Acute ophthalmoparesis without ataxia (AO) is an atypical form of Miller- Fisher syndrome (MFS) and is rare in children. Anti-GQ1b antibodies can be detected in patients with AO, as in MFS. A 5.5-year-old girl had total ophthalmoparesis, blurred vision, ptosis, diplopia and mydriasis non-reactive to light or near stimuli with preserved consciousness and deep tendon reflexes. She had no ataxia. Cerebrospinal fluid (CSF) examination and cranial MRI were normal. Serum antiGQ1b antibodies were positive. She was diagnosed with AO and intravenous Immunoglobulin (IVIG) was ordered, 400 mg/ kg/day, for 5 days. Ophthalmoparesis and blurred vision improved in a few weeks. At the end of the first year, mydriasis still persisted, but improved and became responsive to near stimuli. Pupillary involvement may be seen in approximately 50% of MFS patients, and improvement in a few weeks or months has been reported in adults. Our case shows the expanding clinical spectrum of anti-GQ1b positive cranial neuropathy as early-onset AO and prolonged mydriasis more than one year.

Keywords: Miller- Fisher syndrome, acute ophthalmoparesis, acute ophthalmoparesis without ataxia, anti-GQ1b; mydriasis