Vestibular Pathology and Differential Diagnosis: Peripheral versus Central Reasoning
Building the differential
Start with timing and triggers. Episodic triggered vertigo lasting seconds suggests BPPV; spontaneous episodes lasting minutes to hours suggest Meniere disease or vestibular migraine; acute sustained vertigo suggests vestibular neuritis, stroke, or demyelination. Meniere disease classically combines fluctuating low-frequency sensorineural hearing loss, tinnitus, aural fullness, and episodic vertigo; vestibular migraine often has headache, photophobia, phonophobia, and visual aura with variable exam findings. Vestibular neuritis is unilateral hypofunction without hearing loss, typically after a viral illness, with a positive head impulse and direction-fixed horizontal nystagmus.
Red flags for central causes
Sudden onset with vascular risk factors, new hearing loss plus brainstem signs, vertical or direction-changing nystagmus, skew deviation, gaze-evoked nystagmus, saccadic pursuit, truncal ataxia out of proportion to limb ataxia, and a normal head impulse test in a patient with acute severe vertigo (HINTS plus) point centrally. Posterior circulation stroke can present with isolated vertigo and normal MRI early, so timing of imaging matters.
Other entities
Superior canal dehiscence produces sound- or pressure-induced vertigo with a low-frequency air-bone gap and enhanced VEMP. Vestibular schwannoma causes progressive unilateral hearing loss with reduced caloric and VEMP responses. Bilateral vestibulopathy causes oscillopsia and imbalance in the dark with a positive head impulse bilaterally.
Common traps
Equating a positive head impulse with a peripheral cause, or assuming absence of headache excludes migraine. Another trap is labeling recurrent positional vertigo as BPPV without confirming a canal-specific nystagmus pattern.
Worked rule
For acute continuous vertigo, apply HINTS: head impulse, nystagmus type, test of skew. A normal head impulse with direction-changing nystagmus and skew suggests stroke until proven otherwise.