Isolated Vertigo as an Early Sign of Anti-GQ1b-Positive Miller Fisher Syndrome: Expanding the Spectrum.

Miller Fisher syndrome (MFS) occupies a distinct corner of Guillain-Barré syndrome (GBS), typically presenting with a triad comprising ophthalmoplegia, ataxia, and areflexia. While diplopia and limb incoordination are typically early features, isolated vertigo as a prodromal symptom is exceedingly uncommon and often misdiagnosed as benign vestibular disease. We report a 56-year-old Malay man who presented twice to the emergency department with acute, continuous vertigo and was initially treated symptomatically before subsequently developing bilateral ophthalmoplegia and ataxia. Anti-ganglioside (anti-GQ1b) antibody testing was positive, confirming the diagnosis of MFS, and electrophysiological studies revealed early GBS-spectrum changes. The patient responded well to intravenous immunoglobulin (IVIG) and made a full recovery within six weeks. This case illustrates that vestibular symptoms can occur early within the anti-GQ1b spectrum and may easily be overlooked. It also underscores the importance of careful, repeated neurological and ophthalmological examinations. Early recognition and treatment are critical to ensuring successful recovery.