Definition of Lambert-Eaton syndrome:

Lambert-Eaton syndrome is a disorder in which faulty communication between nerves and muscles leads to muscle weakness.

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.

Lambert-Eaton syndrome may occur with cancers such as small cell lung cancer or autoimmune disorders such as vitiligo, which leads to a loss of skin pigment.

Symptoms:

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:

• Electromyography (EMG) to test the health of the muscle fibers
• Nerve conduction velocity (NCV) to test the speed of electrical activity along nerves

Treatment:

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 increases the release of acetylcholine from nerve cells

Expectations (prognosis):

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.

Complications:

• Difficulty breathing, including respiratory failure
• Difficulty swallowing
• Infections, such as pneumonia
• Injuries from falls and problems with coordination

Calling your health care provider:

Call your health care provider if symptoms of this condition develop.