From the Guidelines
The initial workup for myositis should include a comprehensive history and physical examination, followed by laboratory tests such as creatine kinase (CK), aldolase, lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) to assess muscle damage, as recommended by recent guidelines 1.
Initial Workup
The workup should also include inflammatory markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), along with myositis-specific antibodies.
- Electromyography (EMG)
- Muscle MRI
- Muscle biopsy may be necessary for definitive diagnosis.
Treatment Approach
Treatment typically begins with corticosteroids, usually prednisone at 0.5-1 mg/kg/day (typically 40-60 mg daily) for 4-6 weeks before slowly tapering based on clinical response and CK levels, as suggested by 1.
- For refractory cases, steroid-sparing immunosuppressants like methotrexate (15-25 mg weekly), azathioprine (1-2 mg/kg/day), or mycophenolate mofetil (1-1.5 g twice daily) may be added.
- Intravenous immunoglobulin (IVIG) at 2 g/kg divided over 2-5 days can be used for severe or rapidly progressive disease, as recommended by 1.
Monitoring and Maintenance
Physical therapy is crucial to maintain muscle strength and prevent contractures.
- Patients should be monitored regularly for medication side effects and disease progression with repeated muscle enzyme tests. This approach targets the autoimmune inflammation that causes muscle fiber damage and weakness in myositis, prioritizing morbidity, mortality, and quality of life as outcomes, especially considering the high mortality rate associated with myositis complicated by myocarditis or severe respiratory failure 1.
From the Research
Initial Workup for Myositis
- The initial workup for myositis typically involves a combination of clinical evaluation, laboratory tests, and imaging studies to confirm the diagnosis and determine the underlying cause of muscle inflammation 2.
- Laboratory tests may include serum creatine kinase (CK) levels, which can be elevated in patients with myositis 3.
- A muscle biopsy may be necessary to confirm the diagnosis and rule out other conditions 2.
- The identification of characteristic autoantibodies can also aid in the diagnosis and classification of myositis 2.
Treatment Options for Myositis
- The treatment of myositis depends on the type and severity of the condition, as well as the presence of any systemic complications or comorbidities 2.
- Corticosteroids, such as prednisone, are often used as the initial treatment for myositis, and may be combined with immunosuppressive agents like methotrexate or azathioprine 4, 3, 5, 6.
- Intravenous immunoglobulin (IVIg) may be used as add-on therapy in patients who do not respond to corticosteroids or immunosuppressive agents 4, 6.
- Other treatment options, such as cyclophosphamide, cyclosporin, or chlorambucil, may be considered in patients with refractory myositis 6.
Treatment Strategies
- The treatment strategy for myositis should be individualized based on the specific needs and circumstances of each patient 4, 3, 2.
- A slow corticosteroid taper rate is often recommended to minimize the risk of relapse 3.
- Regular monitoring of serum CK levels and muscle strength can help guide treatment decisions and adjust the treatment plan as needed 3.