Ophthalmoplegia associated with anti-GQ1b antibodies: case report and review.

A 60-year-old man with longstanding bilateral asymmetrical ptosis presented with a partial third nerve palsy. His diplopia improved following an ice pack test. He did not report any symptoms related to the coronavirus disease 2019 (COVID-19), and nasopharyngeal swab was negative. Initial head imaging and blood work-up were normal except for a high titer of anti-GQ1b antibodies. The patient was subsequently diagnosed with acute ophthalmoparesis without ataxia which is part of the anti-GQ1b antibody syndrome spectrum. He made a spontaneous recovery over the following months without the need for immunotherapy. Clinical features, pathophysiology and a review of the literature are discussed herein. It is important to consider anti-GQ1b antibody syndrome in patients with symptoms of diplopia, ptosis or suspected ocular myasthenia.