Myasthenia Gravis (cont.)
In this Article
What are myasthenic crises?
A myasthenic crisis occurs when the muscles that control breathing weaken to the point that ventilation is inadequate, creating a medical emergency and requiring a respirator for assisted ventilation. In individuals whose respiratory muscles are weak, crises -- which generally call for immediate medical attention -- may be triggered by infection, fever, or an adverse reaction to medication.
What is the prognosis?
With treatment, most individuals with myasthenia can significantly improve their muscle weakness and lead normal or nearly normal lives. Some cases of myasthenia gravis may go into remission -- either temporarily or permanently -- and muscle weakness may disappear completely so that medications can be discontinued. Stable, long-lasting complete remissions are the goal of thymectomy and may occur in about 50 percent of individuals who undergo this procedure. In a few cases, the severe weakness of myasthenia gravis may cause respiratory failure, which requires immediate emergency medical care.
What research is being done?
Within the Federal government, the National Institute of Neurological Disorders and Stroke (NINDS), one of the National Institutes of Health (NIH), has primary responsibility for conducting and supporting research on brain and nervous system disorders, including myasthenia gravis.
Much has been learned about myasthenia gravis in recent years. Technological advances have led to more timely and accurate diagnosis, and new and enhanced therapies have improved management of the disorder. There is a greater understanding about the structure and function of the neuromuscular junction, the fundamental aspects of the thymus gland and of autoimmunity, and the disorder itself. Despite these advances, however, there is still much to learn. Researchers are seeking to learn what causes the autoimmune response in myasthenia gravis, and to better define the relationship between the thymus gland and myasthenia gravis.
Different drugs are being tested, either alone or in combination with existing drug therapies, to see if they are effective in treating myasthenia gravis. One study is examining the use of methotrexate therapy in individuals who develop symptoms and signs of the disease while on prednisone therapy. The drug suppresses blood cell activity that causes inflammation. Another study is investigating the use of rituximab, a monoclonal antibody against B cells which make antibodies, to see if it decreases certain antibodies that cause the immune system to attack the nervous system. Investigators are also determining if eculizumab is safe and effective in treating individuals with generalized myasthenia gravis who also receive various immunosuppressant drugs.
Another study seeks further understanding of the molecular basis of synaptic transmission in the nervous system. The objective of this study is to expand current knowledge of the function of receptors and to apply this knowledge to the treatment of myasthenia gravis.
Thymectomy is also being studied in myasthenia gravis patients who do not have thymoma to assess long-term benefit the surgical procedure may have over medical therapy alone.
One study involves blood sampling to see if the immune system is making antibodies against components of the nerves and muscle. Researchers also hope to learn if these antibodies contribute to the development or worsening of myasthenia gravis and other illnesses of the nervous system.
Investigators are also examining the safety and efficacy of autologous hematopoietic stem cell transplantation to treat refractory and severe myasthenia gravis. Participants in this study will receive several days of treatment using the immumosuppressant drugs cyclophosphamide and antithymocyte globulin before having some of their peripheral blood cells harvested and frozen. The blood cells will later be thawed and infused intravenously into the respective individuals, whose symptoms will be monitored for five years.