Caloric vestibular stimulation and postural control in patients with spatial neglect following stroke

Abstract

The impact of spatial neglect remains a substantial challenge to patients undergoing rehabilitation following stroke. Beyond the relatively well-described implications for visuospatial function, neglect is increasingly shown to have a negative impact on the wider aspects of sensori-motor performance with corresponding implications for activities including gait and balance. Caloric vestibular stimulation (CVS) administered to the contralesional ear has previously been shown to improve performance in patients with spatial neglect. Here, in Experiment One, we investigated the effect of CVS on clinical measures of spatial neglect and postural control in three groups of patients following stroke; left brain damaged patients (LBD, n = 6), right brain damaged patients without neglect (RBD-, n = 6), and right brain damaged patients with neglect (RBD+ , n = 6). While post-stimulation scores demonstrated an improvement for participants with spatial neglect, further analysis of postural scores indicated that improvement was selective for asymmetrical activities, with symmetrical activities remaining unchanged. We interpret these results with reference to the related problem of extinction which predicts that activities demanding synchronous bilateral activity (symmetrical activities) would cause greater difficulties for patients with neglect. In Experiment Two, we tested a further six RBD+ patients on the same measures following CVS to the ipsilesional (right) ear. There was no significant improvement in perceptual or postural scores. Our findings are supportive of previous studies that demonstrate improvement in perception and movement for patients with spatial neglect following contralesional CVS and suggest that these improvements may have clinical benefits.

Caloric vestibular stimulation in aphasic syndrome

“…002 still required supervision when climbing the stairs, however he reported that where before this would take up to 10 min, he was now able to complete the task in approximately 5 min. These observations chime with the findings of Sturt and Punt (2013) who recently showed improved postural control in a group of hemi-spatial neglect patients post-CVS, and give reason to assess motor outcome in future studies.…”

Non-Invasive Neuromodulation Using Time-Varying Caloric Vestibular Stimulation

“…Despite the evidence for widespread activation of neural circuits [13] and a long history to support the clinical safety of CVS, investigation into its potential therapeutic efficacy has been limited. Several groups have demonstrated acute benefits of CVS with hemispatial neglect patients [14] – [20] , and a number of studies have explored the therapeutic potential of CVS for pain mitigation [21] – [23] . However, all of these studies have suffered from low patient numbers, minimal details about the CVS protocol, no longitudinal treatment, and cursory follow-up, if any.…”

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.…”