The Episodic Vestibular Syndrome

This is a 55-year-old man with 6 months of episodic vertigo without clear triggers/provocative factors, with each of his 3 previous episodes lasting less than 5 minutes. While in the clinic, he had one of his typical vertigo attacks. There was initially 30 seconds of right-beating-torsional nystagmus in a crescendo-decrescendo pattern which then stopped, and the video seen here follows the first right-beating phase when left-beating-torsional nystagmus is apparent, with a slow increase over about 30 seconds. Nystagmus persisted for another 6.5 minutes or so at which time it gradually slowed down and resolved completely. Head impulse testing was negative/normal during the attack. His left-beating-torsional (towards the left ear) nystagmus was unidirectional and followed Alexander's law, where the nystagmus was maximal in the direction of the fast phase (to the left). Complete ocular motor, vestibular and neurologic examinations performed immediately following the attack were entirely normal. There were no aural, migrainous or neurologic symptoms associated with any of his attacks. MRI IAC protocol with and without gad and MR angiograms of the head and neck were all unremarkable without a fixed vertebrobasilar stenosis, neurovascular contact involving the 8th cranial nerve or acoustic neuroma for instance. Suspicion for typical etiologies of recurrent vertigo including TIAs, Meniere's (despite the reversal of nystagmus, there were no aural symptoms, normal audiogram, and episodes were shorter than would be expected for Meniere's which typically last from 20 minutes to 12 hours), vestibular paroxysmia (no hyperventilation-induced nystagmus or neurovascular contact with thin, heavily weighted T2 CISS imaging), and vestibular migraine (no history of motion sickness, migraine headaches, and no migraine features before, during or after his attacks) were low, and empiric trial of Diamox (which could theoretically treat vestibular migraine, Meniere's or vestibular paroxysmia) led to cessation of attacks in the absence of a clear diagnosis. Audiogram, caloric and vestibular evoked myogenic potentials (VEMPs - ocular and cervical) were all normal. ; A short-lived vestibular (isolated vertigo, imbalance, nausea/vomiting) attack lasting minutes to hours is considered an episodic vestibular syndrome. HINTS (head impulse, nystagmus, test of skew) was developed for the acute vestibular syndrome (AVS), where vertigo and spontaneous nystagmus last days-weeks. However, HINTS is commonly performed only hours after the symptom onset of the AVS. In his case, there was unidirectional nystagmus and the absence of a skew deviation, which are typically suggestive of a "peripheral" (vestibular neuritis) etiology, whereas a normal or negative head impulse test is strongly suggestive of a "central" (stroke/demyelination) etiology in the AVS. However, the 3 step HINTS examination cannot be relied upon in the episodic vestibular syndrome to accurately triage patients as it can in the acute vestibular syndrome.