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Myasthenia Gravis
An autoimmune neurologic disorder
By Lexi Gray & Mary Kacic
Background
 Myasthenia gravis means “grave muscle weakness”
 It is an autoimmune disease affecting the myoneural
junction
 About 60,000 people in the U.S. have this disease
 Women affected more frequently than men, at around
20-40 years of age. Men develop it later, at around 60-70
years of age.
Symptoms
 Causes varying degrees of skeletal muscle weakness
 Hallmark of the disease: muscle weakness increases during
periods of activity and improves during rest.
 Areas that MAY be affected: eyes/eyelid movement, facial
expression, chewing, talking, swallowing
Pathophysiology
 Normal communication between the nerve and muscle is
interrupted at the neuromuscular junction (where nerve cells meet
with the muscles they control)
 Normally, nerve endings release acetylcholine which travels through
the NMJ and binds to receptors, causing muscle contraction.
 In myasthenia gravis, these receptors are blocked or destroyed
Pathophysiology
 Autoimmune disease: the antibodies that attack or block the
acetylcholine receptors are produced by the body’s own
immune system
 Thymic hyperplasia or a thymic tumor is present in 80% of
people with myasthenia gravis
Assessment
 Onset of the disorder may be sudden
 Many times, symptoms are not immediately recognized as
being related to myasthenia gravis
 In most cases, weakness of the eye muscles is noticed first.
Assessment - Severe Symptoms
 Ptosis – drooping of one or both eyelids
 Diplopia – blurred or double vision
 Bulbar symptoms – weakness of muscles of the face & throat
 Bland facial expression
 Difficulty swallowing – increased risk of choking & aspiration
 Dysarthia – impaired speech
 Dysphonia – voice impairment
 Weakness In arms, hands, legs, neck
 Generalized weakness also effects intercostal muscles, resulting
in decreasing vital capacity and respiratory failure.
Confirming the Diagnosis
 Acetylcholinesterase Inhibitor Test
 Confirms the diagnosis of myasthenia gravis. During this test, the
breakdown of acetylcholine is stopped. As a result, acetylcholine is
able to accumulate at the receptor sites.
 For this test, edrophoniumchloride is administered IV. Facial
muscle weakness and ptosis will resolve about 30 second after the
drug is administered, if the patient is positive for a myasthenia
gravis diagnosis. This relief lasts only 5 minutes, so it is not
considered a treatment.
 After the drug is administered, the patient's serum is then tested
for acetylcholine receptor antibodies, which would also be
consistent with the diagnosis.
 In some cases, patients with myasthenia gravis may have an
enlarged thymus gland.
Nursing Diagnosis #1
 Risk for aspiration R/T difficulty swallowing, weakness of
bulbar muscles
 Overall goal: No aspiration will occur
 Interventions
 Give meals with anticholinesterase meds to inhibit breakdown
of acetylcholine and increase its concentration at the NMJ
 Raise the HOB to semi-fowler’s position, which will ensure
upper airway patency.
 Give food with a pudding-like consistency, which can be more
easily swallowed.
Nursing Diagnosis #2
 Deficient knowledge R/T drug therapy, potential for crisis
(myasthenic or cholinergic), and self-care management
 Overall goal: Patient will demonstrate knowledge of
medication management, importance of rest, coping
strategies, and prevention/management of complications
 Interventions
 Teach patient about the actions of meds, and importance of
regimen. The patient will verbalize the consequences delaying
med intake, including S&S of myasthenic and cholinergic crisis.
 Teach strategies for patient to conserve their energy. The patient
will develop coping strategies to avoid overexertion.
 If eyes cannot close properly, instruct patient to patch/tape eyes
closed for short intervals to avoid corneal damage.
Treatment of myasthenia gravis
 Pharmacologic Treatment
 First-line med is pyridostrigmine bromide (Mestinon), an
anticholinesterase that inhibits the breakdown, thus improving
skeletal muscle contraction. Side effects can include
fasciculations, abdominal pain, diarrhea.
 Immunosuppressive Therapy: Corticosteroids decrease the
amount of antibody production. Cytotoxic meds
(Azathioprine) inhibits production of T-and B-cells, and
effects may not be seen for 3-12 months. Hepatotoxicity is a risk
of using cytotoxic meds.
 Some common medications exacerbate the symptoms of
myasthenia gravis, including: antibiotics, beta-blockers,
antiseizure meds, Novocain, morphine and quinine.
Possible Side Effects of
Anticholinesterase Meds
Central
Nervous System
Respiratory/
Cardiovascular
Skeletal Muscles
Irritability
Bronchial relaxation
Fasciculations
Anxiety
Increased bronchial secretions
Spasms
Insomnia
Tachycardia
Weakness
Headache
Hypotension
Genitourinary
Dysarthia
Frequency
Gastrointestinal
Syncope
Abdominal cramps
Seizures
Nausea, vomiting and diarrhea
Urgency
Integumentary
Coma
Anorexia
Rash
Diaphoresis
Increased Salivation
Flushing
Treatments
 Plasmatheresis
 This procedure removes the patient’s plasma and plasma
components through a centrally placed catheter. Blood cells are
separated from antibody-containing plasma. The blood cells are
then mixed with plasma substitute and reinfused. Provides
temporary treatment for severe symptoms.
 Intravenous immune globulin
 Treats exacerbations of myasthenia gravis temporarily. This
procedure does not work as quickly as plasmatheresis.
These are treatments for myasthenia gravis, not cures.
Treatments
 Surgical Treatments
 Thymectomy: Surgical removal of the thymus gland,
which may result in the production of antigen-specific
immunosuppression, which results in clinical
improvement. Results vary; patient may have partial or
complete remission, or no remission at all.
 Nursing considerations for the patient who received a
thymectomy include monitoring respiratory function and
mechanical ventilation.
Myasthenia (or cholinergic) Crisis
 Exacerbation of the disease process. Signs & symptoms include
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muscle/bulbar weakness.
Causes for myasthenia crisis may include a respiratory infection,
pregnancy, or medications.
Primary management is focused on maintaining the airway. The
nurse assesses respiratory rate, depth, breath sounds, and
pulmonary function. Endotracheal intubation and mechanical
ventilation may be necessary.
Assess arterial blood gases, I&O, daily weight.
Avoid sedatives and tranquilizers.
Bradycardia and respiratory distress (emergency situations) are
treated with atropine.
References
Doenges, M., Moorhouse, M., Murr, A. (2010). Nurse’s Pocket
Guide: Diagnoses, Prioritized Interventions, and Rationales
(12th ed.). Philadelphia: F.A. Davis. ISBN: 0803622341.
Smeltzer, S. C., Bare, B. G., Hinkle, J. L. & Cheever, K. H.
(eds.) (2008). Brunner & Suddarth's textbook of medical-surgical
nursing (11th ed.). Philadelphia: Lippincott Williams &
Wilkins.