A 62-year-old man with a history of multiple myeloma was admitted to the medical ICU with respiratory failure due to respiratory muscle weakness. His myeloma had been diagnosed 4 months earlier, when he had presented with a lumbar cord compression and underwent urgent laminectomy. His pathologic specimen revealed myeloma invading the epidural fat. He had undergone 4 months of therapy with dexamethasone and thalidomide, was walking unassisted, and was independent in his activities of daily living. At the time of the present hospital admission, his family described a history of progressive ascending motor weakness over a 6-week period to the point that he was unable to walk.