Comorbidities in vestibular migraine.

A growing body of clinical and epidemiological evidence supports a specific relationship between vestibular symptoms and migraine. Without a biomarker or complete understanding of pathophysiology, diagnosis of vestibular migraine (VM) currently depends upon symptoms in two dimensions: episodic vestibular symptoms temporally related to migraine symptoms. The Bárány Society and the International Headache Society have recently developed consensus diagnostic criteria. However, many issues remain unsettled, including the type, duration, and timing of vestibular symptoms related to headache that should be required for diagnosing VM. This paper focuses on the challenging third dimension of comorbidity, a frequent cause of diagnostic uncertainty that may confound clinical application and research validation of VM criteria. Several other neurotologic conditions occur more frequently in migraineurs than controls, including benign paroxysmal positional vertigo, Ménière's disease, and motion sickness. Patients with VM also have high rates of chronic subjective dizziness, which may be associated with anxious, introverted temperaments that can affect clinical presentation and treatment response. Broadly inclusive studies of well-characterized patients with other neurotologic and psychiatric comorbidities are needed to fully understand how vestibular symptoms and migraine interact in order to truly validate vestibular migraine, distill its essential features, define its boundaries, and characterize overlapping comorbidities.