Myasthenia Gravis (MG) Flashcards
1
Q
Myasthenia Gravis (MG) Patho
A
- translate to “Grave muscle weakness”
- MG is an autoimmune disorder affecting the myoneural junction, characterized by weakness of the voluntary muscles at different levels. Worsens with exercise and improves with rest.
- Myasthenia gravis is an autoimmune disease of the neuromuscular junction (NMJ) caused by antibodies that attack components of the postsynaptic membrane, impair neuromuscular transmission, and lead to weakness and fatigue of skeletal muscle.
- The disease is characterized by an attack on acetylcholine by antibodies, resulting in decreased numbers of acetylcholine receptor sites at the neuromuscular junction.
- Antibodies directed at the acetylcholine receptor sites impair transmission of impulses across the myoneural junction
- leaves fewer receptors available for stimulation, resulting in voluntary muscle weakness that escalates with continued activity
- Excessive secretion of cholinesterase or not enough secretion of acetylcholine, or muscle fibers that do not respond to acetylcholine are causes of MG.
- The thymus gland plays a role in your immune response and is located in the upper chest beneath the sternum. It seems to foster the production of acetylcholine antibodies and can be removed
- Varying degrees of weakness of the skeletal (voluntary) muscles of the body.
- During periods of activity, there is pronounced muscle weakness but weakness improves after periods of rest.
- droopy eyes
- autonomic stuff works but diaphragm may be impacted
2
Q
MG Risk Factors
A
- pregnancy
- stress
- extremes of temperature
- certain drugs
- trauma
- menstruation
- Younger Women 20-30
- Men and women > 50
- Hyperthyroidism
- Genetic
- Thymus
3
Q
MG Nursing Assessment:
A
- Assess respiratory status-causes difficulty breathing & respiratory insufficiency
— decreased vital capacity
— decreased negative inspiratory force - Assess vision for possible double vision(diplopia), droopy eye lid (ptosis)
- Assess energy level
- Observe ability to eat; chewing and swallowing may be affected
- Assess client’s speech, may find difficulty speaking and/or client’s voice fades away with continuous conversation by progressive weakness to muscle. May hear hoarseness.
- Assess for infection as it can exacerbate MG, causing a myasthenic crisis
4
Q
MG s/s:
A
- Ocular- ptosis, diplopia
— dont drive
— A drooping eyelid, is the most frequent early sign of MG - Bulbar-chewing
- swallowing difficulty
- weak voice (dysphonia)
- snarl
- ## Generalized weakness
5
Q
MG Diagnostics/Laboratory Tests:
A
- Electromyography (EMG) detects a delay or failure of neuromuscular transmission-may find poor electrical activity
- *Acetylcholine receptor antibodies test will be positive for the antibodies
- CT to examine the thymus gland for tumors or other abnormalities in a client diagnosed with MG
- MRI: thymus gland
- too much acetylcholine = atropine
6
Q
MG Nursing process
A
- Prevention of corneal damage:
- instill artificial tears
- Diplopia-if this occurs in one eye, patch the affected eye
- Minimize risk for aspiration:
- Eat larger meals in the morning and smaller meals in the evening
- Mealtimes should coincide with peak effects of medication
- Medications must be given on time
- Energy conservation:
— Do most activities in the morning
— Rest before meals
7
Q
MG Nursing Interventions:
A
- Administer anticholinesterase drugs on time and monitor for adverse effects;
- Place emergency equipment at client’s bedside in the event of a cholinergic crisis or myasthenic crisis
- Monitor client’s respiratory system. Ensure effective breathing and monitor for respiratory failure
- Monitor for myasthenic crisis caused by insufficient medication, infection, fatigue or progression of MG that was not identified
- Monitor muscles for improved strength, indicating therapeutic effect of drugs
- Plan activities around times when client’s muscle strength is optimal
- Balance activity and rest to prevent fatigue
- Provide foods that are easy to swallow to decrease risk of aspiration.
- Monitor for aspiration.
