Background: Patients with vestibular disease have an increased rate of reporting symptoms of depersonalisation/ derealisation (DD) and similar symptoms can be provoked in healthy subjects during caloric vestibular stimulation. Objective: To assess the relationship between DD symptoms in patients with peripheral vestibular disease and their ability to update orientation in the environment.
Methods: Sixty healthy subjects and 50 patients with peripheral vestibular disease completed a DD questionnaire (Cox and Swinson, 2002) and the GHQ-12 (Goldberg and Williams,1988). This was followed by a test of updating spatial orientation in which subjects were exposed to 10 manually driven whole body rotations of 45°, 90° or 135° in a square room, which contained distinctive features on the walls, in such a way that the features and corners subtended 45° with respect to the subject. After each rotation subjects reported which wall or corner they were facing. Estimation error was calculated by subtracting the reported rotation from the actual rotation.
Results: DD scores were significantly higher in vestibular patients than in healthy subjects (p<0.05, t test). In patients, the lowest symptom scores and the lowest estimation errors were found in those with a unilateral canal paresis without recent balance symptoms whereas the highest scores and largest estimation errors were found in those with bilateral vestibular loss (p<0.05, ANOVA). Across all patients, DD scores were related to estimation errors (adjusted R2= 0.25, p<0.05, ANCOVA).
Conclusions: Patients with peripheral vestibular disease have a deficit in the ability to update orientation on the environment and a high prevalence of DD symptoms, which may imply a high order effect of the vestibular impairment. Derealisation symptoms in vestibular disease may be a consequence of a sensory mismatch between disordered vestibular input and other sensory signals of orientation.