Interactions between Stress and Vestibular Compensation – A Review

Summary & key facts

This review looked at studies in animals and people about how stress and the balance system (the vestibular system) affect each other. In many animal experiments, vestibular damage or stimulation turns on the body's stress system (the HPA axis) and short-term stress hormones help brain circuits adjust after vestibular loss. Human studies are less clear: some clinical findings and the use of steroids point to a role for stress hormones, but strong, definitive proof in people is lacking. Differences in study methods, surgery effects, and individual variation make the results hard to interpret.

Key facts:

• People with vestibular problems often have higher stress or anxiety, and people with panic or other anxiety disorders often report dizziness or balance loss (from the review's overview).
• In animals, vestibular symptoms can activate the stress axis (the HPA axis that controls hormones like ACTH and cortisol/corticosterone).
• In one animal study (guinea pigs) salivary cortisol was significantly higher 10 hours after unilateral vestibular deafferentation (UVD) compared with preoperative levels (Gliddon et al., 2003).
• In cats, levels of stress-related hypothalamic hormones CRH and AVP rose at 1, 7, and 30 days after unilateral vestibular neurectomy and returned to normal by 90 days; these changes paralleled behavioral recovery (Tighilet et al., 2009).
• A temporary functional inactivation of one ear using trans-tympanic ropivacaine produced a marked rise in plasma ACTH and corticosterone within 30 minutes of symptom onset in rats, showing a rapid stress response to vestibular loss.
• Other animal studies found no rise in serum corticosterone after UVD at some time points (10 hours and 2 weeks), and no increase after bilateral vestibular deafferentation at 3 weeks or 6 months, so results are inconsistent across studies.
• Stress hormones can act directly on brain ion channels and neurotransmission (for example glucocorticoids), and can also affect the inner ear by changing ion transport and inflammation; these are proposed mechanisms but need more study.
• The review says human evidence is complex and inconclusive. Factors limiting clear conclusions include vague clinical definitions, hard-to-measure outcomes, and variation in stress responses between and within people over time.

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.

Topics

Circadian rhythm and melatonin Stress Responses and Cortisol Vestibular and auditory disorders

Categories

Life Sciences Neurology Neuroscience

Tags

Anxiety Audiology Medicine Neuroscience Psychiatry Psychology Vestibular system