Motion sickness represents one of the greatest clinical challenges impacting crew activities following G-transitions. This project seeks to validate a non-pharmaceutical tool using galvanic vestibular reduction (GVR) by transcutaneously delivering bilateral inhibitory signals to suppress vestibular sensitivity and reduce post-landing motion sickness. The first specific aim is to evaluate the effect of timing and magnitude on the administration of our non-pharmaceutical treatment to motion sickness.
While the researchers have previously demonstrated that their approach can mitigate motion sickness if introduced prior to provocative stimuli, one of the goals of this study is to determine the efficacy if they administer the treatment following the onset of symptoms. Validating the efficacy following symptom onset would greatly enhance flexibility to implement this treatment during recovery operations. Using a repeated measures counter-balanced design exposing subjects to provocative Coriolis cross-coupling stimuli on a rotating chair, the researchers will compare motion sickness severity across three treatment interventions: prior to stimulus (symptom) onset, following symptom onset, and placebo control. Symptom severity will be assessed using both subjective reports and objective autonomic measures (e.g., electrogastrography). They expect that the most effective administration will be GVR delivered prior to the onset of symptoms, but that it will continue to be more effective relative to placebo control even if delivered following symptom onset.
In order to leverage their non-pharmaceutical technique that allows continuous adjustments in “dosage” level throughout recovery, the researchers must map changes in GVR level with functional performance. The second specific aim is to characterize the dose response of GVR amplitude to functional fitness task performance. Investigators will measure performance on a sensorimotor and cognitive test battery in steps ranging from 0mA (control) to the level of GVR thought to provide maximal motion sickness protection. The advantages of their non-pharmaceutical countermeasure approach will be to provide rapid therapeutic effect while allowing continuous titration of GVR amplitude during recovery to minimize side effects while enhancing performance.
Thirty healthy subjects with normal vestibular function will be recruited at the Mayo Clinic. Using a repeated measures design, each subject will participate in four sessions. The first session will evaluate the effect of GVR amplitude on functional fitness task performance. For this aim, the same subjects participating in the motion sickness tests will undergo the test battery while exposed to GVR in multiple steps ranging from 0mA (control) to the level of GVR thought to provide maximal motion sickness protection. The sensorimotor test battery will include (1) dynamic posturography, (2) walk and turn obstacle test, (3) flight simulator performance and (4) an ocular cognitive test. Each test will be repeated for up to GVR amplitudes (including 0mA control) presented in random order. The researchers expect performance to decline with increasing GVR amplitude. They will also compare motion perception at different GVR amplitudes using a similar rotator protocol as described below for the motion sickness testing. In addition, the researchers will select the lowest GVR level that reduces motion perception as the amplitude for the motion sickness testing.
The efficacy of GVR to mitigate motion sickness will then be tested over the remaining three sessions by comparing conditions across separate counterbalanced sessions: administration of GVR from the onset of testing, at a midpoint of testing, and placebo control. Each session will be conducted on three separate days at least one week apart so that there is no influence on each other. Symptom severity will be assessed using both subjective reports and objective autonomic measures (e.g., electrogastrography).RESULTS
The combined deliverable from both specific aims will be to validate the efficacy of GVR to (1) administer a custom stimulus level to match an individual subject’s needs, (2) introduce the stimulus following symptom onset, and (3) understand the effects of this non-pharmaceutical approach on crew and functional task performance. Motion sick crewmembers or patients with vestibular hypersensitivity could benefit from non-pharmaceutical treatment options because of their flexibility to turn treatment on or off without sedative effects or other residual effects associated with drug metabolism.
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