Miller Fisher syndrome is a variant of
Guillain-Barre syndrome characterized by the classic triad of
ophthalmoplegia,
ataxia, and areflexia. Pupillary involvement is common in MFS and has been reported in 35-42% of MFS patients. Although case reports have discussed isolated
ophthalmoplegia as a presentation of MFS,
anisocoria and rapid fluctuation of pupillary diameter have not been reported in anti-GQ1b antibody positive individuals. Here we describe an individual who presented with
diplopia and was found to have progressive internal and
external ophthalmoplegia with frequent fluctuations in pupillary diameter and
anisocoria. These exam findings are not commonly described even in atypical presentations of MFS. The onset of symptoms was preceded by an upper respiratory
infection but no gastrointestinal symptoms. Imaging and CSF studies were unremarkable; however serum levels of
immunoglobulin G anti-GQ1b antibody and anti-GAD antibody were elevated confirming the diagnosis of MFS. The patient was treated with
IVIG and intravenous
steroids with mild resolution of
external ophthalmoplegia. He did not go on to develop more typical features of MFS such as
ataxia or areflexia. This demonstrates that isolated external and internal
ophthalmoparesis with rapidly fluctuating pupillary diameter and associated
anisocoria can be the sole manifestation of atypical MFS.