Anti-GQ1b antibody syndrome presenting with visual deterioration as the initial symptom: A case report

RATIONALE: Anti-GQ1b antibody syndrome refers to a distinct variant of Guillain– Barré syndrome. Involvement of the optic nerve in anti-GQ1b antibody syndrome is extremely rare. PATIENT CONCERNS: Here, we report a case of anti-GQ1b antibody syndrome presenting with visual deterioration as the initial symptom. A 73-year-old man presented with a 5-day history of bilateral blurred vision and ptosis. He had a previous history of diarrhea starting 10 days before admission. Physical examination showed visual deterioration, ophthalmoplegia, and peripheral facial paralysis. Testing of both serum and cerebrospinal fluid was positive for anti-GQ1b immunoglobulin G antibodies and negative for anti-aquaporin 4antibodies. DIAGNOSIS: Anti-GQ1b antibody syndrome. INTERVENTIONS: The patient was treated with intravenous methylprednisolone and human immunoglobulin. OUTCOMES: After a 20-day follow-up, the patient's condition took a favorable turn. LESSONS: This case reminds us that anti-GQ1b antibody syndrome should be suspected in patients with visual deterioration and preceding infection.