Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disease that affects your ability to move. Your immune system attacks muscle tissue which leads to difficulty walking and other muscular problems.
The disease can’t be cured, but symptoms can temporarily lessen if you exert yourself. You can manage the condition with medication.
The primary symptoms of LEMS are leg weakness and difficulty walking. As the disease progresses, you’ll also experience:
- weakness in facial muscles
- involuntary muscular symptoms
- dry mouth
- bladder problems
Leg weakness often improves temporarily upon exertion. As you exercise, acetylcholine builds up in large enough amounts to allow strength to improve for a short time.
There are several complications associated with LEMS. These include:
- trouble breathing and swallowing
- injuries due to falling or problems with coordination
In an autoimmune disease, your body’s immune system mistakes your own body for a foreign object. Your immune system produces antibodies that attack your body.
In LEMS, your body attacks nerve endings that control the amount of acetylcholine your body releases. Acetylcholine is a neurotransmitter that triggers muscle contractions. Muscle contractions allow you to make voluntary movements such as walking, wiggling your fingers, and shrugging your shoulders.
Specifically, your body attacks a protein called voltage gated calcium channel (VGCC). VGCC is required for the release of acetylcholine. You don’t produce enough acetylcholine when VGCC is attacked, so your muscles are unable to work properly.
Many cases of LEMS are associated with lung cancer. Researchers believe that the cancer cells produce the VGCC protein. This causes your immune system to make antibodies against VGCC. These antibodies then attack both the cancer cells and the muscle cells. Anyone can develop LEMS in their lifetime, but lung cancer may increase your risk of developing the condition. If there is a history of autoimmune diseases in your family, you may be at higher risk of developing LEMS.
To diagnose LEMS, your doctor will take a detailed history and perform a physical examination. Your doctor will look for:
- decreased reflexes
- muscle tissue loss
- weakness or trouble moving that gets better with activity
Your doctor may order several tests to confirm the condition. A blood test will look for antibodies against VGCC (anti-VGCC antibodies). An electromyography (EMG) tests your muscle fibers by seeing how they react when stimulated. A small needle is inserted into the muscle and connected to a meter. You’ll be asked to contract that muscle, and the meter will read how well your muscles respond.
Another possible test is the nerve conduction velocity test (NCV). For this test, your doctor will place electrodes on the surface of your skin covering a major muscle. The patches give off an electrical signal that stimulates the nerves and muscle. The activity that results from the nerves is recorded by other electrodes and is used to find out how quickly the nerves react to stimulation.
This condition cannot be cured. You’ll work with your doctor to manage any other conditions, such as lung cancer.
Your doctor may recommend intravenous immunoglobulin (IVIG) treatment. For this treatment, your doctor will inject a nonspecific antibody that calms the immune system. Another possible treatment is plasmapheresis. Blood is removed from the body, and the plasma is separated out. The antibodies are removed, and the plasma is returned to the body.
Drugs that work with your muscular system can sometimes relieve symptoms. These include mestinon (pyridostigmine) and 3, 4 diaminopyridine (3, 4-DAP).
These medications are hard to obtain, and you should talk to your doctor to find out more information.
Symptoms may improve by treating other underlying conditions, suppressing the immune system, or removing the antibodies from the blood. Not everyone responds well to treatment. Work with your doctor to come up with an appropriate treatment plan.