SENA - South of England Neurosciences Association

Dr Mohammad S Mahmud

University College London NHSFT

Bárány Society Meeting

25-28 August 2024

I was delighted to be awarded the SENA Bursary in September 2024 which gave me the fantastic opportunity to attend the Bárány Society meeting this September in Uppsala, Sweden. I was fortunate enough to present my abstract below as an oral platform presentation. Over the course of the conference, I had the opportunity to see and discuss the fantastic work of various vestibular experts and discuss my findings and the groundwork it provides for building meaningful future translational research.

Adequate response to discrete perturbation is crucial for maintaining postural stability and mitigating falls. These postural responses rely on the integration of multiple sensory modalities to provide precise postural and muscular responses. At Uppsala we show for the first time in healthy young adults that low level noisy galvanic vestibular stimulation (nGVS) led to improved postural stability likely mediated via modulation of lower limb muscular activity:

Age-related deterioration within the vestibular system is associated with impaired balance and increased risk of falling. nGVS, a non-invasive technique, has emerged as a potential therapeutic route for addressing age-related vestibular decline. This involves a weak random noise stimulation to the vestibular system that modulates balance behaviour. However, to date, the effects of nGVS have been restricted primarily to simple unperturbed stance. We therefore aimed to explore the effects of nGVS on dynamic balance in response to a discrete perturbation to posture.

A randomised double-blinded, sham-controlled trial of 30 healthy young adults was conducted.

Perturbations consisted of discrete forwards platform movement (acceleration = 0.1g, maximum forward displacement = 17cm).
White noise GVS (frequency: 0-500Hz) intensity of 350 µA or sham was given during each perturbation.
Peak angular velocity (deg/s) of trunk sway was calculated as a measure of postural instability.
Muscular activity (EMG) of the tibialis anterior leg muscle (responsible for stabilising posture following forward platform perturbations) was assessed in early (100-200ms post-perturbation) and late (200-300ms) epochs.
nGVS led to significant reductions in peak angular velocity of truncal sway following the perturbation (nGVS, mean = 11.48°/sec; sham, mean = 12.92°/sec; p=0.014). This was accompanied by significant reductions in early-phase EMG activity during nGVS (p=0.036).

This study extends our understanding of the effects that nGVS exerts on postural control. Our findings provide initial evidence that nGVS can modulate balance responses to external perturbations and does this through modulation of early-phase muscle activity.