Lambert-Eaton Syndrome (LES) is a rare autoimmune disorder that affects the neuromuscular junction. It is characterized by muscle weakness and fatigue, particularly in the limbs and torso. There are several synonyms for Lambert-Eaton Syndrome, including myasthenic syndrome, Eaton-Lambert syndrome, LEMS, and autoimmune Lambert-Eaton myasthenic syndrome. Doctors may also use terms like presynaptic neuromuscular junction disorder or voltage-gated calcium channel antibody-associated neuromuscular disorder to describe this condition. It is important to note that LES is a distinct condition from myasthenia gravis, another autoimmune disorder that affects the neuromuscular junction. While both conditions can cause muscle weakness, they have different underlying causes and treatment plans.