A muscle biopsy is the removal of a small piece of muscle tissue for examination.
Biopsy - muscle
How the test is performed
This procedure is usually done while you are awake. The health care provider will apply a numbing medicine (local anesthesia) to the biopsy area.
There are two types of muscle biopsy:
A needle biopsy involves inserting a needle into the muscle. When the needle is removed, a small piece of tissue remains in the needle. The tissue is sent to a laboratory for examination. More than one needle stick may be needed to get a large enough sample.
An open biopsy involves making a small cut in the skin and into the muscle. The muscle tissue is then removed.
How to prepare for the test
No special preparation is usually needed.
How the test will feel
During the biopsy, there is usually minimal or no discomfort. You may feel some pressure or "tugging" sensations.
The anesthetic may burn or sting when injected (before the area becomes numb). After the anesthetic wears off, the area may be sore for about a week.
Why the test is performed
A muscle biopsy may be done to identify or detect:
A muscle biopsy may be also be done to tell the difference between nerve and muscle disorders.
A muscle that has recently been injured, such as by an EMG needle, or is affected by a pre-existing condition, such as nerve compression, is not a good choice for a biopsy.
A normal result means there is normal muscle and related tissue anatomy. There are no abnormalities seen when the tissue sample is stained and examined under a microscope.
What abnormal results mean
A muscle biopsy can help diagnose the following conditions:
Additional conditions under which the test may be performed include:
What the risks are
The risks are small, but may include:
- Damage to the muscle tissue or other tissues in the area (very rare)
- Infection (a slight risk any time the skin is broken)