MRI Findings Suggestive of Trigeminal and Vestibulocochlear Nerve Involvement in Miller Fisher Syndrome

Miller Fisher syndrome (MFS) is a variant of Guillain–Barré syndrome characterized by a triad of ophthalmoplegia, ataxia, and areflexia, typically associated with anti-GQ1b antibodies. While cranial nerve enhancement is sometimes seen on high-resolution MRI, involvement of the trigeminal (CN V) and vestibulocochlear (CN VIII) nerves is rare. We report a 62-year-old woman presenting with diplopia, preceded by ophthalmalgia, nasal congestion, and vertigo. Neurological assessment revealed right-sided ptosis, total ophthalmoplegia, sluggish pupillary reflexes, diplopia without nystagmus, bilateral limb ataxia, hyporeflexia, and impaired vibration and joint-position sensation. Serology was positive for anti-GQ1b antibodies. Contrast-enhanced MRI demonstrated signal changes suggestive of CN V and CN VIII involvement. Although cerebrospinal fluid showed no albuminocytologic dissociation, she was diagnosed with MFS. She received immunotherapy, including intravenous immunoglobulin therapy. While her vertigo, ophthalmalgia and ataxia significantly improved, ophthalmoplegia persisted. The patient was discharged on hospitalization day 44 with residual ocular motility deficits. In this patient, orbital pain with cranial autonomic features (ocular pain, nasal congestion) and vertigo of uncertain localization acted as misleading early signs. This case illustrates an unusual MFS presentation where prodromal CN V and VIII symptoms preceded classic features, highlighting the need for careful clinical evaluation when sensory and vestibular symptoms precede classic features.