The patient was admitted with a diagnosis of progressive delirium with an unclear underlying etiology. Upon admission, the vital signs were within normal ranges. An extensive neurological examination was performed, which revealed dysarthria, sustained gaze-evoked and vertical nystagmus, hypoesthesia at the periumbilical level with both the upper and the lower extremities more prominent on the left side, spinal ataxia and no abdominal skin reflex. There were no signs of nuchal rigidity, no Kernig's and Brudzinski's signs or musculoskeletal weakness in the physical examination.