A 24-year-old man develops diplopia, unsteady gait, and areflexia over 5 days following a febrile illness. Examination shows external ophthalmoplegia affecting upgaze and abduction, marked limb and gait ataxia, and absent ankle jerks. Power is normal. Which antibody is most characteristically associated with this presentation?
- A Anti-GM1
- B Anti-GD1a
- C Anti-GQ1b ✓
- D Anti-sulfatide
Correct answer: C. Anti-GQ1b
Explanation
The triad of ophthalmoplegia, ataxia, and areflexia without significant weakness defines the Miller Fisher syndrome, a variant of Guillain-Barre syndrome. It is strongly associated with IgG antibodies against ganglioside GQ1b, which is concentrated in the oculomotor nerve paranodes. Anti-GM1 is linked to axonal motor GBS and multifocal motor neuropathy, while anti-GD1a relates to acute motor axonal neuropathy after Campylobacter infection.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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