A boy with multiple sclerosis and Miller-Fisher syndrome: a case report

Background: Miller-Fisher syndrome (MFS) is a rare condition that is well-described in the literature as a variant of Guillain-Barr´e syndrome (GBS). Guillain-Barre syndrome (GBS) and multiple sclerosis (MS) are autoimmune demyelinating disorders of the peripheral and central nervous systems, respectively. Anti-GQ1b IgG antibody is a biomarker for and MFS. The co-occurrence of these MFS and MS conditions is rare in the literature. Case Report: Our case report presents a complex case of a 15-year-old male with a history of T1DM and hypothyroidism, which came with ataxia, intentional tremor, suspected white matter disorder, and recent double vision and eyelid ptosis. Initially he was diagnosed with multiple sclerosis (MS), further investigation revealed MillerFisher syndrome (MFS) the rarest variant of Guillain-Barre syndrome (GBS) with anti-GQ1b antibody positivity. Conclusion: Despite rarity, the co-existence of GBS and MS must be kept in mind by neurologists. The wellestablished diagnostic criteria should be met to diagnose both diseases. To the best of our knowledge, this is the first reported patient with this unusual concurrence of MS with MFS.