An autoimmune disorder that negatively affects the nerves that control muscles is called Lambert-Eaton myasthenic syndrome (LEMS). One of the most common symptoms of LEMS is muscle weakness. Moreover, most people with LEMS also have small-cell lung cancer. Doctors often prescribe cancer treatments (including chemotherapy, radiation therapy, and surgery) and other medicines to treat this autoimmune disorder.
In other words, LEMS happens when the immune system mistakenly attacks motor nerves and muscles. It causes damage to the neuromuscular junction, which affects the signals that travel between the nerves and muscles. Most of the time, muscle weakness appears in the upper legs, but it may also affect other groups of muscles in the arms and those that are involved in swallowing, breathing, and speech.
Generally, LEMS is a rare disorder that affects about 2.8 million people worldwide. In the United States, approximately 400 people have LEMS.
Is Small-Cell Lung Cancer The Only Cancer That Occurs in People with LEMS?
While this type of lung cancer is the most common malignancy linked with LEMS, people with this autoimmune disorder may also develop other types of cancer. For example, prostate cancer, thymoma, lymphoproliferative disorders, and others.
What Are The Symptoms of LEMS?
Commonly, people who develop this health condition experience the following symptoms. Examples include:
- Walking problems
- Ptosis (drooping eyelids)
- Constipation
- Muscle weakness and fatigue
- Reduced sweating
- Diplopia (also known as double vision)
- A tingling sensation in the feet or hands
- Muscle stiffness or pain
- Weight loss
- Difficulty urinating
- Erectile dysfunction (ED)
- Dysarthria (speaking problems)
- Dysphagia (difficulty swallowing)
- Shortness of breath (dyspnea) and respiratory failure
If you or your child has any of the symptoms listed above, immediately contact your healthcare professional. Otherwise, it may lead to serious complications.
Causes
This condition is an autoimmune disorder in which the immune system produces antibodies that mistakenly attack healthy tissue in the body. In people with LEMS, it attacks nerve cells that send signals between muscles and the brain (this process is called the neuromuscular junction). Usually, it happens in the following ways. For example:
- Antibodies produced by the immune system bind to block calcium channels that are located at the end of the nerve cells.
- Thus, there are fewer calcium channels, which often means less of the neurotransmitter acetylcholine is released.
- When acetylcholine is released in reduced amounts, the signals between the brain do not reach the muscle fibers. As a result, they cannot be fully activated, causing symptoms such as weakness.
Most of the time, LEMS appears in people who already have small-cell lung cancer. Therefore, the body’s defense begins to produce antibodies to destroy cancerous cells. However, in people with LEMS, antibodies attack the calcium channels at the end of the nerve cells instead of the calcium channels on cancer cells. As a result, the muscles do not receive the signals from the brain and work properly. Nowadays, healthcare providers do not fully understand why this condition happens.
What Are The Possible Complications of LEMS?
It is not rare for people with LEMS to experience the following complications. Examples include:
- Muscle weakness and related problems – For example, walking problems, lifting issues, and falls.
- Autonomic dysfunction – This complication occurs in about 80% to 95% of people who develop LEMS. It often causes the following symptoms. Examples include dry eyes, chronic dry mouth, constipation, erectile dysfunction, and others.
- Respiratory failure – Usually, people experience this complication in rare cases, but when it happens, they may experience emergency breathing problems.
- Severe fatigue
This document does not contain a full list of complications, but your physician may recommend some ways that will help reduce the risk or even prevent them.
How to Prevent LEMS?
Unfortunately, there is no way to prevent this autoimmune disorder because doctors do not fully understand what causes it. Because this condition mostly occurs in people with lung cancer, physicians may recommend some tips to reduce the risk of developing small-cell lung cancer. Check some examples below:
- Stop smoking – If you have problems with smoking cessation, discuss it with your physician. You should also avoid secondhand smoke.
- Avoid exposure to radon because it also significantly increases the risk of lung cancer.
- Get adequate sleep (about 8 hours per day)
- Manage stress
- Avoid hot showers or baths
- Regularly visit your doctor
- Physical exercise – It is recommended to aim for 30 minutes of physical exercise per day, at least 5 days a week.
- Add more fresh fruits and vegetables to your diet – You can also follow the Mediterranean or DASH diet.
Diagnosis
Doctors often start the diagnosis of LEMS with a physical examination in which they will check for irregularities linked to the disease. They may also perform a neurological examination and ask some questions about the symptoms and medical history. Therefore, they may also perform the following tests to get more information about your disease. Examples include:
- Blood tests – These tests are used to check for anti-calcium channel antibodies that are often present in about 85% of people with LEMS.
