Miller Fisher Syndrome – Anti-GQ1b — SCE Neurology MCQ

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ModeratePeripheral Neuropathy & NeuromuscularMiller Fisher Syndrome – Anti-GQ1bSCE Neurology

A 40-year-old woman with GBS (AIDP variant) presents at day 3 of symptoms. She has bifacial weakness, limb areflexia, and ataxia but relatively mild limb weakness. Anti-GQ1b antibodies are positive. What variant of GBS does she have?

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Correct answer: C — Miller Fisher syndrome overlap with GBS

Miller Fisher syndrome (MFS) is characterised by the triad of ophthalmoplegia, ataxia, and areflexia. When MFS overlaps with GBS features (limb weakness, bifacial weakness), it is classified as MFS-GBS overlap. Anti-GQ1b antibodies are present in >90% of MFS cases and are highly specific. GQ1b ganglioside is concentrated in the oculomotor nerves and muscle spindles, explaining the ophthalmoplegia and ataxia. Treatment is supportive for pure MFS; IVIg may be given for MFS-GBS overlap with significant weakness. A: AMAN is axonal and associated with anti-GM1 or anti-GD1a antibodies. C: AMSAN is a severe axonal variant. D: CIDP is chronic (>8 weeks). E: MMN is a chronic condition.

Reference: EAN/PNS GBS Guidelines (2023)