Small fiber neuropathy (SFN) is a form of peripheral neuropathy. It happens when something damages small nerve fibers in your skin, causing symptoms like painful tingling or burning sensations in your hands and feet. The condition also can affect other small nerve fibers that manage essential body functions, like your blood pressure or heart rate.
SNF symptoms can be severe and affect your overall quality of life. While small fiber neuropathy isn’t a serious medical condition, it may be a sign of other conditions that could be life-threatening. Healthcare providers treat the condition by focusing on the underlying causes and with medication that helps with SFN’s painful symptoms.
How common is small fiber neuropathy?
It’s not common. Based on one study, researchers estimate that 53 out of 100,000 worldwide have small fiber neuropathy. But that estimate may be low: Researchers believe not everyone who has the condition receives a diagnosis.
Symptoms and Causes
What are the symptoms of small fiber neuropathy?
Symptoms of small fiber neuropathy vary, but common early symptoms are “pins-and-needles” pain or a burning sensation in your hands and feet. These symptoms may come and go or be constant and often get worse over time. Other symptoms include:
- • Feeling lightheaded or fainting.
- • Heart palpitations.
- • Numbness.
- • Not being able to feel pain and temperature in a small spot on your body.
- • Stomach cramps.
- • Sweating more than usual.
What causes small fiber neuropathy?
About half of small fiber neuropathy cases happen for no known reason. Healthcare providers may call this idiopathic small fiber neuropathy. Research shows several medical conditions, inherited disorders or exposure to toxins may cause SFN.
Medical conditions that cause SNF
Diabetes is the most common condition causing small fiber neuropathy, but you could also develop SNF if you have:
- • Alcohol use disorder.
- • Immune system disorders like celiac, sarcoidosis or Sjögren’s syndrome.
- • Impaired glucose intolerance.
- • Infectious diseases like hepatitis C or human immunodeficiency virus (HIV).
- • Metabolic syndrome.
- • Thyroid disease.
- • Sepsis.
- • Vitamin B deficiency.
Inherited disorders that may cause SFN
You could develop small fiber neuropathy if you inherit certain genetic mutations that affect your cells’ ability to make and send electric signals throughout your peripheral nervous system. Other inherited disorders include:
- • Ehlers-Danos syndrome.
- • Fabry disease.
- • Familial amyloidosis.
- • Pompe disease.
- • Porphyria.
- • Wilson disease.
Toxins that may cause SFN
Some medications may increase your risk of developing small fiber neuropathy, including:
- • Certain antibiotics, including metronidazole (First-Metronidazole 100®), nitrofurantoin (Furadantin®) and linezolid (Zyvox®).
- • Chemotherapy drugs like bortezomib (Velcade®), thalidomide (Thalomid®) and vincristine (Oncovin®).
- • Tumor necrosis factor inhibitors like etanercept (Enbrel®).
What triggers small fiber neuropathy symptoms?
Common triggers include cool air blowing on your skin or fabric brushing against your skin. For example, spreading a bedsheet over your feet can set off painful, intense tingling.
What are the complications of small fiber neuropathy?
Small fiber neuropathy affects your ability to sense pain. For example, you may not notice if you put your hand down on a hot stovetop. It can make you feel dizzy or affect your gait, which increases the chance you’ll be hurt in a fall.
Diagnosis and Tests
How is small fiber neuropathy diagnosed?
Healthcare providers may do a physical examination and ask about your medical history. There’s no single test for small fiber neuropathy, but common tests include:
- • Electromyography (EMG).
- • Genetic tests.
- • Imaging tests like computed tomography (CT) scans or magnetic resonance imaging (MRI) scans.
- • Nerve conduction studies.
- • Skin biopsy (nerve fiber density tests).
- • Quantitative sudomotor axon reflex test (QSART).
They may do tests to screen for conditions that cause small fiber neuropathy, like diabetes.
Management and Treatment
What is the treatment for small fiber neuropathy?
Healthcare providers focus on medication and other ways to ease the pain that this condition causes. Small fiber neuropathy often is a complication of other conditions and providers will treat those conditions. Medications for pain may include:
- • Antiseizure medications, including gabapentin (Horizont®, Gralise®), pregabalin (Lyrica®) and topiramate (Topamax®).
- • Antidepressants, including amitriptyline (Elavil®), nortriptyline (Aventyl®) and desipramine (Norpramin®).
- • Topical anesthetics like lidocaine (Anodyne LPT®) or capsaicin (Capzasin-HP®).
Outlook / Prognosis
What can I expect if I have small fiber neuropathy?
Small fiber neuropathy develops very slowly. Sometimes, symptoms get worse and then stay the same for years at a time. One study showed between 13% and 36% of people with small fiber neuropathy developed large fiber neuropathy, which can affect your ability to feel vibrations and touch, as if you were wearing gloves on your hands.
Your overall prognosis — what you can expect after receiving treatment — depends on why you developed SFN. For example, if you have small fiber neuropathy because you have diabetes, you may need diabetes treatment for the rest of your life. Talk to your healthcare provider about your situation, including how treatment for small fiber neuropathy will help with pain and other symptoms.
Will small fiber neuropathy affect my life expectancy?
No, the condition itself won’t affect your life expectancy. But its underlying cause, like diabetes or HIV, may affect how long you live.
Living With
How do I take care of myself?
One important way to take care of yourself is to manage the pain that small fiber neuropathy causes. Your healthcare provider will prescribe pain medication, but you may want to consider pain management programs that include counseling and therapy, exercise and hands-on treatment like massage or physical therapy.
When should I see my healthcare provider?
Small fiber neuropathy symptoms may change or worsen over time. If you have SFN, contact your provider if you notice symptoms in one part of your body develop elsewhere. For example, talk to your provider if:
- • The painful “pins-and-needles” feeling in your feet now affects your hands.
- • Pain attacks start happening more often or are more severe.
- • You have new symptoms like feeling faint or having trouble walking.
