.
In this study, the BCD is set at one of three settings- turned off, low power level, high
power level, -while the participant is undergoing testing at 60 °/s (patient's own motion
for step velocity testing, or projected image for OKT). The same test methodology and
equipment shall be used for all participants. In total, 6 rotational tests - one
clockwise rotation and one counterclockwise rotation at each of the three power settings,
and 6 static tests - with the visual field moving left then right at each of the three
power settings, will be conducted and the order of the high/low power settings will be
randomized to the second/third set of SVT and OKT. The device is adjusted to a new power
level a few seconds before initiating each SVT and OKT.
Eye movements will be tracked during the SVT and OKT to evaluate decay in amplitudes and
frequency of nystagmus over time (typically around 15 seconds). Comparison will be made
between the three power conditions to evaluate the effect of bone conduction stimulation
on the vestibular sense stimulated by rotation.
The participant will be prompted to report on the Fast Motion Scale (FMS) - a simple,
validated 20 point verbally reported numerical rating scale - prior to and following each
chair session to gauge the momentary level of motion sickness perception. The FMS will be
reported a total of 12 times per participant (pre- & post-rotary tests).
Participants will complete the Motion Sickness Sensitivity Questionnaire Short Form
(MSSQ-SF) to determine their history of sensitivity to provocative motion. Participants
will also complete the Vestibular Migraine Patient Assessment Tool and Handicap Inventory
(VM-PATHI) to assess the correlation of the potential change in time constants and VOR
gain to the perceived severity of their vestibular migraine condition.