Myasthenia gravis (MG) is a rare neuromuscular autoimmune disorder characterized by fluctuating weakness of skeletal muscle groups that worsens with use and improves with rest.
In this article:
- Pathophysiology
- Types of Myasthenia Gravis
- Nursing Process
- Nursing Assessment
- Nursing Interventions
- Nursing Care Plans
- Ineffective Airway Clearance
- Ineffective Breathing Pattern
- Risk for Aspiration
- Risk for Falls
Pathophysiology
Clinical features and treatment response depends on the types of antibodies present in MG. The largest percentage of patients have antibodies that attack the acetylcholine receptors (AChR), disrupting the neurotransmitter acetylcholine and preventing muscle contractions. Less commonly, antibodies may impair the proteins Muscle-specific kinase (MuSK) and low-density lipoprotein receptor-related protein 4 (LRP4) that are important in the signaling process at the neuromuscular junction.
The thymus gland also seems to play a role in the development of MG. This gland is crucial to the immune system through the creation of T-cells, especially in childhood and adolescence. However, in adults with MG, the thymus may appear enlarged or contain tumors (thymomas) linked to abnormal antibody production.
Types of Myasthenia Gravis
Most patients experience eye fatigue or vision changes as their first symptom. This subtype is called ocular myasthenia gravis. Generalized myasthenia gravis affects the eyes as well as muscles used for chewing, breathing, speaking, and movement. Many patients with ocular MG will eventually develop generalized MG.
The most significant concern with MG is the weakness of the respiratory muscles, leading to respiratory failure. This life-threatening complication is referred to as a myasthenic crisis and may require ventilatory support.
The cause of MG is unknown, and there is no cure. Many patients experience a progressive disease course, though flares with periods of remission do occur. Symptoms are manageable through medication and other treatments, and patients can expect a near-normal life span.
Nursing Process
Nurses support patients with MG by administering medications, educating them on triggers and symptoms of exacerbations, and preventing complications. Since MG is a chronic and progressive medical condition, patients require close monitoring and follow-up care.
Nursing Assessment
The first step of nursing care is the nursing assessment, during which the nurse will gather physical, psychosocial, emotional, and diagnostic data. In this section, we will cover subjective and objective data related to myasthenia gravis.
Review of Health History
1. Ask the patient about their general symptoms.
Inquire about the onset of symptoms, the time of day they occur, and if they improve with rest. Patients may initially notice eyelid fatigue or vision changes, such as diplopia. The eyes may appear normal in the morning and then nearly closed by the end of the day from weakness. The patient may report difficulty speaking, chewing, swallowing, or weakness in the extremities.
2. Distinguish fatigable weakness from other causes.
It’s important to differentiate weakness related to MG from other causes of fatigue. Fatigable weakness from MG is worsened by activity and prominent by the end of the day. Nonspecific fatigue or fatigue caused by psychosocial factors is more likely related to general tiredness or lack of energy.
3. Inquire about difficulty eating or drinking.
Difficulty chewing and swallowing is a risk factor for aspiration. Ask about coughing or choking while eating or drinking, liquid regurgitation, and excessive nose-blowing or throat-clearing.
4. Assess the effect on movement and activities.
Patients with MG affecting the limbs may notice weakness with repeated use, such as when climbing stairs, walking, or typing. The upper limbs are more likely to be affected than the lower limbs.
5. Identify the patient’s risk factors.
MG is an autoimmune condition without an identifiable cause in most patients. The following factors increase the risk of MG:
- Female gender
- Age (Female >30 years old; Male >60 years old)
- Other autoimmune conditions
- Thyroid disorders
- Genetics, though MG is not inherited
6. Identify triggers causing flares.
Various causes can exacerbate MG, including pregnancy, poor sleep, illness, stress, and extreme temperature changes.
