Chapter 63: Myasthenia Gravis Flashcards
A nurse is caring for a patient diagnosed with myasthenia gravis (MG). The patient asks, “What should I expect from my condition?” The nurse’s response should include which of the following key characteristics of MG?
A) “You will experience progressive weakness that improves with activity.”
B) “You will have fluctuating weakness in certain muscles that worsens with activity.”
C) “Muscle weakness will remain constant and is not affected by activity.”
D) “Your condition is caused by an overactive immune system that affects the central nervous system.”
B) “You will have fluctuating weakness in certain muscles that worsens with activity.”
Rationale: Myasthenia gravis is characterized by fluctuating weakness in certain skeletal muscles that worsens with activity. This is a hallmark of the disease, as muscle strength often improves with rest and worsens with activity. The other options do not accurately reflect the nature of MG, such as suggesting progressive or constant weakness or involvement of the central nervous system, which is not the primary site of the autoimmune attack in MG.
A nurse is preparing to educate a group of nursing students on myasthenia gravis. Which of the following statements made by the students is correct regarding the disease’s onset?
A) “Myasthenia gravis primarily affects the muscles of the central nervous system.”
B) “Myasthenia gravis only occurs in older adults.”
C) “Myasthenia gravis can occur in anyone, regardless of age or gender.”
D) “Muscle weakness in myasthenia gravis is not affected by activity.”
C) “Myasthenia gravis can occur in anyone, regardless of age or gender.”
Rationale: Myasthenia gravis can occur in individuals of any age or gender. It is an autoimmune disease affecting the neuromuscular junction, not the central nervous system. The disease is not restricted to older adults, and muscle weakness is indeed exacerbated by activity, not unaffected by it.
A nurse is explaining the pathophysiology of myasthenia gravis (MG) to a patient. Which of the following statements should the nurse include in the explanation?
A) “MG occurs when the immune system attacks and destroys muscle fibers directly.”
B) “Myasthenia gravis causes an overproduction of acetylcholine at the neuromuscular junction.”
C) “The primary cause of MG is a genetic mutation that affects acetylcholine production.”
D) “The thymus gland gives incorrect instructions to immune cells, causing them to attack acetylcholine receptors.”
D) “The thymus gland gives incorrect instructions to immune cells, causing them to attack acetylcholine receptors.”
Rationale: In MG, the thymus gland plays a role in providing incorrect instructions to developing immune cells, which results in the production of antibodies that attack acetylcholine (ACh) receptors at the neuromuscular junction. This impairs muscle contraction. The other options incorrectly describe the pathophysiology of MG.
Which of the following findings is most likely to be present in the serum of most patients diagnosed with myasthenia gravis?
A) Anti-AChR antibodies
B) Low levels of acetylcholine
C) High levels of dopamine
D) Elevated white blood cell count
A) Anti-AChR antibodies
Rationale: Anti-acetylcholine receptor (AChR) antibodies are found in the serum of most patients with myasthenia gravis, and these antibodies play a critical role in impairing neuromuscular transmission by attacking and destroying ACh receptors. The other findings are not associated with MG.
A nurse is assessing a patient with myasthenia gravis and notices that they have no detectable autoantibodies. What is the most likely explanation for this finding?
A) The patient is in the early stages of the disease.
B) The patient has a rare form of myasthenia gravis that does not involve autoantibodies.
C) The patient’s antibodies are only detectable in the cerebrospinal fluid, not the serum.
D) The patient’s thymus gland is functioning normally.
B) The patient has a rare form of myasthenia gravis that does not involve autoantibodies.
Rationale: Some patients with myasthenia gravis do not have detectable autoantibodies. This can occur in rare forms of the disease, although most patients with MG will have anti-AChR antibodies in their serum. The other options are less likely explanations.
Which of the following antibody types, in addition to anti-AChR antibodies, is present in some patients with myasthenia gravis and can also reduce acetylcholine receptor sites?
A) IgE
B) MuSK and LRP4 antibodies
C) GABA antibodies
D) Beta-adrenergic antibodies
B) MuSK and LRP4 antibodies
Rationale: MuSK (muscle-specific kinase) and LRP4 (lipoprotein receptor-related protein 4) antibodies are present in some patients with myasthenia gravis and also contribute to reducing acetylcholine receptor (AChR) sites, further impairing neuromuscular transmission. The other antibody types listed are not associated with MG.
A patient diagnosed with myasthenia gravis asks the nurse how the disease affects muscle contraction. What is the nurse’s most accurate response?
A) “The immune system produces too much acetylcholine, overstimulating the muscles.”
B) “The immune system attacks the acetylcholine receptors, reducing the ability of acetylcholine to stimulate muscle contraction.”
C) “Your immune system prevents the release of acetylcholine from nerve endings, leading to muscle paralysis.”
D) “The muscle fibers become resistant to acetylcholine, causing muscle weakness.”
B) “The immune system attacks the acetylcholine receptors, reducing the ability of acetylcholine to stimulate muscle contraction.”
