Myasthenia Gravis

 Patients with myasthenia gravis (MG), a neuromuscular disorder primarily characterized by muscle weakness and muscle fatigue, reported in a new survey by Penn State University researchers that the disease impacts their quality of life. While this finding is not totally unexpected, the fact that a significant percentage reported experiencing pain as a result of their illness is. "That such a large number of surveyed patients reported pain associated with their disease," explained researcher Dr. Milind Kothari, "is very surprising."  Kothari and fellow researcher, Dr. Kevin Scott, anticipated that most of those surveyed would indicate that MG limits their ability to work or perform moderately intense activities. "We were surprised, though, to see 50% of the patients report experiencing significant pain as a result of their illness with over a quarter reporting pain of moderate or greater severity. Pain is not commonly associated with this disease." ...

Symptoms Muscle weakness caused by myasthenia gravis worsens as the affected muscle is used repeatedly. Because symptoms usually improve with rest, your muscle weakness may come and go. However, myasthenia gravis symptoms tend to progress over time, usually reaching their worst within a few years after the onset of the disease. Although myasthenia gravis can affect any of the muscles that you control voluntarily, certain muscle groups are more commonly affected than others. Eye muscles In more than half the people who develop myasthenia gravis, their first signs and symptoms involve eye problems, such as: Drooping of one or both eyelids (ptosis). Double vision (diplopia), which may be horizontal or vertical, and improves or resolves when one eye is closed. Face and throat muscles In about 15 percent of people with myasthenia gravis, the first symptoms involve face and throat muscles, which can cause: Altered speaking.  Your speech may sound very soft or nasal,...

Abstract Autoimmune myasthenia gravis (MG) is a multifactorial disease, markedly influenced by genetic factors, even though it shows limited heritability. The clinically typical form of autoimmune MG with thymus hyperplasia shows the most reproducible genetic associations, especially with the A1-B8-DR3 (8.1) haplotype of the major histocompatibility complex (MHC). However, because of strong linkage disequilibrium, the causative polymorphism in this region is not known yet. Increasing the density of genetic markers has nevertheless recently revealed the complex, but highly significant contribution of this essential genetic region in controlling the disease phenotype and the quantitative expression of serum autoantibodies. The advances of the human genome program, the development of genotyping and sequencing tools with increasing throughput, and the availability of powerful statistical methods now make feasible the dissection of a complex genetic region, such as the MHC and beyon...

To reduce residue in your throat: Moisten solid foods with gravy, sauce, broth, butter, mayonnaise, sour cream or yogurt. Choose chicken or fish instead of tougher meats. Avoid dry crumbly food such as crackers, rice, cookies, nuts, chips or popcorn. Avoid bread products such as sandwiches, bagels and muffins. Focus on the swallow. Hold your head in a different position to try a different swallow pathway. To reduce fatigue: Eat several small meals during the day. Chop or mince solid foods (like meat). Eat your largest meal earlier in the day when you have more energy. Take anticholinesterase medication (for example, Mestinon) shortly before mealtimes. To reduce the risk of food accidentally going into your lungs (called “aspiration”): Thicken all fluids to the consistency recommended by your doctor or speech pathologist. Remember that ice cream and popsicles melt into a thin fluid in your mouth, and that once you chew fruits, the juice released is also a thin li...

What causes gMG? Generalized Myasthenia Gravis (gMG) is a rare disorder caused by the immune system attacking the body's own healthy cells. The antibodies in people with gMG attack the area called the  neuromuscular junction  where the nerves trigger the muscles to work and interrupt the signals between nerves and muscles, which causes muscle weakness.  People who do not respond to available treatments continue to experience significant muscle weakness that makes it difficult to swallow, talk, or engage in simple daily activities like brushing their hair.  Although there is no cure for gMG, management of this disorder has improved over the past 30 years, leading to significantly fewer deaths and better quality of life. 

Research MDA’s commitment to research on myasthenia gravis began many years ago when little was known about the cause of MG and its mortality rate was high. In the early 1970s, MDA-funded researchers helped establish the autoimmune nature of MG. They showed that people with the disease have a reduced number of ACh receptors, and that antibodies to the receptors can induce MG in laboratory animals. These discoveries led swiftly to the lifesaving use of immunosuppressant drugs to treat the disease. MDA-funded researchers also developed  plasmapheresis  as a treatment for MG. Today, they are refining plasmapheresis so that it only sifts out the unwanted antibodies, not the ones that are doing their job properly. Today, several MDA-supported research teams are working to understand the specifics of the autoimmune problems in MG and to refine their detection and treatment. A particular area of focus is "rebalancing" the immune system, rather than the earlier approach o...

