An overview of the Lambert-Eaton myasthenic syndrome

An autoimmune disease, Lambert-Eaton myasthenic syndrome (LEMS) causes the immune system to attack the body’s muscle tissues. It affects the neuromuscular junction (a connection between the muscles and nerves), impacting the nerve cells’ ability to deliver signals to the muscle cells. The immune system particularly strikes the calcium channels situated on nerve endings that are supposed to initiate chemical (acetylcholine) release in the body. Acetylcholine is a form of chemical messenger that prompts muscle contraction. Individuals suffering from LEMS have low levels of acetylcholine, which is inadequate for normal functioning of the muscles, thereby leading to muscle weakness.

This neuromuscular disorder is quite rare, and almost 60% of the cases are associated with Small Cell Lung Cancer (SCLC). Typically, the symptoms of LEMS are identified right before SCLC is diagnosed. The LEMS patients with cancer are often around 60 years old. Likewise, they have a long history of smoking. However, LEMS can affect a person at any age if it is not related to cancer.

Symptoms of Lambert-Eaton myasthenic syndrome (LEMS)
In the initial stages, LEMS will primarily cause weakness in the muscles of the upper legs and hips, making it increasingly difficult for one to walk. It will gradually also cause weakness in the shoulders and upper arms, tapering one’s ability to engage in daily physical activities. The weakness then further affects one’s speech, swallowing, and eye muscles. Some additional symptoms associated with this condition are constipation, a dry mouth, decreased sweating, and impotence.

Causes of Lambert-Eaton myasthenic syndrome (LEMS)
As mentioned before, in this condition, the immune system mistakenly damages the calcium channels that are responsible for generating muscle movement. Researchers believe that LEMS associated with SCLC is caused as the immune system attempts to fight off cancer by generating antibodies. These antibodies then harm the nerve endings. This occurs because the nerve endings share some common proteins with the cancer cells. However, in the remaining 40% of cases where cancer isn’t involved, the cause of LEMS still remains undetermined.

Treating Lambert-Eaton myasthenic syndrome (LEMS)
The treatment course for LEMS depends on the age, the severity of the symptoms, and the overall health condition of the patient. The doctors will primarily use the following treatment methods:

  • Cholinesterase inhibitors
    These medications help keep the acetylcholine in the neuromuscular junction and autonomic nervous system for a longer time. However, these medications have their own set of side effects, including abdominal cramps, excessive saliva, and diarrhea.
  • Immunosuppressants
    As the name suggests, these medications are used to suppress the immune system response or to help correct the signals between the muscle and nerve cells.
  • Plasmapheresis
    One might also have to undergo a treatment known as plasmapheresis. It involves removing the harmful immune system proteins by replacing the plasma in the blood.
    If the LEMS is associated with cancer, the patient will have to opt for an SCLC treatment that could help alleviate some of the LEMS symptoms.

Preventing Lambert-Eaton myasthenic syndrome (LEMS)
One of the best ways to reduce the risk of LEMS associated with small cell lung cancer is through abstinence from smoking. However, in cases where cancer isn’t involved, the exact cause isn’t fully understood, and researchers can’t specifically recommend any prevention methods.