Galvanic vestibular stimulation reduces the pathological rightward line bisection error in neglect—A sham stimulation-controlled study

• Published in: Neuropsychologia 2011-04, Vol.49 (5), p.1219-1225
• Main Authors: Utz, Kathrin S., Keller, Ingo, Kardinal, Mareike, Kerkhoff, Georg
• Format: Article
• Language: English
• Subjects: Adult and adolescent clinical studies; Aged; Aged, 80 and over; Attention; Biological and medical sciences; Brain Injuries - complications; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Electric Stimulation - methods; Female; Functional Laterality - physiology; Humans; Line bisection; Male; Medical sciences; Middle Aged; Neglect; Nervous system (semeiology, syndromes); Neurology; Neurotechnology; Organic mental disorders. Neuropsychology; Perceptual Disorders - etiology; Perceptual Disorders - rehabilitation; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Recovery; Space Perception - physiology; Vestibular Nerve - physiology; Vestibular stimulation; Vestibule, Labyrinth - physiology; Visual Fields - physiology
• ISSN: 0028-3932; 1873-3514; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2011.02.046

▸ Galvanic vestibular stimulation reduces line bisection error in neglect patients. ▸ Right-cathodal GVS is most effective. ▸ Activation of remnants in the lesioned right parietal cortex may cause effect. Patients with right hemisphere lesions often show left spatial neglect and the typical rightward deviation in horizontal line bisection. Previous studies have shown that sensory stimulation modulates line bisection. A less well-known but promising sensory stimulation method is galvanic vestibular stimulation (GVS). This non-invasive technique leads to activation of the vestibular cortices and adjacent cortical areas in the temporo-parietal cortex via polarization effects of the vestibular nerves. This is accomplished by application of weak direct currents, delivered by two electrodes attached to the mastoids. Despite the relative benefits of GVS its effects on line bisection have not yet been studied in neglect patients. Thus, the present study investigated the impact of GVS on performance in a modified line bisection task in right-brain damaged patients with versus without leftsided visual neglect. In neglect patients, but not in control patients, left-cathodal and right-cathodal GVS significantly reduced the rightward line bisection error as compared to Baseline (without GVS) and sham stimulation. A larger decrease of the rightward line bisection error was observed during right-cathodal GVS. Sham stimulation showed no specific effects on line bisection. The beneficial effects of GVS might be due to activation of preserved structures of the lesioned right posterior parietal cortex which is known to be involved in line bisection.