Abstract Myasthenia gravis (MG) is often complicated by respiratory failure, known as a myasthenic crisis. However, most of the patients who develop respiratory symptoms do so during the late course of disease and have other neurological signs and symptoms. However, in some patients respiratory failure is the initial presenting symptom. We report the case of a 68-year-old woman with MG who presented with isolated respiratory failure as her first presenting symptom. As illustrated by this case, it is important to consider neuromuscular disorders in cases of unexplained respiratory failure. Keywords:  Myasthenia gravis, Respiratory insufficiency INTRODUCTION Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disease. MG is characterized by autoantibody attack of acetylcholine receptors at the motor end plate of striated muscles, which results in variable muscle weakness made worse by exercise [ 1 ]. Patients with MG commonly experience respiratory failure. Ho...

Patients are defined as being in remission if they have no symptoms, their examination is normal (or showing no abnormalities consistent with Myasthenia Gravis), and they are taking no medications for at least 6 months. The nerve-muscle communication point can "heal itself" after the immune system is stopped from attacking it. Experts in MG are always careful to say patients are in remission (and not cured) because once MG occurs, there is a chance that a patient in remission can develop symptoms again in the future. The longer a person remains in remission, the less likely it is that the disease will recur. It is rare for patients to have a recurrence after decades of remission. There is some data that suggest that children who go into remission are more likely to stay in remission. It is possible for a patient to go into remission more than once, however, multiple remissions suggest to me that a patient was never truly in remission to begin with.  Some patients may have...

There are two forms of thymic hyperplasia:  1- True thymic hyperplasia (or rebound hyperplasia), in which there are normal proportions of glandular/ lymphoid elements in an enlarged gland secondary to rebound following stress-related atrophy, illness, or immune suppression (following chemotherapy or discontinuation of corticosteroid administration) [15,19]. When the body is exposed to stress the thymus may shrink to as little as 40% of its original volume (depending on the severity and duration of the stress) [20]. Once the body recovers, the thymus can usually grows back to its original size within 9 months, but it can grow to be as much as 50% larger [20]. Approximately 10-25% of patient who undergo chemotherapy may develop rebound hyperplasia [20].  Most cases of thymic hyperplasia secondary to chemotherapy occur within a year or two and the gland typically returns to normal size [8,20]. Because of bolstered cell-mediated immunity, thymic hyperplasia has been associated...

Between 25% to 50% of thymomas are undetectable on PA chest radiographs [6,12]. CT scan is the study of choice in the evaluation of patients with myesthenia gravis or a suspected thymoma [12]. CT has a sensitivity of 91% and a specificity of 97% for the diagnosis of a thymic mass [12]. MR adds little additional information. Note: The use of iodinated contrast agents in patients with myasthenia gravis has been reported to cause increased weakness. Although not contraindicated, intravenous contrast agents should not be used routinely in the assessment of these patients. [1]  On CT, thymomas appear as a lobulated, well-defined, soft tissue density mass with rounded margins in the anterior mediastinum and growth is usually to one side. Mild, homogeneous contrast enhancement is characteristic. Calcification is common (20% of cases on plain film). Cystic areas (due to hemorrhage or necrotic degeneration) are also found in 20-30% and these are typically larger lesions. A clue to the...

Stage I- tumor with intact capsule; Stage II- transcapsular extension into the mediastinal fat (IIa- microscopic invasion through the capsule and IIb- macroscopic invasion into surrounding fat); Stage III- invasion of the adjacent organs - focal pleural or pericardial, mediastinal structures (great vessels, heart), or lung; Stage IVa- pleural or pericardial dissemination; and Stage IVb- Lymphatic or hematogenous metastases [21]. Stage I lesions are treated with surgical resection alone, while stage II lesions are treated with surgery and post op XRT if the resection is incomplete [21]. For stage III and IVa lesions, patients receive adjuvant chemotherapy followed by surgery and XRT if required [21]. Stage IVb lesions are treated with palliative chemotherapy [21]. Prognosis for a non-invasive thymoma is very good with only a 2% recurrence rate for encapsulated lesions. Invasive lesions have a 50-78% 5 year survival [2]. The reported average time to recurrence of a completely resec...

