Myositis Treatment | Diagnosis & Cost

The myositis diagnosis criteria begin with a detailed consultation and a thorough review of the patient's symptoms and medical history, focusing on patterns of muscle weakness and functional limitations. Because symptoms usually develop slowly and can mimic other neuromuscular conditions, early recognition may be difficult. A neurologist or rheumatologist considers the following before selecting the appropriate tests to diagnose myositis: 

• Taking medical history 
• Performing a physical examination 

Taking medical history 

To diagnose myositis and distinguish it from other neuromuscular disorders, a thorough medical history is essential, including the onset, progression, and associated features of symptoms. Doctors use the following targeted questions to delve deeper into systemic involvement and muscle-specific complaints.

• What is the main problem you’re experiencing with your muscles or shoulders?
• When did the weakness, pain, or stiffness start? Does it worsen with movement or at night?
• Was the onset sudden or gradual?
• Can you describe the type of pain or discomfort (like aching, burning, cramping, fatigue)?
• On a scale of 0–10, how severe is it?
• Have you noticed any weakness or difficulty with movements like lifting arms, climbing stairs, or getting up from a chair?
• How has this affected your daily activities, such as combing hair, dressing, or reaching for objects?
• Have you noticed any skin changes, rashes, or swelling?
• Do you have difficulty swallowing, breathing, or speaking?
• Any previous muscle/joint injuries, surgeries, or periods of immobility?
• Do you have medical conditions like autoimmune disease, diabetes, or thyroid problems?

Performing a physical examination 

• Physical examination for myositis disease starts with observing overall appearance and movement. Difficulty rising from a chair, climbing onto the table, or walking usually indicates proximal muscle weakness, and a waddling gait or visible muscle atrophy may be seen.
• The skin needs to be checked for rashes suggestive of dermatomyositis, like a heliotrope rash (purplish periorbital edema) around the eyes, Gottron's papules on the knuckles, or photosensitive rashes on the shoulders and chest. Nailfold changes and mechanic's hands can also provide important clues.
• Muscle strength is evaluated using the MRC scale (0-5 grading), mainly on proximal muscles like the neck ,shoulders, and hips, while also checking distal muscles for involvement seen in conditions like inclusion body myositis. Muscle bulk and tone are evaluated for atrophy or asymmetry.
• Functional testing includes asking the patient to rise from a seated or squatting position, lift their arms, or walk on heels and toes, which helps reveal myopathic weakness. 
• Reflexes are usually normal, and sensation remains intact in pure myositis, helping differentiate it from neuropathies.
• Respiratory, cardiac, and swallowing evaluations are done to detect complications. Shallow breathing or crackles may suggest interstitial lung disease (ILD), while cardiac abnormalities, though rare, can occur. 
• Difficulty swallowing or cough indicates pharyngeal muscle involvement and raises concern for aspiration.
  

Diagnostic Evaluation

Based on the above information, a rheumatology or neuromuscular specialist may advise some diagnostic tests to evaluate suspected myositis. The following tests might be recommended to confirm the diagnosis and assess disease activity:

• Laboratory tests 
• Creatine kinase (CK), also called as creatine phosphokinase (CPK)
• Aldolase, lactate dehydrogenase (LDH)
• Transaminases (AST, ALT)
• Erythrocyte sedimentation rate (ESR)
• Antinuclear antibody (ANA) test
• C-Reactive Protein (CRP)
• Myositis-specific antibody panel
• Electromyography (EMG) 
• Nerve Conduction Studies
• Imaging
• Magnetic Resonance Imaging (MRI)
• Muscle Biopsy
• Genetic Testing
  
  

