High variability of the subjective visual vertical test of vertical perception, in some people with neck pain – Should this be a standard measure of cervical proprioception?

BackgroundSubjective visual vertical (SVV) assesses visual dependence for spacial orientation, via vertical perception testing. Using the computerized rod-and-frame test (CRFT), SVV is thought to be an important measure of cervical proprioception and might be greater in those with whiplash associated disorder (WAD), but to date research findings are inconsistent.ObjectiveThe aim of this study was to investigate the most sensitive SVV error measurement to detect group differences between no neck pain control, idiopathic neck pain (INP) and WAD subjects.DesignCross sectional study.MethodsNeck Disability Index (NDI), Dizziness Handicap Inventory short form (DHIsf) and the average constant error (CE), absolute error (AE), root mean square error (RMSE), and variable error (VE) of the SVV were obtained from 142 subjects (48 asymptomatic, 36 INP, 42 WAD).ResultsThe INP group had significantly (p < 0.03) greater VE and RMSE when compared to both the control and WAD groups. There were no differences seen between the WAD and controls.ConclusionThe results demonstrated that people with INP (not WAD), had an altered strategy for maintaining the perception of vertical by increasing variability of performance. This may be due to the complexity of the task. Further, the SVV performance was not related to reported pain or dizziness handicap. These findings are inconsistent with other measures of cervical proprioception in neck pain and more research is required before the SVV can be considered an important measure and utilized clinically.