Miller Fisher Syndrome Presenting With Bilaterally Impaired Adduction In Horizontal Gaze And Dissociated Nystagmus Of The Abducting Eyes

The patient is a 58-year-old woman presenting a 5-day history of diplopia that started 2 weeks after an upper respiratory tract infection. Neurological examination revealed bilaterally impaired adduction in horizontal gaze with dissociated nystagmus of the abducting eyes, which resembled dissociated nystagmus observed in internuclear ophthalmoplegia (INO). She also exhibited slightly impaired abduction and impaired supraduction in both eyes, right-sided ptosis, and slight truncal ataxia. There were no abnormal findings on contrast-enhanced MRI of the brain. The diagnosis of Miller Fisher syndrome was confirmed by positive serum anti-GQ1b and GT1a antibodies. The patient fully recovered without specific treatment. Impaired adduction in horizontal gaze with dissociated nystagmus of the abducting eye is generally presumed to be indicative of INO, a lesion in the medial longitudinal fasciculus. We presumed that an imbalance between severely restricted adduction and preserved abduction of the opposite eye led to the unique ocular motility disturbances observed in our patient.