Assessment of visual space recognition in patients with unilateral spatial neglect using head mounted display (HMD) system: Case study with left unilateral spatial neglect

To quantitatively evaluate visual-spatial recognition in cerebrovascular disease patients, we developed a new measurement system able to present a versatile visual information. The system uses a head-mounted display (HMD) as the device that presents visual information. Quantitative evaluations are possible through simultaneous measurements of eye movement and head movement using a video motion analysis device. Here, we used the system with a patient with left unilateral spatial neglect (USN) and investigated its effectiveness. The influence of spatial recognition and eye movement was examined by presenting visual information in the form of test sheet reductions and administering stimuli to arouse focus. The results showed a large rightward bias in the ratio of eye position under no reduction conditions. However, the ratio on the left side of the test sheet increased based on the direction of reduction and the administration of alert stimulation. Furthermore, eye movement angular velocity to the right was faster on the right side of the sheet, whereas angular velocity to the left was faster on the left side of the sheet. In motion analysis, more left rotation of the head was observed during line cancellation on the left side of the test sheet with center reduction compared with no reduction. The above data shows that with this system, presentation of versatile visual information turned his/her attention to the left. The manifestation of head movement was confirmed, as well. These results verified the effectiveness and usefulness of the system.