Case Report: Anti-GT1a antibody-associated ocular flutter.

Mounting evidence suggests that antiganglioside antibodies play a crucial role in the pathogenesis of Guillain-Barré syndrome (GBS) and its variants. Among them, anti-GT1a ganglioside immunoglobulin G (IgG) antibody (anti-GT1a IgG) is most strongly associated with cranial nerve involvement. We report a rare case of a 26-year-old woman who developed ocular flutter and mild ataxia following an upper respiratory tract infection. Neurological examination revealed rapid, conjugate horizontal saccadic oscillations without intersaccadic intervals, along with a mildly ataxic gait. Brain magnetic resonance imaging (MRI) and cerebrospinal fluid analysis were unremarkable. Serological testing revealed isolated positivity for anti-GT1a IgG, with negative results for other antibodies typically associated with paraneoplastic or autoimmune diseases, such as anti-GQ1b, anti-GM1, and anti-GM2 antibodies. The patient responded well to intravenous immunoglobulin (IVIG), with marked improvement in both ocular flutter and gait disturbance. Although this presentation does not fulfill the diagnostic criteria for classic GBS, it likely represents a restricted variant within the anti-GT1a antibody spectrum. This case highlights the importance of recognizing atypical manifestations of ganglioside-associated neuropathies and supports early immunotherapy as a key factor in favorable outcomes.