Rationale: In myasthenia gravis, the immune system attacks and destroys acetylcholine (ACh) receptors at the neuromuscular junction, preventing ACh from attaching to the receptors and stimulating muscle contraction. This leads to muscle weakness. The other responses incorrectly describe the pathophysiology of MG.
Which of the following is the primary cause of myasthenia gravis?
A) Overproduction of acetylcholine by the motor neurons
B) Genetic mutations affecting neurotransmitter receptors
C) An autoimmune response that targets acetylcholine receptors
D) Degeneration of the motor neurons in the spinal cord
C) An autoimmune response that targets acetylcholine receptors
Rationale: The primary cause of myasthenia gravis is an autoimmune response in which antibodies attack and destroy acetylcholine receptors at the neuromuscular junction. This impairs muscle contraction and leads to fluctuating muscle weakness. The other options are not accurate descriptions of the disease’s etiology.
A patient with myasthenia gravis (MG) reports difficulty speaking and swallowing after a long conversation. Which of the following is the most likely explanation for this finding?
A) The patient is experiencing a myasthenic crisis due to respiratory insufficiency.
B) The patient has developed muscle atrophy, which is affecting speech and swallowing.
C) Muscle weakness from MG worsens with continued activity, particularly in muscles used for speech and swallowing.
D) The patient is experiencing sensory loss, which is affecting their ability to speak and swallow.
C) Muscle weakness from MG worsens with continued activity, particularly in muscles used for speech and swallowing.
Rationale: Muscle weakness in myasthenia gravis worsens with continued activity, particularly in muscles involved in repetitive movements, such as those used for speaking and swallowing. This can lead to difficulties after prolonged use. MG does not cause muscle atrophy or sensory loss, and a myasthenic crisis is typically triggered by respiratory infection or stress, not prolonged speech.
Which of the following muscles is most likely to be affected first in a patient with myasthenia gravis (MG)?
A) Muscles of the trunk and limbs
B) Ocular muscles
C) Muscles of the neck and shoulders
D) Muscles responsible for breathing
B) Ocular muscles
Rationale: In more than half of patients with myasthenia gravis, the first muscles affected are the ocular muscles, leading to symptoms like ptosis (drooping of the eyelids) and double vision. The other muscle groups may be affected later in the disease course.
A nurse is caring for a patient with myasthenia gravis who is experiencing fatigue and muscle weakness by the end of the day. What is the most appropriate nursing intervention to improve the patient’s strength?
A) Encourage the patient to engage in strenuous physical therapy.
B) Advise the patient to take a period of rest during the day to restore strength.
C) Instruct the patient to eat larger meals with increased protein intake.
D) Recommend the patient take over-the-counter pain relievers to reduce muscle discomfort.
B) Advise the patient to take a period of rest during the day to restore strength.
Rationale: Muscle weakness in MG is often relieved by rest, as muscles are typically strongest in the morning and become fatigued with continued activity. Resting during the day can help restore muscle strength. Strenuous physical therapy, increased protein intake, and pain relievers are not effective interventions for this type of fatigue.
Which of the following is the most common trigger for a myasthenic crisis in a patient with myasthenia gravis?
A) Stress
B) Hypokalemia
C) Dehydration
D) Sensory loss
A) Stress
Rationale: Stress is a common trigger for a myasthenic crisis, along with other factors such as respiratory infection, surgery, pregnancy, and exposure to certain drugs. Stress can exacerbate muscle weakness in MG, leading to a crisis. Hypokalemia and dehydration are not common triggers for a myasthenic crisis, and sensory loss is not associated with MG.
Which of the following is a complication of myasthenic crisis related to the muscles affected by myasthenia gravis?
A) Aspiration or respiratory insufficiency
B) Hemorrhagic stroke
C) Cardiac arrhythmias
D) Urinary retention and kidney failure
A) Aspiration or respiratory insufficiency
Rationale: In a myasthenic crisis, muscle weakness in the respiratory muscles or muscles involved in swallowing can result in aspiration or respiratory insufficiency. This is a life-threatening complication that may require a ventilator or noninvasive respiratory support. The other options are not associated with myasthenic crises.
A nurse is reviewing the medication list for a patient with myasthenia gravis. Which of the following medications should the nurse be cautious about, as it may exacerbate the patient’s symptoms?
A) Penicillin
B) β-adrenergic blockers
C) Acetaminophen
D) Diuretics
B) β-adrenergic blockers
Rationale: Certain drugs, including β-adrenergic blockers, calcium channel blockers, lithium, quinidine, and aminoglycoside antibiotics, can worsen symptoms of myasthenia gravis. These medications may further impair neuromuscular transmission, exacerbating weakness. The other drugs listed are not typically associated with worsening MG symptoms.
A patient with myasthenia gravis asks the nurse about the role of the thymus in their condition. What is the most accurate response?
A) “The thymus produces acetylcholine, which is necessary for muscle contraction.”
B) “The thymus is unaffected in myasthenia gravis and does not contribute to the disease process.”
C) “The thymus regulates the function of the neuromuscular junction and prevents muscle weakness.”
D) “The thymus gives incorrect instructions to immune cells, causing them to attack acetylcholine receptors.”
