AUTHOR=Noioso Ciro Maria , Bevilacqua Liliana , Acerra Gabriella Maria , Della Valle Paola , Serio Marina , Vinciguerra Claudia , Piscosquito Giuseppe , Toriello Antonella , Barone Paolo , Iovino Aniello TITLE=Miller Fisher syndrome: an updated narrative review JOURNAL=Frontiers in Neurology VOLUME=Volume 14 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1250774 DOI=10.3389/fneur.2023.1250774 ISSN=1664-2295 ABSTRACT=Introduction: Miller Fisher syndrome (MFS) is considered a rare variant of Guillain-Barré syndrome (GBS), a group of acute-onset immune-mediated neuropathies characterised by the classic triad of ataxia, areflexia and ophthalmoparesis. The present review aims to provide a detailed and updated profile of all aspects of the syndrome through a collection of published works on the subject, ranging from initial description to recent developments related to COVID-19. Methods: We searched PubMed, Scopus, EMBASE, Web of Science, 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 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 approximately 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 central nervous system involvement. The most consistent electrophysiological findings in MFS are reduced sensory nerve action potentials and absent H reflexes. Although MFS is generally self-limited and with excellent prognosis, rare recurrent forms have been documented. Conclusions: This article gives an updated narrative review of MFS with special emphasis on clinical characteristics, neurophysiology, treatment and prognosis of MFS patients.