7. Review the medication list.
Medications can worsen MG symptoms. Examples include:
- Antibiotics
- Lithium
- Verapamil
- Prednisone
- Anticholinergics
Physical Assessment
1. Assess the neuromuscular status.
Muscle weakness from MG may affect different muscle groups. The following symptoms are found in MG:
- Ocular symptoms
- Ptosis (eyelid drooping)
- Double vision
- Blurred vision
- Photophobia (light sensitivity)
- Bulbar symptoms
- Difficulty swallowing
- Slurred speech
- Difficulty chewing
- Facial or neck weakness
- Limb weakness
- Decreased muscle strength
- Difficulty ambulating
2. Examine the eyes.
Ocular symptoms are the most common initial symptom of MG. The patient may appear sad or tired-looking from eye drooping. Looking at older photos of the patient may offer a baseline comparison. Ptosis usually occurs on one side, though it may be bilateral, or may change sides.
3. Assess the speech.
Listen to the patient talk and note any nasal quality to the voice or slurring. Slurred speech may worsen the longer the patient talks.
4. Assess facial muscles.
Facial weakness is an expected finding. The patient may have difficulty with facial expressions and smiling. Attempts to have the patient whistle, suck through a straw, or blow a balloon will be unsuccessful.
5. Monitor the patient’s respiratory status.
Orthopnea is an early indication of diaphragmatic weakness in patients. Assess their ability to breathe while lying flat. Other symptoms may include difficulty drawing in a full breath, tachypnea, and shallow breathing. Any respiratory distress requires emergent evaluation.
6. Perform provocative maneuvers.
The nurse can implement provocative maneuvers to assess for weakness in MG. Ask the patient to perform the following:
- Look up for 1-2 minutes: Will evoke ptosis
- Look laterally for 1-2 minutes: Will cause diplopia
- Raise the arms out to the sides for 2 minutes: Unable to hold arms up
- Repeated rising from a chair without using the arms: Early fatigue with forward lean
- Lie supine and lift one leg for 90 seconds: Unable to hold the leg up
- Count aloud to 50: Causes difficulty speaking or dyspnea
Diagnostic Procedures
1. Obtain blood samples for testing.
The presence of anti-acetylcholine receptor (AChR) antibody (Ab) diagnoses MG. Results are positive in most patients with generalized MG, but false negatives may occur in patients with ocular MG. Approximately half of patients who are negative for AChR Ab will be positive for anti-MuSK antibodies. Patients who are negative for either antibody will possess anti-lipoprotein-related protein 4 (LRP4) antibodies.
2. Rule out other conditions.
Patients with MG are at an increased risk of having co-occurring autoimmune diseases. Perform lab tests to assess for rheumatoid arthritis or systemic lupus erythematosus. Thyroid function tests are also important to assess for Graves disease or hyperthyroidism that commonly occur with MG and can mimic or exacerbate symptoms.
3. Assist with electrodiagnostic studies.
Repetitive nerve stimulation (RNS) or single fiber electromyography (SFEMG) tests for disruptions at the neuromuscular junction. SFEMG is the most sensitive for diagnosing MG.
4. Perform the ice pack test.
Placing an ice pack over the eye for several minutes may improve ptosis. There is some discussion about whether the ice or rest is the actual cause for improvement. Either way, a positive finding is sensitive for MG.
5. Prepare the patient for further diagnostic testing.
An MRI or CT scan is considered in the diagnosis of MG to assess for thymoma or other lesions.
Nursing Interventions
Nursing interventions and care are essential for the patients recovery. In the following section, you will learn more about possible nursing interventions for a patient with myasthenia gravis.
1. Administer prescribed medications.
Medications are used to control symptoms and disease activity and may include:
- Acetylcholinesterase (AChE) inhibitors (these medications will not work for patients with MuSK antibodies)
- Immunosuppressants
- Corticosteroids
- Monoclonal antibodies
- IV or SQ immunoglobulin (IVIG or SCIG)
2. Discuss plasma exchange with the patient.
Plasma exchange (or plasmapheresis) replaces the patient’s plasma (and anti-AChR antibodies) with donor plasma or a plasma solution. This intervention is reserved for myasthenic crisis or cases that are unresponsive to other treatments.
3. Monitor and educate on complications of medications.
Immunosuppressants increase the risk of infections and certain cancers. Side effects of long-term steroid use include osteoporosis, hyperglycemia, weight gain, infections, and more. Overuse of cholinesterase inhibitors may cause a life-threatening cholinergic crisis. Educate the patient on symptoms and when to seek medical attention.
