Suprathreshold Galvanic Vestibular Stimulation as an analog of
vestibular dysfunction
Valentina Dilda¹, Tiffany Morris¹, Marcos Rossi-Izquierdo², Andres Soto-Varela³,
Sofia Santos-Perez³, Steven Moore¹. ¹ Icahn School of Medicine at Mount Sinai;
²University Hospital Lucus Augusti, Spain; ³University of Santiago de Compostela, Spain.
VESTIBULAR
120
Suprathreshold GVS refers to the application of current across
the mastoid processes at amplitudes (3.5-5 mA) that adversely
impact vestibular function (sensorimotor and cognitive
performance) in healthy individuals.
VISUAL
SOMATOSENSORY
*
What is Suprathreshold Galvanic Vestibular
Stimulation (GVS)?
* p < .01
* p < .05/3= .016
* *
What is the research question?
We propose that healthy subjects exposed to suprathreshold
GVS would experience postural deficits consistent with those
observed in patients with vestibular dysfunction.
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What did you do?
*
We tested balance in a groups of healthy subjects at GVS
amplitudes of 1, 3.5, or 5 mA after a baseline (no GVS) test.
Patients with unilateral (right and left) or bilateral vestibular
hypofunction performed the same balance test as well as a
group of healthy aged-matched control subjects. We used the
sensory organization test (SOT) on the Equitest computerized
posturography platform. The SOT is able to selectively assess
the visual, vestibular, and somatosensory contribution to
balance and posture.
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GVS
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VESTIBULAR
VISUAL
SOMATOSENSORY
What is the vestibular effect size of
GVS used with healthy subjects
compared to vestibular patients?
Cohen’s d effect size
What did you find?
We found that Suprathreshold GVS significantly affects
vestibular control of posture compared to baseline at all current
amplitudes, whereas somatosensory and visual performance
remained unaffected. Vestibular patients showed a significant
decrease in all sensory modalities compared to age-matched
healthy controls. Suprathreshold GVS showed a large effect
size compared to baseline, similar to the large effect found in
unilateral and bilateral vestibular loss patients relative to their
age-matched controls. Note that postural function rapidly
returned to baseline after GVS exposure.
How will this help?
These results demonstrate that the vestibular dysfunction
generated by suprathreshold GVS is a reversible analog of
postural dysfunction due to vestibulopathy. The GVS analog
may help design and test interventions for vestibular
hypofunction.
GVS also replicates postural
deficits observed in astronauts
after return from spaceflight.
Analyses:
Wilcoxon tests were run to compare the 0 GVS scores (baseline) to each GVS
amplitude per sensory modality.
Patients groups are all independent from each other: Mann Whitney tests were
used to calculate which patient group differs from healthy aged-matched controls.
0 GVS vs 1 mA
0.06
0.03
0 GVS vs 3.5 mA
1.08
0.47
0 GVS vs 5 mA
1.98
0.7
Control vs unilateral L
2.78
0.81
Control vs unilateral R
2.84
0.82
Control vs bilateral
4.17
0.9
Direct comparison is not possible, so effect size was
calculated using Cohen’s d (comparing the GVS
vestibular effect relative to 0 GVS for healthy
subjects; and comparing unilateral and bilateral
magnitude of vestibular effect relative to aged
matched controls).
• Dilda, V, MacDougall HG, Moore ST. (2011). Tolerance to extended Galvanic vestibular stimulation: determining optimal exposure for astronaut training. Aviat Space Environ Med; 82:770-774.
• Rossi-Izquierdo M, Santos-Pérez S, Soto-Varela A. (2011). What is the most effective vestibular rehabilitation technique in patients with unilateral peripheral vestibular disorders?
Eur Arch Otorhinolaryngol; 268(11):1569-74.
Rossi-Izquierdo et al. (2009). Vestibular rehabilitation with computerised dynamic posturography in patients with Parkinson's disease: improving balance impairment. Disabil Rehabil ;31(23):1907-16.
• Moore, ST, Dilda V, MacDougall HG. (2011). Galvanic vestibular stimulation as an analog of spatial disorientation after spaceflight. Aviat Space Environ Med; 82:770-774.
• Moore et al. (2006). Modeling locomotor dysfunction following spaceflight with Galvanic vestibular stimulation. Exp Brain Res. 174: 647-659.
For questions contact: valentina.dilda@mssm.edu or visit our website: http://research.mssm.edu/moores01.This work was funded by NASA NCC 9-58 and NNX09AL14G