A nerve biopsy is a medical procedure in which a small segment of nerve tissue is extracted for microscopic examination. This diagnostic tool allows healthcare professionals to investigate the underlying causes of various conditions impacting the peripheral nervous system. Analyzing the nerve sample helps doctors gain insights into the specific nature of nerve damage or disease.
Understanding the Purpose
A nerve biopsy is performed to diagnose various peripheral neuropathies, conditions affecting nerves outside the brain and spinal cord. It helps identify the specific type and cause of nerve damage when other diagnostic tests are inconclusive. For instance, it can distinguish between different forms of inflammatory neuropathies, such as chronic inflammatory demyelinating polyneuropathy (CIDP).
The procedure is also valuable in diagnosing conditions like amyloidosis, where abnormal protein deposits accumulate in nerves, or vasculitic neuropathy, which involves inflammation of blood vessels supplying nerves. It can help confirm a diagnosis of leprosy, sarcoidosis, or certain inherited neuropathies. Microscopic analysis of the nerve tissue guides medical professionals toward a precise diagnosis.
How a Nerve Biopsy is Performed
Before a nerve biopsy, patients receive instructions about fasting and adjusting medications, particularly blood thinners, to minimize bleeding risk. The procedure is performed on an outpatient basis, meaning the patient can go home the same day. The sural nerve, located near the ankle, is a common site for biopsy due to its accessibility and the fact that its removal results in minimal functional impairment. Another potential site is the superficial peroneal nerve, also in the lower leg.
Once the biopsy site is chosen, the area is cleaned, and a local anesthetic is injected to numb the skin and underlying tissues, to ensure comfort during the procedure. A small incision, 1 to 3 centimeters long, is then made through the skin. The surgeon locates the nerve and excises a small segment, typically 2 to 4 centimeters long.
After the nerve sample is removed, the incision is closed with sutures, and a sterile dressing is applied to the wound. The entire process takes about 30 to 60 minutes. The collected nerve tissue is sent to a pathology laboratory. There, pathologists process the sample, which is then examined under a microscope to identify abnormalities or signs of disease.
What to Expect After the Procedure
Following a nerve biopsy, patients can return home within a few hours, though they should arrange for someone to drive them. The biopsy site will be covered with a sterile dressing, and instructions for wound care will be provided, involving keeping the area clean and dry for several days. Mild pain or discomfort at the incision site is common and can be managed with over-the-counter pain relievers.
Patients are advised to limit strenuous activities, such as heavy lifting or vigorous exercise, for one to two weeks to allow the incision to heal properly. It is common to experience temporary numbness, tingling, or a burning sensation in the area supplied by the biopsied nerve. This sensation is due to the nerve being cut and often diminishes over time, though some degree of persistent altered sensation might occur.
The sutures, if not dissolvable, are removed by a healthcare professional within 7 to 14 days after the procedure. The timeline for receiving results from the laboratory can vary, but it takes several days to a few weeks, depending on the complexity of the tests performed on the nerve sample. Following all post-operative instructions helps ensure proper healing and minimizes potential complications.
Potential Considerations and Risks
While considered a safe procedure, a nerve biopsy carries potential risks. Bleeding at the incision site can occur, though it is typically minor and controlled with pressure. Infection is another risk, as with any surgical procedure, but it can be minimized through sterile techniques and proper wound care. Signs of infection might include increased redness, swelling, warmth, or pus around the incision.
A specific risk is persistent numbness or altered sensation in the area supplied by the biopsied nerve. Because a segment of the nerve is removed, some degree of permanent sensory change is common. While rare, motor weakness in the affected limb is a risk if a nerve with significant motor function is damaged or chosen for biopsy, though the commonly biopsied nerves are primarily sensory. Pain at the biopsy site, which can sometimes be chronic, is another consideration. These risks are low, and healthcare providers weigh the diagnostic benefits against these risks before recommending the procedure.
References
“Nerve Biopsy – an overview | ScienceDirect Topics”. 2018.
“Nerve Biopsy – Procedure, Test, Side Effects, and Recovery”. 2024.
“Nerve Biopsy: What to Expect, Recovery, and More”. 2023.
“Nerve Biopsy: Purpose, Procedure, Results”. 2024.