Derealization symptoms according to the subjective visual vertical during unilateral centrifugation in patients with type 2 diabetes mellitus.

BACKGROUND: A recent study has shown variability on the perception of verticality during unilateral centrifugation among patients with type 2 diabetes mellitus; it is yet unknown if it is related to symptoms of unreality. OBJECTIVE: In patients with type 2 diabetes mellitus compared to age matched healthy volunteers, to assess depersonalization/derealization (DD) symptoms before and after unilateral centrifugation, according to the subjective visual vertical (SVV). METHODS: 47 patients with type 2 diabetes mellitus and 50 age matched healthy volunteers participated in the study. They replied to standardized questionnaires of symptoms related to balance, depression, and anxiety. Then, after neuro-otological evaluation, they completed a DD inventory before and after unilateral centrifugation (300°/s, 3.85 cm) with SVV estimation. RESULTS: Right/left asymmetric SVV during centrifugation was identified in 17 patients (36%) and no SVV change during centrifugation was identified in 6 patients (13%). Before centrifugation, patients with asymmetric SVV already reported some of the DD symptoms, while patients with no SVV change reported almost no DD symptoms. Unilateral centrifugation provoked an increase of DD symptoms in both healthy volunteers and the entire group of patients (repeated measures ANOVA, p < 0.01), except in the 6 patients with no SVV change. Before centrifugation, the DD score showed influence from the SVV subgroup and the evidence of depression (MANCoVA, p < 0.01); after centrifugation, which provoked asymmetry of the right/left utricular input, only the influence from depression persisted. No influence was observed from the characteristics of the subjects, including retinopathy, peripheral neuropathy (assessed by electromyography) or weight loss, or from the total score on the questionnaire of symptoms related to balance. CONCLUSIONS: In patients with type 2 diabetes mellitus and healthy volunteers, utricular stimulation by unilateral centrifugation may provoke DD symptoms, with an influence from depression. The results support that the aphysiological utricular input given by unilateral centrifugation may contribute to create a misleading vestibular frame of reference, giving rise to 'unreal' perceptions.