D) “The thymus gives incorrect instructions to immune cells, causing them to attack acetylcholine receptors.”
Rationale: In myasthenia gravis, the thymus gland is thought to give incorrect instructions to developing immune cells, leading to the production of antibodies that attack acetylcholine receptors. This is a key feature of the disease’s pathophysiology. The other options are not accurate regarding the role of the thymus in MG.
Which of the following muscle groups is most likely to be affected in the later stages of myasthenia gravis?
A) Ocular muscles
B) Muscles of the trunk and limbs, particularly the proximal muscles of the neck, shoulder, and hip
C) Muscles of the face and jaw
D) Muscles involved in digestion and elimination
B) Muscles of the trunk and limbs, particularly the proximal muscles of the neck, shoulder, and hip
Rationale: In later stages of myasthenia gravis, muscle weakness often involves the proximal muscles of the trunk and limbs, particularly those in the neck, shoulders, and hips. The ocular muscles are often affected first, and facial muscles may also be involved later. Muscles of digestion and elimination are not typically involved in MG.
Which of the following statements is true regarding muscle weakness in patients with myasthenia gravis?
A) Muscle weakness is most pronounced in the morning and improves with activity.
B) Muscle weakness is constant throughout the day, regardless of activity levels.
C) Muscle weakness worsens with activity, especially in muscles used for repetitive movements.
D) Muscle weakness is always accompanied by sensory loss and abnormal reflexes.
C) Muscle weakness worsens with activity, especially in muscles used for repetitive movements.
Rationale: In myasthenia gravis, muscle weakness worsens with activity, particularly in muscles used for repetitive movements. This includes muscles such as those used for eye movement, chewing, and speaking. Muscle strength is often stronger in the morning and improves with rest.
A nurse is assessing a patient with myasthenia gravis who is experiencing double vision and drooping eyelids. Which of the following actions should the nurse prioritize?
A) Administer a corticosteroid to manage inflammation.
B) Assist the patient with activities of daily living to reduce fatigue.
C) Monitor respiratory status and assess for signs of aspiration.
D) Encourage the patient to increase fluid intake to prevent dehydration.
C) Monitor respiratory status and assess for signs of aspiration.
Rationale: Although double vision and drooping eyelids are common manifestations of myasthenia gravis, the most critical action is to monitor respiratory status and assess for aspiration risk, as muscle weakness affecting swallowing and breathing can lead to life-threatening complications. The other actions, while important, are not as immediately life-threatening.
A nurse is preparing to assist with the edrophonium test for a patient suspected of having myasthenia gravis (MG). Which of the following actions should the nurse take to ensure patient safety during the test?
A) Administer atropine if the patient shows signs of muscle weakness after the injection.
B) Monitor the patient for signs of respiratory distress only if the patient has a history of asthma.
C) Instruct the patient to hold their breath after receiving the injection to prevent complications.
D) Have atropine readily available to counteract any adverse effects of the test.
D) Have atropine readily available to counteract any adverse effects of the test.
Rationale: Edrophonium is an anticholinesterase agent that can cause adverse effects such as bradycardia or respiratory distress. Atropine, a cholinergic antagonist, should be readily available to counteract these effects during the diagnostic test. It is not recommended to administer atropine unless there are specific symptoms requiring it.
Which of the following findings on a single-fiber EMG would most likely confirm a diagnosis of myasthenia gravis (MG)?
A) A decreased response to repeated stimulation of the hand muscles, showing muscle fatigue.
B) Increased muscle fiber activity during sustained muscle contractions.
C) Normal response to repeated stimulation of the hand muscles.
D) Abnormal spontaneous muscle fiber contractions without stimulation.
A) A decreased response to repeated stimulation of the hand muscles, showing muscle fatigue.
Rationale: Single-fiber EMG is highly sensitive for diagnosing myasthenia gravis and typically shows a decreased response to repeated stimulation, reflecting muscle fatigue. This is a key diagnostic feature of MG.
A nurse is explaining the purpose of a chest CT scan to a patient diagnosed with myasthenia gravis (MG). Which of the following is the most accurate statement the nurse can make?
A) “The chest CT scan is used to detect any possible infections that may be present in your lungs.”
B) “The chest CT scan will help us assess the size and condition of your thymus gland.”
C) “A chest CT scan can determine the exact cause of your muscle weakness.”
D) “The CT scan is performed to assess for any brain abnormalities causing MG symptoms.”
B) “The chest CT scan will help us assess the size and condition of your thymus gland.”
Rationale: In patients with myasthenia gravis, a chest CT scan is used to evaluate the thymus gland, as it may be abnormal in some individuals with MG. This is not typically used to assess for infections or brain abnormalities.
Which of the following diagnostic tests is highly sensitive and commonly used to confirm the diagnosis of myasthenia gravis (MG)?
A) Chest X-ray
B) Single-fiber EMG
C) MRI of the brain
D) Serum potassium levels
B) Single-fiber EMG
Rationale: Single-fiber EMG is highly sensitive in confirming the diagnosis of myasthenia gravis. It can reveal muscle fatigue and decreased response to repeated stimulation, which is characteristic of MG.
