Initial Treatment for Myasthenia Gravis

Diagnostic Workup Before Treatment

The American College of Cardiology recommends testing for acetylcholine receptor (AChR) antibodies in blood; if negative, test for muscle-specific kinase (MuSK) and lipoprotein-related protein 4 (LRP4) antibodies in patients with suspected myasthenia gravis 1, 2
Pulmonary function assessment with negative inspiratory force (NIF) and vital capacity (VC) should be performed in patients with myasthenia gravis to evaluate respiratory function 1
Checking CPK, aldolase, ESR, and CRP can help evaluate for possible concurrent myositis in patients with myasthenia gravis 2
An MRI of the brain and/or spine may be considered depending on symptoms to rule out CNS involvement in patients with myasthenia gravis 1
If respiratory insufficiency or elevated CPK/troponin is present, a cardiac examination with ECG and transthoracic echocardiogram should be performed to evaluate for possible myocarditis in patients with myasthenia gravis 2
Neurological consultation is recommended for patients with myasthenia gravis to evaluate disease severity and develop a treatment plan 1
Electrodiagnostic studies, including neuromuscular junction testing with repetitive stimulation and/or jitter studies, can help diagnose myasthenia gravis 2

The initial treatment for myasthenia gravis should be pyridostigmine, starting at 30 mg orally three times a day and gradually increasing to a maximum of 120 mg orally four times a day as tolerated and based on symptoms, according to the American Academy of Neurology 2, 3
For patients with mild disease (MGFA Class I-II), pyridostigmine should be started at 30 mg PO three times daily and gradually increased to a maximum of 120 mg PO four times daily as tolerated 2, 3
If symptoms persist despite optimal pyridostigmine dosing, prednisone 0.5-1.5 mg/kg orally daily may be added to the treatment regimen for patients with myasthenia gravis 2, 3
For patients with moderate to severe disease (MGFA Class III-V), corticosteroids (prednisone 1-1.5 mg/kg orally daily) should be added to the treatment regimen, and hospital admission may be necessary for respiratory concerns 2, 3
IVIG 2 g/kg IV over 5 days (0.4 g/kg/d) or plasmapheresis for 5 days may be considered for patients with myasthenia gravis who require rapid improvement 2, 3

Medications that can worsen myasthenia, such as β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolide antibiotics, should be avoided in patients with myasthenia gravis 2, 3

Close monitoring is essential for patients with myasthenia gravis, particularly when initiating treatment, as the disease can rapidly progress to respiratory compromise 2, 3

In patients with myasthenia gravis experiencing a myasthenic crisis with respiratory compromise, IV hydrocortisone 50–100 mg every 6–8 hours is recommended as a stress‑dose regimen to rapidly control inflammation and support ventilation. 4, 5
After clinical stabilization, the IV stress dose should be tapered to oral maintenance therapy over 5–7 days, allowing a smooth transition while preventing adrenal insufficiency. 4, 5

For ongoing glucocorticoid coverage, oral hydrocortisone 15–20 mg divided into two‑to‑three doses (approximately 2/3 in the morning and 1/3 in the early afternoon) mimics the physiological diurnal cortisol rhythm and can be employed as an alternative to prednisone in selected patients. 4, 5
The maximum recommended daily hydrocortisone dose is 30 mg for patients who require residual adrenal support, to limit the risk of glucocorticoid‑related adverse effects. 4
Hydrocortisone 20 mg is pharmacologically equivalent to prednisone 5 mg, providing clinicians a clear conversion factor when switching between agents. 4

Clinicians should monitor for signs of iatrogenic Cushing’s syndrome (e.g., bruising, thin skin, edema, weight gain, hypertension, hyperglycemia) during hydrocortisone therapy and reduce the dose promptly if such adverse effects emerge. 4

Evidence level for the above recommendations was not explicitly stated in the cited sources.