A 25-year-old woman develops progressive ascending weakness over 10 days, starting in the feet and reaching the thighs. Deep tendon reflexes are absent. CSF shows protein 220 mg/dL with WBC 4 cells/µL (albumin-cytological dissociation). Anti-ganglioside antibody testing is positive for anti-GQ1b. What is the likely diagnosis and its distinctive clinical feature?
- A Classic AIDP — ascending weakness with respiratory involvement
- B Miller Fisher syndrome variant of GBS — ophthalmoplegia, ataxia, and areflexia ✓
- C CIDP — chronic relapsing demyelinating neuropathy
- D Botulism — descending paralysis with pupil dilation
Correct answer: B. Miller Fisher syndrome variant of GBS — ophthalmoplegia, ataxia, and areflexia
Explanation
Anti-GQ1b antibodies are the diagnostic hallmark of Miller Fisher syndrome (MFS), a variant of Guillain-Barré syndrome characterised by the triad of ophthalmoplegia, ataxia, and areflexia, with relative sparing of limb strength. Though the stem describes ascending weakness, the anti-GQ1b positivity is the discriminating clue pointing to MFS. Classic AIDP has anti-GM1 or no specific antibodies. CIDP has a chronic course (>8 weeks) and botulism has a descending 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.