Small fiber neuropathy occurs as a result of damage to the small fibers of the peripheral nervous system. These small fibers detect pain, heat, and itching sensations in the skin. They also regulate the autonomic functions of the cardiovascular system and the gastrointestinal tract.

Damage to the peripheral nervous system that affects the small fibers can cause burning pain or tingling sensations that begin at the feet and progress up the legs to the rest of the body.

Small fiber neuropathy may sometimes signal that a person has an underlying health condition, such as diabetes or an autoimmune disease.

Keep reading to learn more about the causes and symptoms of small fiber neuropathy, as well as how doctors diagnose and treat this condition.

a woman with pain in her hand due to small fiber neuropathyShare on Pinterest
GettyImages/Jose Luis Pelaez Inc

A person experiencing pain in their feet and hands is the most common early symptom of small fiber neuropathy. However, this condition can also reduce the body’s ability to feel pain in a concentrated area and sense temperature.

As the disease progresses, people may notice symptoms in their knees, legs, and arms.

Other symptoms of small fiber neuropathy include:

Symptoms of small fiber neuropathy can range from mild to severe. People often experience mild symptoms that may go unnoticed in the early stages. Over time, symptoms typically worsen and progress to other areas of the body.

Treatment for small fiber neuropathy varies depending on the underlying cause. People may notice their neuropathy symptoms improve or resolve entirely when they manage or receive treatment for the underlying medical condition.

For individuals who have diabetes or other metabolic disorders, this means managing blood sugar levels, maintaining a moderate body weight, and eating a healthy, balanced diet.

Exercising regularly and quitting smoking can help heal constricted blood vessels that supply vital nutrients to the nerves.

Doctors may prescribe immunosuppressive drugs to treat people who have autoimmune diseases. These medications suppress immune activity in the body and reduce inflammation.

Other treatment options can help reduce pain due to small fiber neuropathy. These can include:

People often develop small fiber neuropathy due to an underlying medical condition, such as diabetes. According to one study, up to 50% of people who have prediabetes or diabetes also develop small fiber neuropathy.

The National Institutes for Health (NIH) notes that mutations in the SCN9A and SCN10A genes can cause small fiber neuropathy. These genes carry instructions for making sodium channels, which cells use to produce and transmit electrical signals.

Examples of medical conditions that can cause small fiber neuropathy include:

Other causes include:

  • vitamin B-12 deficiency
  • alcohol use disorder
  • exposure to chemotherapy
  • physical injuries
  • illicit or prescription drug use

A doctor may diagnose a person with idiopathic small fiber neuropathy if they do not identify an underlying cause. In a 2018 study of 921 people with small fiber neuropathy, researchers found that 53% of the participants had no associated underlying condition.

Doctors use a wide range of medical tests when diagnosing small fiber neuropathy. They will begin the diagnostic process by reviewing a person’s medical history and performing a physical exam.

A doctor may ask questions about an individual’s family medical history and any current or previous medical conditions that may explain symptoms.

Many medical professionals consider skin biopsies the “gold standard” test for diagnosing small fiber neuropathy. A skin biopsy is a minimally invasive procedure in which a doctor takes several small skin samples for laboratory analysis.

A technician or pathologist will examine the skin samples under a microscope. A doctor may diagnose small fiber neuropathy if the samples have fewer small nerve fibers than healthy skin.

In some cases, a doctor may also perform a nerve conduction test, electromyography, or both. Although doctors cannot conclusively diagnose small fiber neuropathy with these tests, they can use them to rule out other peripheral neuropathies and muscle disorders.

If necessary, doctors can use laboratory tests to check a person’s blood or urine for signs of glucose intolerance, immune system dysfunction, vitamin deficiencies, and liver or kidney problems.

Research published in 2021 suggests that small fiber neuropathy is rare, but more people are receiving a diagnosis.

The authors conclude that most people with a diagnosis do not develop major neurological impairments or disability, but many have other conditions alongside, such as diabetes, Sjögren’s syndrome, and lupus.

Some of these conditions, known as comorbidities, can increase the risk of cardiovascular problems. This, in turn, can affect a person’s overall health and life expectancy.

Doctors can find it challenging to distinguish fibromyalgia from small fiber neuropathy. In 2021, some research suggested the following similarities and differences may exist:

Small fiber neuropathyFibromyalgia
Similar symptomswidespread pain
anxiety
depression
widespread pain
anxiety
depression
Symptoms potentially specific to each conditionmore intense pain
stabbing pain
burning or prickling sensation
areas that are sensitive to touch
dry eyes, mouth, or both
changed sweating patterns
changes in skin color
reduced hair or nail growth on feet
changes in experience of temperature in parts of the body

headache
problems with the jaw
Causesloss or dysfunction of small nerve fibers between skin layersproblems with central pain processing
Other conditions that commonly occur alongsidediabetes and other aspects of metabolic disorder
exposure to neurotoxins
Sjögren’s syndrome
sarcoidosis
HIV
post-traumatic stress disorder
history of sexual abuse
inflammatory disease
musculoskeletal disease

Small fiber neuropathy is a type of peripheral neuropathy that affects the small nerve fibers in the skin.

This condition usually causes an unpleasant tingling sensation or burning pain in the feet. However, people who have small fiber neuropathy may have reduced sensitivity to heat and certain types of pain.

Although the symptoms of small fiber neuropathy usually begin in a person’s feet, they can also affect their legs, hands, arms, and torso.

People can develop small fiber neuropathy due to nerve damage from another underlying medical condition, such as diabetes, an autoimmune disease, or an injury.

Treatments depend on the underlying cause. In most cases, managing the underlying medical condition can relieve the symptoms of small fiber neuropathy.