Lambert-Eaton syndrome is a disorder in which faulty communication between nerves and muscles leads to muscle weakness.
Myasthenic syndrome; Eaton-Lambert syndrome; Lambert-Eaton myasthenic syndrome; LEMS
Causes, incidence, and risk factors
Lambert-Eaton syndrome occurs when nerves cells do not release enough of a chemical called acetylcholine. This chemical transmits impulses between nerves and muscles.
The result is muscle weakness and other symptoms similar to myasthenia gravis. However, unlike myasthenia gravis, as the muscles continue to contract, acetylcholine can build up in large enough amounts for strength to improve slightly. Instead of the muscle getting quickly weaker as it contracts repeatedly, it gets stronger for a short period of time.
Symptoms may include:
- Weakness or loss of movement that can be more or less severe, including:
- Difficulty chewing
- Difficulty climbing stairs
- Difficulty lifting objects
- Difficulty talking
- Drooping head
- Need to use hands to get up from sitting or lying positions
- Swallowing difficulty, gagging, or choking
- Vision changes such as:
- Blurry vision
- Double vision
- Problems keeping a steady gaze
Symptoms related to the autonomic nervous system usually occur, and include:
- Blood pressure changes
- Dizziness upon standing
- Dry mouth
Signs and tests
A detailed medical history will be taken to determine risk factors, such as a history of certain cancers.
A physical examination shows:
- Decreased reflexes
- Possible loss of muscle tissue
- Weakness or paralysis that gets slightly better with activity
Tests to help diagnose and confirm the condition may include:
The main goals of treatment are to:
- Identify and treat any underlying disorders, such as lung cancer
- Give treatment to help with the weakness
A treatment called plasma exchange usually improves symptoms. Plasma exchange involves removing blood plasma from the body and replacing it with donated plasma. This helps to make sure that any harmful proteins (antibodies) that are interfering with nerve function are removed from the body.
Plasmapheresis may also be effective. During this treatment, the blood is removed from the body. The plasma is separated, the antibodies are removed, and the plasma is returned to the body.
Medications that suppress the immune response, such as prednisone, may improve symptoms in some cases. Medications may also include:
- Anticholinesterase medications such as neostigmine or pyridostigmine (although these are not very effective when given alone)
- 3, 4-diaminopyridine, which increase the release of acetylcholine from nerve cells
The symptoms of Lambert-Eaton syndrome may improve by treating the underlying disease, suppressing the immune system, or removing the antibodies. However, not everyone responds well to treatment.
Calling your health care provider
Call your health care provider if symptoms of this condition develop.
Vincent A, Newsom-Davis J. Disorders of neuromuscular transmission. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 448.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.