Small Fibre Neuropathy (SFN)
Small Fibre Neuropathy (SFN) is a condition affecting the smallest nerve fibres in the body. These tiny nerves carry pain and temperature sensations while also helping regulate automatic body functions such as sweating, heart rate, blood pressure and digestion. When they become damaged, people may experience burning pain, tingling, numbness and symptoms affecting several body systems.
One of the greatest challenges with SFN is that standard nerve conduction studies (EMG/NCS) are often normal because they assess only the larger nerve fibres. Understanding this difference is essential for recognising the condition, obtaining the appropriate investigations and identifying its underlying cause.
This information is intended for educational purposes and should not replace professional medical advice. If you have new, severe or worsening symptoms, always seek advice from your GP or specialist healthcare team.
KEY FACTS
✔ Medical name
Small Fibre Neuropathy (SFN)
✔ What it affects
The small sensory (Aδ and C) nerve fibres responsible for pain, temperature sensation and autonomic nervous system function.
✔ Common symptoms
Burning pain, tingling, numbness, electric shock sensations, altered temperature sensation, dizziness on standing, sweating abnormalities, digestive symptoms and dry eyes or mouth.
✔ Who can be affected?
SFN can occur at any adult age. Diabetes and prediabetes are among the most common causes, although autoimmune diseases, vitamin deficiencies, infections, medications and genetic conditions may also contribute.
✔ How is it diagnosed?
Diagnosis combines a detailed clinical assessment with appropriate investigations. While nerve conduction studies are usually normal, skin biopsy measuring intraepidermal nerve fibre density (IENFD) is considered the gold-standard confirmatory test.
✔ Can it be treated?
Treatment focuses on identifying and managing the underlying cause where possible, alongside improving symptoms and supporting long-term function.
✔ Associated conditions
Diabetes and prediabetes
Fibromyalgia
POTS
Hypermobility Spectrum Disorder
Hypermobile Ehlers-Danlos Syndrome
Sjögren syndrome
Coeliac disease
Sarcoidosis
Vitamin B12 deficiency
✔ When should I seek urgent medical advice?
Rapidly progressive symptoms, new weakness, swallowing or breathing difficulties, unexplained weight loss, severe autonomic symptoms or rapidly worsening neurological changes require urgent medical assessment.
UNDERSTANDING THE CONDITION
Your nervous system contains different types of nerve fibres, each with a specialised role.
Some fibres are large, heavily insulated and conduct signals rapidly. These nerves allow you to feel vibration, know where your limbs are in space and control muscle movement.
Alongside them is another network made up of much smaller, thinly insulated or uninsulated nerve fibres.
These "small fibres" carry:
Pain
Temperature sensation
Itch
Automatic (autonomic) signals controlling sweating, heart rate, blood vessels and digestion.
In Small Fibre Neuropathy, these tiny nerve fibres become damaged or function abnormally.
Because they are involved in both sensation and the autonomic nervous system, symptoms often extend well beyond pain alone.
Some people mainly experience burning feet.
Others develop dizziness, altered sweating, digestive problems or changes in skin temperature.
The pattern depends on which small nerve fibres have been affected.
Unlike many other forms of peripheral neuropathy, muscle strength and vibration sensation usually remain normal during the early stages because the larger nerve fibres are not significantly affected.
Understanding Your Body's "Fine Wiring"
One of the easiest ways to understand SFN is to imagine your nervous system as having two different types of electrical wiring.
The first consists of large, well-insulated cables.
These carry information about movement, vibration and position.
Alongside them runs a network of very fine wires.
These thinner fibres carry pain, temperature and many of the automatic signals that regulate blood vessels, sweating and digestion.
In Small Fibre Neuropathy, it is these fine wires that become damaged.
This explains why symptoms such as burning pain or altered temperature sensation may develop even though muscle strength remains normal.
It also explains one of the greatest frustrations experienced by many patients.
Why Can My Nerve Tests Be Normal?
Many people are understandably confused after being told: "Your EMG was normal."
They may assume this means that their symptoms cannot be caused by nerve damage.
In fact, the opposite is often true.
