Editing Myasthenia gravis (section)

==Signs and symptoms==
The initial, main symptom in MG is painless [[Muscle weakness|weakness]] of specific muscles, not fatigue.<ref name="Engel2012">{{Cite book |last=Engel AG |url=https://books.google.com/books?id=V61KHl4T9vkC |title=Myasthenia Gravis and Myasthenic Disorders |date=2012 |publisher=Oxford University Press, US |isbn=978-0-19-973867-0 |edition=2nd |pages=109–110 |archive-url=https://web.archive.org/web/20170908162031/https://books.google.com/books?id=V61KHl4T9vkC |archive-date=8 September 2017 |url-status=live}}</ref> The muscle weakness becomes progressively worse ([[Muscle fatigue|fatigue]]) during periods of physical activity and improves after periods of rest. Typically, the weakness and fatigue are worse toward the end of the day.<ref name="Scully2014">{{Cite book |last=Scully C |url=https://books.google.com/books?id=OZXdAwAAQBAJ |title=Scully's Medical Problems in Dentistry |publisher=Elsevier Health Sciences UK |year=2014 |isbn=978-0-7020-5963-6 |archive-url=https://web.archive.org/web/20170908162031/https://books.google.com/books?id=OZXdAwAAQBAJ |archive-date=8 September 2017 |url-status=live}}</ref> Myasthenia gravis generally starts with ocular (eye) weakness; it might then progress to a more severe generalized form, characterized by weakness in the extremities or in muscles that govern basic life functions.<ref name="Goldenberg">{{EMedicine|article|1171206|Myasthenia Gravis}}</ref>

===Eyes===
In about two-thirds of individuals, the initial symptom of MG is related to the muscles around the eye.<ref name="Engel2012" /> Eyelid drooping ([[ptosis (eyelid)|ptosis]] may occur due to weakness of m. [[levator palpebrae superioris]])<ref name="Nair2014" /> and double vision ([[diplopia]],<ref name="Engel2012" /> due to weakness of the [[extraocular muscles]]).<ref name="Scully2014" /> Eye symptoms tend to get worse when watching television, reading, or driving, particularly in bright conditions.<ref name="Engel2012" /> Consequently, some affected individuals choose to wear sunglasses.<ref name="Engel2012" /> The term "ocular myasthenia gravis" describes a subtype of MG where muscle weakness is confined to the eyes, i.e. extraocular muscles, m. levator palpebrae superioris, and m. [[orbicularis oculi]].<ref name="Nair2014" /> Typically, this subtype evolves into generalized MG, usually after a few years.<ref name="Nair2014" />

===Eating===
The weakness of the muscles involved in swallowing may lead to swallowing difficulty ([[dysphagia]]). Typically, this means that some food may be left in the mouth after an attempt to swallow,<ref name="Scherer2005">{{Cite journal |vauthors=Scherer K, Bedlack RS, Simel DL |date=April 2005 |title=Does this patient have myasthenia gravis? |journal=JAMA |volume=293 |issue=15 |pages=1906–1914 |doi=10.1001/jama.293.15.1906 |pmid=15840866}}</ref> or food and liquids may regurgitate into the nose rather than go down the throat ([[velopharyngeal insufficiency]]).<ref name="Scully2014" /> Weakness of the muscles that move the jaw ([[muscles of mastication]]) may cause difficulty chewing. In individuals with MG, chewing tends to become more tiring when chewing tough, fibrous foods.<ref name="Engel2012" /> Difficulty in swallowing, chewing, and speaking is the first symptom in about one-sixth of individuals.<ref name="Engel2012" />

===Speaking===
Weakness of the muscles involved in speaking may lead to [[dysarthria]] and [[hypophonia]].<ref name="Engel2012" /> Speech may be slow and slurred,<ref name="Rajendran2014">{{Cite book |last1=Rajendran A |url=https://books.google.com/books?id=WnhtAwAAQBAJ&pg=P867 |title=Shafer's Textbook of Oral Pathology |last2=Sundaram S |date=2014 |publisher=Elsevier Health Sciences APAC |isbn=978-81-312-3800-4 |edition=7th |pages=867 |archive-url=https://web.archive.org/web/20170402091932/https://books.google.com/books?id=WnhtAwAAQBAJ&pg=P867 |archive-date=2 April 2017 |url-status=live}}</ref> or have a [[Nasality (disorder)|nasal quality]].<ref name="Scully2014" /> In some cases, a singing hobby or profession must be abandoned.<ref name="Scherer2005" />

===Head and neck===
Due to weakness of the [[muscles of facial expression]] and muscles of mastication, facial weakness may manifest as the inability to hold the mouth closed<ref name="Engel2012" /> (the "hanging jaw sign") and as a snarling expression when attempting to smile.<ref name="Scully2014" /> With drooping eyelids, facial weakness may make the individual appear sleepy or sad.<ref name="Engel2012" /> Difficulty in holding the head upright may occur.<ref name="Rajendran2014" />

===Other===
The [[Muscles of respiration|muscles that control breathing]] and limb movements can also be affected; rarely do these present as the first symptoms of MG, but develop over months to years.<ref>{{MedlinePlusEncyclopedia|000712|Myasthenia gravis}}</ref> In a myasthenic crisis, a [[paralysis]] of the respiratory muscles occurs, necessitating [[assisted ventilation]] to sustain life.<ref name="Rosen2014">{{Cite book |title=Rosen's emergency medicine: concepts and clinical practice |vauthors=Marx JA |date=2014 |publisher=Elsevier/Saunders |isbn=978-1-4557-0605-1 |edition=8th |location=Philadelphia |pages=1441–1444}}</ref> Crises may be triggered by various biological stressors such as infection, fever, an adverse reaction to medication, or emotional stress.<ref name="Rosen2014" />