Vestibular migraine

Episodic vestibular symptoms in a patient with migraine. The interictal chair report is often disappointingly normal — but a careful look at high-frequency phase rewards the patient eye.

Clinical picture

The Bárány Society / IHS criteria require at least five episodes of vestibular symptoms of moderate or severe intensity lasting 5 minutes to 72 hours; a current or past history of migraine with or without aura; and migrainous features (headache, photo-phonophobia, visual aura) in at least half of the vertigo episodes Lempert T 2012.

Pathophysiology

The underlying mechanism is not fully understood. Current models invoke transient dysfunction of central vestibular processing, possibly involving cortical spreading depression in vestibular association cortex, abnormal serotonergic modulation, and heightened central sensory gain.

RCT pattern

Inter-ictally, SHA gain, phase and symmetry are usually within normal limits. The most consistent finding from large normative studies is a reduced phase lead at higher frequencies — most clearly at 0.64 Hz — attributed to a hyperactive velocity- storage mechanism in motion-susceptible and migrainous individualsWang Y 2022. The step-test Tc can be slightly prolonged. None of this is diagnostic — RCT in vestibular migraine principally serves to exclude alternative explanations.

Diagnosis & differential

• Diagnosis is clinical and based on the consensus criteria.
• RCT, vHIT and caloric are usually normal between attacks.
• Beware co-existing Ménière's disease and SCD — vestibular migraine often coexists with both.
• The chair is most useful as a baseline before starting prophylaxis and after a year of treatment.