Myasthenia Gravis: Overview and Practice Questions (2023)

Myasthenia Gravis is a chronic autoimmune disorder marked by progressive muscle weakness and fatigue.

The condition stems from a breakdown in neuromuscular communication, attributed to antibodies that block or destroy muscle receptor cells, impacting voluntary muscle control and causing symptoms such as ptosis, diplopia, and difficulty swallowing.

This guide provides an overview of Myasthenia Gravis and lists helpful practice questions for those looking to learn the essentials of this condition.

What is Myasthenia Gravis?

Myasthenia Gravis is a chronic autoimmune neuromuscular disorder characterized by weakness and rapid fatigue of any of the muscles under voluntary control. It is caused by a breakdown in the normal communication between nerves and muscles due to the immune system producing antibodies that attack receptors on muscle cells that are necessary for the muscles to respond to nerves.

Symptoms

Signs and symptoms of Myasthenia Gravis may include:

• Muscle weakness
• Drooping of one or both eyelids (ptosis)
• Blurred or double vision (diplopia)
• Slurred speech (dysarthria)
• Difficulty swallowing (dysphagia)
• Weakness in arms, hands, fingers, legs, and neck
• Chronic muscle fatigue
• Changes in facial expression
• Shortness of breath

Diagnosis

The diagnosis of Myasthenia Gravis is often confirmed through a series of tests such as blood tests, edrophonium test, nerve conduction studies, electromyography (EMG), and imaging studies.

Treatment

Treatment for Myasthenia Gravis focuses on managing symptoms and can include:

• Medications: Cholinesterase inhibitors such as pyridostigmine can improve communication between nerves and muscles. Immunosuppressive drugs may also be used.
• Thymectomy: The surgical removal of the thymus gland, which is thought to play a role in the abnormal immune response seen in Myasthenia Gravis.
• Plasmapheresis and intravenous immunoglobulin (IVIG): These therapies help to remove the antibodies that block neurotransmission or give the body a more normal balance of antibodies, temporarily decreasing the symptoms of Myasthenia Gravis.
• Chronic immunosuppression: This can involve long-term use of steroids or other immunosuppressive agents to control the autoimmune response.

Prognosis

While there is no cure for Myasthenia Gravis, treatment can help manage symptoms, and many people with the condition can lead normal or nearly normal lives.

In some cases, the disease may go into remission, either spontaneously or as a response to treatment, and muscle weakness may disappear completely so that medications can be discontinued.

Myasthenia Gravis Practice Questions

1. What is the definition of myasthenia gravis?
A chronic disorder of the neuromuscular junction that interferes with the chemical transmission of acetylcholine (ACh) between the axonal terminal and the receptor sites of voluntary muscles characterized by weakness and rapid fatigue of any of the muscles under your voluntary control.

2. What causes myasthenia gravis?
A breakdown in the normal communication between nerves and muscles.

3. What is the hallmark clinical feature of myasthenia gravis?
Fluctuating skeletal muscle weakness, often with true muscle fatigue.

4. How to memorize myasthenia gravis?
Remember that it’s a descending disorder. Furthermore, you can memorize it by using the first letters, ‘M’ and ‘G’, because the disease progresses from the ‘mind’ to the ground.

5. What are two clinical types of myasthenia gravis?
Ocular and generalized

6. What is ocular myasthenia gravis?
A type of myasthenia gravis where muscle weakness is limited to the eyelids and extraocular muscles.

7. What form of myasthenia gravis manifests muscle weakness involving a variable combination of muscles of the mouth and throat, which is responsible for speech and swallowing, limbs, and respiratory muscles?
Generalized myasthenia gravis

8. How will a generalized myasthenia gravis patient appear if facial muscles are involved?
Expressionless

9. What form of myasthenia gravis may, or may not, involve the ocular muscle?
Generalized

10. How may myasthenia gravis associated with abnormal weakness manifest itself?
It may be confined to an isolated group of muscles (e.g., the drooping of one or both eyelids), or it may manifest as a generalized weakness that in severe cases includes the diaphragm.

11. What is a “myasthenic crisis”?
It is a complication of myasthenia gravis characterized by worsening muscle weakness, resulting in respiratory failure that requires intubation and mechanical ventilation. When the diaphragm is involved, ventilatory failure can develop.

