Miller–Fisher syndrome complicated by Bickerstaff brainstem encephalitis

RATIONALE Bickerstaff brainstem encephalitis (BBE) and Miller-Fisher syndrome (MFS) might be a pedigree disease. Herein, we report a rare case that fits the diagnoses of both MFS and BBE. PATIENT CONCERNS A 48-year-old woman was hospitalized due to blurred vision and unsteady gait lasting for 9 days, and numbness of the limbs lasting for 6 days. Physical examination showed restricted eye movement without nystagmus, bilateral flattening of forehead and nasolabial folds, and positive eyelash sign. Her tongue deviated to the left when protruded. She had negative tendon reflex, bilateral Babinski signs, hypalgesia, and numbness in all limbs. She had positive Romberg sign and failed the right heel-knee-tibia tests. Her brain diffusion-weighted magnetic resonance imaging (DWI) showed an abnormally high circular signal in the brainstem surrounding the fourth ventricle. She also had cerebral spinal fluid (CSF) albuminocytological dissociation and GQ1b-IgG antibodies in both CSF and serum. DIAGNOSES The case fits the diagnoses of both MFS and BBE. INTERVENTIONS The patient was treated with dexamethasone. OUTCOMES The condition of the patient significantly improved after the administration of dexamethasone. Her symptoms had continued to improve by the 6-week and 2-month follow-ups. LESSONS These results suggest that BBE and MFS might be a pedigree disease and timely hormone therapy is expected to improve patients'outcomes.