Association between spatial neglect and lateralized asymmetry of structural brain connectivity in chronic moderate-to-severe traumatic brain injury: An exploratory pilot study.

Spatial neglect (SN), especially left SN, has been extensively studied in stroke survivors. Very few prospective studies have focused on SN in individuals with traumatic brain injury (TBI). The present pilot study included 17 individuals with chronic, moderate-to-severe TBI (14 men and 3 women; mean age 46.3 years; on average 103.8 months post TBI). Participants completed visuospatial tests for SN and multi-shell diffusion-tensor imaging (DTI). Based on prior retrospective studies in inpatient rehabilitation settings, we expected that less than 30% of the participants would show signs of SN given that they had returned to communities and in the chronic stage post injury. Five (29%) participants were classified as having left SN, and none had right SN. Rightward-biased global attention (indicated by the starting column of a cancellation test and line bisection performance) was associated with reduced integrity of the corpus callosum. Case studies of two representative individuals suggested that SN was associated with the lateralized asymmetry index of white matter integrity in the superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, and the extended connections of the corpus callosum. Large scale studies using multi-shell DTI to investigate the neural structural mechanisms of SN are needed to replicate these findings and draw definitive conclusions. The present results replicate prior retrospective studies, showing that SN can occur after TBI and may persist in individuals with moderate to severe TBI for months and years.