Autonomic Dysfunction in Miller Fisher Syndrome: Paralytic Ileus and Isolated Internal Ophthalmoplegia.

We describe a rare case of Miller Fisher syndrome (MFS) in a 37-year-old woman characterized by paralytic ileus and isolated internal ophthalmoplegia without any external ophthalmoplegia. The patient initially presented with severe abdominal pain and photophobia. A physical examination revealed mydriasis, impaired pupillary light reflexes, ataxia, and areflexia; however, her extraocular movements were preserved. The serum test results were positive for anti-GQ1b IgG antibodies. Treatment with intravenous immunoglobulin led to a near-complete resolution of the symptoms. This case demonstrates that MFS can manifest as significant gastrointestinal autonomic dysfunction and isolated internal ophthalmoplegia, which may not fit the classic triad presentation. Clinicians should include MFS in the differential diagnosis of patients with unexplained autonomic symptoms even in the absence of external ophthalmoplegia, and a thorough pupillary examination is crucial.