An Overlapping Case of Miller Fisher Syndrome, Bickerstaff's Encephalitis, and the ASMAN Variant of Guillain-Barre Syndrome.

A 56-year-old man presented with a 3-day history of progressive tingling of the hands, unsteadiness, and diplopia. He was initially diagnosed clinically with Miller Fisher Syndrome (MFS) but later developed limb weakness consistent with Guillain-Barre Syndrome (GBS) and subsequently reduced consciousness consistent with Bickerstaff's brainstem encephalitis (BBE). Neurophysiology revealed an axonal motor and sensory neuropathy, in keeping with the Acute Motor and Sensory Axonal Neuropathy (AMSAN) variant of GBS. We believe that our patient had an MFS-AMSAN-BBE overlap syndrome. This is supported by his glycolipid antibody profile with high titres of anti-GQ1b IgG antibody and anti-GD1a IgG antibody. Anti-GQ1b antibodies are frequently found in both MFS and BBE and the anti-GD1a antibody is associated with axonal forms of GBS. Overlapping cases of MFS and BBE are well described, and because the same antibody is often found in both conditions, it is thought that they share a common autoimmune mechanism. BBE has also been previously reported in association with GBS lending support that it also lies on the same spectrum. This overlapping case of ASMAN variant of GBS, MFS, and BBE provides further support that these conditions are part of the same spectrum.