The effect of repeated sessions of galvanic vestibular stimulation on target cancellation in visuo-spatial neglect: preliminary evidence from two cases.

OBJECTIVE In recent years it has emerged that the attentional disorder of visuo-spatial neglect can be overcome via artificial stimulation of the balance system. One means of achieving this is via galvanic vestibular stimulation (GVS), a simple procedure in which tiny, electrical currents are discharged to the part of the scalp overlying the vestibular nerves. Attempts to remediate neglect with GVS have utilized only a single session of stimulation and, although this can induce spontaneous recovery, symptoms resurface soon after stimulation. This study assessed whether repeated sessions induce longer carry-over. METHODS Two individuals diagnosed with neglect post-stroke received 5 days of sub-sensory, left anodal GVS. Performance was assessed via the letter and star cancellation tasks of the Behavioural Inattention Test on four occasions; 3 days before the start of stimulation, on the first and last day of stimulation and 3-days after stimulation. RESULTS Analyses of variance indicated that both participants missed significantly fewer targets in both tasks on the fifth day of stimulation compared to baseline. More so, this improvement was still evident at follow-up 3 days later. CONCLUSION The results strengthen the need for a larger, sham-controlled trial to establish whether repeated GVS provides lasting relief from neglect.