Lambert-Eaton syndrome (LES) is a rare disorder in which faulty communication between nerves and muscles leads to muscle weakness.
LES is an autoimmune disorder. This means your immune system mistakenly targets healthy cells and tissues in the body.
With LES, antibodies produced by the immune system attack at the connection between nerve and muscle (the neuromuscular junction) making nerves cells unable to release enough of acetylcholine and interferes with the ability of nerve cells to send signals to muscle cells. The result is muscle weakness.
LES may occur with cancers such as small cell lung cancer or autoimmune disorders such as vitiligo, which leads to a loss of skin pigment.