IS THERE A DIFFERENCE IN VESTIBULAR SYSTEM REACTIVITY BETWEEN PATIENTS WITH SCHIZOPHRENIA AND HEALTHY CONTROL PARTICIPANTS?

Abstract Background Conventional caloric vestibular stimulation (CVS), which involves the irrigation of cold or warm water into the external ear canal induces a temperature gradient across the semicircular canals of the vestibular apparatus stimulating the vestibular nerve and eliciting the vestibulo-ocular reflex. It is commonly used in both otolaryngology to assess vestibular function and neurology to test brain stem function. In schizophrenia, there is no conclusive link between psychopathology and vestibular dysfunction. Initial data from another CVS study by our group suggests that individuals with schizophrenia may have greater reactivity to body temperature (37° C) CVS, as measured by the peak slow phase velocity of the resulting nystagmus (PSPV), than would be expected for healthy participants1. However, we are unaware of any studies that have investigated the differential effects of CVS temperature gradients on individuals with schizophrenia versus healthy control participants. Aim & Objective In the current study we aimed to examine if individuals with schizophrenia have greater reactivity to caloric vestibular stimulation than healthy control (HC) participants. Methods Patients with schizophrenia and HC participants received three conditions bilaterally: (1) body temperature (37° C) CVS; (2) warm CVS (44° C), and (3) cold CVS (30° C). All conditions were performed by an audiologist. The physiological response of vestibular stimulation was assessed with videonystagmography, which provides a measure of the intensity of the nystagmus via PSPV. Independent sample t-tests were conducted to compare vestibular reactivity (i.e., nystagmus) between patients and HC participants for each CVS condition. Results A total of 20 patients (mean age 39.2, SD=12.6, 25% female) and 20 HC participants (mean age 37.9, SD=13.1; 25% female) completed the study. There was no statistically significant difference between patients and HC participants in body temperature, warm or cold CVS (p>0.05). Discussion & Conclusion In schizophrenia, there is no conclusive link between psychopathology and vestibular dysfunction, and we are not aware of any data that exists on the range of responses to CVS in persons with schizophrenia. We did not find any differences in vestibular reactivity between patients with schizophrenia and HC participants in response to CVS. References Gerretsen, P.et al.(2017) ‘Vestibular stimulation improves insight into illness in schizophrenia spectrum disorders’, Psychiatry Research, 251, pp. 333–341. doi:10.1016/j.psychres.2017.02.020.