Identifying the Signs of Lambert-Eaton Syndrome


Lambert-Eaton syndrome is an autoimmune disease when your body’s immune system attacks the contact point between nerve cells and muscle fibers. This disrupts the communication needed to move muscles, causing weakness and other symptoms.

Muscle Weakness

Muscle weakness is a crucial symptom of Lambert-Eaton syndrome. It is essential to distinguish between muscle weakness and pain, which can accompany this condition. True weakness only occurs when one or more parts of the pathway that usually signals a muscle to contract—through the spinal cord, nerves, or muscles themselves—are damaged or diseased. Injury to the spinal cord can affect the signals that travel from the brain, while poisoning or prolonged immobilization can cause nerve damage and interfere with regular muscle contractions. In Lambert-Eaton Syndrome, the immune system produces antibodies that attack where nerve fibers meet muscle fibers (the neuromuscular junction). The antibodies bind to and block calcium channels at the end of the nerve cells, which disrupts normal signaling between the brain and the muscles. This leads to muscle weakness and tingling sensations like pins and needles, problems with automatic body function such as breathing and swallowing, and sometimes trouble seeing or hearing (dysarthria or dysphonia). Symptoms typically develop slowly over weeks or months but may appear more quickly in cases associated with cancer.

Tingling or Numbness in the Hands or Feet

Lambert-Eaton syndrome happens when your immune system makes antibodies that attack the nerve endings where signals from your brain reach your muscles to contract. These are called neuromuscular junctions. They are usually the first place that people with this condition notice weakness and other symptoms. The antibodies that cause LEMS target a protein called voltage-gated calcium channel, or VGCC, in the muscle cells. Usually, these channels let calcium into nerve cells to send messages to make muscle fibers contract and strengthen. When you have Lambert-Eaton syndrome, the VGCCs in your nerve cells don’t work correctly, so the signals from your brain aren’t getting through. Almost all cases of Lambert-Eaton syndrome appear in association with cancer called small cell lung cancer (SCLC). In many of those, myasthenic syndrome results from your body’s effort to fight the underlying cancer. If you have LEMS, your healthcare provider may order an imaging test like a CT scan or magnetic resonance image (MRI) of your chest to check for lung cancer. Your healthcare provider might also ask you to schedule cancer screenings every three to six months for two years.

Trouble Walking

The first sign of LEMS is difficulty getting up from a chair or walking upstairs. Other signs of the condition include slurred speech, trouble swallowing, and weakness in your arms and legs. If you’re experiencing these symptoms, you should see a doctor immediately. Often, a neurologist will perform a series of tests to diagnose the condition. For example, they may look for antibodies attacking the contact point where nerve cells meet your blood’s muscle fibers (neuromuscular junction). They might also do repetitive nerve stimulation to look for a decrease in the size of the muscle action potential after exercise. Other tests might be used to determine if the disease is autoimmune or paraneoplastic. In autoimmune cases, the disease develops slowly over weeks or months and can begin at any age. Paraneoplastic cases develop in middle age or older and most frequently in people with small-cell lung cancer.


Your doctor will ask you questions about your symptoms and do a physical exam. Your doctor may also order blood tests for antibodies attacking your neuromuscular junctions. They may send electrical currents through your muscles to see how they respond. A fever is a sign that your body is fighting an infection. If your fever keeps returning, it’s important to tell your doctor. Your provider may be able to help you get relief from your symptoms by treating the cancer that is causing them.

Lambert-Eaton syndrome is a condition that develops when your immune system makes antibodies that attack where nerve cells meet muscle fibers (neuromuscular junction). These antibodies bind to and block calcium channels at the end of presynaptic nerve cells, preventing them from sending signals that cause muscles to contract. The condition most often occurs in people with small-cell lung cancer, but it can also happen in people without cancer. Your doctor will check for cancer in your lungs and other body parts. They will also treat any cancer you have if it is found, which may improve your symptoms from Lambert-Eaton syndrome. Your provider will probably prescribe medicines to suppress your immune system and to help improve the signals between your nerve and muscle cells.

Dry Mouth

Are you always thirsty and waking up often at night desperate for water to wash over your sticky, arid tongue and throat? Does your mouth taste dry and gritty despite brushing, flossing, and using mouthwash as you should? These are signs that you may be experiencing persistent dry mouth or xerostomia. A doctor can diagnose dry mouth by conducting a physical exam and asking you to record your symptoms, such as how long they last. They will also take your medical and prescription drug history. The major salivary glands will be palpated for sensitivity, and the amount of saliva they produce will be evaluated. While dry mouth isn’t usually a serious medical condition, it can indicate underlying issues such as LEMS or an adverse reaction to certain medications. Left untreated, it can lead to other complications, such as tooth decay and gum disease. It can also interfere with your ability to speak and eat.