12. What is the etiology of myasthenia gravis?
It is related to circulating antibodies of the autoimmune system. This disease is provoked by emotional upset, physical stress, exposure to extreme temperature changes, pregnancy, and febrile illness.

13. What is the past medical history of myasthenia gravis patients?
Gradual onset of weakness and may have previous admissions for myasthenia gravis.

14. What is the physical appearance of patients with myasthenia gravis?
General weakness that improves with rest, drooping eyelids (ptosis), double vision (diplopia), and dysphasia.

15. What is the respiratory pattern seen in myasthenia gravis patients?
Shallow breathing

16. What breath sounds are seen in myasthenia gravis patients?
Diminished

17. What are the special tests for myasthenia gravis?
Edrophonium (Tensilon) Challenge Test, electromyography, blood test for Ach Receptor Antibodies, and the Ice Pack Test.

18. What spontaneous ventilatory parameters are seen with myasthenia gravis?
Decreasing Vt, VC, and MIP.

19. What pulmonary function testing results are seen with myasthenia gravis?
Reduced volumes (i.e., FVC, Vt)

20. What are the basic therapeutic modalities for myasthenia gravis?
Acetylcholinesterase inhibitors, immunotherapy, rapid immunotherapies, thymectomy, and the avoidance of drugs that may exacerbate myasthenia.

21. What should be done if the Vt, VC, MIP, and weakness worsens with Tensilon?
Administer atropine to reverse Tensilon

22. What is the treatment for myasthenia gravis?
Closely monitor Vt, VC, and MIP; intubate and institute mechanical ventilation when indicated; bedrest restriction and soft diet to reduce symptoms; oxygen therapy for hypoxemia and pulmonary hygiene; other treatment modalities include corticosteroids in severe cases, thymectomy, and plasmapheresis.

23. What is the usual peak age of myasthenia gravis onset?
In females between 15 to 35 years old and between 40 to 70 years old in males.

24. When is death caused by myasthenia gravis possible?
During the first few years after onset.

25. What are the screening methods and tests used to diagnose myasthenia gravis?
Clinical presentation and history; bedside tests; immunologic studies; electrodiagnostic studies; and, evaluation of conditions associated with myasthenia gravis.

26. What is a generalized characteristic of myasthenia gravis?
The muscles become progressively weaker during periods of activity and improve after periods of rest.

27. What are the signs and symptoms of myasthenia gravis?
Facial muscle weakness; ptosis (drooping of one or both eyelids); diplopia (double vision); ophthalmoplegia (paralysis or weakness of one or more of the muscles that control eye movement); difficulty in breathing, speaking, chewing, and swallowing; unstable gait; and, weakness in arms, hands, fingers, legs, and neck brought on by repetitive motions.

28. What are especially susceptible and are usually affected first in myasthenia gravis?
The muscles that control the eyes, eyelids, face, and throat.

29. What can become weak and impair patients’ ventilation in myasthenia gravis?
The respiratory muscles of the diaphragm and chest wall.

30. What will impairment in deep breathing and coughing predispose myasthenia gravis patients to?
Excessive bronchial secretions, atelectasis, and pneumonia.

31. What are the characteristics of the signs and symptoms of myasthenia gravis during the early stages?
Often elusive.

32. What are the characteristics of myasthenia gravis onset?
Subtle, intermittent, or sudden and rapid.

33. How is the direction of paralysis in myasthenia gravis characterized?
Descending (i.e., mind to ground)

34. What could occur if a myasthenia gravis patient is not properly managed?
Mucous accumulation with airway obstruction, alveolar consolidation, and atelectasis.

35. When do myasthenia gravis patients show signs of weakness?
Late in the day or evening.

36. What is an important sign and symptom for a respiratory therapist to be aware of in myasthenia gravis?
The development of a sudden and transient generalized weakness that includes the diaphragm, and ventilatory failure.

37. What is the first noticeable symptom of myasthenia gravis in most cases?
Weakness of the eye muscles (droopy eyelids) and a change in the patient’s facial expressions.

