Lambert-Eaton syndrome happens when your immune system attacks the areas where nerves and muscles connect. It can occur with certain cancers, including small-cell lung cancer, and it’s also linked to other autoimmune diseases. Your healthcare provider may order blood tests for underlying cancer or other health conditions. Your doctor may also prescribe medicines to suppress your immune system or help improve the signals between nerves and muscles.
Symptoms
In Lambert-Eaton syndrome, your body’s immune system makes antibodies against the calcium channel at the nerve end of a muscle cell (the neuromuscular junction). The antibodies interrupt the regular presynaptic influx of calcium that generally occurs to initiate acetylcholine release at the neuromuscular junction. This disrupts the passage of nerve impulses from the brain to muscles and causes weakness and fatigue. This disorder can occur with or without cancer. Also, understanding Lambert-Eaton syndrome is essential for early detection. LEMS is considered paraneoplastic because it happens in people with small-cell lung cancer, especially when they have a tumor at the base of the lungs. Symptoms of LEMS include proximal muscle weakness, depressed tendon reflexes, and autonomic changes. The weakness of this condition is not improved with movement and can be worsened by stress or fatigue. Many things can help you manage your symptoms, such as eating a balanced diet, getting adequate sleep, and exercising regularly.
Diagnosis
Diagnosis begins with a healthcare provider asking about your medical history and conducting a physical exam. A series of tests involving muscle strength, reflexes, balance, coordination, and sense of touch will be conducted to evaluate your neurological health. Blood tests can detect antibodies that attack neuromuscular junctions and other sites. Electrodiagnostic testing, such as repetitive nerve stimulation (which sends an electrical current through muscles), helps identify a weakness. These tests will also look for signs of cancer since LEMS is often associated with certain types of cancer. A type of lung cancer called small cell lung cancer (SCLC) is most often found in people with LEMS. However, LEMS has also been seen in people with prostate cancer, thymoma, and other lymphoproliferative malignancies. The miscommunication that occurs in a person with LEMS is due to the action of antibodies at the point where nerve cells meet muscle fibers (neuromuscular junction). These antibodies prevent the release of a chemical called acetylcholine, which transmits impulses from nerves to muscle tissue. More than 85% of people with LEMS have antibodies that target P-type voltage-gated calcium channels at the neuromuscular junction. Another antibody targets a presynaptic protein called synaptotagmin, which releases acetylcholine. The presence of these antibodies can lead to a diagnosis of paraneoplastic Lambert-Eaton myasthenic syndrome.
Treatment
Lambert-Eaton syndrome occurs when your immune system attacks the area where nerves connect to muscles called the neuromuscular junction. This causes your muscles not to receive the signaling they need to get stronger, causing weakness. Lambert-Eaton syndrome is most often seen in people with certain cancers, such as small cell lung cancer (SCLC), but it can also occur in people without cancer. Your healthcare provider will ask you about your symptoms and do a physical exam. They may order X-rays or a CT scan of your lungs. They may also do an electromyography test to determine how well your muscles work. Your provider may check for other conditions with similar symptoms, such as myasthenia gravis. If your healthcare provider determines you have Lambert-Eaton syndrome, they will check for cancer. If there is an underlying cancer, they will treat it, which may help improve your condition. If not, they will monitor you for signs and symptoms of cancer or other autoimmune disorders. They may also prescribe medicines to suppress your immune system or help improve nerve and muscle cell signals. Some studies show that if you have LEMS with cancer, your prognosis is better than if you have this condition and don’t have cancer. Other studies show that patients with this condition without cancer have a lower survival rate than those who do not have this combination.
Prevention
A lot of the time, Lambert-Eaton syndrome can be cured by treating the cancer-causing it. This is called paraneoplastic LEMS. The cancer is usually small-cell lung cancer but can also be prostate, thymoma, or lymphoma. The underlying cancer can be treated with surgery, radiation, or chemotherapy. Having regular check-ups and talking to your healthcare provider about any changes or new symptoms can help prevent cancer from developing in the first place. In about 90% of cases of LEMS, it’s caused by autoantibodies against the calcium channel at nerve endings at the neuromuscular junction. These antibodies disrupt the passage of excitation from nerve fibers to muscle, which causes weakness and fatigue. LEMS isn’t usually linked to a specific cause in the other 10% of cases. It can occur at any age and typically starts in the legs. Symptoms start slowly over weeks or months and worsen as the disease progresses. Over time, they affect the strength of your leg muscles, then your shoulder and arm muscles, the muscles in your hands and feet, and the muscles that control your speech and swallowing.
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