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| ==Symptoms== | | ==Symptoms== |
| The hallmark of myasthenia gravis is [[muscle weakness]] that increases during periods of activity and improves after periods of rest. Muscles that control eye and eyelid movement, facial expression, [[chewing]], [[Manner of articulation|talking]], and [[swallowing]] are especially susceptible. The muscles that control [[breath]]ing and neck and limb movements can also be affected. Often the physical examination is within normal limits.<ref name="Scherer">{{cite journal | author=Scherer K, Bedlack RS, Simel DL. | title=Does this patient have myasthenia gravis? | journal=[[JAMA]] | year=2005 | volume=293 | issue=15 | pages=1906–14 | pmid=15840866 | doi=10.1001/jama.293.15.1906}}</ref>
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| The onset of the disorder can be sudden or rapid. Often symptoms come and go over time. The diagnosis of myasthenia gravis may be delayed if the symptoms are subtle or variable.
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| In most cases, the first noticeable symptom is weakness of the eye muscles. In others, difficulty in swallowing and slurred speech may be the first signs. The degree of muscle weakness involved in MG varies greatly among patients, ranging from a localized form, limited to eye muscles ([[ocular myasthenia]]), to a severe or generalized form in which many muscles - sometimes including those that control breathing - are affected. Symptoms, which vary in type and severity, may include asymmetrical [[ptosis (eyelid)|ptosis]] (a drooping of one or both [[eyelid]]s), [[diplopia]] (double vision) due to weakness of the muscles that control eye movements, unstable or waddling gait, weakness in arms, hands, fingers, legs, and neck, a change in facial expression, [[dysphagia]] (difficulty in swallowing), shortness of breath and [[dysarthria]] (impaired speech, often nasal due to weakness of the pharyngeal muscles).
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| In ''myasthenic crisis'' a [[paralysis]] of the respiratory muscles occurs, necessitating [[assisted ventilation]] to sustain life. In patients whose respiratory muscles are already weak, crises may be triggered by [[infection]], [[fever]], an adverse reaction to medication, or emotional stress.<ref>{{cite journal | author=Bedlack RS, Sanders DB. | title=How to handle myasthenic crisis. Essential steps in patient care. | journal=Postgrad Med | year=2000 | volume=107 | issue=4 | pages=211–4, 220-2 | url=http://www.postgradmed.com/issues/2000/04_00/bedlack.htm | pmid=10778421}}</ref> Since the [[cardiac muscle|heart muscle]] is stimulated differently, it is never affected by MG.
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| ==References== | | ==References== |