A 40-year-old man being evaluated for gait ataxia and lightning pains in the lower limbs is found to have small, irregular pupils that constrict briskly on accommodation but show minimal reaction to bright light. This pupillary finding is classically associated with:
- A Neurosyphilis affecting the dorsal midbrain ✓
- B Diabetic autonomic neuropathy
- C Holmes-Adie syndrome
- D Chronic bilateral optic neuropathy
Correct answer: A. Neurosyphilis affecting the dorsal midbrain
Explanation
The Argyll Robertson pupil shows light-near dissociation with small, irregular pupils that react poorly to light but well to near effort, and it is classically described in tabes dorsalis due to neurosyphilis. The lesion is thought to involve intercalated neurons in the dorsal midbrain near the aqueduct. Holmes-Adie pupils are large and unilateral with segmental iris movements, the direct opposite of the small miotic Argyll Robertson pupil. Diabetic pupillopathy does not produce this classic pattern.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.