Undiagnosed polycythemia, an uncommon cause of Wallenberg syndrome: A case report.

A 26-year-old man presented with difficulty swallowing, dizziness, hiccups, and Horner's syndrome. Clinical and neuroimaging collaboration confirmed lateral medullary syndrome. Polycythemia was identified as the only attributable risk factor. However, the cause of polycythemia could not be assessed further. Polycythemia was managed with phlebotomy.