What Is Myopathy?
Myopathy is a condition that affects the skeletal muscles that connect the muscles to the bones. They can be inherited or acquired during life. The people suffering from myopathies will have difficulty doing daily activities.
What Are the Different Types of Myopathies?
There are two types of myopathies, and they are:
1. Inherited Myopathy - Inherited myopathies are the ones that are passed down from their parents through an abnormal gene mutation. The inherited myopathies include the following:
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Mitochondrial Myopathies - Mitochondria are the powerhouse of the cells. Any defect in this part of the cell especially cells of the muscle will get affected with their function resulting in mitochondrial myopathy. The other organs that can be affected include GIT, brain, and stomach. This could be due to the mutation in the gene that is causing this.
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Congenital Myopathies - It is a type of myopathy that is present at the time of birth and the symptoms are seen right after the birth. They are different from the acquired myopathies as their symptoms are not mostly progressive and are seen to affect all muscles not just the proximal muscles.
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Metabolic Myopathies - Metabolic myopathies are caused by defects in the enzyme which are responsible for the normal functioning and movement of the muscles. They are often seen as pain on exertion in the shoulders and thighs, exercise intolerance, and non-traumatic rhabdomyolysis (muscle fiber condition). There can also be episodes of muscle weakness.
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Muscular Dystrophies - It is caused by abnormal or insufficient proteins to support the structure resulting in progressive degeneration of muscle tissues. They can affect the muscles of the eyes, face, arms or legs to varying degrees.
2. Acquired Myopathy - Acquired myopathies are the types of myopathies that develop later in life. They can develop infections, electrolyte imbalances, exposure to certain medications, and may be due to other medical conditions. The acquired myopathies include the following:
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Autoimmune/Inflammatory Myopathy - Autoimmune or inflammatory myopathies are diseases in which your body attacks itself, causing problems with muscle function.
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Toxic Myopathy - This type of myopathy when some toxins interfere with the function or structure of the muscles. Certain toxins like toluene and alcohol which are used for substance abuse might cause this condition. Other than that certain medications like immunotherapy, corticosteroids, statins, antivirals and drugs used for treating HIV can cause this condition.
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Endocrine Myopathies - The myopathy caused due to problems with the hormone function and affect the functioning of the muscles is called the endocrine myopathies. The endocrine myopathies could be caused by the variation in the amounts of hormones produced by the thyroid and parathyroid glands. It could also be due to Cushing syndrome and Addison’s disease affecting the adrenal glands too.
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Infectious Myopathies - There are some infections that affect the functioning of the muscle. This can be caused by viral infections like influenza, HIV, and Epstein-Barr infection. Other parasitic infections and fungal infections like toxoplasmosis, cysticercosis, Candida and Coccidiomycosis can als cause this condition
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Electrolyte Imbalance - The low or high levels of the electrolytes can affect muscle function. The electrolyte levels that mainly affect are the potassium (hypokalemia and hyperkalemia) and magnesium.
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Critical Illness Myopathy - Critical illness is the type of myopathy that affects the muscles that help in the breathing and limbs. It can be caused due to prolonged duration of stay in the intensive care unit or when a person is immobilized for a long duration that is a person is bedridden or can be caused by the use of certain medications like muscle relaxants, corticosteroids, or sedatives.
What Are the Symptoms of Myopathies?
Most of the myopathies have similar symptoms, and they are discussed below:
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Muscle weakness, mostly of the upper arms and shoulders and thighs.
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Muscle cramps and spasms.
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Muscle stiffness.
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Fatigue with exertion.
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Lack of energy.
How Is Myopathy Diagnosed?
The healthcare provider will take the medical history along with drug history as well as the symptoms. Then following that they will do a physical examination, which includes the skin, reflexes, balance, sensation, and muscle strength. Other than this, they will ask to get the following tests.
Blood Tests:
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Muscle enzymes - Aldolase and creatine kinase (CK) as they may be increased due to muscle fiber breakdown.
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Electrolyte levels - Sodium, magnesium, potassium, phosphorus and calcium.
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Autoimmune disease testing- Antinuclear antibodies (ANA), sedimentation rate, rheumatoid factor, and c-reactive protein.
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Endocrine testing like thyroid hormone.
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Electromyography (EMG and nerve conduction studies), like testing the electrical conduction of the nerves and needle examination of the muscles to assess the type and degree of muscle damage.
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Genetic tests.
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Magnetic resonance imaging (MRI) of the muscles.
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Muscle biopsy, in which the doctor surgically removes a piece of muscle tissue for testing.
What Is the Treatment for Myopathy?
Before starting on how to treat the condition, the type of myopathy needs to be determined. The treatment will decide on which type of myopathy a person has. According to that the healthcare provider will make a treatment plan depending on the symptoms. The treatment will include occupational therapy, physical therapy, and exercises. Most of the acquired myopathies can be controlled with the treatment. The inherited myopathies can be treated to control the progression of the disease. There is no specific treatment for inherited myopathy but physical therapy and other exercises can help the symptoms.
Inflammatory and Autoimmune-related Myopathies:
The goal of treatment is to decrease inflammation and your body’s autoimmune response. These myopathies are often treated with:
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Immunomodulatory or immunosuppressant drugs - Methotrexate, Cyclosporine, Tacrolimus, Azathioprine, Mycophenolate, Rituximab and intravenous or subcutaneous immunoglobulin.
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Corticosteroids like Prednisone or Methylprednisolone.
Inherited and Genetic Myopathies:
In general, most of the inherited and genetic myopathies do not have any specific treatment or cure. The symptoms are managed and controlled with different therapies.
Other Acquired Myopathies:
The acquired myopathies can be treated by identifying the causing factor and treating them first. If some toxin is causing the myopathy, then stopping them will improve the symptoms. In case the myopathy is caused by an infections, treating the underlying infection with antibiotics, antivirals or antifungals depending on the causing agent will be the cure
Conclusion
Myopathies are a group of diseases affecting the muscles. There are different types of myopathies, acquired or inherited. People with myopathies will have difficulty carrying out their daily activities, like standing up, or walking, as they suffer from muscle pain and spasm. They might need to undergo various therapies to help with the symptoms. Consult a doctor if there are any symptoms.
