Case Report: Bilateral Cranial Nerve VI Palsy in Miller Fisher Syndrome.

SIGNIFICANCE: Miller Fisher syndrome, a variant of Guillain-Barré syndrome, is a condition characterized by ophthalmoplegia, ataxia, and areflexia. Diplopia, particularly secondary to a bilateral abduction deficit, is the most common presenting symptom. The telltale neurologic symptoms associated with this condition can easily be overlooked by eye care providers, delaying timely diagnosis and treatment. PURPOSE: This study aimed to report a case of diplopia secondary to an uncommon condition (Miller Fisher syndrome) and to highlight the eye care provider's role in helping with diagnosis and management of this condition. CASE REPORT: A 31-year-old woman presented to the emergency eye care service because of a 2-day history of sudden-onset diplopia, for which no cause was found 1 day prior at a local hospital emergency department. She also reported weakness in her legs, difficulty walking, balance problems, and reduced sensation of her left hand for the past 2 days. Clinical testing revealed bilateral abduction deficits, ataxia, and areflexia, the combination of which suggested Miller Fisher syndrome. Because of the acute onset and progressive severity of her neurologic symptoms, she was referred to a different hospital emergency department for confirmatory diagnosis and treatment of Miller Fisher syndrome. CONCLUSIONS: Diplopia is a symptom commonly encountered by eye care providers, regardless of their mode of practice. Although there are many potential etiologies of diplopia, performing a comprehensive eye examination combined with a neurologic evaluation can potentially pinpoint the specific cause. Miller Fisher syndrome is one such condition in which the diagnostic triad can be uncovered with in-office ocular motility testing and neurologic examination. Eye care providers need to be aware of the clinical features of Miller Fisher syndrome to aid in prompt diagnosis and treatment for patients with this acute condition.