Anxiety affects vestibulospinal function of labyrinthine-defective patients during horizontal optokinetic stimulation

Comorbidity of vestibular and anxiety disorders was suggested by epidemiological studies and, recently, new insights into potential neural circuits which subserve both balance control and emotions, appear to support this hypothesis. In particular, disorienting visual surroundings, such as those generated by full-field moving scenes, equally disrupt postural control of patients with vestibular or panic disorders. In the present study, behaviour of body sway was assessed in response to an optokinetic stimulation by means of static posturography in 20 patients with vestibular neuritis (10 patients with normal affect and 10 with generalized anxiety disorders, as diagnosed according to the American Psychiatric Association criteria), and 20 normal subjects who served as controls. Optokinetic responses and vestibulo-spinal function during a full-field, bi-directional horizontal optokinetic stimulation, were recorded simultaneously. Labyrinthine-defective patients with low and high level of anxiety showed a common pattern of asymmetric optokinetic reflexes. On the contrary, body sway was found to be increased more by eye closure and optokinetic stimulation towards the defective labyrinth in patients affected by high level of anxiety as compared to those with normal affect and controls. These data confirm the combined effect of anxiety and labyrinthine dysfunction on vestibulo-spinal function which is disclosed by both visual suppression and disorienting visual contexts.