A man presented with difficulty walking and urinary incontinence. On examination, his pupils were nonreactive to bright light but constricted when focusing on a near object. What is the diagnosis?
High-Yield Explanation
Answer B. Tabes dorsalisThe correct answer is tabes dorsalis. Pupils that are nonreactive to bright light but briskly constrict when focusing on a near object are known as Argyll Robertson pupils, which are characteristic of tabes dorsalis. Tabes dorsalis is a form of neurosyphilis that is characterized by degeneration of the nerves in the dorsal columns of the spinal cord, which leads to ataxia and loss of proprioception, as well as this pupil finding. The patient improved with intravenous penicillin.