Lamber-Eaton myasthenic syndrome associated with multiple myeloma: A case report

Lambert-Eaton myasthenic syndrome (LEMS) is an uncommon illness of the neuromuscular junction. It typically manifests as a combination of proximal muscular weakness, autonomic dysfunction, and areflexia. It is typically associated with small cell lung cancer. However, this paraneoplastic syndrome has been discovered in other clinical entities, such as multiple myeloma, which is a rare and infrequent occurrence. We report the case of 54-year-old female with history of tobacco usage, who presented with generalized weakness. The patient underwent multiple tests, including blood work up, electromyography, and imaging. The laboratory results yielded high protein levels and anemia, which prompted clinicians to pursue SPEP work up that yielded an elevated M spike, establishing MGUS diagnosis. Neurology evaluation was done in the setting of worsening symptoms. Antibody testing was positive for voltage-gated calcium channels, establishing diagnosis for Lambert-Eaton Myasthenic Syndrome. She underwent prednisone, pyridostigmine and amifampridine treatment noticing symptom improvement. Months later lab work showed unchanged M spike, and bone marrow biopsy showed 10% IgA plasma cells, establishing Multiple Myeloma. She was started on daratumumab, decadron, lenalidomide and later on stem cell transplantation with success. Coexistence of LEMS with multiple myeloma is a clinical entity with few published occurrences, providing diagnostic and therapy challenges due to the limited knowledge known about the potential link between the two.