A 24-year-old man develops diplopia, gait ataxia, and areflexia one week after a diarrhoeal illness. He has complete external ophthalmoplegia and dilated unreactive pupils. MRI brain is normal and CSF protein is elevated with normal cell count. Which antibody should be tested to confirm the diagnosis?
- A Anti-AChR antibodies
- B Anti-GM1 ganglioside antibodies
- C Anti-GQ1b ganglioside antibodies ✓
- D Anti-P/Q-type VGCC antibodies
Correct answer: C. Anti-GQ1b ganglioside antibodies
Explanation
The triad of ophthalmoplegia, ataxia, and areflexia defines the Miller Fisher variant of Guillain-Barre syndrome, and anti-GQ1b IgG antibodies are present in more than 90 percent of cases. Anti-GM1 is associated with acute motor axonal neuropathy and multifocal motor neuropathy. AChR antibodies indicate myasthenia gravis and P/Q-type VGCC antibodies indicate Lambert-Eaton syndrome, neither of which produces areflexia.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.