From the Guidelines
When monitoring a patient with myasthenia gravis, it is crucial to look for signs of respiratory compromise, such as dysphagia, facial weakness, and respiratory muscle weakness, as these can indicate a myasthenic crisis requiring immediate intervention, as suggested by the most recent guidelines 1.
Key Symptoms to Monitor
- Fluctuating muscle weakness that worsens with activity and improves with rest
- Ocular symptoms, including drooping eyelids and double vision
- Facial weakness
- Difficulty swallowing or speaking
- Limb weakness, especially in proximal muscles
Medication Management
- Pyridostigmine (Mestinon) should be started at 30 mg PO three times a day and gradually increased to a maximum of 120 mg PO four times a day as tolerated and based on symptoms 1
- Corticosteroids, such as prednisone, should be administered at a dose of 0.5 mg/kg orally daily, with tapering based on symptom improvement 1
Triggers and Comorbidities
- Be vigilant for triggers that may exacerbate symptoms, such as infections, stress, surgery, certain medications (aminoglycosides, fluoroquinolones, magnesium), and extreme temperatures
- Monitor for comorbid autoimmune conditions like thyroid disease
Pulmonary Function Tests
- Regular pulmonary function tests, particularly forced vital capacity, are important to detect early respiratory decline 1
Severity-Based Management
- For G2 symptoms, hold ICPi and consider resuming if symptoms resolve, with neurology consultation and initiation of pyridostigmine and corticosteroids 1
- For G3-4 symptoms, permanently discontinue ICPi, admit the patient for ICU-level monitoring, and initiate IVIG or plasmapheresis, with frequent pulmonary function assessment and daily neurologic review 1
From the FDA Drug Label
Although failure of patients to show clinical improvement may reflect underdosage, it can also be indicative of overdosage. As is true of all cholinergic drugs, overdosage of pyridostigmine bromide may result in cholinergic crisis, a state characterized by increasing muscle weakness which, through involvement of the muscles of respiration, may lead to death Myasthenic crisis due to an increase in the severity of the disease is also accompanied by extreme muscle weakness, and thus may be difficult to distinguish from cholinergic crisis on a symptomatic basis The differential diagnosis of the two types of crisis may require the use of edrophonium chloride as well as clinical judgment
The patient diagnosed with myasthenia gravis should be monitored for signs of:
- Cholinergic crisis: increasing muscle weakness, which can lead to death
- Myasthenic crisis: extreme muscle weakness due to an increase in the severity of the disease Key considerations include:
- Distinguishing between cholinergic and myasthenic crisis, which may require edrophonium chloride and clinical judgment 2
- Atropine may be used to treat cholinergic crisis, but its use can also mask signs of overdosage, leading to inadvertent induction of cholinergic crisis.
From the Research
Patient Assessment
When assessing a patient diagnosed with myasthenia gravis, several factors should be considered:
- Clinical presentation: The patient's symptoms, such as muscle weakness, ptosis, diplopia, facial bulbar weakness, and limb weakness, should be evaluated 3.
- Serum autoantibodies: The presence of acetylcholine receptor (AChR) antibodies, muscle-specific kinase (MuSK) antibodies, or low-density lipoprotein receptor-related protein 4 (Lrp4) antibodies should be determined 3.
- Disease severity: The severity of the disease should be assessed to guide treatment decisions 4.
- Comorbidities: The patient's comorbidities should be considered when developing a treatment plan 4.
Treatment Options
The treatment options for myasthenia gravis include:
- Symptomatic treatment: Pyridostigmine is commonly used to relieve symptoms, but its effectiveness and side effects should be monitored 5, 6.
- Immunosuppressive treatment: Azathioprine, corticosteroids, and other immunosuppressants may be used to reduce disease severity 7, 3.
- Thymectomy: Thymectomy may be considered in patients with thymoma or those who are refractory to other treatments 3.
Monitoring and Management
Patients with myasthenia gravis require regular monitoring and management to optimize treatment outcomes:
- Side effects: The patient should be monitored for side effects of pyridostigmine, such as flatulence, urinary urgency, muscle cramps, blurred vision, and hyperhidrosis 5.
- Disease progression: The patient's disease progression should be regularly assessed to adjust treatment as needed 4, 3.
- Treatment adherence: The patient's adherence to the treatment plan should be encouraged and monitored to ensure optimal outcomes 5, 6.