Anti-GQ1b Antibody Syndrome Presented as Locked-In Syndrome: A Rare Case Report.

Anti-GQ1b antibodies are considered a hallmark of Miller-Fisher syndrome (MFS), a rare variant of Guillain-Barré syndrome (GBS). The typical clinical presentation of MFS includes ophthalmoplegia, ataxia, and areflexia. Here, we present an unusual case of a 65-year-old man with acute-onset quadriplegia and bulbar weakness resembling locked-in syndrome. Imaging studies did not show structural lesions as a cause for his clinical symptoms. Nerve conduction studies showed severe axonal sensory-motor polyneuropathy. Serum studies were all negative except for a positive anti-GQ1b antibody. He was treated with plasmapheresis as MFS, with a quick improvement in muscle strength. Our case report provided further information on the clinical variation of anti-GQ1b syndrome. Physicians should pay more attention to unusual presentations of anti-GQ1b syndrome because, when it is recognized early with prompt treatment, patients are expected to have a good recovery.