Influence of unilateral spatial neglect on vertical perception in post-stroke pusher behavior

Pusher behavior (PB) impairs verticality in the frontal plane and is often associated with unilateral spatial neglect (USN). However, it is unclear whether USN affects verticality among patients with PB. We aimed to clarify the characteristics of verticality among PB, with and without USN. The study included 43 patients with right hemisphere stroke, including 12 without PB or USN, 10 with only USN, 10 with PB only, and 11 with PB and USN, and 15 age-matched healthy individuals. The subjective visual vertical (SVV), subjective postural vertical with eyes closed (SPV), and subjective postural vertical with eyes open were assessed. Under each condition, the mean (tilt direction) and standard deviation (variability) across trials were calculated. The variability of SVV was significantly greater among patients with only USN (6.9°±5.9°) or those with PB and USN (7.6 ± 4.3°). On SPV, the contralesional tilt was significantly greater, with higher variability, in patients with only PB (-2.2°±1.1° and 6.3°±1.4°, respectively) and those with PB and USN (-2.1°±2.0° and 6.6°±2.0°, respectively) than in the other groups. In patients with PB, SVV differed depending on the presence of USN, but it was suggested that SPV might not be affected by USN. These findings are important to plan PB treatment.