Noisy Galvanic Vestibular Stimulation (Stochastic Resonance) Changes Electroencephalography Activities and Postural Control in Patients with Bilateral Vestibular Hypofunction

Li-Wei Ko; Rupesh Kumar Chikara; Po-Yin Chen; Ying-Chun Jheng; Chien-Chih Wang; Yi-Chiang Yang; Lieber Po-Hung Li; Kwong-Kum Liao; Li-Wei Chou; Chung-Lan Kao

doi:10.3390/brainsci10100740

Noisy Galvanic Vestibular Stimulation (Stochastic Resonance) Changes Electroencephalography Activities and Postural Control in Patients with Bilateral Vestibular Hypofunction

Brain Sci. 2020 Oct 15;10(10):740. doi: 10.3390/brainsci10100740.

Authors

Li-Wei Ko^{1

2

3

4}, Rupesh Kumar Chikara^{1

2

3}, Po-Yin Chen^{5

6}, Ying-Chun Jheng^{5

6

7}, Chien-Chih Wang^{8

9}, Yi-Chiang Yang⁶, Lieber Po-Hung Li^{7

10}, Kwong-Kum Liao¹¹, Li-Wei Chou^{3

5}, Chung-Lan Kao^{3

6

7}

Affiliations

¹ Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu 300, Taiwan.
² Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan.
³ Center for Intelligent Drug Systems and Smart Bio-Devices (IDS2B), National Chiao Tung University, Hsinchu 300, Taiwan.
⁴ Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
⁵ Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei 112, Taiwan.
⁶ Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei 112, Taiwan.
⁷ School of Medicine, National Yang-Ming University, Taipei 112, Taiwan.
⁸ Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital Yuli Branch, Hualien 98142, Taiwan.
⁹ Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan.
¹⁰ Department of Otolaryngology, Cheng Hsin General Hospital, Taipei 112, Taiwan.
¹¹ Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei 112, Taiwan.

Abstract

Patients with bilateral vestibular hypofunction (BVH) often suffer from imbalance, gait problems, and oscillopsia. Noisy galvanic vestibular stimulation (GVS), a technique that non-invasively stimulates the vestibular afferents, has been shown to enhance postural and walking stability. However, no study has investigated how it affects stability and neural activities while standing and walking with a 2 Hz head yaw turning. Herein, we investigated this issue by comparing differences in neural activities during standing and walking with a 2 Hz head turning, before and after noisy GVS. We applied zero-mean gaussian white noise signal stimulations in the mastoid processes of 10 healthy individuals and seven patients with BVH, and simultaneously recorded electroencephalography (EEG) signals with 32 channels. We analyzed the root mean square (RMS) of the center of pressure (COP) sway during 30 s of standing, utilizing AMTI force plates (Advanced Mechanical Technology Inc., Watertown, MA, USA). Head rotation quality when walking with a 2 Hz head yaw, with and without GVS, was analyzed using a VICON system (Vicon Motion Systems Ltd., Oxford, UK) to evaluate GVS effects on static and dynamic postural control. The RMS of COP sway was significantly reduced during GVS while standing, for both patients and healthy subjects. During walking, 2 Hz head yaw movements was significantly improved by noisy GVS in both groups. Accordingly, the EEG power of theta, alpha, beta, and gamma bands significantly increased in the left parietal lobe after noisy GVS during walking and standing in both groups. GVS post-stimulation effect changed EEG activities in the left and right precentral gyrus, and the right parietal lobe. After stimulation, EEG activity changes were greater in healthy subjects than in patients. Our findings reveal noisy GVS as a non-invasive therapeutic alternative to improve postural stability in patients with BVH. This novel approach provides insight to clinicians and researchers on brain activities during noisy GVS in standing and walking conditions in both healthy and BVH patients.

Keywords: bilateral vestibular hypofunction (BVH); electroencephalography (EEG); galvanic vestibular stimulation (GVS); independent component analysis (ICA).