Association between migraine and vestibular disorders

Abstract

Dizziness (vertigo) and migraine headache are among the most common neurological disorders. The association of dizziness and migraine in the population occurs more often than these conditions diagnosed separately. The probability of their random coincidence is about 1% among the adult population, and the prevalence of migraines combined with dizziness is 3.2%, i. e. about 3 times higher than a mere coincidence. Epidemiological studies have found that the associations between migraine and vertigo is bi-directional. On the one hand, migraine is more common among patients with dizziness, and on the other hand, dizziness is more common among patients with migraine. Moreover, such comorbidity with dizziness is more typical for migraine, and not for other forms of headache. On this background, the term “migraine-associated dizziness”, or “vestibular migraine” (VM) has been introduced. In 2001, H. Neuhauser et al. proposed a list of diagnostic criteria for VM, and this condition has been recently included in the ICDB-3 beta version as a separate nosological unit. By now, the pathophysiology of the VM is not well understood; the current hypotheses are mainly based on the pathophysiology of migraine itself. Yet, a number of recent studies have made a significant contribution to the understanding of the neurophysiological processes involved in the development of VM. There is a hypothesis that dizziness in migraine represents a migraine aura; this mechanism is based on the phenomenon of spreading cortical depression, i. e., a wave of depolarization that originates in the occipital cortex and slowly moves to the ventrally located areas. Vestibular disorders are known to be caused by the release of neuropeptides (substance P, neurokinin A, calcitonin-like peptide); these peptides stimulate the impulse activity of the sensory epithelium in the inner ear and the vestibular nuclei of the brain stem. In addition to the existence of vestibular migraine, as an independent form of headache, other migraine-associated vestibular disorders have been identified. The most commonly seen are nonspecific symptoms, e. g., motion sickness (that occurs in about 50% of patients), peripheral vestibulopathies, and subclinical vestibular disorders detected in patients with migraine by an instrumental neurovestibular examination in the interictal period. The precise mechanisms of the association between migraine and vertigo are not well understood. Clarifying the clinical and pathophysiological details of the relationship between these conditions is very important for optimal management of patients with migraine.