Myasthenia Gravis

Myasthenia Gravis

• Autoimmune disease affecting the neuromuscular transmission of impulses in the muscles of the body

• Long-term neuromuscular disease that leads to varying degrees of skeletal muscle weakness

• Weakness increases with muscle use.

Myasthenia Gravis characterized by the presence

•  acetylcholine receptor (AChR) antibodies, which interferes with Acetylcholine, the chief neurotransmitter of the parasympathetic nervous system.

• This is the part of the autonomic nervous system that contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rate.

Nursing Assessment

• Normally begins at the top (head)

  • Diplopia

  • Ptosis

  • Masklike affect

    • Sleepy appearance due to facial muscle involvement

  • Weakness of laryngeal and pharyngeal muscles

    • Dysphagia, choking, food aspiration, difficulty speaking

  • Advanced cases: 

    • Respiratory failure, aspiration, respiratory infection

  • Muscle weakness improves with rest; worsens with activity

Diagnostic Studies

• history and physical exam

• tensilon test

• EMG

History and physical exam

• Muscle weakness

• Fatigue with prolonged upward gaze (2 to 3 min)

Tensilon (edrophonium chloride) Test

• Edrophonium chloride blocks an enzyme that breaks down acetylcholine, the chemical that transmits signals from your nerve endings to your muscle receptor sites. (which is important in regulating  neuromuscular transmission). 

• Temporary improvement in strength following injection of Tensilon indicates MG

EMG

• Decreased response to repeated stimulation of the hand muscles

Cholinergic crisis

• Trigger: Too much medication.  Over-stimulation at a neuromuscular junction due to an excess of anticholinesterase drugs.  Weakness 1 hour after ingestion of anticholinesterace drugs.  

• Acute worsening of muscle weakness (ptosis, dyspnea, salivation diarrhea, n, v, abd cramps, bronchial secretions, sweating, weak jaw and facial muscles)

Myasthenic crisis

• Trigger: Too little medication.  Resp infection, surgery, emotional distress, pregnancy, exposure to drugs, use of corticosteroids, or undermedication (not enough or drug resistance)

• Acute worsening of muscle weakness (ptosis, dyspnea, difficulty swallowing, difficulty articulating, weak jaw and facial muscles)

• Improved strength after administration of IV anticholinesterase drugs.

Collaborative Care…Drug Therapy

• Anticholinesterase agents…Ex. pyridostigmine. Enhance transmission at neuromuscular junction

• Corticosteroids…Ex. prednisone

• Immunosuppressive agents…Ex. azathioprine, mycophenolate

• FcRn inhibitors…Ex. efgartigimod. monoclonal antibody that stops the autoimmune response

Nursing Interventions

• If patient is hospitalized, ensure tracheostomy kit available for possible myasthenic crisis

• Teach patient importance of wearing a Medic Alert bracelet

• Administer medications as prescribed

• Encourage Coughing/Deep Breathing every 4-6 hrs 

  • Muscle weakness limits ability to cough up secretions

  • Prevent URI

• Bladder and respiratory infections are often a recurring problem with advanced disease

when should activities be scheduled

• Schedule morning activities to conserve energy

  • Allow for rest periods. Bedrest often relieves symptoms 

  • Plan activities during high energy times (often in early morning, after meds)

instruct the patient to avoid

•  situations that produce fatigue or physical or emotional stress 

  • Stress can exacerbate symptoms: Physical, emotional, spiritual

encourages foods that

•  are easily chewed and swallowed

teach patients to be aware

• medications such as β adrenergic blockers, calcium channel blockers, lithium, and aminoglycoside ATBS can worsen symptoms

• Patient requires frequent health promotion teachings

  • Teach side effects of medications (chol, myast crisis)

education about eyes for Myasthenia Gravis

• Protect eyes: dark glasses, artificial tears, ointment, report pain or drainage

Priority Problems and Goals

• Problems

  • Ineffective airway clearance  

  • Risk for injury  

  • Impaired physical mobility  

  • Risk for imbalanced nutrition: less than body requirements  

• Goals

  • Optimal muscle functioning

  • Free for med side effects

  • No complication (crisis) from MG

  • Maintain quality of life

A patient with myasthenia gravis asks the nurse “What is going to happen to me?” When formulating a response, the nurse understands which about the prognosis of this disease?

a. It is very good with proper treatment

b. It is a slowly progressive disease without remissions

c. It is a chronic condition marked by remissions and exacerbations

d. It is poor with death occurring in a few months

While caring for a patient with Myasthenia Gravis, you note that the patient is having difficulty mobilizing secretions. Which interventions should be implemented for this problem? Select all that apply.

a. Oropharyngeal suctioning as needed

b. Coughing and deep breathing

c. Oxygen at 2 L per nasal cannula

d. Chest physiotherapy

e. Plasmapheresis

During morning care for a patient with Myasthenia Gravis, the patient is able to brush her teeth, wash her face, and brush her hair but then becomes fatigued after performing these actions.  What would be the nurse’s best action?

a. Encourage her to continue with her own morning care to increase her strength.

b. Let her rest for 20 minutes and then continue self morning care.

c. Document that the patient refuses morning care because of fatigue.

d. Provide assistance in completing the patient’s morning care.