Do we need to consider head-on-body position, starting roll position and presence of visuospatial neglect when assessing perception of verticality after stroke?

Abstract

BACKGROUND AND OBJECTIVEConsidering various factors influence the accuracy of the Subjective Visual Vertical (SVV) and Subjective Postural Vertical (SPV), standardization of assessment methods is needed. This retrospective study examined the contribution of Head-on-Body (HOB) position, starting roll position (SRP) and visuospatial neglect (VSN) to SVV and SPV constant errors (i.e., deviation from true vertical). Also, the contribution of HOB position and VSN presence to SVV and SPV variability (i.e., intra-individual consistency between trials) was assessed METHODSFirst-ever unilateral hemispheric stroke survivors (<85 years; <100 days post-stroke) were assessed with three HOB positions (neutral, contralesional and ipsilesional) and seven starting positions (20° contralesional to 20° ipsilesional) of the laser bar and tilt chair. Linear mixed models were selected to evaluate the contribution of HOB, SRP and VSN to SVV/SPV constant errors and variability. RESULTSThirty-four subjects (24 VSN-/ 10 VSN+) were assessed. A tilted HOB position led to significantly higher constant errors for the SVV and SPV (latter only in the VSN-group), and an increased SVV variability. SRP only significantly contributed to the SVV constant errors and only in the VSN-group. Furthermore, VSN presence resulted in a significantly higher SVV and SPV variability. CONCLUSIONSHOB position, SRP and VSN presence are important factors to consider during SVV and SPV measurements. Assessment with a neutral HOB position leads to more accurate results. HOB position and SRP influence the results of the SVV and SPV differently in individuals with and without VSN, which highlights the relevance of VSN assessment.