Recognizing LEMS

The early recognition of LEMS is crucial for improving clinical outcomes but remains a major challenge.1
—Merino-Ramírez et al, 2016

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of the neuromuscular junction.6 It causes debilitating and progressive muscle weakness and fatigue, the effects of which leave patients with diminished physical functioning and a poorer quality of life.1,3,6,7 And, while it is considered a rare disease—about 3,000 people in the US are affected—it is estimated that about half of these individuals are still undiagnosed.4,7 They suffer despite the fact there are simple tests available to clinicians that can accurately diagnose the disorder and effective medicines that can mitigate its devastating effects.4

By becoming more “LEMS aware,” you may be better equipped to recognize the disorder and expedite the treatment journey for patients.

Pathophysiology of LEMS

LEMS is caused by autoantibodies to presynaptic P/Q-type voltage-gated calcium channels (VGCCs), leading to impaired neuromuscular transmission of acetylcholine (ACh).4,7,8

  • In up to 60% of cases, the pathogenic autoantibodies are produced in response to an underlying tumor, generally small cell lung cancer4
LEMS Diagram

AChR=acetylcholine receptor.

Progression of LEMS

LEMS is progressive and debilitating and may contribute to a high level of disease burden, which can worsen over time3,4,9,10

In a 2012 study of patients living with LEMS3:

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75% reported partial or total restriction in activities of daily living, such as rising from a chair or climbing stairs3

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More than 50% reported severe leg weakness, dry mouth, and difficulty focusing their sight3

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Based on EQ-5D* scores, the health-related quality of life for patients with LEMS is comparable to the most severe forms of multiple sclerosis3

*A measure that generates a single index value for health status with considerable potential for use in healthcare evaluation.

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In a 2001 study, 25% of LEMS patients required a wheelchair all of the time or for mobilization outside of the home10

Symptoms of LEMSShare Copy LinkCOPIED!

The progressive nature of LEMS and the diagnostic challenges that it presents make early symptom recognition critical for optimal patient care.

Presentation of LEMS

LEMS is often suspected based on a clinical triad of signs and symptoms4:

  • Proximal muscle weakness

  • Autonomic symptoms (eg, dry mouth, impotence)

  • Areflexia

LEMS Symptom
Map4Share Copy LinkCOPIED!

LEMS Symptom Map
LEMS Symptom MapLEMS Symptom Map

*Estimated percentages.

Insights from a LEMS expert

Mazen Dimachkie, MD, is a leading consultant in the study of LEMS. As the Director of Neuromuscular Research at the University of Kansas Medical Center, he manages one of the busiest neuromuscular clinical trial units in North America.

NeuroseriesLive hosted a webinar featuring Dr. Dimachkie discussing LEMS: “Are My Muscles Aging? One Often-misdiagnosed Cause of Weakness and Fatigue.” Excerpts from this program appear throughout this website, and you can watch the full webinar here.*

*Sponsored by Catalyst Pharmaceuticals.


If you suspect a patient may have LEMS, here are 3 questions to ask that can help advance the conversation.

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Do you or does anyone in your family have a history of autoimmune disorders?

In non-tumor LEMS, pre-existing autoimmune conditions are frequently observed. Examples include: hypo- and hyperthyroidism, celiac disease, type 1 diabetes, ulcerative colitis, Addison’s disease, and rheumatoid arthritis. Like many other autoimmune disorders, a genetic susceptibility may be present in non-tumor LEMS.4,9,11

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Do you have a history of smoking and/or unexplained weight loss?

In addition to advanced age, a history of smoking and unexplained weight loss are independent predictors of paraneoplastic LEMS.11

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Where did your muscle weakness begin, and how did it spread?

Another differentiating feature of LEMS may be the direction of symptom spread. In LEMS, symptoms typically start in the lower body and spread upward, while symptoms of myasthenia gravis—a more common neuromuscular junction disorder—typically start in the face/neck and spread downward.1

Take the lead
on LEMSShare Copy LinkCOPIED!

Use this simple word-play to help remember the clinical triad of signs and symptoms that should point to a suspicion of LEMS.

L = Lower-
E = Extremity weakness
A = Autonomic dysfunction
D = Diminished reflexes

Stay informed

LEMS Aware is designed to be a resource for physicians to find the latest clinical data, news, and information regarding the diagnosis and treatment of patients with LEMS. Sign up for email alerts so that we can let you know as new content—such as teaching aids, webinars, and other useful resources—becomes available.