Small Fiber Skin Biopsy
Less is known about small-fiber sensory neuropathies than about other types of neuropathies, mostly because many conventional tests for painful neuropathies can give false normal results and fail to provide evidence of damage to small unmyelinated nerves. Skin biopsies have a better track record (sensitivity) for diagnosing these conditions. Rapid progress is being made in this field, which will hopefully lead to better
What is a Small Fiber skin biopsy?
Removing a small piece of skin and looking at it by microscope
is a safe and effective way to examine sensory nerve cells
Many people have had skin biopsies to remove suspicious skin growths. In the 1990s,
it was learned that skin biopsies could also be used to look at
the peripheral sensory nerves.1,2 Nearly all parts of
the body have microscopic nerves running through them to allow
sensation and movement. Skin biopsies can be processed in a way
that allows us to see and count the number of sensory nerve
endings, and to look for any neural abnormalities.
For many patients being evaluated for painful sensory neuropathies, skin biopsy can replace sural nerve biopsy for gaining information about small sensory axons
Patients suspected of having peripheral nerve disease are evaluated by tests on muscles (electromyography or EMG), or by studying how large nerves conduct signals (nerve conduction studies or NCS). These standard tests are often used for evaluating patients with suspected neuropathy (nerve damage). The types of nerve cells that are damaged in painful sensory neuropathies (small, unmyelinated and thinly myelinated axons) are not well studied by EMG and NCS, and these tests can give false "normal" results in patients with small-fiber neuropathies. In the past, the best way of getting information about sensory neuropathies that cause pain was surgical removal of a part of the sural nerve at the ankle. This left patients with permanent numbness, and caused other complications in some patients.3 5 Today, skin biopsy, a minor procedure with no serious complications, gives much of the same information. In addition, skin biopsy may even be more sensitive than sural nerve biopsy because it samples the nerves closer to their endings in the skin, where disease usually starts.6