Do supine position and deprivation of visual environment influence spatial neglect?

It has been suggested that in spatial neglect, placing the patient in a supine position and performing tasks in the dark would reduce the rightward bias in line bisection and cancellation tasks. However, these findings remain debated and have not been extended to other tasks such as reading or visual exploration. Here, in the same study, we examined the effect of body position (BP) and visual environment (VE) on relatively ecological tests of spatial neglect. Among 17 patients with right-hemisphere stroke, 12 were neglect and five were non-neglect in clinical tests. They were compared with 12 healthy control participants in four tasks: line bisection, text reading, number reading, and visual exploration. Tasks were performed on a computer screen in two BP (sitting and supine) and two VE (light and dark) conditions. We found that placing patients in darkness reduced contralesional omissions in the visual exploratory task and, to a smaller extent, in number reading. Conversely, the supine position did not influence performance, and even resulted in cognitive slowing, especially in reading. In conclusion, we confirmed that reducing visual information can improve performance, but only to a limited extent. This justifies strict control of peripheral visual information when exploring neglect patients. Conversely, positioning neglect patients in the supine position can have a discrete negative effect on cognitive functioning, and this effect must be taken into account during therapy.