Comparison of uni- and multimodal motion stimulation on visual neglect: A proof-of-concept study

Spatial neglect is characterized by the failure to attend stimuli presented in the contralesional space. Typically, the visual modality is more severely impaired than the auditory one. This dissociation offers the possibility of cross-modal interactions, whereby auditory stimuli may have beneficial effects on the visual modality. A new auditory motion stimulation method with music dynamically moving from the right to the left hemispace has recently been shown to improve visual neglect. The aim of the present study was twofold: a) to compare the effects of unimodal auditory against visual motion stimulation, i.e., smooth pursuit training, which is an established therapeutical approach in neglect therapy and b) to explore whether a combination of auditory + visual motion stimulation, i.e., multimodal motion stimulation, would be more effective than unimodal auditory or visual motion stimulation. 28 patients with left-sided neglect due to a first-ever, right-hemispheric subacute stroke were included. Patients either received auditory, visual, or multimodal motion stimulation. The between-group effect of each motion stimulation condition as well as a control group without motion stimulation was investigated by means of a one-way ANOVA with the patient's visual exploration behaviour as an outcome variable. Our results showed that unimodal auditory motion stimulation is equally effective as unimodal visual motion stimulation: both interventions significantly improved neglect compared to the control group. Multimodal motion stimulation also significantly improved neglect, however, did not show greater improvement than unimodal auditory or visual motion stimulation alone. Besides the established visual motion stimulation, this proof-of-concept study suggests that auditory motion stimulation seems to be an alternative promising therapeutic approach to improve visual attention in neglect patients. Multimodal motion stimulation does not lead to any additional therapeutic gain. In neurorehabilitation, the implementation of either auditory or visual motion stimulation seems therefore reasonable.