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Related to myasthenic: Myasthenic crisis


Relating to myasthenia.



Relating to myasthenia.


(mī″ăs-thē′nē-ă) [ my- + -asthenia]
Muscular weakness and abnormal fatigue. myasthenic (-then′ik), adjective

myasthenia gravis

Abbreviation: MG
An autoimmune motor disorder marked by muscular fatigue that develops with repetitive muscle use and improves with rest or with the application of a cold pack. It is caused by antibodies to the acetylcholine receptor in the neuromuscular junction and a decrease in receptor sites for acetylcholine. Because the smallest concentration of acetylcholine receptors in the body is in the cranial nerves, weakness and fatigue of the eye muscles, muscles of mastication, and pharyngeal muscles are the most prominently affected in most patients, but any (skeletal) muscle group may be involved. The disease is rare, affecting about 14 people out of 100,000.


Diagnosis is made on the basis of patient history, a thorough neurological examination, electromyography, repetitive nerve stimulation, a Tensilon test, or a combination of these tests. Intravenous injection of Tensilon significantly improves muscle weakness within 60 sec, lasting up to 30 min Acetylcholinesterase receptor antibody titers in the blood are elevated in about 50% to 70% of patients with myasthenia gravis.


Clinical signs include ptosis of the eyelid and double vision due to fatigue and weakness in the extraocular muscles, and difficulty chewing and swallowing from impaired facial and pharyngeal muscles. Speech that becomes progressively more dysarthric during prolonged dialogue is another common symptom. Symptoms are exacerbated by repetitive muscle use, and, in some patients, by menses, emotional stress, prolonged exposure to sunlight or cold, and infections. Myasthenia gravis crisis is a sudden exacerbation of symptoms with respiratory failure.


The primary treatment is with anticholinesterases and immunosuppressive agents. Anticholinesterase therapy often becomes less effective as the disease worsens. In selected patients, removal of the thymus, plasmapheresis, or immunoglobulin therapy is used.

Patient care

The patient with MG should seek medical attention immediately if he or she experiences difficulty breathing, talking, chewing, or swallowing. These symptoms may herald a myasthenic crisis. In crisis the patient's cardiovascular, neurologic, and respiratory status should be monitored in an intensive care unit. Suctioning the airway and postural changes may sometimes maintain adequate oxygenation and ventilation. If not, the patient will need intubation and positive-pressure ventilation. Exercise, meals, and care activities should be planned around medication-induced energy peaks. The patient should be taught that soft but solid foods are more easily managed than liquids when swallowing is difficult. Additional help for patients is available through support groups and Internet-based resources such as the Myasthenia Gravis Foundation of America (


Because edrophonium (Tensilon) occasionally causes significant bradycardia or asystole, atropine should be kept at the bedside of any patient given this medication.
References in periodicals archive ?
After surgery, patients were transferred to the intensive care unit for elective overnight ventilation; midazolam and fentanyl infusions were discontinued early morning of the following day, no anticholinesterase drugs were added, and patients received their normal myasthenic therapy via the nasogastric tube.
At the age of 40, he had a myasthenic crisis with intercostal and diaphragmatic muscle effort; invasive MV was initiated to maintain vital functions.
A thymectomy, often performed on myasthenic patients, renders varying degrees of success.
Andrew Engel, director of the Neuromuscular Research Laboratory at the Mayo Clinic and senior author of the finding, explains that the myasthenic patient exhibited normal function at the neuromuscular junction, but once the signal traveled to the muscle, it failed to excite, or spread over, the length of the muscle.
There were no associated myasthenic or paraneoplastic symptoms in all these cases.
In patients with myasthenia gravis or myasthenic (Eaton-Lambert) syndrome, small doses of non-depolarizing neuromuscular blocking agents may have profound effects.
Alsharabati's proposal to investigate subcutaneous immunoglobulin (SCIg) versus intravenous immunoglobulin (IVIg) in the management of neuromuscular junction (NMJ) disorders was chosen for its focus on myasthenia gravis and Lambert Eaton Myasthenic Syndrome.
Subjects with probable congenital myasthenic syndromes, i.
Two-year-old Isabella Shotton suffers from the incredibly rare condition Congenital Myasthenic Syndrome (CMS), a terrifying illness that means she could stop breathing at any moment.
Kerry Webster, whose sons James and Adam have the rare muscle disease congenital myasthenic syndrome, have been taking the drug 3,4DAP for the past 10 years.