Multimodal neglect and spatial perception deficits after stroke – new routes to treatment
Patients with acquired stroke, particularly of the right cerebral hemisphere often suffer from multimodal spatial neglect, a disorder where patients ignore visual, auditory or tactile stimuli in the contralesional part of space or their own body. A related and often associated disorder is extinction of sensory stimuli during bilateral simultaneous stimulation. While several treatments are available for visuospatial neglect, less is known about how neglect/extinction in the auditory or tactile modality can be treated effectively. My talk deals with 3 different but associated topics: Part 1 will show the results of 2 recent randomized controlled treatment studies assessing the effects of smooth pursuit eye movement training using optokinetic stimulation on auditory and visual neglect, unawareness, and on functional measures. Part 2 addresses potential treatment effects of a new technique termed Galvanic-Vestibular-Stimulation (GVS), known to stimulate the thalamocortical network, and in particular parieto-temporal brain regions involved in tactile extinction. GVS significantly modulated left-hand tactile extinction scores during GVS, and led to a significant and stable reduction of left tactile extinction after repeated GVS sessions. These data suggest that vestibular information influences bodily awareness for tactile stimuli and may be an interesting treatment option. Part 3 deals with spatial-perceptual disorders, which occur as frequently after stroke as neglect, but few research about potentially effective treatments exists for these disorders. Recently, we evaluated the effects of a novel feedback-based, perceptual re-learning on visual line orientation discrimination in a pilot study. All patients improved not only in the trained orientation, but showed graded transfer to other orientations and related visuospatial skills (constructional apraxia, clock reading, spatial dysgraphia) as well. Improvements were independent from the eye trained and occurred also in the absence of eye movements. These and the above findings will be discussed with respect to the mechanisms involved and future perspectives.