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Myopathy or muscular disease that includes muscle inflammation and muscle weakness. Myopathies affecting the skeletal muscle can have many origins - inherited, drug induced or endocrine issues. Mostly a Myopathy is transitory in nature and rarely results in complete loss of function. Muscular Dystrophy is possibly an exception in that it can be severe and sometimes even fatal if it occurs early in life.

Genetic Myopathies

These inherited Myopathies occur due to a genetic defect in the synthesis of a protein. There are many kinds in genetic Myopathies:

  • Central Core Disease : Weakness in the muscles affecting hips and legs resulting in problems in running, jumping and climbing stairs

  • Centronuclear Myopathy or Myotubular Myopathy : Weakness in the muscles affecting face, legs, arms and the trunk resulting in drooping upper eyelids, facial weakness or foot drop

  • Myotonia Congenita : Muscles in the face, arms or legs are affected and result in muscular stiffness (myotonia) after contracting of muscles - usually after a trigger in the form of stress, fatigue, cold or a long period of no motion

  • Nemaline Myopathy : Weakness in the muscles of arms, legs and the trunk resulting in poor or absent reflexes, long or narrow face, abnormal facial features

  • Paramyotonia Congenita : Stiffness of muscles in the face, forearms and hands

  • Periodic Paralysis : Temporary muscle weakness episodes in hypokalemic form (low calcium) as a result of vigorous exercises, intake of food high in carbohydrates, stress, alcohol, insulin, pregnancy or infection. In the hyperkalemic form (high calcium) it can occur as a result of vigorous exercises, stress, pregnancy, skipping food, high potassium levels or steroids

  • Mitochondrial Myopathies : Progressive weakness of muscles in the eye (ocular myopathy) or arms and the legs or multisystem issues

Endocrine related Myopathies : Hormone deficiency can cause Myopathies. Hyperthyroid Myopathy is the result of excess secretion of thyroxine from the thyroid gland affecting muscles in the shoulders, hips or eyes. Hypothyroid Myopathy occurs when too little hormone is secreted and results in stiffness, cramps and weakness of legs and arms muscles.

Inflammatory Myopathies : Some Myopathies result in inflamed, weakened or wasted muscles. Dermatomyositis affects the connective tissue and the severity of the affected muscle loss can result in crippling movement.

Chronic muscle inflammation is called as Myositis. It is usually caused due to allergic reaction, infectious disease or rheumatism. Sometimes Myopathies are hereditary. Symptoms of Myopathy can also include cramps, spasms and stiffness. There is progressive deterioration in muscle strength resulting in pain and fatigue on walking and tripping and falling. This is not due to nerve dysfunction. Some patients might notice facial weakness, foot drop, droopy eyelids and poor reflexes in affected muscles.

Muscle Biopsy

This is a procedure in which muscle tissue is removed from an organism and examined microscopically. Muscle biopsies can distinguish between Myopathies, (the pathology is in the muscle tissue itself) and neuropathies (pathology is at the nerves innervating those muscles) by means of microscopic analysis. Problems could be detected in a nervous system, in connective tissue, vascular or musculoskeletal system. A variety of Myopathies can cause centronuclear biopsy and hence a specific genetic testing becomes increasingly important.

What is muscle biopsy?

This is a procedure when a small sample of tissue is removed for testing in a laboratory. The test detects an infection or disease in the muscles. This is a relatively simple procedure. It is done as an outpatient basis, and the patient is free to leave on the same day as the procedure. As it is often done on a local anesthesia, the doctor removes the tissue from the area but the patient remains awake for the test.

Reasons for a muscle biopsy

This is done when the doctor suspects an infection in the muscle. The biopsy is done to help the doctor rule out certain conditions that could cause the symptoms and then proceed with an appropriate treatment plan.

  • Biopsy is done if the doctor suspects that there may be defects in the way the muscles metabolize or use energy.
  • Diseases that affect the blood vessels and connective tissues, where the arteries become swollen.
  • Infections related to the muscles, such as the one caused by a type of roundworm.
  • Muscle disorders including muscular dystrophy, genetic disorders that lead to muscle weakness.

Risks of a muscle biopsy

There is always a risk of infection or bleeding or bruising possible when a medical procedure that breaks the skin is performed. However, since the incision here is quite small, especially in needle biopsy, the risk is much lower. An electromyography is done in case of recent muscle damage. Very rarely there could be damage to the muscle where the needle is inserted.

