The Japanese journal of neuropsychology

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ArticleTitle	Distributions of omissions in the Behavioural Inattention Test, Japanese edition, after right-hemisphere stroke: Analysis of the laterality index in the conventional test
Language	J
AuthorList	Kaori Misonou¹⁾, Sumio Ishiai¹⁾, Yasumasa Koyama¹⁾, Keiko Seki²⁾, Hajime Hirabayashi³⁾
Affiliation	1) Department of Rehabilitation, Tokyo Metropolitan Institute for Neuroscience 2) Faculty of Health Science, Kobe University School of Medicine 3) Department of Clinical Psychology, Kakeyu Hospital Rehabilitation Center
Publication	Japanese Journal of Neuropsychology: 17 (2), 121-129, 2001
Received	Jul 21, 2000
Accepted	Nov 2, 2000
Abstract	Behavioural Inattention Test (BIT; Wilson et al, 1987) is a test battery to evaluate unilateral spatial neglect, which includes six conventional subtests and nine behavioural subtests. We examined 48 righi brain damaged patients to analyze lateral distribution of omissions in the conventional subtests of BIT, Japanese edition. They showed abnormal performance in at least one subtest according to the cut-off score. BIT subtests are scored by subtracting the number of omissions, and their spatial distribution is not taken into account in the diagnosis of neglect. To quantify the laterality of omissions, Halligan et al (1991) devised the "laterality index" that indicates the proportion of the left hemispatial score against the total score on both sides. When the left side is completely ignored, the laterality index is 0 (contralateral neglect). The index between 0.1 and 0.47 means more omissions on the left than the right side (left bias inattention). By contrast, 0.53 or more means more omissions on the right side (right bias inattention). Non-lateralised distribution of errors is shown as 0.48 to 0.52 (non-lateralised inattention). The results indicated that in all six subtests, the laterality index became smaller as the score was decreased, which validated the original scoring methods of BIT. Additionally, we investigated the relationship between laterality index and severity of unilateral spatial neglect. We classified the patients into the mild, moderate, and severe groups according to the number of the subtests in which they showed abnormal score. The severe group showed contralateral neglect and left bias inattention more frequently than the moderate and mild groups. Patients with neglect have been reported to show a few omissions in the ipsilesional space. Some patients in this study also showed right bias inattention in one or two subtests while they exhibited left bias inattention in the other tests. We therefore consider that all six conventional subtests should be given to patients for reliable diagnosis of unilateral spatial neglect.
Keywords	Behavioural Inattention Test (Japanese edition), Unilateral Spatial Neglect, inattention