Muscle biopsy

The biopsy muscle is a surgical procedure in which one or more small pieces of muscle tissue are removed for further examination under the microscope or biochemical techniques. The procedure, commonly used in the diagnosis of a neuromuscular disorder, is considered a minor surgery and is performed under local anesthesia.

Alternative name

  • Muscle biopsy


This procedure is usually done while you are awake. The doctor will apply 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 on the needle, which is sent to a laboratory for analysis. More than one needle stick may be needed to obtain a large enough sample.

An open biopsy involves making a small incision in the skin and into the muscle. Then the muscle tissue is removed.

What the test feels like

There is generally little or no discomfort during the biopsy, although pressure or “pulling” sensations may be experienced.

When anesthesia is injected, you may experience a burning or stinging sensation (before numbing the area), and when the anesthesia wears off, the area may be sore for about a week.

Reasons to take the exam

A muscle biopsy can be done to identify or detect:

  • Connective tissue and blood vessel diseases (such as polyarteritis nodosa)
  • Infections that affect the muscles (such as trichinosis or toxoplasmosis)
  • Muscle disorders such as muscular dystrophy or congenital myopathy
  • Metabolic muscle defects

A muscle biopsy can also be done to differentiate between nerve and muscle disorders. A muscle that has recently been injured, such as from an EMG needle, or that is affected by a pre-existing condition such as nerve compression, is not a good choice for a biopsy.

Normal values

A normal result means that the muscle and associated tissue anatomy are normal. No abnormalities are seen when the tissue sample is stained and examined under a microscope.

Meaning of abnormal results

A muscle biopsy can help diagnose the following conditions:

  • Atrophy (loss of muscle mass)
  • Dermatomyositis
  • Duchenne muscular dystrophy
  • Inflammation of the muscle
  • Muscular dystrophy
  • Myopathic changes (destruction of muscle)
  • Necrosis (tissue death) of the muscle
  • Necrotizing vasculitis
  • Traumatic muscle damage
  • Polymyositis


The risks are small, but they can be:

  • Bleeding
  • Hematoma
  • Damage to muscle tissue or other tissues in the area (very rare)
  • Infection (a slight risk any time the skin is broken

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