Fisher- Bickerstaff syndrome is part of the clinical spectrum of the syndrome known as anti-GQ1b. It is an immune-mediated polyneuropathy, which showed overlap between Miller Fisher syndrome, characterized clinically by ophthalmoplegia, ataxia and areflexia, and Bickerstaff encephalitis, unlike the previous one where there is a shortage of long tracts with altered state of consciousness accompanying ophthalmoplegia and ataxia. The diagnosis will be made by the clinical presentation, considering that, given the common pathogenic mechanism may have characteristics of both entities.