A small nerve fiber biopsy is the extraction of a tiny, circular piece of skin, from the surface of the skin. This piece of skin is smaller than the diameter of a pencil eraser and it contains part of a small nerve for examination. The skin specimen is processed such that the small nerve fibers in the skin can be visualized and counted.

No special preparation is required for this test.

The entire procedure takes about 30 minutes.

A physician will interpret the study afterward and a report will be sent to your referring provider. Expect to hear from your ordering physician/provider after the test.

After the test is completed, you are free to resume normal activities.

A small nerve fiber biopsy is a minimally invasive, relatively painless procedure. At most, you will feel a pinprick when you are injected with Lidocaine to numb the sample area. The biopsy size is small, so stiches are not necessary.

Small nerve fibers are responsible for pain and temperature sensations. Sometimes, patients will suffer an injury to their small nerve fibers, and develop a condition called Small Fiber Sensory Neuropathy (SFSN). SFSN is a form of neuropathy that affects small sensory nerves, and patients with SFSN typically exhibit symptoms such as tingling, numbness, and pain.

Small nerve fibers have a slower conduction response that cannot be identified by standard nerve conduction studies or EMG testing. For these reasons, small nerve fiber biopsies are ordered.

During a small nerve fiber biopsy, the physician will start by injecting the site with Lidocaine to numb the area.

Once the area is sufficiently numb, the physician will use a 3 mm punch tool to extract the sample. If multiple samples are required, the process will be repeated in the areas needed. Subsequently, a band-aid will be placed over the site(s).