Ataxia and ophthalmoplegia: an atypical case of Miller Fisher syndrome (MFS) with anti-GAD antibody

Miller Fisher syndrome: an updated narrative review

Introduction

Miller Fisher syndrome (MFS) is considered a rare variant of Guillain-Barré syndrome (GBS), a group of acute-onset immune-mediated neuropathies characterized by the classic triad of ataxia, areflexia, and ophthalmoparesis. The present review aimed to provide a detailed and updated profile of all aspects of the syndrome through a collection of published articles on the subject, ranging from the initial description to recent developments related to COVID-19.

Methods

We searched PubMed, Scopus, EMBASE, and Web of Science databases and gray literature, including references from the identified studies, review studies, and conference abstracts on this topic. We used all MeSH terms pertaining to "Miller Fisher syndrome," "Miller Fisher," "Fisher syndrome," and "anti-GQ1b antibody."

Results

An extensive bibliography was researched and summarized in the review from an initial profile of MFS since its description to the recent accounts of diagnosis in COVID-19 patients. MFS is an immune-mediated disease with onset most frequently following infection. Anti-ganglioside GQ1b antibodies, detected in ~85% of patients, play a role in the pathogenesis of the syndrome. There are usually no abnormalities in MFS through routine neuroimaging. In rare cases, neuroimaging shows nerve root enhancement and signs of the involvement of the central nervous system. The most consistent electrophysiological findings in MFS are reduced sensory nerve action potentials and absent H reflexes. Although MFS is generally self-limited and has excellent prognosis, rare recurrent forms have been documented.

Conclusion

This article gives an updated narrative review of MFS with special emphasis on clinical characteristics, neurophysiology, treatment, and prognosis of MFS patients.

A Patient With Miller Fisher Syndrome With Positive GQ1b and Aquaporin-4 Antibodies: Will There Be an Aquaporin-4 Antibody Associated Disorder?

There have been many advancements in the field of neuromyelitis optica and neuromyelitis optica spectrum disorder since the discovery of aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein antibodies. It is also recognized that the pathological features associated with myelin oligodendrocyte glycoprotein antibodies are beyond the domain of neuromyelitis optica spectrum disorder and there is a separate nomenclature, namely myelin oligodendrocyte glycoprotein antibody associated disease. Currently, there is no aquaporin-4 antibody associated disorder, even though aquaporin-4 antibodies are not as widely present in other disorders.  Miller Fisher syndrome (MFS) is a variant of Guillain Barré syndrome, in which there are positive GQ1b antibodies with no evidence of myelitis or optic neuritis. MFS is not considered a component of neuromyelitis optica spectrum disorder. We report on a patient with MFS that was positive for GQ1b and aquaporin-4 antibodies but negative for myelin oligodendrocyte glycoprotein antibodies and is devoid of any features of neuromyelitis optica spectrum disorder. This finding may lead to investigations and reports of other pathologies that are associated with the aquaporin-4 antibody.