Miller Fisher Syndrome
A 12-year-old boy presented with complaints of sudden-onset diplopia noted in the morning starting 3 days ago. One month ago, he had an episode of dizziness, chest tightness, and a common cold which resolved spontaneously. He denied any past medical history of head injury or epistaxis. Visual acuity was 6/6 in both eyes. A Hirschberg test showed a 5° esotropia on primary gaze. A prism cover test revealed 25 prism diopters of esotropia on primary gaze, which decreased to 18 on right gaze and increased to 40 on left gaze. Extraocular movements showed mild limitation of abduction in right gaze (−1 OD) and moderate limitation in left gaze (−2 OS) (Fig. 36.1). Anterior segments, pupillary reflexes, and fundoscopic examinations were normal. He received a brain CT scan which was also normal. One week later, he developed bilateral ptosis and total ophthalmoplegia (Fig. 36.2). A neostigmine test by intramuscular injection was performed in-office. However, no improvement in lid position or extraocular movement was observed. Thus, he was admitted for further investigation.