An Atypical Case of Miller Fisher Syndrome.

Miller Fisher syndrome (MFS) is a rare variant of Guillain-Barré syndrome (GBS) characterized by a classic triad of external ophthalmoplegia, ataxia, and areflexia, often following a recent infection.  Understanding atypical presentations of MFS is crucial for timely diagnosis and management, as the syndrome may be mistaken for other neurological disorders. This report aims to highlight the clinical journey of the patient, including symptom onset, diagnostic challenges, and therapeutic interventions, with a discussion of the broader implications of such atypical cases in the context of MFS.  In this case, a 28-year-old male presented with binocular diplopia and numbness. The patient had recently returned from Europe, where he experienced a viral diarrheal infection. He presented to the emergency department with diplopia and numbness throughout his entire body and complained of difficulty ambulating because of the loss of sensation in his feet. The examination was significant for binocular diplopia, bilateral disconjugate gaze with esotropia, diminished sensations, and absent deep tendon reflexes in all four extremities, but no ataxia or weakness was elicited. His case was discussed with neurology with concern for GBS or MFS, and he was hesitantly admitted to the floor with a negative inspiratory force (NIF) of -22 (normal < -60) under the resident admitting service. Lumbar puncture (LP) studies including meningitis/encephalitis pathogen panel, venereal disease research laboratory (VDRL), myelin basic protein, anti-GQ1b antibody, and bacterial cultures were initially unremarkable. Even despite suspicion of the diagnosis, no treatment was started until neurology started IV immunoglobulin (IVIG) the next day when his symptoms worsened with bilateral knee weakness. He received five days of 400 mg/kg of IVIG with an improvement of his distal weakness, numbness, and diplopia, as well as respiratory function with a NIF of -48. With an improved ability to ambulate, he was discharged without new medications with a presumed diagnosis of GBS as the gastrointestinal (GI) polymerase chain reaction (PCR) test showed and . Lumbar puncture studies were eventually positive for the anti-GQb1 antibody, which is consistent with the Miller Fisher variant of GBS. Ultimately, this case exemplifies the need for heightened awareness among healthcare professionals regarding the diverse manifestations of the MFS. As our understanding deepens, we can improve diagnostic accuracy and treatment outcomes for patients suffering from this rare and challenging condition.