8
Q
myasthenic crisis s/s / treatment
A
- Result of disease exacerbation or precipitating event, most commonly a respiratory infection
- Severe generalized muscle weakness with respiratory and bulbar weakness
- Patient may develop respiratory compromise failure
hypertension, tachycardia, and dilated pupils
— Treatment: Increase Anticholinesterase medications
— Monitor for cholinergic crisis caused by too much anticholinesterase medication.
9
Q
cholinergic (parasympathetic) crisis s/s. / treatment
A
- Caused by *overmedication with cholinesterase inhibitors (anticholinestrase drugs)
- Severe muscle weakness with respiratory and bulbar weakness
- Patient may develop respiratory compromise and failure
SLUD: salivation, lacrimation, urination, defication - nausea
- vomiting
- abdominal pain
- increased bronchial secretions
- blurred vision
- sweating
- constricted pupils
- bradycardia
- hypotension
— Treatment: Atropine (anticholinergic drug) (given if bradycardia) / let med pass out of system and support
10
Q
Anticholinergic crisis S/S:
A
- hot as a hare
- Dry as a bone
- Blind as a bat (dilated pupils)
- Red as a beet
- Mad as a hatter
11
Q
MG Medical Management (MEDs)
A
- Immunosuppressants – Imuran, Cytoxin
- Prednisone: a corticosteroid used to treat the immune response (keep pt on these corticosteroids)
- *Cholinesterase inhibitors
— Neostigmine: an anticholinesterase drug
— *Pyridostigimine bromide (Mestinon): an anticholinesterase
—- MOA: Inhibits the destruction of Ach by cholinesterase thereby making it more available
Side effects: Think parasympathetic stimulation (bradycardia, sweating, gi (rest n digest)
—- Atropine is the antidote (Atropine sulfate: Anticholinergic drug)
—- take meds 1 hour before meals to increase pt strength
12
Q
MG exacerbations (myasthenic crisis) meds/ treatment
A
Intravenous immune globulin (IVIG):
- Treat exacerbations (myasthenic crisis)
- IVIG is the administration of pooled human gamma-globulin and is usually given over a few hours, with multiple infusion over a few days
- Side effects: Patient may experience headaches, body aches and chills during the infusion; *pre-medicate as ordered
- Selected patients - used on a long-term adjunctive basis
- Improvement lasts about 28 days after infusion
13
Q
MG Non Pharmacological management
A
- Plasmapheresis (TPE- therapeutic plasma exchange)
- Blood is removed from the body and blood cells are separated from the plasma; the anticholinesterase antibodies are removed and blood cells are infused back into the body.
- Patient may have daily session for up to two weeks (during crisis)
- Patient may have low blood pressure, dizziness, blurred vision, and thrombosis
- Plasmapheresis improves MG symptoms within days and improvement lasts 6-8 weeks.
- Also removes meds (no meds prior?)
- Risks:
— Low BP
— dizziness
— blurred vision
— formation of blood clots (thrombosis).
14
Q
MG Surgical Treatment:
A
- Thymectomy-removal of the thymus gland
— *Three approaches; trans-sternal; trans-cervical and video-assisted thoroscopic surgery (safest/ least invasive)
—- trans-sternal: monitor Respritory status
— Patient is monitored in ICU post operatively
— Monitor respiratory status closely
— May take 3 years for the patient to benefit due to the long life of circulating T cells - Monitor respiratory status closely post op; complaints of chest pain could indicate bleeding which requires immediate notification of surgeon
15
Q
*A client with myasthenia gravis has been prescribed to take pyridostigmine (Mestinon). What health teaching will the nurse include related to this drug? Select all that apply.
A
- A. “Watch for signs and symptoms of myasthenic crisis.”
- B. “Take the drug about an hour before eating a meal.”
- C. “Take the same dose of medication every day.”
- D. “Take the drug with food to prevent nausea.”
- E. “Do not take sedatives or sleeping pills while on this drug.”
A, B, C, E.
