Eaton-Lambert Syndrome (ELS) is a rare autoimmune disorder that affects the connection between nerves and muscles, resulting in muscle weakness and difficulty moving. Although ELS is its formal name, this condition also goes by Lambert-Eaton Myasthenic Syndrome, Lambert-Eaton Syndrome, and Autoimmune Lambert-Eaton Syndrome. These terms are used interchangeably because they reflect the same disorder. ELS usually develops as a paraneoplastic syndrome that appears concurrently with cancer. This syndrome causes antibodies to attack the calcium channels in the nerve cells, leading to the production of fewer neurotransmitters. The resulting muscle weakness can affect a person's ability to stand, walk, or even hold objects. Treatment can involve immunotherapy, plasmapheresis, and medications, such as corticosteroids or immunosuppressants.