A 45-year-old male is brought to the hospital for difficulty walking and appearing confused. He does not have any significant medical history. He has diminished sensation to light touch bilaterally...

A 45-year-old male is brought to the hospital for difficulty walking and appearing confused. He does not have any significant medical history. He has diminished sensation to light touch bilaterally involving the upper and lower extremities and looks at his feet while walking. Proprioception is markedly diminished, with a positive Romberg sign. Reflexes are almost completely absent, including no pupillary reflex to light. What is the most likely diagnosis?

A. Peripheral neuropathy

B. Syringomyelia

C. Neurosyphilis

D. Subacute combined systems degeneration

E. Brown-Séquard syndrome