medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

, a nerve biopsy is an invasive procedure in which a piece of

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...

is removed from an

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

and examined under a microscope. A nerve

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...

can lead to the discovery of various

necrotizing vasculitis Necrotizing vasculitis, also called systemic necrotizing vasculitus, is a category of vasculitis, comprising vasculitides that present with necrosis. Examples include giant cell arteritis, microscopic polyangiitis, and granulomatosis with polyang ...

amyloidosis Amyloidosis is a group of diseases in which abnormal proteins, known as amyloid fibrils, build up in tissue. There are several non-specific and vague signs and symptoms associated with amyloidosis. These include fatigue, peripheral edema, weight ...

sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...

leprosy Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria ''Mycobacterium leprae'' or ''Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve damag ...

, metabolic neuropathies, inflammation of the nerve, loss of

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...

tissue, and

demyelination A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impairs the conduction of signals in the affected nerves. In turn, the reduction in conduction ability causes deficiency i ...

Biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...

literally means an examination of tissue removed from a living body to discover the presence, cause, or extent of a disease. A nerve biopsy may be necessary when a patient experiences numbness, pain, or weakness in places such as the fingers or toes. A nerve biopsy can help to determine the cause of such symptoms. The procedure is usually only performed when all other options have failed in determining the cause of a disease. It is an outpatient procedure that is performed under

local anesthetic A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general an ...

Uses

A nerve biopsy can potentially find the cause of the numbness and/or pain experienced in the limbs. It can reveal if these symptoms are caused by damage to the

myelin Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be ...

sheath, damage to the small nerves, destruction of the axon in the nerve cells or neuropathies.

Procedure

A sample piece of a nerve is cut from an affected area. The three different types of nerve biopsies each employ a slightly different procedure. For each procedure, the patient is given a local anesthetic to numb the area to be operated on. The patient remains conscious throughout the procedure. The surgeon makes a small incision and removes part of the nerve before closing the incision. Once the nerve has been removed, it is sent to a laboratory for examination.

Types

Sensory

For this procedure, a 1-inch patch of sensory nerve is removed from the ankle or shin, during which the patient may experience temporary or permanent numbness on the top or side of the foot.

Selective motor nerve

A nerve sample is taken from the inner thigh when a motor nerve is affected.

Fascicular

The nerve is exposed and separated, then given a small electrical impulse to help understand which nerve should be removed and examined.

Risks

The most significant risk is long-term nerve damage and loss of sensation. Less significant risks include discomfort after the procedure, allergic reaction to the anesthetic, and infection.

References

{{Peripheral nervous system tests and procedures Biopsy