A 48-year-old man visited our emergency outpatient on day X with the chief complaint of dizziness from an hour ago. He was sent back home, because examination revealed no neurological deficits, and no abnormalities were detected on head CT or head MRI. The following day, he experienced vertigo and returned to the emergency outpatient again. Head positional testing revealed direction-fixed right beating horizontal nystagmus. He was hospitalized on the same day with suspected peripheral vertigo, and initiated on conservative treatment. Although the vertigo resolved, on day X+5, the patient was found to show left Horner's syndrome, decreased pain (and temperature) sensation on the left side of the face and decreased pain (and temperature) sensation in the right trunk and limbs. Two-point alternating gaze test confirmed undershoot toward the right side, and OKP (optokinetic nystagmus pattern) confirmed poor resolution on the right side. In the caloric test, visual suppression of right beating nystagmus had almost disappeared. We suspected central disease, and repeated the head MRI. MRA revealed left vertebral artery dissection and the patient was transferred to the Stroke Department. Cerebral angiography was performed on day X+10. The pearl and string sign was observed, and the patient was diagnosed as having lateral medullary syndrome due to left vertebral artery dissection. In a patient presenting with vertigo associated with head and neck pain, the possibility of central disease should be borne in mind, even if the patient is young.
