A preliminary study of clinical assessment of left unilateral spatial neglect using a head mounted display system (HMD) in rehabilitation engineering technology

PURPOSE: Unilateral spatial neglect (USN) is a common syndrome in which a patient fails to report or respond to stimulation from the side of space opposite a brain lesion, where these symptoms are not due to primary sensory or motor deficits. The purpose of this study was to analyze an evaluation process system of USN in various visual fields using HMD in order to understand more accurately any faults of USN operating in the object-centred co-ordinates. METHOD: Eight stroke patients participated in this study and they had Left USN in clinical test, and right hemisphere damage was checked by CT scan. Assessments of USN were performed the BIT common clinical test (the line and the stars cancellation tests) and special tests the zoom-in condition (ZI) condition and the zoom-out condition (ZO) condition. The subjects were first evaluated by the common clinical test without HMD and then two spatial tests with HMD. Moreover, we used a video-recording for all tests to analyze each subject's movements. RESULTS: For the line cancellation test under the common condition, the mean percentage of the correct answers at the left side in the test paper was 94.4%. In the ZI condition, the left side was 61.8.% and the right side was 92.4.%. In the ZO condition, the left side was 79.9% and the right side was 91.7.%. There were significant differences among the three conditions. The results of the stars cancellation test also showed the same tendency as the line bisection test. CONCLUSION: The results showed that the assessment of USN using a technique of HMD system may indicate the disability of USN more than the common clinical tests. Moreover, it might be hypothesized that the three dimensional for USN test may be more related to various damage and occurrence of USN than only the two dimensional test.