Definition of Nerve biopsy:

A nerve biopsy is the removal of a small piece of a nerve for examination.

How the test is performed:

The sural nerve (in the ankle), or the superficial radial nerve (wrist) are the sites most often used for biopsy. A local anesthetic is used to numb the area. A small incision is made, and a portion of the nerve is removed. The sample is then examined using either a regular (light) microscopic or an electron microscope. Individual nerve fibers may also be examined.

How to prepare for the test:

There is no special preparation.

Infants and children:

The preparation you can provide for this test depends on your child's age and experience. For general information regarding how you can prepare your child, see the following topics:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• Schoolage test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

The amount of pain during and after the procedure depends on the patient. Because a local anesthetic is used, discomfort during the procedure is usually minimal. The anesthetic may burn or sting when first injected. After the procedure, the area may feel tender or sore for a few days.

Why the test is performed:

Nerve biopsy may be performed to help distinguish between demyelination (destruction of parts of the myelin sheath covering the nerve) and axon degeneration (destruction of the axon portion of the nerve cell), to identify inflammatory nerve conditions (neuropathies), or to confirm specific diagnoses.

Normal Values:

There is normal nerve anatomy, with no abnormal growths or inclusions.

What abnormal results mean:

Conditions or disorders that may be revealed include:

• Necrotizing vasculitis
• Amyloidosis (sural nerve biopsy is most often used)
• Sarcoidosis
• Leprosy
• Metabolic neuropathies
• Inflammation of the nerve
• Loss of axon tissue
• Demyelination

• Alcoholic neuropathy
• Axillary nerve dysfunction
• Brachial plexopathy
• Charcot-Marie-Tooth disease (hereditary)
• Common peroneal nerve dysfunction
• Distal median nerve dysfunction
• Mononeuritis multiplex
• Mononeuropathy
• Necrotizing vasculitis
• Neurosarcoidosis
• Radial nerve dysfunction
• Tibial nerve dysfunction

What the risks are:

• Permanent nerve damage (uncommon; minimized by careful site selection)
• Discomfort after the procedure
• Infection (a slight risk any time the skin is broken)
• Allergic reaction to the local anesthetic

Special considerations:

Nerve biopsy is invasive and is useful only in certain circumstances. These include diagnosis of asymmetric and multifocal nerve disorders, conditions in which a nerve is palpably enlarged (the enlargement can be felt with the fingers), and suspected inherited pediatric nerve disorders.