Unusual Presentation of Double-seronegative Myasthenia Gravis with Positive Anti-LRP4 Antibody: Diagnostic Utility of a Videofluoroscopic Swallowing Study.

An 86-year-old woman was admitted to our hospital with cryptogenic progressive dyspnea and dysphagia following a tracheostomy procedure 4 months prior to presentation. She exhibited fluctuating diplopia, bilateral vocal fold paralysis, normal nerve test results, negative findings for serum anti-acetylcholine receptor and anti-muscle-specific kinase antibodies, and positive findings for anti-LDL-receptor related protein 4 (LRP4). A videofluoroscopic swallowing study (VFSS) with edrophonium revealed an improvement in bulbar paralysis.