A Rare Case of Miller Fisher Syndrome Following Legionella Pneumonia: Expanding the Spectrum of Post-infectious Neurological Complications

Miller Fisher syndrome (MFS) is a rare variant of Guillain-Barré syndrome (GBS), typically presenting with ophthalmoplegia, ataxia, and areflexia, most often after viral or bacterial infections. Legionella pneumophila has been reported as a trigger for GBS, but its association with MFS has not been clearly described. We present a 70-year-old man with a history of ankylosing spondylitis who was hospitalized for Legionella pneumonia and subsequently developed progressive weakness, paresthesias, dysarthria, ptosis, facial droop, and ophthalmoplegia over 10 days. Spinal imaging showed chronic cervical cord compression, but lumbar puncture revealed albuminocytologic dissociation consistent with GBS. Nerve conduction studies and electromyography were not performed; diagnosis was made on the basis of clinical features and CSF findings. Following initiation of intravenous immunoglobulin, his symptoms began improving within one week: dysarthria, ptosis, and ophthalmoplegia resolved, paresthesias disappeared, and limb strength improved on neurological examination. He was transferred to an inpatient rehabilitation facility, where mobility and strength further improved, allowing him to ambulate with a walker. By day 56, he returned to his neurological baseline with normal cranial nerve function, reflexes, and gait assisted by his walker. This case underscores a potential novel association between Legionella and MFS and expands the spectrum of post-infectious etiologies of demyelinating neuropathies.