Nerve Fiber Density (NFD)

Nerve Fiber Density

The skin provides a barrier that protects the body from pathogens, mediates sensations, and helps maintain the body’s internal environment. Its functions are helped by specialized structures or receptors that are connected to the spinal cord and brain via the peripheral nerves. Damage to the peripheral nerves can disrupt the skins normal functions.

The human skin consists of three layers; the epidermis, the dermis and a third layer called the hypodermis. Free nerve endings in the epidermis can detect painful stimuli or temperature changes. Nerve Fiber Density testing (skin biopsy) can determine if there is small fiber neuropathy occurring. The testing procedure includes a final report that contains an analysis, color images of the microscopic field, and diagnostic information.

What are Nerve Fiber Density tests?

When is the NFD test useful?

Nerve Fiber Density (NFD) testing is particularly helpful for patients who have symptoms or signs of neuropathy, and test normal on EMG or Nerve Conduction Studies. This often occurs when the neuropathy predominantly affects the small nerve fibers, as these are not detected in the electro-diagnostic studies. Although the NFD is the most sensitive test for diagnosing small fiber neuropathy, a normal test does not necessarily exclude the presence of neuropathy.

How does the NFD test help me?

It provides peace of mind in knowing the cause of your pain. This helps define a quantifiable measure that helps you follow the progression of the neuropathy and your response to therapy. This will also aid in any additional recommended diagnostic tests and treatments. Occasionally, it helps identify the presence of other factors that are important in treating your condition.

What is the skin biopsy procedure?

Dr. Mir will perform the biopsy in the office during your office visit. The skin is numbed with an anesthetic before a small piece of skin is removed with a small tool. Specimens are approximately 3 mm in diameter and 2 mm deep.

Why can't test results be given directly to the patient?

Laboratory results may only be given to a physician, his or her agent, or other person authorized by law to use the results in the conduct of his or her practice or the fulfillment of official duties. The majority of laboratory test results must be placed in the context of the patient’s condition, medical history and symptoms by a trained professional. Laboratories are required to release test results to the physician ordering the tests so that a full explanation may be provided at the time that the patient receives the test results.

Where is the test done?

There are three established biopsy sites: thigh, calf and foot. Taking a biopsy from these sites allows the neurologist to provide a diagnosis by comparing the nerve fiber density of the patient against established normal values. If focal or compressive neuropathy is suspected, the biopsy can be done at the affected region and compared to the corresponding unaffected region as a control.

How do I get my test results?

Dr. Mir will provide you with the results on your biopsy during your follow up visit. Please make sure to schedule a follow up appointment with your doctor two weeks after the skin biopsy appointment. The skin biopsy analysis promises to be a valuable technique to aid in the diagnosis of neuropathy and help clarify the underlying physical issues.