Prioritizing unmet needs
Patient and loved one with Catalyst burst

Lambert-Eaton Myasthenic
Syndrome (LEMS)

LEMS is a rare autoimmune disease that affects about 1 in every 100,000 people worldwide. In LEMS, the body attacks nerve cells that control a chemical called acetylcholine (ACh). ACh is an important chemical because it helps send messages between nerve cells and muscle cells. In LEMS, the nerve cells lose the ability to release ACh, which can affect how muscles work. LEMS causes muscles to feel weak because it affects the neuromuscular junction—the place where nerve cells meet muscle cells.1-3

LEMS can occur at any age, but it is commonly diagnosed in people who are over 40 years of age. Approximately 50% of people with LEMS also develop cancer. The most common form is a type of lung cancer called small cell lung cancer (SCLC), which is also known as Cancer-Associated LEMS. Cancer-Associated LEMS typically occurs in people with a history of smoking and who are 50 years of age or older. Cancer is an important diagnostic criterion in people with LEMS, so cancer testing is recommended.

When considering treatment options, which are limited, patients with LEMS should consult with a board-certified neurologist who specializes in neuromuscular diseases.
Amifampridine is the only evidence-based, FDA-approved treatment for adult patients with Lambert-Eaton Myasthenic Syndrome (LEMS).

Icon of a stethoscope
Icon of a stethoscope

Symptoms

In LEMS, general muscle weakness, especially in the legs, is typically the first sign of the disease. People with LEMS may find it difficult to walk, get up from a chair, climb steps, or get out of a car.1,2

Other symptoms include:

  • Tingling sensations
  • Fatigue
  • Falling down
  • Slurred speech
  • Trouble with vision
  • Difficulty swallowing
  • Always feeling tired
  • Dry mouth, eyes, skin
  • Impotence
  • Constipation
  • Less often: weakness in the muscles of the eyes and neck
Icon of a magnifying glass
Icon of a magnifying glass

Diagnosis

Because LEMS is so rare and its symptoms are similar to many other diseases, it is frequently misdiagnosed.

LEMS is commonly mistaken for fibromyalgia, lupus, myasthenia gravis (MG), and multiple sclerosis. MG and other conditions, like Guillain-Barré syndrome, amyotrophic lateral sclerosis (ALS), or other neuromuscular diseases, may need to be ruled out before the correct diagnosis of LEMS is reached.

A diagnosis of LEMS is generally made based on clinical symptoms during a physical examination, the degree of muscle weakness, assessment of reflexes, and the function of the nervous system. People typically get electrodiagnostic tests in which the nerves are stimulated electrically, and the nerve impulses in the muscles are then measured. Blood tests to check the function of the immune system are also common.

Icon of a medical treatment bag
Icon of a medical treatment bag

Treatment

Currently, amifampridine is the only evidence-based, FDA-approved treatment for adult patients with Lambert-Eaton Myasthenic Syndrome (LEMS).

Treatments include:

  • Amifampridine, which improves muscle function by stimulating the release of more acetylcholine into the synaptic cleft and enhancing neuromuscular transmission
  • Steroids, which help suppress the immune system
  • Intravenous immunoglobulin, which helps “mop up” immune cells
  • Plasmapheresis, which filters blood through a machine that removes overactive immune cells and then infuses the cleansed blood back into the bloodstream
  • Drugs that help improve the electrical impulses between nerve cells and muscle cells

References:

  1. Titulaer MJ, Lang B, Verschuuren JJ. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. Lancet Neurol. 2011;10(12):1098-1107.
  2. Harms L, Sieb JP, Williams AE, et al. Long-term disease history, clinical symptoms, health status, and healthcare utilization in patients suffering from Lambert Eaton myasthenic syndrome: results of a patient interview survey in Germany. J Med Econ. 2012;15(3):521-530.
  3. Orpha.net. Lambert-Eaton myasthenic syndrome https://www.orpha.net/en/disease/detail/43393 Accessed December 13, 2017.

All information contained on the Catalystpharma.com website is intended for informational and educational purposes. The information provided on this website is not intended to be a replacement or substitute for professional medical advice. Any information that you have received from Catalystpharma.com should be verified with your licensed healthcare provider. Individuals should never disregard or delay seeking medical advice due to the content of this site.

Up Next

See how we partner with patient communities to change the standard of care.

Patient Advocacy
Catalyst Background

“It’s important that Catalyst is looking for opportunities for us to have products for patients with rare disease. They need the compassion, and they need companies that are willing to take the risk.”  

—Patty Flores, Marketing Director

Headshot of Catalyst employee, Patty Flores