A muscle biopsy is a procedure used to diagnose diseases involving muscle tissue. Tissue and cells from a specific muscle are removed and viewed microscopically. The procedure requires only a small piece of tissue to be removed from the designated muscle.
The tissue sample is obtained by inserting a biopsy needle into the muscle. If a larger sample is required, your doctor may make an incision in the skin (open biopsy) and remove a larger section of muscle.
The muscle selected for the biopsy depends on the location of symptoms that may include pain or weakness. The muscles often selected for sampling are the bicep (upper arm muscle), deltoid (shoulder muscle), or quadriceps (thigh muscle).
A related procedure that may be used to diagnose neuromuscular problems is electromyography (EMG). EMG measures the electrical activity of muscle during rest, slight contraction, and forceful contraction. Please see this procedure for additional information.
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 with the nervous system, connective tissue, vascular system, or musculoskeletal system.
A muscle biopsy helps to determine the source of the disease process ensuring initiation of appropriate treatment.
Muscle biopsies may be performed to diagnose neuromuscular disorders, infections that affect the muscle, and other abnormalities in the muscle tissue. The following is a list of some conditions diagnosed by muscle biopsy:
Muscular dystrophy (MD). A broad term that describes a genetic (inherited) disorder of the muscles. Muscular dystrophy affects skeletal muscles and other organ systems. The muscles break down and are replaced with fatty deposits over time. There are many different types of muscular dystrophy.
Duchenne muscular dystrophy (DMD). The most common form of muscular dystrophy. DMD usually affects only males.
Becker muscular dystrophy. Similar to Duchenne muscular dystrophy (DMD) but usually more mild with the onset of symptoms occurring later in life.
Trichinosis. An infection caused by a parasite that lives in raw meat. Symptoms may include muscle pain.
Toxoplasmosis. An infection caused by a parasite that invades the tissue and can damage the central nervous system, especially in infants.
Myasthenia gravis (MG). A complex, autoimmune disorder in which antibodies destroy neuromuscular connections. This causes problems with the nerves that communicate with muscles. MG affects the voluntary muscles of the body, especially the eyes, mouth, throat, and limbs.
Polymyositis. A chronic disease involving skeletal muscles.
Dermatomyositis. A collagen disorder that causes inflammation to the skin, muscles, and subcutaneous tissue often resulting in weakened muscles.
Amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig disease, ALS is a disease that attacks the nerves signaling voluntary muscle movement, eventually causing paralysis.
Friedreich ataxia. An inherited, genetic disorder that involves balance and coordination.
There may be other reasons for your doctor to recommend a muscle biopsy.
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
Prolonged bleeding from the biopsy site
Infection of the biopsy site
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Before the procedure
Your doctor 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 gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
In addition to a complete medical history, your doctor may perform a complete physical examination to ensure you are in good health before undergoing the procedure. You may undergo blood tests or other diagnostic tests.
Notify your doctor if you are sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general).
Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
Notify your doctor 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.
If you are pregnant or suspect that you are pregnant, you should notify your doctor.
You may be asked to fast for several hours prior to the procedure.
You may receive a sedative prior to the procedure to help you relax. Because the sedative may make you drowsy, you will need to arrange for someone to drive you home.
Based on your medical condition, your doctor may request other specific preparation.
During the procedure
A muscle biopsy may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor’s practices.
Generally, a muscle biopsy follows this process:
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 doctor injects a local anesthetic to numb the area, you will feel a needle stick and a brief stinging sensation.
Your doctor will insert the biopsy needle through the numbed skin, and into the muscle where the sample is taken. You may feel some pressure or pulling sensation during the procedure.
If a larger sample is required, a small incision will be made into the skin’s surface. Sections of the muscle tissue may be cut using small, sharp scissors instead of a biopsy needle. You may feel mild discomfort when the muscle is cut.
The biopsy needle will be withdrawn and firm pressure will be applied to the biopsy site for a few minutes, until the bleeding has stopped.
The doctor will close the opening in the skin with adhesive strips or stitches, if necessary.
A sterile bandage or dressing will be applied.
The muscle tissue sample will be sent to the lab for examination.
After the procedure
Once you are home, it is important to keep the biopsy area clean and dry. Your doctor will give you specific bathing instructions. If stitches are used, they will be removed during a follow-up office visit. If adhesive strips are used, they should be kept dry and generally will fall off within a few days.
The biopsy site may be tender or sore for 2 to 3 days after a muscle biopsy. Take a pain reliever for soreness as recommended by your doctor. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications.
Notify your doctor to report any of the following:
Redness, swelling, bleeding, or other drainage from the biopsy site
Increased pain around the biopsy site
You may resume your usual diet and activities unless your doctor advises you differently. Your doctor may restrict your activity for 24 hours following the procedure and ask that you avoid excessive use of the biopsied muscle.
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.