Ataxia and ophthalmoplegia: an atypical case of Miller Fisher syndrome (MFS) with anti-GAD antibody

Background: Miller Fisher syndrome (MFS) is frequently encountered variant of Gillian Barre Syndrome (GBS). It has distinct clinical and serological features. Here we describe an atypical GQ1b seronegative case with significantly elevated anti-glutamic acid decarboxylase antibody (GAD-Ab). Case description: A 24-year-old previously healthy Caucasian male presented with rapidly progressive ascending weakness, binocular diplopia and autonomic instability for 2 days. Examination was remarkable for asymmetrical facial weakness (L > R), opthalmoplegia and truncal ataxia without areflexia. MRI brain was normal. CSF analysis showed elevated protein. Electromyography/Nerve Conduction Study (EMG/NCS) within the first week was normal. Antiganglioside antibodies were negative. Extended serological and neoplastic workup revealed negative anti-GQ1b antibody, but significant increase of GAD-Ab, Voltage Gated Calcium Channel (VGCC) Ab, and mild elevation of TPO Ab IgG and Thyroglobulin (Tg) Ab IgG. Clinical diagnosis of partial MFS was made. He received a course of IVIg (2 g/kg over 5 days) and had complete recovery in 3 months. Conclusion: There are incomplete or atypical forms of MFS. Recognition of its various clinical presentations is essential for early diagnosis and optimal management. Further investigation is needed to elucidate the role of anti-GAD-ab and other autoimmune antibodies in the pathogenesis of GQ1b-seronegative MFS patients.