Interactions between Stress and Vestibular Compensation - A Review

Abstract

Elevated levels of stress and anxiety often accompany vestibular dysfunction, while conversely complaints of dizziness and loss of balance are common in patients with panic and other anxiety disorders. The interactions between stress and vestibular function have been investigated both in animal models and in clinical studies. Evidence from animal studies indicates that vestibular symptoms are effective in activating the stress axis, and that the acute stress response is important in promoting compensatory synaptic and neuronal plasticity in the vestibular system and cerebellum. The role of stress in human vestibular disorders is complex, and definitive evidence is lacking. This article reviews the evidence from animal and clinical studies with a focus on the effects of stress on the central vestibular pathways and their role in the pathogenesis and management of human vestibular disorders.

Keywords: plasticity; stress; vestibular compensation.

Figure 1

Diagrammatic representation of the interconnections between the central nervous system structures implicated in stress responsiveness and vestibular dysfunction.

Figure 2

Stress response evoked by the functional inactivation of the right inner ear by trans-tympanic injection of 3% ropivacaine. (A) ACTH and corticosterone plasma concentrations (pg/ml and ng/ml respectively) measured by radioimmunoassay of trunk blood taken from rats sacrificed 30 min after the onset of the symptoms of unilateral vestibular loss. Symptom severity (spontaneous ocular nystagmus, barrel-rolling, postural asymmetry) was estimated on a behavioral scale as described in detail in Bergquist et al. (2008). Note sham-treated animals (n = 5) developed no symptoms and maintained low ACTH and corticosterone levels, while ropivacaine-treated animals (n = 6) developed marked behavioral symptoms and showed ACTH and corticosterone levels that were elevated in relation to the severity of the symptoms. (B) Mean ± SD of plasma ACTH and corticosterone concentrations in the sham-treated group (open bars) and the ropivacaine-treated group after functional unilateral labyrinthectomy (UL, closed bars). Bergquist, F., Brunton, P., and Dutia, M. B., unpublished data.