Recognizing LEMS
The early recognition of LEMS is crucial for improving clinical outcomes but remains a major challenge.
—Merino-Ramírez et al, 20161
The early recognition of LEMS is crucial for improving clinical outcomes but remains a major challenge.
—Merino-Ramírez et al, 20161
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.
About LEMS
Pathophysiology of LEMS
LEMS is caused by autoantibodies to presynaptic P/Q-type voltage-gated calcium channels (VGCCs) that reduce the release of acetylcholine into the NMJ, inhibiting neuromuscular transmission.8-10
- In up to 60% of cases, LEMS is associated with an underlying cancer, generally small cell lung cancer4
Progression of LEMS
LEMS is progressive and debilitating and may contribute to a high level of disease burden, which can worsen over time3,4
In a 2012 study of patients living with LEMS3:
75% reported partial or total restriction in activities of daily living3, such as rising from a chair or climbing stairs11
50% reported severe leg weakness; other frequently reported symptoms included dry mouth and difficulty focusing eyesight3
Based on EQ-5D scores*, the health-related quality of life for LEMS patients 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.
In a 2001 study, ~25% of LEMS patients required a wheelchair all of the time or for mobilization outside of the home.12
Symptoms of LEMS
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)
Hyporeflexia or areflexia
The LEMS Gait
Meet Emily
At the age of 33, Emily began experiencing symptoms that included leg heaviness, trouble rising from a chair, and problems with her gait. In this story, you’ll see video taken by Emily’s mother that shows how her gait was affected by LEMS. Not every LEMS patient with exhibit this gait, but when it’s present, it’s a strong indicator of LEMS.
LEMS Symptom Map4
*Estimated percentages.
LEMS Pop Quiz
In addition to proximal muscle weakness, what other LEMS signs or symptoms would you need to see before ordering a diagnostic antibody test for your patient?
(Select all that apply)Because many patients with LEMS spend an average of 4.4 years searching for a correct diagnosis3, proximal muscle weakness is reason enough to order a LEMS antibody test for your patients.
The presentation of areflexia/hyporeflexia—and autonomic symptoms such as dry mouth, dry eyes, double vision, constipation, and impotence-only adds to the urgency to test for LEMS. And with the availability of a free anti-VGCC antibody test from Catalyst, there’s no reason to delay testing that can help identify patients struggling with unidentified symptoms of LEMS.
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.
3 QUESTIONS TO ASK YOUR PATIENTS
If you suspect a patient may have LEMS, here are 3 questions to ask that can help advance the conversation.
Do you or does anyone in your family have a history of autoimmune disorders?
In LEMS not associated with cancer, 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 LEMS not associated with cancer.4,13,14
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.14
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 LEMS
Use this simple wordplay to help remember the clinical triad of signs and symptoms that should point to a suspicion of LEMS.
