Miller Fisher Syndrome (MFS) is a rare variant of Guillain-Barré Syndrome (GBS) that has a geographically variable incidence. following an upper respiratory illness. The patient exhibited the classic triad of ataxia areflexia and opthalmoplegia characteristic of MFS but also had less common PF-2545920 signs and symptoms making for a more challenging diagnostic workup. Our suspected diagnosis of MFS was serologically confirmed with positive anti-GQ1b antibody titer and the patient was successfully treated PF-2545920 with Intravenous immune globulin (IVIG). Introduction The triad of ataxia areflexia and opthalmoplegia was first described by James Collier in 1932. It was subsequently reported as a variant of Guillain-Barré Syndrome (GBS) by Charles Miller Fisher in three clinical cases in 1956.1 Fisher recognized both the uniqueness of this cluster of clinical signs and its relationship to what is now considered a heterogeneous group of immune-mediated PF-2545920 neuropathies classified under Guillain-Barré Syndrome.1-3 Aptly named Miller Fisher Syndrome (MFS) is usually a geographically variable variant of GBS observed in about 1% – 5% of all GBS cases in Western countries yet up to 19% and 25% in Taiwan and Japan respectively.4 There is an established male predominance at a ratio of 2:1 and a mean age of PF-2545920 onset of 43.6 years although cases of MFS have been reported in all age ranges.2 5 As in GBS an antecedent infectious illness can be identified in the majority of MFS cases. and have been the most commonly implicated pathogens; however multiple others are also associated including Mycoplasma pneumonia and cytomegalovirus. Upper respiratory contamination is the most commonly described prodromic entity followed by gastrointestinal illness.2 4 Unlike the classic ascending weakness or paralysis that is characteristic of the more common types of GBS neurological deficits follow a top down pattern in MFS starting with diplopia in the eyes; caused by external opthalmoplegia-the most common presenting symptoms.4 5 In a clinical series of 50 consecutive cases of MFS in Japan it was discovered that 78% of cases presented initially with diplopia 46 with ataxia and 34% with both. Other abnormalities reported albeit less frequently were limb dysethesia; blepharoptosis; face bulbar and pupillary palsies; moderate (grade 4) motor weakness; and mictruition disturbance.4 An acute onset PF-2545920 is typical of MFS beginning with neurologic symptoms approximately 8-10 days (range of 1-30) following the antecedent illness.2-4 The disease then progresses until a clinical nadir is reached approximately 6 days (range of 2-21) after the initial neurologic symptoms.4 The recovery period is marked by gradual improvement and often resolution of symptoms; although rarely serious complications such as respiratory failure or cardiac arrhythmia (that are common in GBS with 30% of cases requiring ventilator support) have been reported.2 Ataxia and opthalmoplegia handle within 1-3 months after onset and near complete recovery is expected within 6 months.4 Areflexia may persist but is not associated with functional disability. Although self-limiting disease course is expected disease modifying treatment options for MFS are no different than for GBS and include intravenous immune globulin (IVIG) and plasmapheresis. Benefits of treatment are not as clear in MFS but a rationale for treatment is usually to encourage faster resolution of symptoms and perhaps decreased likelihood of complications.6 Despite its rarity MFS has played an important role in understanding the pathogenesis of immune-mediated neuropathies which is thought to involve molecular mimicry incited by antecedent infection.6-8 Chiba et al first reported the presence of anti-GQ1b antibodies in strong association with MFS in 1992.9 This serological marker present in well over 90% of afflicted patients has become an important diagnostic tool in MFS and has been implicated in other variants of GBS that involve ocular muscles.7 8 The following case presents key clinical features of MFS and Odz3 offers a discussion of focused differential diagnoses anti-GQ1b antibody test prognosis and available treatments. Familiarity with this rare syndrome will clue the clinician to consider MFS in patients presenting with areflexia ataxia and ophthalmic symptoms. Case Report A 50-year-old part-Hawaiian man presented to the emergency department (ED) with a principal complaint of generalized weakness. An emergency.