Thymomas generally occur in patients over the age of 30 years abd are rare in children (70% of lesions are found in adults between the 5th and 6th decades) [12,21]. Thymomas occur with equal frequency in men and women [20,21]. Approximately 35% of thymomas are invasive, but they are usually indistinguishable from benign tumors radiographically. Most patients are asymptomatic (20-50% of patients [12]), however, thymomas are associated with  myasthenia gravis . About 35-40% of patients with thymomas have myasthenia, whereas 10-15% of myasthenia patients have a thymoma [21]. Thymomas associated with myasthenia are typically less aggressive and have a better prognosis. Thymomas are also associated with other hematologic disorders such as hypogammaglobulinemia (Good's Syndrome-in 5% of cases) and red cell aplasia (in about 5%- particularly spindle cell thymoma). Conversely, about 10% of patients with hypogammaglobulinemia are discovered to have a thymoma, while about 50% of patients...

The thymus arises from the third and fourth branchial pouches and contains elements from all three germ cell layers [15]. The gland consists of two lateral lobes placed in close contact along the midline of the upper chest [14]. The thymus increases from birth to between 4 and 8 months of age and then decreases [14]. It normally weighs about 15 gm at birth and 35 gm at puberty [14]. It is most active and largest during puberty after which it shrinks in size and activity in most people and is replaced with fat [14]. Total fatty involution of the thymus occurs around the age of 40 years when only about 5% of residual thymic tissue is retained [19]. However, the normal thymus can still be identified in up to 100% of patients under the age of 30 years, in up to 73% of patients between the ages of 30-49 years, and in up to 17% of patients older than 49 years [13].  On CXR in infants and young children the thymus is strikingly large- it usually has smooth borders and remains visibl...

Thallium-201 ( 201  Tl) single photon emission CT (SPECT) scanning is useful for the evaluation of thymic lesions associated with myasthenia gravis, including lymphoid follicular hyperplasia and thymoma.  [ 12 ]  On early images, 201  Tl accumulation is more intense in thymomas than in the normal thymus and in lymphoid follicular hyperplasia. On delayed images, uptake is more intense in thymoma and in lymphoid follicular hyperplasia than in the normal thymus. Therefore, 201  Tl SPECT scanning can be used to differentiate normal thymus from lymphoid follicular hyperplasia and thymoma in patients with myasthenia gravis. Degree of confidence 201  Tl uptake is considered to reflect various factors, including cellular metabolic activity, regional blood flow, and the number of viable cells in the lesion; hence, 201  Tl imaging is in some respects superior to CT scanning

The MRI signal characteristics of untreated lymphomas are different from those of treated lymphomas. Untreated lymphomatous tissue has high signal intensity, whereas a homogeneous, hypointense pattern is characteristic of inactive residual fibrotic masses in patients receiving successful therapy for lymphoma. A heterogeneous pattern with mixed hypointensity and hyperintensity is often seen in untreated nodular sclerosing Hodgkin disease. A heterogeneous pattern with mixed areas of low and high signal intensity on T1- and T2-weighted images is seen in lesions containing mixed fat (high signal intensity) and fibrous tissue (low signal intensity). This pattern is seen after treatment of patients with sterilized tumors. (Positron emission tomography [PET] CT may play a role in assessing for residual lymphoma.)  [ 3 ,  4 ,  10 ,  5 ,  6 ,  11 ]  Degree of confidence With MRI of the thorax, motion artifacts may occur. Breathing motion and pulsation ...

Thymic hyperplasia Thymic hyperplasia and normal thymus share the same characteristics on MRI. In the case of thymolipoma, T1-weighted MRIs reveal high signal intensity, which represents fat; strands of intermediate intensity represent thymic tissue. Thymic cyst T1-weighted MRIs of thymic cysts reveal low signal intensity; T2-weighted images show high signal intensity consistent with the fluid component of the lesion. T1-weighted images naturally show high signal intensity if the cyst contains blood from hemorrhage or if it is rich in proteinaceous fluid. Qualitative evaluation of gross thymic morphology (ie, size, shape, margins, and signal intensity) is usually sufficient for distinguishing normal thymus from abnormal thymus. The abnormal thymus generally is enlarged, multilobular, or inhomogeneous because of the presence of cystic degeneration, hemorrhage, septations, fibrosis, or calcification, as seen on pathologic sections. In patients with lymphoma, associated lymp...