One day after heavy exercise, a 39 year-old man presented to the emergency department with sudden-onset headache and spontaneous continuous vertigo.

Neurology was consulted and found left-beating nystagmus in all gaze directions, catch-up saccades with head-impulses to the right, no skew deviation, and no hearing loss. The remainder of his neurologic exam was normal except difficulty with tandem gait. Despite the peripheral-appearing exam, a central source was suspected given the severe headache and onset after exercise. MRI and MR-angiogram were obtained which showed no diffusion restriction or other evidence of ischemia, but did reveal nonopacification and narrowing of the right cervical vertebral artery with corresponding intramural hematoma on dissection protocol images. Aspirin 81mg daily was administered. His symptoms significantly improved overnight, and he was discharged the following day.

Days later he reported his symptoms had nearly resolved. He had no spontaneous nystagmus with fixation, and left-beating nystagmus with fixation removed. Caloric testing showed an 87% unilateral weakness in the right ear, and video head-impulse testing showed scattered catch-up saccades on head thrust to the right. There were no central findings on the remainder of his video-oculography or examination, and his hearing was symmetrically normal.

This case is a rare example of Acute Vestibular Syndrome with a Head Impulse, Nystagmus, Test of Skew, and Hearing (HINTS+) exam indicating a peripheral vestibular impairment, but originating from a central vascular source. Labyrinthine infarction is a possible cause of acute vestibular syndrome, but is classically associated with ipsilateral hearing loss. In this case, we propose an embolus traversed through the labyrinthine artery and occluded the anterior vestibular artery, infarcting the superior and lateral semicircular canals and utricle while sparing the remaining inner ear including the cochlea. This case highlights the importance of careful attention to history despite an otherwise reassuring examination.