Diagnosis and Differential Diagnosis

Diagnosing vestibular migraine can be challenging because there's no single definitive test, and symptoms can overlap with many other vestibular disorders. The diagnosis relies primarily on clinical criteria established by the International Headache Society and the Bárány Society, which require a combination of vestibular symptoms, migraine features, and temporal relationships between these symptoms. The current diagnostic criteria for "definite" vestibular migraine include: at least five episodes of vestibular symptoms of moderate or severe intensity lasting 5 minutes to 72 hours, current or previous history of migraine with or without aura, at least 50% of episodes accompanied by migraine features (headache, photophobia, phonophobia, or visual aura), and exclusion of other causes.

"Probable" vestibular migraine is diagnosed when patients have at least five episodes of vestibular symptoms of moderate or severe intensity lasting 5 minutes to 72 hours, but only some episodes are associated with migraine features, or patients have a history of migraine and vestibular symptoms but the temporal relationship is unclear. This category recognizes that many patients have symptoms consistent with vestibular migraine but don't meet all strict criteria for the definite diagnosis.

The clinical history is the most important diagnostic tool, requiring careful documentation of symptom patterns, triggers, family history, and response to treatments. Patients should be questioned about both their vestibular symptoms and their migraine history, as many people don't initially connect these symptoms. A detailed headache history may reveal subtle migraine features that patients haven't recognized or reported. Keeping a symptom diary for several weeks can help identify patterns and triggers that support the diagnosis.

Physical examination during vestibular migraine episodes may show abnormal eye movements (nystagmus), though this is not universal. Between episodes, the neurological examination is typically normal, which is an important distinguishing feature from some other vestibular disorders. The examination should include assessment for other neurological signs that might suggest alternative diagnoses, such as acoustic neuroma or multiple sclerosis.

Vestibular function testing can help rule out other causes of dizziness but is typically normal in vestibular migraine patients, at least between episodes. Some patients may show subtle abnormalities on specialized testing, but these are usually not sufficient to explain the severity of symptoms. Normal vestibular test results in a patient with typical symptoms can actually support a vestibular migraine diagnosis by ruling out peripheral vestibular disorders.

Audiometric testing (hearing tests) should be performed to rule out conditions like Meniere's disease, which can cause similar symptoms but typically includes hearing loss. Most vestibular migraine patients have normal hearing, though some may have mild hearing loss unrelated to their vestibular symptoms. MRI scanning is sometimes performed to rule out structural causes of vestibular symptoms, particularly when symptoms are atypical or severe, but is typically normal in vestibular migraine.

The differential diagnosis for vestibular migraine includes many other causes of episodic dizziness. Meniere's disease shares the episodic nature but typically includes hearing loss and tinnitus. BPPV causes positional vertigo but episodes are much briefer and clearly position-dependent. Vestibular neuritis causes severe but usually single episodes of vertigo. Anxiety disorders can cause dizziness but typically lack the specific migraine features. Central nervous system disorders like multiple sclerosis or brainstem lesions may require imaging to exclude.