A 32-year-old man develops diplopia, gait unsteadiness, and numbness over both feet 10 days after an episode of diarrhea. Examination shows bilateral complete external ophthalmoplegia, dilated sluggishly reactive pupils, limb ataxia, and areflexia, with normal power. CSF protein is elevated with 2 cells/mm3. Which antibody should be tested to confirm the diagnosis?
- A Anti-GM1 ganglioside antibody
- B Anti-AQP4 antibody
- C Anti-GQ1b ganglioside antibody ✓
- D Anti-MuSK antibody
Correct answer: C. Anti-GQ1b ganglioside antibody
Explanation
The triad of ophthalmoplegia, ataxia, and areflexia with preserved power defines the Miller Fisher variant of Guillain-Barre syndrome, strongly associated with IgG antibodies against GQ1b ganglioside, which is highly concentrated in cranial nerve paranodes. Anti-GM1 is linked to axonal motor GBS after Campylobacter infection rather than the Fisher phenotype.
Reference: Adams and Victor's Principles of Neurology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.