What’s a nerve biopsy?
A nerve biopsy is a medical process that involves removal of nerve components from an organism and its microscopic examination. Biopsy simply means investigating the presence, cause or extent of a disorder by extracting tissue from a living body. Discoveries such as leprosy, metabolic neuropathies, nerve inflammation, loss of axon tissue, amyloidosis, sarcoidosis, demyelination and necrotizing vasculitis have been traced with the help of nerve biopsy.
In cases where the patient experiences weakness, numbness, pain in his fingers or toes, nerve biopsy may be an appropriate option. It helps to discover the reason for such discomfort. The test is typically only carried out after all the other approaches for assessing the causes of infection have failed.
A doctor through a nerve biopsy can determine the root cause of the symptoms involving:
- An insulating layer called the myelin sheath whose damage can be detected.
- Loss of the axon, the fibre-like nerve cell extensions that aid signal transmission.
- Any kind of damage in the nerves.
Why a nerve biopsy is done?
Nerve biopsy enables the doctor to detect any dysfunction in the nerves. The doctor may recommend you go undergo a nerve biopsy under the following conditions:
- Alcoholic polyneuropathy – A neurological condition in which the peripheral nerves concurrently work throughout the entire body.
- Axillary nerve dysfunction – is peripheral neuropathy which occurs when there is a damage in the axillary nerve. This nerve controls the deltoid muscles present in the shoulder and the skin around it. In case of any dysfunction in even one nerve the term used is mononeuropathy.
- Brachial plexopathy – is a peripheral neuropathy caused by the damage of brachial plexus, an area on either side of the neck which separates nerve roots from the backbone and into the nerves of each arm.
- Charcot- Marie- tooth disease- is a group of inherited disorders which damage the nerve and primarily occurs in your arms and legs.
- Common peroneal nerve dysfunction– Popular peroneal nerve dysfunction is caused by damage to the peroneal nerve resulting in loss of movement or sensation in the foot and leg.
- Distal median nerve dysfunction– is a type of disorder in which movement of hands or sensation is affected. Carpal tunnel syndrome is a common type of distal median nerve dysfunction.
- Mononeuritis multiplex– is a painful asymmetric disorder in which two different nerve areas(can be of different body parts) are affected.
- Necrotizing vasculitis – In this disorder, blood vessels experience inflammation and break the regular flow of blood.
- Neurosarcoidosis– Is a central nervous disorder in which inflammation is caused in the brain, nervous system, spinal cord and optic nerve. Inflammation can be experienced in one or more such areas.
- Radial nerve dysfunction– is a dysfunction in the radial nerve which may result in loss of sensation and movement in arms, wrist and fingers.
- Tibial nerve dysfunction – is a disorder wherein the tibial nerve gets compressed and results in loss of movement and sensation in the foot. It may also trigger a feeling of numbness, a tingling sensation or weakness at the bottom of the foot.
Risks of a nerve biopsy
A nerve biopsy may expose you to risk of long term nerve damage, but this situation arises under rare circumstances. Usually, a nerve biopsy is performed in the ankle or wrist. There are chances of the wound oozing out after the completely normal treatment. In case of excessive bleeding or infection in the wound, a doctor must be consulted. In the case of excess pain, pain killers can be used. A small area on the outer side of the foot may experience some sensation due to the sural nerve.
This can lead to loss of sensation or altered feeling, including stirring and/or discomfort and persistent pain. Neuropathic patients already have sensory losses in these areas. If even after the therapy, the pain remains constant, it may be due to entanglement of the nerves for which a doctor must be consulted.
Usually, after the therapy, the body part where the biopsy is performed remains numb, but may not be of great concern as a small area is affected. Some even complain of allergic reactions and infections post-biopsy therapy, again a doctor should be consulted to solve this issue.
Procedure for nerve biopsy
The type of ailment or issue plays a key role in determining the type of procedure opted by the doctor. These include- sensory nerve biopsy, fascicular nerve biopsy and selective motor nerve biopsy.
Sensory nerve biopsy- in this procedure, a nerve equivalent to 1-inch in length is removed from the ankle or tibia which may result in temporary or permanent numbness.
Fascicular nerve biopsy– this procedure involves exposing the sensory nerve to an electrical impulse to determine the nerve to be removed.
Selective motor nerve biopsy– this procedure is opted for in case of problem in the motor nerve. Usually, a sample from the inner thigh is taken to be subjected to laboratory screening.
All the procedures require the use of anaesthesia to numb that area so that the process is not painful for the patient due to numbness. However, one remains in his senses during the process as only a part of the body is made numb. The doctor proceeds by making incisions and thereby, removes a small portion of the nerve. Later it is closed by making the use of sutures. The removed portion is subjected to laboratory testing.
Steps to be taken before the therapy
Certain steps must be followed before the therapy:
- The patient may also be asked to undergo a physical examination.
- The patient is advised to stay away from alcohol, smoke or any kind of drug before the procedure.
- A blood test is mandatory.
- The medical history of a patient may be of much significance for the therapy.
- If the patient uses pain relievers, anticoagulants or any such medicine which may affect bleeding, they are advised to stop its consumption.
Is nerve biopsy useful or not?
Even though the requirement of nerve biopsy therapy has increased over the years. However, some have also complained that this procedure did not prove to be beneficial for them. The results that one can expect from the procedure depends on a lot of factors-
- The kinds of patients opting for the procedure of the nerve biopsy.
- The expertise of the laboratory in examining the nerve.
- The kind of techniques used in the procedure.
There are people who have experienced positive results after the procedure, too. It treats nerve disorder, giving the patient a feeling of relief.