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| {{CMG}} | | {| class="infobox" style="float:right;" |
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| | | [[File:Siren.gif|30px|link=Myasthenia gravis resident survival guide]]|| <br> || <br> |
| | | [[Myasthenia gravis resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']] |
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| | '''For patient information click [[Myasthenia gravis (patient information)|here]].''' |
| {{Myasthenia gravis}} | | {{Myasthenia gravis}} |
| | {{CMG}}; {{AE}} {{Fs}} |
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| ==Diagnosis==
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| ===Pulmonary function test===
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| [[Spirometry]] (lung function testing) may be performed to assess respiratory function if there are concerns about a patient's ability to breathe adequately. The vital capacity (VC) may be monitored at intervals in order not to miss a gradual worsening of muscular weakness. Severe myasthenia may cause [[respiratory failure]] due to exhaustion of the respiratory muscles. | | ==[[Myasthenia gravis overview|Overview]]== |
| ===Pathological findings===
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| [[Immunofluorescence]] shows [[IgG]] antibodies on the neuromuscular junction. (Note that it is not the antibody which causes myasthenia gravis that fluoresces, but rather a [[secondary antibody]] directed against it.) Muscle electron microscopy shows receptor infolding and loss of the tips of the folds, together with widening of the [[Chemical synapse|synaptic]] clefts. Both these techniques are currently used for research rather than diagnostically. | | ==[[Myasthenia gravis historical perspective|Historical Perspective]]== |
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| ==Associations== | | ==[[Myasthenia gravis classification|Classification]]== |
| Myasthenia Gravis is associated with various [[autoimmune]] diseases, including:
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| * [[Thyroid]] diseases, including [[Hashimoto's thyroiditis]] and [[Graves' disease]]
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| * [[Diabetes mellitus type 1]]
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| * [[Rheumatoid arthritis]]
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| * [[Systemic lupus erythematosus|Lupus]], and
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| * [[Demyelinating disease|Demyelinating CNS diseases]]
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| Seropositive and "double-seronegative" patients often have [[thymoma]] or thymic hyperplasia. However, anti-MuSK positive patients do not have evidence of thymus pathology.
| | ==[[Myasthenia gravis pathophysiology|Pathophysiology]]== |
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| ==Treatment== | | ==[[Myasthenia gravis causes|Causes]]== |
| Treatment is by medication and/or surgery. Medication consists mainly of [[cholinesterase inhibitors]] to directly improve muscle function and [[immunosuppressant drug]]s to reduce the autoimmune process. [[Thymectomy]] is a surgical method to treat MG. For emergency treatment, [[plasmapheresis]] or [[IVIG]] can be used as a temporary measure to remove antibodies from the blood circulation.
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| ===Medication=== | | ==[[Differentiating Myasthenia gravis from other diseases|Differentiating Myasthenia Gravis from other Diseases]]== |
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| * [[Cholinesterase inhibitors]]: [[neostigmine]] and [[pyridostigmine]] can improve muscle function by slowing the natural enzyme [[cholinesterase]] that degrades [[acetylcholine]] in the motor end plate; the neurotransmitter is therefore around longer to stimulate its receptor. Usually doctors will start with a low dose, eg 3x20mg pyridostigmine, and increase until the desired result is achieved. If taken 30 minutes before a meal, symptoms will be mild during eating. Side effects, like perspiration and diarrhea can be countered by adding [[atropine]]. Pyridostigmine is a short-lived drug with a half-life of about 4 hours.
| | ==[[Myasthenia gravis epidemiology and demographics|Epidemiology and Demographics]]== |
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| * [[Immunosuppressive drugs]]: [[prednisone]], [[cyclosporine]], [[mycophenolate mofetil]] and [[azathioprine]] may be used. It is common for patients to be treated with a combination of these drugs with a cholinesterase inhibitor. Treatments with some immunosuppressives take weeks to months before effects are noticed.
| | ==[[Myasthenia gravis risk factors|Risk Factors]]== |
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| * [[Penicillamine]]
| | ==[[Myasthenia gravis screening|Screening]]== |
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| ===Plasmapheresis and IVIG=== | | ==[[Myasthenia gravis natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| If the myasthenia is serious (myasthenic crisis), [[plasmapheresis]] is used to remove the putative antibody from the circulation. Similarly, [[intravenous immunoglobulin]]s (IVIG) are used to bind the circulating antibodies. Both of these treatments have relatively short-lived benefits, typically measured in weeks.