- Electromyography – This test is used to see how well the muscles and nerves are working together. Commonly, LEMS makes very specific findings on electromyography, which may help confirm the diagnosis.
- Imaging tests – These tests are often done in people with LEMS to check for lung cancer. They often perform lung X-rays, CT (computerized tomography) scans, or MRI (magnetic resonance imaging) of the chest.
In most cases, LEMS appears between 6 months and 5 years after lung cancer.
Treatment
Usually, doctors prescribe different treatments for people with LEMS. They often depend on the severity of the lung cancer and LEMS, existing health problems, age, gender, and preferences. Check below some treatment options that are usually prescribed for people with this condition:
- Chemotherapy, radiation therapy, and surgery – These treatments are often used to treat small-cell lung cancer.
- Amifampridine and Guanidine – These medicines help improve muscle strength and increase the release of the neurotransmitter acetylcholine at the neuromuscular junction.
- Pyridostigmine – Doctors usually prescribe this medicine for people with LEMS to prevent the breakdown of acetylcholine at the neuromuscular junction. As a result, it improves the signaling and muscle strength. Sometimes, doctors recommend this medicine along with Amifampridine to ease the symptoms. Furthermore, Pyridostigmine is an off-label medicine, which means it is not approved by the FDA (Food and Drug Administration) for this autoimmune condition.
- Immunosuppressants – This group of medications is used to suppress the immune system that mistakenly attacks healthy tissue in the body. It often helps relieve the symptoms. Doctors usually recommend Prednisone, Azathioprine, or Cyclosporine.
- Plasma exchange – During this procedure, a specific machine separates the blood cells from the liquid part of the blood. In the blood plasma, antibodies are localized that attack healthy cells. After changing the plasma, the blood is returned to the body.
- Immunoglobulins – Some people may notice improvements with high-dose immunoglobulin therapy.
Frequently Asked Questions
Is there a cure for Lambert-Eaton myasthenic syndrome?
Unfortunately, it is not possible to cure this condition. That’s why the treatment goal is to ease the symptoms, prevent serious complications, and improve your quality of life.
Who gets Lambert-Eaton myasthenic syndrome?
About 60% of diagnosed cases occur in people with an underlying malignancy. One of the most common types of cancer is small-cell lung cancer, but it may also happen in people with other types of cancer. The remaining 40% of LEMS cases do not have an underlying cancer.
What is the difference between Lambert-Eaton myasthenic syndrome and myasthenia gravis?
While these disorders share some symptoms (such as muscle weakness and fatigue), they are different disorders. Commonly, myasthenia gravis (MG) affects the muscles around the eyes and those used for swallowing. However, if the condition progresses, it may also affect breathing muscles and muscles of the arms and legs.
Can Lambert-Eaton myasthenic syndrome affect breathing?
Yes. Although uncommon, LEMS can weaken the muscles involved in breathing. In severe cases, this may lead to respiratory failure, which is a medical emergency that requires immediate treatment.
How is Lambert-Eaton myasthenic syndrome diagnosed if no cancer is found?
Doctors can diagnose LEMS through a combination of physical examination, neurological assessment, blood tests that detect antibodies, and electromyography (EMG). Even if no cancer is initially detected, they often continue screening for several years because cancer can develop after LEMS symptoms begin.
Does exercise help people with LEMS?
Moderate physical activity may help maintain muscle strength, flexibility, and overall health. However, strenuous exercise can worsen fatigue and muscle weakness in some people. It is important to discuss an appropriate exercise plan with your healthcare provider or physical therapist.
Is Lambert-Eaton myasthenic syndrome hereditary?
LEMS is generally not considered an inherited disorder. Most cases occur because the immune system mistakenly attacks the neuromuscular junction. While certain genetic factors may influence the risk of autoimmune diseases, LEMS itself is not usually passed directly from parents to children.
Can symptoms of LEMS fluctuate throughout the day?
Yes. Many people notice that their symptoms vary in severity. Muscle weakness may improve temporarily after repeated muscle use, which is a characteristic feature of LEMS. However, fatigue and weakness can worsen during illness, stress, or periods of physical exertion.
What is the life expectancy of someone with Lambert-Eaton myasthenic syndrome?
Life expectancy depends largely on whether the condition is associated with an underlying cancer and how well that cancer responds to treatment. People with non-cancer-related LEMS often have a near-normal life expectancy with appropriate medical care and symptom management.
Should people with LEMS have regular cancer screenings?
Yes. Because LEMS is strongly associated with small-cell lung cancer and other malignancies. That’s why healthcare providers often recommend periodic cancer screenings, especially during the first few years after diagnosis. Early detection of cancer can improve treatment outcomes and may also help reduce LEMS symptoms. Ask your healthcare provider if you have additional questions.
