[Miller-Fisher/Guillain-Barré overlap syndrome following COVID-19 vaccination].

Background: Anti-GQ1B syndrome includes a group of diseases characterized by antibody-mediated polyneuropathy. Guillain Barre syndrome (GBS) and the Miller-Fisher syndrome (MFS) have been related to COVID-19 vaccine application. Clinic case: 48-year-old man, with history of Pfizer-BioNTech vaccination against COVID-19, 5 days prior to the symptoms, who assisted to the Emergency room with blurred vision and diplopia; adding dysarthria, facial diplegia and left upper limb weakness after 48 hours. In his first evaluation it was found ophthalmoplegia, facial diplegia, decreased gag reflex, weakness of thoracic limbs, bilateral trapezius muscle and areflexia. Serum studies and nuclear magnetic resonance of the brain were performed without alterations. It was complemented with IgG anti-ganglioside GQ1b antibodies with a positive result. Once the diagnosis was confirmed, treatment was started with immunoglobulin calculated at 2 g per kg for 5 days. The patient was discharged once the immunoglobulin was administered with evaluation at 2 months without ataxia, ophthalmoplegia, areflexia and weakness. Conclusions: Following the documented reports of GBS and its variants secondary to vaccination, neurological side effects have been catalogued as being of great importance. Therefore, the reported case can be used as a point of reference to consider this clinical spectrum as a differential diagnosis in patients with post-vaccination neurological symptomatology.