A muscle biopsy is the removal of a small piece of muscle tissue for examination.
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:
After either type of biopsy, the tissue is sent to a laboratory for examination.
No special preparation is usually needed. If you will have anesthesia, follow instructions on not eating or drinking anything before the test.
During the biopsy, there is usually little or no discomfort. You may feel some pressure or tugging.
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.
A muscle biopsy is done to find out why you are weak when the doctor suspects you have a muscle problem.
A muscle biopsy may be done to help identify or detect:
A muscle biopsy may 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, should not be selected for a biopsy.
A normal result means the muscle is normal.
A muscle biopsy can help diagnose the following conditions:
There are additional conditions under which the test may be performed.
The risks of this test are small, but may include:
Reviewed By: Gordon A. Starkebaum, MD, ABIM Board Certified in Rheumatology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.