Myositis

Symptoms

• Muscle Weakness: Progressive weakness in the muscles, particularly in the hips, shoulders, and neck, making it difficult to perform activities such as climbing stairs, rising from a chair, or lifting objects.
• Muscle Pain and Tenderness: Some patients experience aching, soreness, or tenderness in the affected muscles, although this is less common than weakness.
• Skin Changes: In dermatomyositis, a distinctive rash often appears, including the heliotrope rash (a purplish discoloration around the eyes) and Gottron’s papules (red or purple bumps over the knuckles, elbows, or knees).
• Fatigue: Extreme tiredness and lack of energy, which can significantly impact daily functioning.
• Difficulty Swallowing (Dysphagia): In some cases, especially with inclusion body myositis, weakness of the muscles involved in swallowing can lead to difficulty eating or drinking.
• Shortness of Breath: In severe cases, respiratory muscles can become weakened, leading to difficulty breathing.
• Joint Pain: Some individuals with myositis also experience inflammation of the joints (arthritis), which can cause pain and swelling.

How is the diagnosis done ?

• Medical History and Physical Examination: The doctor will evaluate symptoms like muscle weakness, pain, and the presence of skin changes (particularly in dermatomyositis). A physical exam will assess muscle strength and tenderness.
• Blood Tests:
  • Creatine Kinase (CK): Elevated levels of CK indicate muscle damage and are a key marker in diagnosing myositis.
  • Antibody Tests: Specific autoantibodies can help distinguish between types of myositis. These include anti-Jo-1 (common in polymyositis and dermatomyositis), anti-Mi-2 (linked to dermatomyositis), and anti-SRP (associated with severe muscle involvement).
  • Muscle Enzymes: Other markers like aldolase and lactate dehydrogenase (LDH) may also be elevated in myositis.
• Electromyography (EMG): This test assesses electrical activity in the muscles and helps determine whether muscle weakness is due to nerve damage or muscle inflammation.
• Muscle Biopsy: A muscle biopsy involves taking a small sample of muscle tissue to examine under a microscope. This helps confirm inflammation and may show characteristic changes associated with myositis, such as muscle fiber damage and infiltration by immune cells.
• MRI of Muscles: MRI can identify areas of muscle inflammation and damage, particularly in deeper muscles that are difficult to examine physically.
• Pulmonary Function Tests: If respiratory involvement is suspected, these tests can assess lung function, especially in cases of interstitial lung disease, which can occur in some forms of myositis.

Why is Early Diagnosis Important?

• Prevention of Muscle Damage: Early treatment can help reduce the degree of muscle inflammation, which prevents long-term muscle damage and weakness.
• Avoiding Complications: In severe cases, untreated myositis can lead to complications like respiratory failure, swallowing difficulties, or even life-threatening infections due to immunosuppressive treatments.
• Targeted Therapy: Early diagnosis allows for timely initiation of medications (like corticosteroids, immunosuppressive drugs, or biologics) that can control inflammation and prevent progression.
• Improved Quality of Life: With early intervention, symptoms like fatigue, pain, and difficulty with activities of daily living can be better managed, improving overall quality of life.
• Prevention of Other Organ Involvement: In some cases, myositis can affect organs beyond muscles, such as the lungs (interstitial lung disease), heart, or joints. Early diagnosis and treatment can prevent or manage these complications more effectively.

Treatment

• Corticosteroids: Prednisone is commonly used to reduce inflammation and control symptoms. It is often the first-line treatment, but long-term use can have side effects, so dose adjustments are made based on response.
• Immunosuppressive Drugs:
  • Methotrexate and azathioprine are frequently used to suppress the immune system and reduce inflammation in more severe cases.
  • Mycophenolate mofetil and cyclophosphamide may be considered in resistant cases.
• Biologic Agents: Biologics like rituximab (which targets B-cells) or tocilizumab (which targets IL-6) can be used for patients who don’t respond to traditional immunosuppressives.
• Plasmapheresis: This is a process that removes antibodies from the blood and is used in severe, refractory cases, especially when there is rapid muscle weakness.
• Physical Therapy: Regular physical therapy to improve strength and function, as well as occupational therapy, can help patients maintain daily activities.
• Supportive Treatments:
  • Pain Relief: Nonsteroidal anti-inflammatory drugs (NSAIDs) can help manage mild pain.
  • Speech Therapy: If swallowing or speech is affected, speech therapy may be recommended.
• Respiratory Support: In cases where the lungs are involved, supplemental oxygen or ventilator support may be needed.

Prognosis

• Variable Outcomes: The prognosis for myositis varies depending on the type, severity, and how well the condition responds to treatment.
• Good Prognosis with Early Treatment: Many people with myositis, especially those with polymyositis or dermatomyositis, can live a normal or near-normal life with appropriate treatment. Early treatment helps prevent long-term damage and complications.
• Progressive and Severe Cases: Inclusion body myositis (IBM) is generally more resistant to treatment and has a slower but progressive course. Some individuals with IBM may experience worsening muscle weakness and disability over time.
• Organ Involvement: In cases where myositis affects the lungs, heart, or other organs, the prognosis can be more guarded. Respiratory issues, particularly interstitial lung disease, can be a significant cause of morbidity and mortality in these cases.
• Potential for Remission: With appropriate therapy, many people experience periods of remission, where symptoms improve or even disappear for extended periods. However, relapses can occur, and ongoing management is often required.

Scoring

Several scoring systems and tools are used to assess disease activity and response to treatment in myositis:

• Myositis Disease Activity Assessment Tool (MDAAT): This tool assesses disease activity based on clinical findings, including muscle strength, fatigue, pain, and other symptoms. It is useful for monitoring disease progression and response to treatment.
• Manual Muscle Testing (MMT): This scale evaluates muscle strength on a 0–5 scale for specific muscle groups. It helps assess the degree of muscle weakness and monitor changes over time.
• Health Assessment Questionnaire (HAQ): A commonly used tool to assess functional ability, including daily activities like dressing, eating, and walking.
• The Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI): This tool is specific to dermatomyositis and evaluates the severity of skin involvement (e.g., rash, ulcers).
• The Physician Global Assessment (PGA): This tool is used by healthcare providers to give an overall assessment of disease activity and severity. It combines clinical, laboratory, and physical findings to create a global rating.
• Muscle Enzyme Levels: Regular monitoring of creatine kinase (CK) levels and other muscle enzymes helps assess the degree of muscle damage and monitor response to treatment.

These tools help doctors assess the activity and impact of the disease, guide treatment decisions, and track improvements or deteriorations over time