Muscle biopsy procedure

There are two ways in which muscle biopsies are performed - the common method is called a needle biopsy and for this procedure, the doctor inserts a thin needle through the skin and remove the muscle tissue. This could be:

Core needle biopsy with a medium sized needle, similar to the way core samples are taken from the earth

Fine needle biopsy using a thin needle attached to a syringe, fluids and cells are drawn out.

Image-guided biopsy where the needle biopsy is guided with imaging procedure; such as x rays and CT scans.

Vacuum assisted biopsy uses suction from a vacuum to collect more cells.

The patient receives a needle biopsy after a local anesthesia and will not feel any pain or discomfort. There will be pressure in the area where the biopsy is taken and the area may be sore for about a week. In case the muscle sample is far to reach and is in deep muscles, the doctor may choose to perform an open biopsy. The doctor will make a small cut in the skin and then remove the muscle tissue from there.

For instance, if patient needs have a biopsy in the leg, he/she must expect to use crutches or another assistive device for two full days after biopsy. Training with crutches is provided. Some patients may need assistance at home during the recuperation period. If patients have had a biopsy in the arm, they must expect to wear a sling for two days. Stitches do not need to be removed but must remain completely dry for a couple of days.

In general, there are few complications and the resulting scar heals well. After the tissue sample is taken, it is sent to a laboratory for testing and the results would be ready in a couple of week's time. A report on frozen or paraffin specimens will be sent to the referring physician. The small piece of muscle tissue is examined by microscopic techniques to check for presence of fibrous tissue or other abnormalities. The extracted tissue can also be stained for detecting absence of presence of particular proteins. Microscopic examination can also reveal if the muscle fibers are being infiltrated by the immune system.

In case the results are abnormal, it could mean there is an infection or disease in the muscles and this may cause them to weaken or die. The doctor may prescribe additional tests to confirm the diagnosis and how far the condition has gone. Treatment options are discussed and further steps taken.


Polymyositis is a chronic inflammatory disease of the skeletal muscle. It is a predominant form of muscular dystrophy, noticed among elderly people. It is categorized as one of the three important forms of myopathies that exist. The response to this condition varies from person to person depending on the strength and dexterity of the muscle tissue. Polymyositis is generally not localized and hence many muscle groups are affected by it.

The most common muscle groups affected by this disease are the muscles associated with the neck (sternocleido mastoid), shoulders (scapular region), trapezoid region, hands and legs mainly hams and quadriceps during walking and running. The symptoms of polymyositis are usually self-limiting. However in case of adverse muscular inflammation, medical attention is required in order to prevent progressive damage of the muscle tissue.

Clinical manifestations of Polymyositis

Polymyositis has many causes - some of the common causes include infections (bacterial or viral), and inherited forms. Viral myagias are one of the forms, which can affect the muscle tissues in an intense manner if ignored. The appropriate intervention for viral Myalgia causing Polymyositis is to identify the exact cause in ruling out other infective forms such as bacterial infection through laboratory diagnosis.

Viral particles can induce the onset of fever causing muscular weakness and fatigue. Sometimes, polymyositis can affect children under these scenarios. Other generalized clinical manifestations of the disease include low-grade fever, weakness, irritability, tenderness, decreased appetite and shortness of breath. Some forms of polymyositis have long-term effects and hence such patients are advised to incorporate immunosuppressive agents. This is recommended when Polymyositis takes the autoimmune disease form.

Diagnosis of Polymyositis

Polymyositis is predominantly diagnosed by the determination of biochemical values such as creatine kinase in the blood. Creatine kinase is produced in case of muscle cell damage, the estimation of which determines the extent of muscle damage caused. Electromyograph (EMG) is also recommended to understand the neuromuscular physiology and the disorders associated with them such as myogenic condition. This is identified by the neuromuscular electrical conduction studies.

In some cases, biopsy is recommended to understand the pathophysiology of the disease through histological anomalies. The specimen is usually taken from the quadriceps or shoulders (deltoid). The pathological identification includes the presence of infiltrated muscle cells and focal regions of muscular degeneration in the muscle fibers.

Treatment of Polymyositis

Polymyositis is predominantly treated by the administration of corticosteroids in order to reduce the inflammation. These drugs can be either given by oral route or through IV administration. Other forms of treatment include immunosuppressant administration in case of autoimmune form of the disease. Azathioprine and methotexrate are generally given as immune suppressants. Appropriate intervention through corticosteroids or immune suppressants can facilitate the motor recovery in neuromuscular conduction.

Tags: #Myopathy #Muscle Biopsy #Polymyositis
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Collection of Pages - Last revised Date: March 2, 2024