Clinical Reasoning: A 49-year-old man with progressive numbness, weakness, and evidence of leptomeningeal enhancement.

Section 1 A 49-year-old man with a medical history significant for diabetes mellitus, a left thigh sarcoma that was resected 5 years prior, and a seizure disorder on valproic acid presentedwith 2months of progressive numbness and weakness. Symptoms began with painful paresthesias in both thumbs that progressed to numbness. His feet subsequently became numb, and within 3 weeks he noted gait unsteadiness. During this time he also experienced a 25-pound weight loss. He subsequently developed intermittent diplopia, worst on downgaze. He denied recent sick contacts, prior exposure to tuberculosis, or tick bites. He was admitted to an outside hospital and subsequently transferred to our facility for further care.