Lambert-Eaton myasthenic syndrome (LEMS)



Occurs when the immune system attacks the areas where the nerves and muscles of the body connect (neuromuscular junctions). As a result, patients experience muscular weakness.

There are two types of LEMS:

LEMS associated with small cell lung cancer (SCLC-LEMS)
LEMS not associated with cancer (NT-LEMS)

Common Symptoms

Muscle weakness and fatigue, dry mouth, dry eyes, constipation, erectile dysfunction, decreased sweating, diminished tendon reflexes, significant weight loss, eyelid drooping, trouble speaking and swallowing, and tingling sensations in the hands and feet. Symptoms usually have a gradual onset, but progress more quickly if LEMS is associated with cancer.

Coexisting Diseases and Conditions

About 60% of LEMS cases are associated with having small cell lung cancer. Other malignancies such as prostate cancer and thymoma have also been associated with the LEMS.

Risk Factors and Prevalence


  1. Article Sources
    1. Jayarangaiah, A., & Theetha Kariyanna, P. (2021). Lambert Eaton Myasthenic Syndrome. In StatPearls. StatPearls Publishing.

    2. Lambert-Eaton Myasthenic Syndrome. (n.d.). NORD (National Organization for Rare Disorders). Retrieved July 12, 2021, from

    3. Maddison, P., Lipka, A. F., Gozzard, P., Sadalage, G., Ambrose, P. A., Lang, B., & Verschuuren, J. J. (2020). Lung cancer prediction in Lambert-Eaton myasthenic syndrome in a prospective cohort. Scientific Reports, 10(1), 10546.

    4. Wirtz, P. W., Willcox, N., van der Slik, A. R., Lang, B., Maddison, P., Koeleman, B. P. C., Giphart, M. J., Wintzen, A. R., Roep, B. O., & Verschuuren, J. J. G. M. (2005). HLA and smoking in prediction and prognosis of small cell lung cancer in autoimmune Lambert-Eaton myasthenic syndrome. Journal of Neuroimmunology, 159(1–2), 230–237.