4. Anticipate surgery.
Removal of the thymus gland is recommended for patients with thymoma or those without thymoma who have generalized MG (not MuSK MG), as evidence shows improved long-term outcomes.
5. Implement swallowing precautions.
Certain foods may become difficult if fatigue occurs with chewing. Thin liquids are often more difficult to swallow, and the patient may require thickened liquids.
6. Exercise with caution.
Patients should continue participating in exercise, though limit the length of time and rest frequently to reduce fatigue.
7. Inform the patient of emergent symptoms.
Myasthenic crisis is a serious concern with MG as it can lead to respiratory failure, requiring mechanical ventilation. Educate the patient that they should seek immediate evaluation if they experience a change in breathing, dyspnea, a weak cough, voice hoarseness, or weakness in the tongue or jaw.
8. Plan for weakness and fatigue.
Encourage patients to schedule important tasks, appointments, or activities earlier in the day when they have the most strength. Plan rest periods during the day to regain or conserve energy.
9. Help the patient avoid MG flares.
Avoiding triggers is important to prevent MG exacerbations. Educate the patient to take the following measures to avoid triggering symptoms:
- Prioritize sleep and rest
- Stay hydrated
- Learn coping strategies to manage stress
- Get vaccinated to reduce infections
- Avoid extreme temperature changes
Nursing Care Plans
Once the nurse identifies nursing diagnoses for myasthenia gravis, nursing care plans help prioritize assessments and interventions for both short and long-term goals of care. In the following section, you will find nursing care plan examples for myasthenia gravis.
Fatigue
Myasthenia gravis is associated with muscle weakness and rapid fatigue in voluntary muscle groups.
Nursing Diagnosis: Fatigue
Related to:
- Disease process
- Muscle weakness
As evidenced by:
- Decreased gait velocity
- Difficulty maintaining usual physical activity
- Difficulty maintaining usual routines
- Ptosis
- Diplopia
- Weak facial expressions
- Expresses tiredness
- Expresses weakness
- Inadequate role performance
- Lethargy
- Falls
Expected outcomes:
- Patient will demonstrate increased activity levels and participate in desired activities.
- Patient will participate in supportive therapy to improve fatigue and muscle strength.
Assessment:
1. Assess the patient’s severity and frequency of fatigue.
Assessing fatigue severity and frequency can help formulate the most appropriate treatment plan for the patient. Fatigue can lead to falls, injuries, and poor quality of life if not properly evaluated.
2. Assess the patient’s ability to perform ADLs.
This will help determine the degree of assistance that the patient will require in performing self-care and other activities of daily living.
3. Provoke fatigue.
The nurse can assess for muscle fatigue by having the patient demonstrate repetitive or prolonged maneuvers that cause fatigue with use. Examples include:
- Asking the patient to look up for 1-2 minutes
- Having the patient hold their arms out to the sides for 2 minutes
- Requesting the patient rise from a chair without using the arms
Interventions:
1. Encourage the patient to perform activities as tolerated.
Allowing the patient to perform activities of daily living with adequate rest periods in between will promote a sense of control and independence.
2. Assist the patient in identifying MG triggers.
A patient can prevent an MG flare by understanding their triggers. Common triggers include illness/infections, inadequate sleep, some medications, extreme temperatures, menstruation, alcohol, and stress.
3. Refer the patient to appropriate therapies.
Physical therapy and occupational therapy can assist with motor strength exercises and recommend strategies and equipment to assist with ADLs.
4. Prepare for IVIG therapy.
Intravenous immunoglobulin (IVIG) is a transfused blood product that is believed to destroy damaged antibodies through healthy donor antibodies. A nurse can administer the transfusion in a medical office or the patient’s home. This treatment can be given for an MG crisis, to prevent an impending crisis, or as a treatment to stabilize the patient prior to surgery.
5. Prepare for surgery.
For some patients, the thymus gland itself or a tumor in the thymus gland (known as a thymoma) may contribute to MG. In an attempt to reduce symptoms, and in some cases cure patients, a thymectomy is performed.
