Unilateral Abducens Nerve Palsy as an Early Feature of Multiple Mononeuropathy Associated with Anti-GQ1b Antibody

Patients with anti-GQ1b antibody syndrome show various combinations of ophthalmoplegia, ataxia, areflexia, or altered sensorium as clinical features. We describe herein a unique case with unilateral abducens nerve palsy as an early feature of multiple mononeuropathy involving dysfunctions of the inferior dental plexus and the ulnar nerve, which was thought to be associated with anti-GQ1b antibody. A 27-year-old man presented with acute-onset diplopia. He subsequently experienced numbness not only in the right lower teeth and gums but also on the ulnar side of the left hand. Neurological examinations revealed dysfunctions of the right abducens nerve, the right inferior dental plexus, and the left ulnar nerve, suggesting multiple mononeuropathy. Serum anti-GQ1b antibody was positive. This is a rare case report of a patient with unilateral abducens nerve palsy as an early feature of multiple mononeuropathy associated with anti-GQ1b antibody. We suggest that anti-GQ1b antibody syndrome should be taken into consideration as a differential diagnosis of acute multiple mononeuropathy if ophthalmoplegia is present unilaterally.