CINCINNATI—Myasthenia gravis is a chronic autoimmune neuromuscular disease whose name, translated from Greek and Latin, means "grave muscle weakness.” But with proper diagnosis and treatment, a UC Health specialist says, patients can get back on track with their normal lives.
"As a neuromuscular condition, myasthenia gravis affects a person’s strength and control of their muscles,” says John Quinlan, MD, a professor in the neurology and rehabilitation medicine department at the University of Cincinnati (UC) College of Medicine and medical director of the UC Neuroscience Institute’s Neuromuscular Disorders Program. "A person will have muscles that work fine at one time of the day and then not work at all later. They often complain of fatigue.”
According to the National Institute of Neurological Disorders and Stroke (NINDS), myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. The body’s own immune system blocks the receptor for a substance called acetylcholine which is crucial to the generation of muscle contraction.
Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking and swallowing are often involved in the disorder, NINDS says. The muscles that control breathing and neck and limb movements may also be affected.
Approximately 70,000 individuals in the United States have been diagnosed with the disorder, according to the Myasthenia Gravis Foundation of America, which has designated June as MG Awareness Month. It can occur in patients of any age. Researchers do not believe that it is directly inherited, but a genetic predisposition to autoimmune diseases can run in families. Myasthenia gravis is not contagious.
"This is a disorder that comes out of the blue,” says Quinlan. "With one exception—pathology of the thymus—we can’t really identify any triggers.” A tumor on the thymus gland occurs in about 5 to 10 percent of patients, Quinlan says. Alternatively, some myasthenia patients have a hyperactive thymus.
Quinlan says a medical history and physical exam is the first step in diagnosis of myasthenia gravis. "We want to distinguish chronic fatigue syndrome from myasthenia gravis,” he says. "Chronic fatigue patients may be running on empty, but they don’t have absolute failure in muscle function.”
Blood tests can detect abnormally elevated levels of certain antibodies, Quinlan says. Repetitive nerve stimulation with small pulses of electricity can demonstrate gradual decreases of muscle action potential. Diagnostic imaging of the chest can identify the presence of a thymus tumor.
The UCNI Neuromuscular Disorders Program offers single-fiber EMG services, in which a fine needle is placed in a muscle and electrical activity is measured. Hani Kushlaf, MD, is specially trained in this procedure, which is considered to be the most sensitive diagnostic test currently available.
While there is no cure of myasthenia gravis, Quinlan says, its symptoms can be controlled with medication. (In the case of a thymus tumor, a thymectomy—removal of the thymus—is recommended.)
"If the condition is mild, I use symptom treatment that has very low side effects,” says Quinlan. "In more severe cases, we would look to immunosuppressant medications, being vigilant to limit side effects.”
Quinlan notes that the UCNI Neuromuscular Disorders Program has five neuromuscular specialists, all collaborating with each other and sharing knowledge of the disorder for enhanced familiarity with diagnostics and treatment options.
The program is also part of the Muscular Dystrophy Association (MDA) clinic network, which assists with payment for services and selected tests associated with a confirmed diagnosis of muscle disease that are not covered by private or public insurance plans or other community resources. Information on the clinic and the local myasthenia gravis support group is available from the Greater Cincinnati MDA office at 513-231-2222.