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| ===Surgery=== | | ==Diagnosis== |
| {{main|thymectomy}}
| | [[Myasthenia gravis history and symptoms|History and Symptoms]] | [[Myasthenia gravis physical examination|Physical Examination]] | [[Myasthenia gravis laboratory findings|Laboratory Findings]] | [[Myasthenia gravis electrocardiogram|Electrocardiogram]] |[[Myasthenia gravis chest x ray|Chest X Ray]] | [[Myasthenia gravis CT|CT]] | [[Myasthenia gravis MRI|MRI]] | [[Myasthenia gravis echocardiography or ultrasound| Echocardiography or Ultrasound]] | [[Myasthenia gravis other imaging findings|Other Imaging Findings]] | [[Myasthenia gravis other diagnostic studies|Other Diagnostic Studies]] |
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| Thymectomy, the surgical removal of the [[thymus]], is essential in cases of [[thymoma]] in view of the potential neoplastic effects of the tumor. However, the procedure is more controversial in patients who do not show thymic abnormalities. Although some of these patients improve following thymectomy, some patients experience severe exacerbations and the highly controversial concept of "therapeutic thymectomy" for patients with thymus hyperplasia is disputed by many experts and efforts are underway to unequivocally answer this important question.
| | ==Treatment== |
| | | [[Myasthenia gravis medical therapy|Medical Therapy]] | [[Myasthenia gravis surgery|Surgery]] | [[Myasthenia gravis primary prevention|Primary Prevention]] | [[Myasthenia gravis secondary prevention|Secondary Prevention]] | [[Myasthenia gravis cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Myasthenia gravis future or investigational therapies|Future or Investigational Therapies]] |
| There are a number of surgical approaches to the removal of the thymus gland: transsternal (through the [[sternum]], or breast bone), transcervical (through a small neck incision), and transthoracic (through one or both sides of the chest). The transsternal approach is most common and uses the same length-wise incision through the sternum (breast bone)used for most open-heart surgery. The transcervical approach is a less invasive procedure that allows for removal of the entire thymus gland through a small neck incision. There has been no difference in success in symptom improvement between the transsternal approach and the minimally invasive transcervical approach.<ref name=Calhoun_1999>{{cite journal |author=Calhoun R, et al. |title=Results of transcervical thymectomy for myasthenia gravis in 100 consecutive patients. |journal=Annals of Surgery |volume=230 |issue=4 |pages=555-561 |year=1999 |pmid=10522725}}</ref>
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| Thymoma is relatively rare in younger (<40) patients, but paradoxically especially younger patients with generalized MG without thymoma benefit from thymectomy. Of course, resection is also indicated for those with a thymoma, but it is less likely to improve the MG symptoms.
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| ====Contraindicated medications====
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| {{MedCondContrAbs
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| |MedCond = Myasthenia gravis|Dicyclomine|Hyoscyamine|[[Gemifloxacin mesylate]]|Quinidine gluconate|Orphenadrine|Norfloxacin}}
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| ==Prognosis==
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| With treatment, patients have a normal life expectancy, except for those with a malignant [[thymoma]] (whose lesser life expectancy is on account of the thymoma itself and is otherwise unrelated to the myasthenia). Quality of life can vary depending on the severity and the cause. The drugs used to control MG either diminish in effectiveness over time ([[cholinesterase|cholinesterase inhibitors]]) or cause severe side effects of their own ([[Immunosupressive drug|immunosupressants]]). A small percentage (around 10%) of MG patients are found to have tumors in their [[thymus]] glands, in which case a [[thymectomy]] is a very effective treatment with long-term remission. However, most patients need treatment for the remainder of their lives, and their abilities vary greatly. It should be noted that MG is not usually a progressive disease. The symptoms may come and go, but the symptoms usually do not get worse as the patient ages. For some, the symptoms decrease after a span of 3–5 years.
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| ==References==
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| <!-- ----------------------------------------------------------
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| See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a
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| discussion of different citation methods and how to generate
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| footnotes using the <ref>, </ref> and <reference /> tags
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| <div class="references-2column"><references/></div>
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| ==External links==
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| * [http://www.myasthenia.org The Myasthenia Gravis Foundation of America]
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| * [http://www.mgauk.org The Myasthenia Gravis Association (MGA) in the United Kingdom & the Republic of Ireland]
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| {{PNS diseases of the nervous system}}
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| [[Category:Autoimmune diseases]]
| | ==Case Studies== |
| [[Category:Neurology]] | | [[Myasthenia gravis case study one|Case #1]] |
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| | [[Category:Rheumatology]] |
| | [[Category:Help]] |
| | [[Category:Needs content]] |
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| {{WH}} | | {{WH}} |
| {{WS}} | | {{WS}} |
