Hemispatial inattention is a neuropsychological symptom associated with right hemisphere damage. Affected persons do not attend or respond normally to stimuli on the left side of allocentric and/or egocentric space. Previous research has demonstrated an association between hemispatial inattention and damage to the superior longitudinal fasciculus (SLF), a white matter tract connecting several brain regions important for attention. Here, we tested the hypothesis that greater SLF disconnection in neurological patients with focal brain lesions would correlate with more severe hemispatial inattention.

Data from 80 focal lesion patients who completed MRI scans and the line cancellation test were collected from an existing lesion patient database. SLF disconnection was defined as the weighted sum of the voxels on a single coronal MRI slice that overlapped between a patient’s lesion mask and the Johns Hopkins University (JHU) SLF atlas. The coronal MRI slice with the maximal weighted sum of the overlapping voxels served as the target slice. Voxels were weighted by JHU SLF atlas intensity values. Hemispatial inattention was defined as the number of successful right-sided bisections minus the number of successful left-sided bisections.

In support of our hypothesis, the results demonstrated that greater SLF disconnection was associated with higher line cancellation scores (r = .39, p < .001). A Spearman rank order correlation corroborated this finding (r = .30, p < .01).

These results extend findings from previous studies suggesting that the SLF is involved in spatial attention. Our measure of SLF disconnection may be a viable method of measuring white matter damage.