1. Myasthenia GravisAn autoimmune neurologic disorder By Lexi
Gray & Mary Kacic
2. 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.
3. 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
4. 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
5. Pathophysiology Autoimmune disease: the antibodies that
attack or block the acetylcholine receptors are produced by the
bodys own immune system Thymic hyperplasia or a thymic tumor is
present in 80% of people with myasthenia gravis
6. 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.
7. 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.
8. 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 patients 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.
9. 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-fowlers position, which will
ensure upper airway patency. Give food with a pudding-like
consistency, which can be more easily swallowed.
10. 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
11. 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:
12. Possible Side Effects ofAnticholinesterase Meds Central
Respiratory/ Skeletal Muscles Nervous System Cardiovascular
Irritability Bronchial relaxation Fasciculations Anxiety Increased
bronchial Spasms secretions Insomnia Tachycardia Weakness Headache
Hypotension Genitourinary Dysarthia Frequency Gastrointestinal
Syncope Abdominal cramps Urgency Seizures Nausea,vomiting and
diarrhea Integumentary Coma Anorexia Rash Diaphoresis Increased
Salivation Flushing
13. Treatments Plasmatheresis This procedure removes the
patients 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.
14. 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.
15. Myasthenia (or cholinergic) Crisis Exacerbation of the
disease process. Signs & symptoms include 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.
16. ReferencesDoenges, M., Moorhouse, M., Murr, A. (2010).
Nurses 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 & Suddarths textbook of
medical-surgical nursing (11th ed.). Philadelphia: Lippincott
Williams & Wilkins.