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Myasthenia Gravis

What conditions might be confused with Myasthenia Gravis?

  1. What is the difference between MG and Lambert-Eaton Syndrome?
  2. What is the difference between Myasthenia Gravis and Multiple Sclerosis?
  3. What is the relationship between fibromyalgia and chronic fatigue syndrome to Myasthenia Gravis?
  4. What is the relationship between Myasthenia Gravis and Muscular Dystrophies?
  5. What is the relationship of Systemic Lupus Erythematosus and Myasthenia Gravis?

What is the difference between MG and Lambert-Eaton Syndrome?

Myasthenia Gravis causes muscle weakness that becomes significantly worse with activity. Double vision, swallowing and speaking abnormalities, difficulty walking and using the arms are common symptoms. Lambert-Eaton Myasthenic Syndrome (LEMS) may produce similar symptoms, as well as muscle aches and dry mouth, but double vision is less common. Patients may also have impotence, constipation, impaired sweating, blurred vision and difficulties with urination.

Myasthenia Gravis is an autoimmune disease in which antibodies damage the acetylcholine receptors and compromise the muscle side of the nerve-muscle communication point. LEMS is an autoimmune disease that affects the nerve and not the muscle. LEMS may be triggered by a lung cancer. An EMG test performed by an experienced neurologist differentiates Myasthenia Gravis from LEMS. Blood tests for certain antibodies may also help with their differentiation. Many of the treatments for the disorders are similar, although patients with LEMS may not respond as well. A thymectomy is not used to treat LEMS.

What is the difference between Myasthenia Gravis and Multiple Sclerosis?

Both Myasthenia Gravis and Multiple Sclerosis are autoimmune diseases, but differ in that MS affects the central nervous system (brain and spinal cord), while MG affects the nerve-muscle communication point of the peripheral nervous system. The presence of both MS and MG in a single patient is rare. With appropriate testing, your neurologist would be able to distinguish the two conditions. There is no clear connection between MG and MS.

What is the relationship between fibromyalgia and chronic fatigue syndrome to Myasthenia Gravis?

The cause of fibromyalgia or chronic fatigue syndrome is not known and neither is known as an autoimmune disease. There is no clear link between chronic fatigue syndrome, fibromyalgia and MG. Chronic fatigue syndrome is characterized by a set of symptoms that may have many causes (that is why it is called a syndrome). Although both are manifested by fatigue, MG causes muscle fatigue that can be identified objectively by specific muscle tests, such as an EMG. Mestinon has been used for chronic fatigue syndrome, but my understanding is that it ultimately has not been shown to be effective.

What is the relationship between Myasthenia Gravis and Muscular Dystrophies?

We are not aware of any relation between MG and Muscular Dystrophy. Muscular dystrophies are genetic diseases and having MG does not put you at risk for developing such a disease. In fact, the eye muscles, which we studied in patients with advanced DMD, are always spared, in contrast to the eye muscles in MG that tend to be affected early in the disease.

What is the relationship of Systemic Lupus Erythematosus and Myasthenia Gravis?

Systemic Lupus Erythematosus (SLE) is a complicated autoimmune condition that may affect the nervous system in many different ways. MG and SLE can occur in the same patient. Myasthenia Gravis produces weakness while SLE produces any combination of joint pain and swelling, rash, kidney problems, eye and brain abnormalities, and others. There are blood tests to confirm the diagnosis of SLE.

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Last Reviewed: Dec 29, 2003

Henry J Kaminski, MD Henry J Kaminski, MD
Formerly, Professor of Neurology
School of Medicine
Case Western Reserve University