A muscle biopsy is a procedure used to diagnose diseases involving muscles. A small piece of muscle is removed from the designated muscle, processed in the laboratory, and viewed microscopically. The tissue sample is obtained by your physician who will make an incision (approximately 1.5 inches long) in the skin (open biopsy) and remove 3–4 very small pieces from designated muscle.
The muscle selected for the biopsy depends on the location of symptoms, which may include pain or weakness. The muscles often selected for sampling are the biceps (an upper arm muscle) or quadriceps (a thigh muscle).
Reasons for the Procedure
A muscle biopsy is performed to assess the musculoskeletal system for abnormalities. Various disease processes can cause muscle weakness or pain. These conditions may be related to problems within the nervous system, connective tissue, vascular system, or musculoskeletal system.
There may be other reasons for your physician to recommend a muscle biopsy.
A muscle biopsy helps to determine the source of the disease process, ensuring initiation of the appropriate management. The following is a list of common conditions diagnosed by muscle biopsy:
- Muscular dystrophy (MD)
A broad term that describes a genetic/inherited disorder of the muscles. Muscular dystrophy causes the muscles in the body to become very weak. The muscles break down and are replaced with fatty deposits over time. There are many different types of muscular dystrophies.
- Metabolic, toxic, mitochondrial myopathies
These muscle disorders are due to specific enzyme defects, exposure to toxins including certain medications, and abnormalities of the mitochondria.
A disorder that causes inflammation of many of the skeletal muscles.
A multisystem disorder that causes inflammation of the skin, muscles, and subcutaneous tissues often resulting in muscle weakness.
- Inclusion Body Myositis
A chronic progressive disorder of the muscle also considered autoimmune in nature.
- Neurogenic atrophy
Disorders of the motor neurons and nerves cause muscle atrophy and sometime muscle biopsies are necessary for diagnosis and management.
Risks of the Procedure
As with any surgical procedure, complications can occur. Some possible complications may include, but are not limited to, the following:
- Bruising and discomfort at the biopsy site
- Bleeding from the biopsy site
- Infection of the biopsy site
There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.
Stages of the Procedure
Before the Procedure
- Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
- You will be asked to sign a consent form that provides permission to perform the procedure. Read the form carefully and ask questions if something is not clear.
- Notify your physician if you are sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general).
- Notify your physician of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
- Notify your physician if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop these medications prior to the procedure.
- You will need to arrange for someone to drive you home after the procedure.
During the Procedure
A muscle biopsy is typically performed on an outpatient basis. Procedures may vary depending on your condition and your physician’s practices.
This routine is followed generally:
- You will be asked to remove clothing and will be given a gown to wear.
- During the procedure, you will need to lie as still as possible.
- The skin over the biopsy site will be cleansed with an antiseptic solution.
- As the physician injects a local anesthetic to numb the area, you will feel a needle stick and a brief stinging sensation.
- The physician will close the opening in the skin with stitches and adhesive strips.
- A sterile bandage/dressing will be applied.
- The muscle tissue sample will be sent to the laboratory for processing and examination.
After the Procedure
- Once you are home, it is important to keep the biopsy area clean and dry.
- Since self-absorbing stitches are used, they will not be removed by anyone. Adhesive strips generally will fall off within a few days.
- The biopsy site may be tender or sore for two to three days after a muscle biopsy. Take a pain reliever for soreness as recommended by your physician. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications.
- Notify your physician to report any of the following:
- Drainage from the biopsy site
- Increased pain around the biopsy site
- You may resume your usual activities as instructed by your physician. Usually you will be required not to bear any weight with the biopsied leg for 2–3 days. Please keep this in mind when planning for the procedure.
- Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.
Processing of the Muscle
The muscle biopsy is processed and examined under a microscope. Different tests are performed depending on the suspected diagnosis. The processing may take at least one week or more. This is followed by detailed analysis leading to a full report, which may take up to three to four weeks. The result is sent to the referring doctor, who will then explain the findings to you. Any sample remaining after this analysis is stored in case further analysis or re-analysis is required in the future.