Ineffective Airway Clearance
Myasthenia gravis is associated with muscle weakness usually affecting the muscles that control the eyes, throat, mouth, and limbs that worsen with activity. Weakness in the upper airway muscles can result in upper airway obstruction and respiratory failure.
Nursing Diagnosis: Ineffective Airway Clearance
Related to:
- Disease process
- Weak oropharyngeal muscle contractions
- Decreased ability to cough and swallow
As evidenced by:
- Absent or ineffective cough
- Adventitious breath sounds
- Altered respiratory rhythm
- Rapid, shallow breathing
- Cyanosis
- Difficulty verbalizing
- Nasal flaring
Expected outcomes:
- Patient will demonstrate effective coughing, clear breath sounds, and clear airways without respiratory distress symptoms.
- Patient will verbalize one strategy to maintain airway strength and support.
Assessment:
1. Assess respiratory rate, rhythm, and lung sounds.
Diminished lung sounds or the presence of adventitious lung sounds can indicate a blocked airway. Alterations in respiratory rate and rhythm are present when there is an attempt to compensate for ineffective airway clearance and breathing.
2. Evaluate and monitor ABG values.
Alterations in the patient’s ABG levels can indicate worsening respiratory failure. Do not rely on this information for treatment as abnormal values may not be obvious until respiratory failure is occurring.
3. Have the patient perform the single-breath test count.
This test has the patient inhale a maximal breath and then count out loud as long as they can before taking another breath. The ability to count to 50 indicates normal breathing. A count of less than 15 signals respiratory muscle weakness.
Interventions:
1. Monitor the patient’s ability to swallow or cough.
Since the primary symptom of MG is muscle weakness, it is important to monitor the patient’s ability to swallow or cough. This can help determine the progression of the disease and the need for additional interventions to protect the patient’s airway.
2. Suction secretions as needed.
Suctioning secretions help patients with MG who are unable to cough or swallow.
3. Elevate the head of the bed.
Elevating the head of the bed improves lung expansion and makes breathing easier.
4. Educate on myasthenic crisis symptoms.
An MG crisis occurs when the respiratory muscles weaken and result in respiratory failure. This can be life-threatening and requires emergency assistance. Educate the client to seek assistance if they notice dyspnea, accessory muscle use, and a weak cough.
5. Refer for pulmonary function tests.
PFTs can monitor the progression of the disease. Not all patients will experience respiratory muscle involvement, but routine assessment can help prevent a crisis or other complications.
Ineffective Breathing Pattern
The most serious complication of myasthenia gravis is weakness in the respiratory muscles, resulting in an ineffective breathing pattern and inadequate oxygenation.
Nursing Diagnosis: Ineffective Breathing Pattern
Related to:
- Fatigue of diaphragmatic muscles
- Myasthenic crisis
As evidenced by:
- Tachypnea
- Shallow breathing
- Dyspnea
- Orthopnea
- Decreased vital capacity
Expected outcomes:
- Patient will verbalize respiratory symptoms that require immediate intervention.
- Patient will demonstrate a respiratory rate, depth, and pattern within normal limits.
Assessment:
1. Assess and monitor the patient’s respiratory status.
If myasthenia gravis affects the respiratory muscles, it may cause difficulty breathing when lying flat, shortness of breath, or the inability to draw in a deep breath. The patient may display shallow and rapid breathing.
2. Assess the patient’s peak expiratory flow rate (PEFR).
Measuring the patient’s PERF helps estimate the respiratory function of patients with myasthenia gravis to plan or prepare interventions.
3. Perform provocative maneuvers.
The nurse can obtain an estimate of the patient’s vital capacity by having them count aloud up to 20 and multiplying the highest number achieved in one breath by 100 (20 x 100 = 2000 cc. 3,000 – 5,000 cc is normal).
Interventions:
1. Administer supplemental oxygen as indicated.
Patients experiencing respiratory muscle weakness or myasthenic crisis require oxygen or BiPAP to ensure adequate oxygenation while decreasing the work of breathing.
2. Do not rely on pulse oximetry.
In the early phase of hypoventilation in an MG crisis, carbon dioxide is retained, as well as oxygen in the blood, which can falsely appear as a normal SpO2.
