Egocentric and allocentric neglect after right and left hemisphere lesions in a large scale neglect study of acute stroke patients: Prevalence and recovery.
Demeyere N., Gillebert C., Loftus L., Humphreys G.
Left neglect is traditionally reported to be much more common and more severe than right neglect. Often this is taken as support for a right hemispheric specialisation of visuo-spatial attention. Here, we explore the incidence and severity of ego-and allocentric neglect in a consecutive acute stroke sample (N=298) and compare left versus right neglect recovery 6 months post stroke (N=121). Patients completed the hearts cancellation task from the Oxford Cognitive Screen on average after 6 days and again 6 months post-stroke. The results demonstrated that egocentric and allocentric neglect are separable subtypes with egocentric and allocentric neglect occurring in isolation in 46 and 27% of the acute neglect patients, respectively. In addition, we found that in participants with only allocentric neglect there was no egocentric spatial laterality to the false positive errors made. Though left egocentric neglect was more prevalent (67%) in right hemisphere patients, the severity was not significantly different from that in left hemisphere cases (in terms of the absolute asymmetry scores). In addition, there was an equal incidence of left and right allocentric neglect (51% vs 49%). However, in terms of recovery, at 6 months post stroke, right neglect was much more likely to recover (only 2 patients still demonstrated right neglect at follow up). There were no differences in recovery rates for ego- vs allocentric neglect. The lack of an effect of egocentric spatial bias to allocentric errors provides strong evidence that these disorders are independent. In addition, the greater likelihood of left neglect continuing at 6 months, despite it having the same severity for left and right hemisphere patients, is consistent with right hemisphere patients (and patients with chronic neglect) having disorders additional to a bias in spatial orienting. Meeting abstract presented at VSS 2015.