Galvanic vestibular stimulation in hemi-spatial neglect

Abstract

Hemi-spatial neglect is an attentional disorder in which the sufferer fails to acknowledge or respond to stimuli appearing in contralesional space. In recent years, it has become clear that a measurable reduction in contralesional neglect can occur during galvanic vestibular stimulation, a technique by which transmastoid, small amplitude current induces lateral, attentional shifts via asymmetric modulation of the left and right vestibular nerves. However, it remains unclear whether this reduction persists after stimulation is stopped. To estimate longevity of effect, we therefore conducted a double-blind, randomized, dose-response trial involving a group of stroke patients suffering from left-sided neglect (n = 52, mean age = 66 years). To determine whether repeated sessions of galvanic vestibular stimulation more effectively induce lasting relief than a single session, participants received 1, 5, or 10 sessions, each lasting 25 min, of sub-sensory, left-anodal right-cathodal noisy direct current (mean amplitude = 1 mA). Ninety five percent confidence intervals indicated that all three treatment arms showed a statistically significant improvement between the pre-stimulation baseline and the final day of stimulation on the primary outcome measure, the conventional tests of the Behavioral Inattention Test. More remarkably, this change (mean change = 28%, SD = 18) was still evident 1 month later. Secondary analyses indicated an allied increase of 20% in median Barthel Index (BI) score, a measure of functional capacity, in the absence of any adverse events or instances of participant non-compliance. Together these data suggest that galvanic vestibular stimulation, a simple, cheap technique suitable for home-based administration, may produce lasting reductions in neglect that are clinically important. Further protocol optimization is now needed ahead of a larger effectiveness study.

A durable gain in motor and non-motor symptoms of Parkinson’s Disease following repeated caloric vestibular stimulation: A single-case study

“…Artificial stimulation of the peripheral balance organs, via either galvanic or thermal current, up-regulates metabolic activity across a range of cortical, striatal and cerebellar brain areas (Lopez, Blanke & Mast, 2012). The clinical relevance of this metabolic activity has been demonstrated in a number of acquired neurological conditions including hemi-spatial neglect (Wilkinson et al, 2014), aphasia (Wilkinson, Morris, Milberg & Sakel, 2013), mania (Levine et al, 2012), central pain (McGeoch, Williams, Lee & Ramachandran, 2008) and post-stroke postural instability (Sturt & Punt, 2013). Despite these promising results, comparably little investigation has been conducted with individuals who suffer from neuro-degenerative disease.…”

The Moving History of Vestibular Stimulation as a Therapeutic Intervention

“…Brocklehurst-Woods, 1990). Moreover, we only briefly mention the effects of vestibular stimulation on hemispatial neglect, albeit this is probably one of the most promising and thus already most discussed (Schmidt et al, 2013;Utz et al, 2010;Wilkinson et al, 2014) research branch of this field.…”

“…Since then the use of vestibular stimulation to increase spatial functioning in hemineglect has gained importance, and while early studies report short-term effects during single applications (e.g. Cappa et al, 1987;Rubens, 1985), more recent studies suggest that long-term effects can be induced using multiple sessions of artificial vestibular stimulation (Wilkinson et al, 2014). Alongside successful application of vestibular stimulation to normalize space awareness (see e.g.…”

“…This mechanism has particularly been put forward to help explain the positive effects on neglect and similar symptoms (see e.g. Karnath and Dieterich, 2006;Wilkinson et al, 2014). Such an attention shift could be caused by an unspecfic activation of parietotemporal cortical areas contralateral to the stimulated ear.…”

Galvanic Vestibular Stimulation Induces a Spatial Bias in Whole-body Position Estimates

“…Dear Editor, Peripheral galvanic vestibular stimulation (GVS) has been shown to temporarily ameliorate left spatial neglect [1]. Specifically, anodal (facilitatory) stimulation over the left mastoid bone coupled with cathodal (inhibitory) over the right mastoid reduces visuospatial-neglect scores in line cancellation [2] and line bisection tasks [3,4].…”