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In 1890, German medical professor Wilhelm Erb and two of his colleagues gave the name myasthenia gravis to a neuromuscular disease which had previously been reported by more than one physician. All three physicians noted that the "grave muscular weakness" -- whether it affected the eye muscles first, or created difficulty in talking, chewing and swallowing, or in using the arms and legs -- was neither hereditary nor contagious. Myasthenia gravis and the less common Lambert-Eaton (myasthenic) syndrome are diseases affecting how nerve impulses are transmitted to muscle at the neuromuscular junction. Both are "autoimmune" diseases in which the body generates an immune system attack against its own skeletal muscles. Although people with myasthenia virtually always do very well when treated properly, myasthenia gravis (MG) and Lambert-Eaton syndrome (LEMS) can be life-threatening when muscle weakness interferes with respiration. A milestone in myasthenia gravis research occurred in the early 1970s when Muscular Dystrophy Association-supported researchers discovered that the disease affected acetylcholine receptors of the skeletal muscles. Using snake venom that binds to acetylcholine receptors, they discovered that myasthenic patients had decreased numbers of these receptors. Acetylcholine receptors are protein molecules on the muscles cell's surface that contain channels which allow electrically charged sodium atoms, or ions, to flow into the cell. When sodium ions enter the muscle cells, they trigger a chain of events leading to muscle contraction. Simultaneously, another MDA-supported group found that, in rabbits, an immune attack against the acetylcholine receptors resulted in muscle membrane damage that is similar to that seen in human myasthenia gravis. Further studies of this rabbit model are responsible for a large portion of what scientists now know about myasthenia gravis. In addition to advances in understanding myasthenia gravis and Lambert-Eaton syndrome, MDA has fostered great progress in the treatment of these disorders. As you'll read here, these diseases are highly treatable, and for many people, the first year of muscle weakness is by far the most severe. While some other neuromuscular disorders get progressively worse over time, with proper and timely treatment, people with MG and LEMS can usually maintain good muscle function. These diseases of the neuromuscular junction are among the 40 diseases covered by MDA's program. The Association is committed to helping patients with myasthenia gravis and Lambert-Eaton syndrome through a variety of services, including medical care and research projects aimed at finding treatments and cures.
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