Myasthenic syndrome; Eaton-Lambert syndrome; Lambert-Eaton myasthenic syndrome; LEMS; LES
Lambert-Eaton syndrome (LES) is a rare disorder in which faulty communication between nerves and muscles leads to muscle weakness.
LES is an autoimmune disorder. This means your immune system mistakenly targets healthy cells and tissues in the body. With LES, antibodies produced by the immune system attack nerve cells. This makes nerves cells unable to release enough of a chemical called acetylcholine. This chemical transmits impulses between nerves and muscles. The result is muscle weakness.
LES affects men more often than women. Common age of occurrence is around age 60 years. LES is rare in children.
Weakness or loss of movement that can be more or less severe, including:
Weakness is generally mild in LES. Leg muscles are mostly affected. Weakness may improve after exercise, but continuous exertion causes fatigue in some cases.
Symptoms related to the other parts of the nervous system often occur, and include:
The health care provider will perform a physical exam and ask about the symptoms. The exam may show:
Tests to help diagnose and confirm LES may include:
The main goals of treatment are to:
Plasma exchange, or plasmapheresis, is a treatment that helps remove from the body any harmful proteins (antibodies) that are interfering with nerve function. This involves removing blood plasma that contains the antibodies. Other proteins (such as albumin) or donated plasma are then infused into the body.
Another procedure involves using intravenous immunoglobulin (IVIg) to infuse a large amount of helpful antibodies directly into the bloodstream.
Medicines that may also be tried include:
Symptoms of LES may improve by treating the underlying disease, suppressing the immune system, or removing the antibodies. However, paraneoplastic LES may not respond as well to treatment. (Paraneoplastic LES symptoms are due to an altered immune system response to a tumor). Death is due to underlying malignancy.
Complications of LES may include:
Call your provider if symptoms of LES develop.
Evoli A, Vincent A. Disorders of neuromuscular transmission. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 394.
Moss HE. Eyelid and facial nerve disorders. In: Liu GT, Volpe NJ, Galetta SL, eds. Liu, Volpe, and Galetta's Neuro-Ophthalmology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 14.
Sanders DB, Guptill JT. Disorders of neuromuscular transmission. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 109.BACK TO TOP
Review Date: 6/23/2020
Reviewed By: Amit M. Shelat, DO, FACP, FAAN, Attending Neurologist and Assistant Professor of Clinical Neurology, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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