3. Educate on when to seek assistance for symptoms.
Ensure the patient is aware of symptoms that require immediate evaluation. This includes any change or difficulty in breathing, voice horseness, weakness in the jaw or throat muscles, a weak cough, and difficulty swallowing.
4. Prepare for intubation and ventilation.
A myasthenic crisis is life-threatening and may require mechanical ventilation if respiratory failure occurs.
Risk for Aspiration
Dysphagia or swallowing difficulties are common in patients diagnosed with MG, making the risk for aspiration high. Silent aspiration can also occur in MG due to weak oropharyngeal muscle contractions, resulting in myasthenic crisis and aspiration pneumonia.
Nursing Diagnosis: Risk for Aspiration
Related to:
- Disease process
- Weak oropharyngeal muscle contractions
- Depressed gag reflex
As evidenced by:
A risk diagnosis is not evidenced by signs and symptoms, as the problem has not occurred yet and nursing interventions are directed at the prevention of symptoms.
Expected outcomes:
- Patient will maintain a patent airway and demonstrate clear breath sounds.
- Patient will demonstrate strategies to safely swallow.
Assessment:
1. Assess the patient’s ability to swallow and cough.
Assessing the patient’s swallow and gag reflexes is necessary to reduce the risk of aspiration and maintain clear airways.
2. Auscultate breath sounds.
Breath sounds assess the patient’s pulmonary status. Coarse crackles are often heard during auscultation with aspiration.
Interventions:
1. Assist the patient to a sitting position when eating and drinking.
Keeping the patient in an upright position while eating or drinking, and for 30 minutes following meals, can help prevent aspiration.
2. Consider the use of feeding tubes.
In severe cases of MG, a nasogastric feeding tube may be required for dysphagia until the client recovers from their MG flare.
3. Administer medications as indicated.
Medications like pyridostigmine are prescribed to help alleviate symptoms of MG.
4. Adjust the eating routine.
Educate the patient to eat when they have optimal muscle strength. Take time to chew, and focus on smaller meals. Choosing softer foods will require less chewing.
5. Consult with speech therapy.
A speech therapist can perform swallowing assessments and determine foods that are safe or unsafe to eat. They can also work with the client on strengthening their mouth and throat muscles.
Risk for Falls
Patients with generalized myasthenia gravis may experience limb weakness, which increases the risk of falls.
Nursing Diagnosis: Risk for Falls
Related to:
- Progressive or fluctuating skeletal muscle weakness
- Fatigue
- Visual disturbances (from ocular MG)
- Poor posture
As evidenced by:
A risk diagnosis is not evidenced by signs and symptoms, as the problem has not occurred yet, and nursing interventions are directed at prevention.
Expected outcomes:
- Patient will remain free from falls.
- Patient will demonstrate behaviors and interventions that reduce the patient’s risk for falls.
Assessment:
1. Assess the extent of muscle weakness.
Myasthenia gravis causes muscle weakness that increases with muscle use. Some patients may only experience ocular symptoms, while others have weakness to the extremities. It is vital to determine where the patient experiences weakness, the time of day, and if certain activities exacerbate the weakness to determine their risk for falls.
2. Assess for symptoms that affect vision.
Many patients only have ocular MG, which causes eyelid drooping or vision changes. Still, these symptoms have the potential to contribute to falls if the patient has difficulty visualizing their environment.
Interventions:
1. Encourage frequent rest periods.
MG worsens with prolonged activity and improves with rest. Remind the patient to take frequent breaks, especially when exercising or performing strenuous activities, to prevent fatigue and the incidence of falls.
2. Implement modifications to improve safety.
Suggest equipment such as raised toilet seats or shower benches to preserve strength and reduce falls. Mobility devices, such as walkers with seats, allow patients to ambulate but rest when needed.
3. Manage ocular symptoms.
The patient is still at risk for falls even if they only have ocular MG, as diplopia, light sensitivity, and ptosis can cause a loss of balance and falls. Dark glasses can reduce photosensitivity when outdoors, and an eyepatch can help reduce double vision.
4. Remain active.
Patients with MG should continue to participate in exercise, especially balance training, which will reduce the risk of falls. Avoid exercising in the heat and stay hydrated to prevent exacerbating MG symptoms.
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