Laboratory Tests

• Creatine kinase (CK/CPK): CK is an enzyme found in muscle tissue that is released into the bloodstream when muscles are damaged. Elevated CK levels are a hallmark of active myositis and help assess disease severity.
• Aldolase, Lactate dehydrogenase (LDH): These enzymes are also released from damaged muscle fibers. Their elevated levels support the presence of muscle inflammation and help differentiate myositis from other conditions.
• Transaminases (AST, ALT): Though primarily liver enzymes, they can increase with muscle injury. Elevated levels, in conjunction with other markers, can indicate muscle involvement rather than liver disease.
• Erythrocyte sedimentation rate (ESR): It is a nonspecific inflammatory marker. High ESR levels suggest ongoing inflammation and can correlate with disease activity in myositis.
• Antinuclear antibody (ANA) test: ANA testing detects antibodies that target the body’s own cells. Positive results indicate an autoimmune process, which is often associated with inflammatory myositis.
• C-Reactive Protein (CRP): CRP is a protein produced in response to inflammation. Raised CRP levels can indicate active systemic inflammation and are used to monitor response to therapy.
• Myositis-specific antibody panel: This panel detects antibodies associated with specific myositis subtypes, such as anti-Jo-1. It helps in confirming diagnosis, predicting complications, and guiding right treatment decisions.
  
  

Electromyography (EMG)

It measures the electrical activity of muscles both at rest and during contraction. It can detect abnormal patterns consistent with muscle inflammation or damage, differentiate myositis from other nerve disorders, and identify muscles most suitable for biopsy. EMG is valuable for assessing severity of the disease and monitoring response to treatment.

Nerve Conduction Studies

These studies evaluate how well electrical signals travel along peripheral nerves. In patients with weakness, nerve conduction studies (NCS) help distinguish between muscle diseases like myositis and neuropathic conditions. Normal nerve conduction in the presence of weakness supports a primary muscle disorder.

Imaging 

Magnetic Resonance Imaging (MRI): It provides detailed images of muscle tissue, showing inflammation, edema, or fatty replacement. It helps localize affected muscles for biopsy, monitor disease progression, and assess response to therapy. MRI can detect early changes even before symptoms become severe.

Muscle Biopsy

A muscle biopsy involves removing a small tissue sample for microscopic examination. It can reveal inflammation, necrosis, fiber regeneration, and other characteristic changes of myositis. Biopsy is considered the gold standard for confirming the diagnosis and differentiating between the subtypes of inflammatory myopathy.

Genetic Testing

It identifies inherited or congenital muscle disorders that may mimic myositis. It helps distinguish between autoimmune inflammatory myopathies and genetic myopathies, guiding correct treatment and family counseling. It is particularly useful in atypical or refractory cases.

Myositis Differential Diagnosis

The differential diagnosis of myositis includes a wide range of conditions with overlapping symptoms such as muscle weakness and elevated muscle enzymes. The major categories are as follows:

• Muscular Dystrophies
• Metabolic Myopathies
• Drug- or Toxin-Induced Myopathies
• Neuropathies
• Infectious Myositides
• Granulomatous Myositis
• Miscellaneous Causes
  
  

Muscular Dystrophies:  These are genetic disorders characterized by progressive muscle weakness without inflammation. Differentiation from myositis is important since muscular dystrophies do not respond to immunosuppressive therapy.

Metabolic Myopathies:  These involve defects in muscle metabolism leading to weakness and exercise intolerance. They can mimic myositis but typically lack the inflammatory markers and autoantibodies seen in myositis.

Drug- or Toxin-Induced Myopathies:  Certain medications (e.g., statins) and toxins can cause muscle damage mimicking inflammatory myopathy. Evaluation of medication history is critical to distinguish these.

Neuropathies:  Some neuromuscular diseases present with weakness that resembles myositis but involves nerve pathology rather than primary muscle inflammation.

Infectious Myositides:  Infections, particularly viral, bacterial, or parasitic, can cause muscle inflammation and weakness, requiring exclusion before diagnosing idiopathic inflammatory myopathies.

Granulomatous Myositis:  A rare form characterized by granuloma formation in muscle, often associated with systemic diseases such as sarcoidosis or infections. Differentiation depends on biopsy and clinical context.

Miscellaneous Causes:  Other conditions like endocrine disorders, inflammatory bowel disease-associated myositis, and paraneoplastic syndromes can mimic myositis; thorough clinical and laboratory evaluation helps in differentiation.

Goals of Treatment 

The treatment of myositis aims to control inflammation and improve muscle strength. It also focuses on relieving symptoms, preventing complications, and maintaining quality of life. The goals include :

• To reduce muscle inflammation using medications
• To improve muscle strength and function through exercise and therapy
• To relieve pain, fatigue, and other symptoms
• To prevent complications like lung or swallowing problems
• To maintain overall quality of life