Beyond anti-GQ1b: unravelling atypical Miller Fisher syndrome

Abstract

Anti-GQ1b negative Miller Fisher syndrome (MFS) is an uncommon variant of the classic MFS, a condition that is typically characterized by a triad of ataxia, ophthalmoplegia and areflexia, often accompanied by the presence of anti-GQ1b antibodies. In patients with anti-GQ1b negative MFS, these characteristic clinical features are observed despite the absence of the hallmark antibodies, posing a diagnostic challenge. The pathophysiology underlying this variant remains poorly understood, though alternative immune mechanisms, such as the involvement of other ganglioside antibodies or T-cell mediated autoimmunity, are suspected. The absence of anti-GQ1b antibodies necessitates reliance on clinical presentation, neurophysiological evaluations, and the exclusion of other potential causes for diagnosis. Treatment strategies remain similar to those for the antibody-positive form, typically involving immunotherapies such as intravenous immunoglobulin (IVIG) or plasmapheresis. Recognizing anti-GQ1b negative MFS is essential for timely and effective management, as early intervention can improve patient outcomes despite the absence of the usual antibody marker. Further research is needed to elucidate the underlying immune mechanisms and refine diagnostic and therapeutic approaches for this rare variant of MFS.Here we are presenting case report of a 53 year old female presented with diplopia, unilateral ptosis, tingling sensation in all limbs and ataxia. The patient exhibited the classic triad of ataxia, areflexia and opthalmoplegia characteristic of MFS but negative anti-GQ1b antibody titre and the patient was successfully treated with IVIG.