38. Where can weakness develop as myasthenia gravis becomes more generalized?
In the arms and legs.

39. Where is muscle weakness usually more pronounced with myasthenia gravis?
In the proximal parts of the extremities.

40. What is the ice pack test?
A very simple, safe, and reliable procedure for diagnosing myasthenia gravis in patients who have ptosis.

41. What is the advantage of using the ice pack test in myasthenia gravis?
It does not require special medications or expensive equipment and is free of adverse effects.

42. What does the ice pack test consist of?
The application of an ice pack to the patient’s symptomatic eye for 3 to 5 minutes.

43. When can tests be considered positive for myasthenia gravis?
If there is an improvement in the ptosis (i.e., an increase of at least 2 mm in the palpebral fissure from before to after the test).

44. What is a major disadvantage of the ice pack test?
It is useful only when ptosis is present.

45. What is ptosis?
Drooping of one or both eyelids

46. What is diplopia?
Double vision

47. What is ophthalmoplegia?
Paralysis or weakness of one or more of the muscles that control eye movement.

48. What difficulties may be shown in a myasthenia gravis patient’s clinical history?
Breathing, speaking, chewing, and swallowing

49. What kind of gait is manifested by myasthenia gravis patients?
Unstable

50. What can be brought on by repetitive motions in myasthenia gravis patients?
Weakness in arms, hands, fingers, legs, and neck.

51. Why is the reliability of the ice pack test in patients with diplopia without ptosis questionable?
Because the patients’ personal impression of the diplopia is subjective.

54. When is the edrophonium (Tensilon) test used?
In patients with obvious ptosis or ophthalmoparesis.

55. What can occur when muscular weakness is caused by myasthenia gravis and edrophonium is used?
A dramatic transitory improvement in muscle function lasting about 10 minutes.

56. What is a disadvantage of the edrophonium test?
It can be complicated by cholinergic side effects that include cardiac arrhythmias and cardiopulmonary arrest.

57. What neurotransmitter is associated with myasthenia gravis?
Acetylcholine receptor antibodies destroy Ach receptors, which prevent the transmission of muscle actions.

58. What age and gender does myasthenia gravis affect most often?
Women under 40 and men over 60

59. What is the rate of progression of myasthenia gravis?
Relatively sudden

60. What is dysarthria?
Difficulty speaking

61. What is dysphagia?
Difficulty swallowing

62. How is myasthenia gravis diagnosed?
Physical test: reveals easy fatigability; Blood test: tests for antibodies against acetylcholine receptor; Ice test: put on the eyelid to see if the droop contracts, the antibody of ACh are blocked, where the ice pack is applied, it shows muscle improvement; and, Spirometry: lung functions.

63. What is the goal of medical treatment for myasthenia gravis?
Treat respiratory problems.

64. What are the four common medical interventions for myasthenia gravis?
Medications: ACh inhibitors/steroids; Surgery: thymectomy; IVIG: intravenous immune globulin, immune system booster: and, Plasmapheresis: filters things out of your bloodstream (effective but temporary).

65. What are the challenges experienced with myasthenia gravis?
Muscle weakness, fatigue, and cognitive problems from fatigue.

66. What is the difference between ALS and myasthenia gravis?
Myasthenia gravis is not progressive, while ALS is.

67. What may be found in a physical examination of myasthenia gravis patients?
Adverse respiratory rate and cyanosis (in severe cases)

68. What is the FVC value for impending acute ventilatory failure related to myasthenia gravis?
Less than 20 mL/kg

69. What is the PaCO2 value for impending acute ventilatory failure related to myasthenia gravis?
Greater than 45 mmHg

70. What is neonatal myasthenia?
A transient condition affecting some newborns born to mothers with myasthenia gravis, an autoimmune disorder. This condition occurs when antibodies from a mother with myasthenia gravis are transferred to the baby during pregnancy, affecting the communication between nerves and muscles.

Final Thoughts

While there is no cure for Myasthenia Gravis, advancements in medical interventions and management strategies enable many affected individuals to lead normal lives.

Early diagnosis and appropriate treatment are crucial to managing symptoms effectively, improving the quality of life, and reducing the impact of this neuromuscular disorder on affected individuals.