Miller Fischer syndrome after COVID-19 infection and vaccine: a systematic review

BACKGROUND: COVID-19 (CoranaVirus disease 2019) is an ongoing infectious disease caused by the RNA SARS-CoV-2 virus (Severe Acute Respiratory Syndrome CoronaVirus-2). The virus mainly causes respiratory symptoms, but neurological symptoms have also been reported to be part of the clinical manifestations of the disease. The aim of this study was to systematically review Miller fisher syndrome (MFS) published cases, in the context of COVID-19 infection or vaccination. METHODS: A systematic literature review on Medline was performed. A total of 21 papers were included in the present review. RESULTS: Twenty-two MFS cases (77% males) were identified, 14 related to COVID-19 infection and 8 to vaccination against COVID-19. The median age of the adult patients was 50 years (interquartile range 36–63 years). Sixteen patients (73%) had the classic triad of MFS (ophthalmoplegia, ataxia, areflexia), four (18%) had acute ophthalmoplegia and one other characteristic symptom and two patients (9%) had only one other characteristic symptom, but they tested positive for GQ1b antibodies. Nine (41%) patients had positive GQ1b antibodies and were classified as “definite” MFS. Albuminocytologic dissociation was found in half of the cases. The outcome was favourable in the majority of cases (86%) whereas one patient, despite the initial improvement, died because of a cardiac arrest, after cardiac arrythmia. CONCLUSIONS: MFS after COVID-19 infection/vaccination was found to have the typical epidemiological characteristics of classic MFS; being rare, occurring more often after infection than vaccination, affecting mainly middle-aged males usually within 3 weeks after the event and having an excellent prognosis after treatment with IVIG or even with no treatment at all. We found no evidence that MFS after COVID-19 infection was different from MFS after COVID-19 vaccination, although the former tended to occur earlier. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13760-023-02336-5.