Standard nerve conduction studies (NCS) and electromyography (EMG) measure only the large nerve fibres.
Because small fibres are too small to be assessed by these tests, the results are usually normal in people with pure Small Fibre Neuropathy.
A normal EMG therefore does not exclude SFN.
This single fact explains why diagnosis is often delayed and why many people spend years searching for an explanation for their symptoms.
COMMON SYMPTOMS
The symptoms of Small Fibre Neuropathy vary considerably from person to person.
Some people experience only burning pain in their feet, while others develop widespread sensory symptoms together with disturbances affecting the autonomic nervous system.
Symptoms often begin gradually and may worsen over months or years, although the progression depends largely on the underlying cause.
Sensory Symptoms
Small sensory nerve fibres transmit pain and temperature signals.
When these fibres become damaged, common symptoms include:
Burning pain
Stabbing or electric shock-like sensations
Tingling ("pins and needles")
Numbness
Increased sensitivity to touch (allodynia)
Increased sensitivity to painful stimuli (hyperalgesia)
Reduced ability to feel hot or cold
Symptoms that are often worse at night
Many people describe a combination of numbness and burning pain occurring in the same area, particularly in the feet.
Autonomic Symptoms
Because small fibres also regulate many automatic body functions, SFN may affect far more than sensation alone.
Possible symptoms include:
Cardiovascular
Dizziness when standing
Light-headedness
Palpitations
Exercise intolerance
Skin
Reduced sweating
Excessive sweating
Dry skin
Colour changes
Temperature changes in the hands or feet
Digestive System
Bloating
Early fullness after meals
Altered bowel habit
Constipation or diarrhoea
Eyes and Mouth
Dry eyes
Dry mouth
These symptoms reflect involvement of the autonomic nervous system and may overlap with conditions such as POTS or autoimmune disorders including Sjögren syndrome.
Where Do Symptoms Usually Begin?
The most common presentation is called length-dependent SFN.
Because the longest nerves are the most vulnerable, symptoms usually begin in the feet before gradually progressing upwards.
People often describe:
Burning soles
Tingling toes
Feet that feel unusually hot or cold
Pain that spreads slowly towards the ankles or legs
If symptoms later affect the hands, this is sometimes described as a "stocking-and-glove" pattern.
When Symptoms Start Somewhere Else
Not everyone develops symptoms in the feet first.
Some people experience symptoms affecting:
The face
The trunk
The scalp
The arms
Patchy areas of the body
This is known as a non-length-dependent presentation.
Although less common, it is clinically important because it raises suspicion of an autoimmune, inflammatory or genetic cause and usually requires earlier specialist assessment.
CAUSES, MECHANISMS AND DIAGNOSIS
Why Does It Happen?
Small Fibre Neuropathy is not a disease in itself.
Instead, it describes the type of nerve fibres that have been damaged.
Many different medical conditions can produce this pattern of nerve injury, which is why identifying the underlying cause is one of the most important parts of the assessment.
Diabetes and Prediabetes
The most common causes of SFN are diabetes and impaired glucose regulation.
Persistently raised blood glucose levels can damage the tiny nerve fibres through several mechanisms, including reduced blood supply, oxidative stress and metabolic injury.
Importantly, these changes may develop before diabetes is formally diagnosed, meaning SFN can sometimes be the first sign of impaired glucose regulation.
Vitamin Deficiencies
Healthy nerves depend on an adequate supply of essential nutrients.
Vitamin B12 deficiency is one of the most important reversible causes of peripheral neuropathy.
Because treatment may prevent further nerve damage, screening for nutritional deficiencies forms part of the standard assessment.
Autoimmune Diseases
In some people, the immune system mistakenly attacks the small nerve fibres.
Autoimmune conditions associated with SFN include:
Sjögren syndrome
Coeliac disease
Sarcoidosis
Systemic lupus erythematosus
Research is also investigating newer autoantibodies that may contribute to previously unexplained cases of SFN, although this remains an evolving area of medicine.
Medications and Toxic Exposure
Some medications and toxins may damage small nerve fibres.
Examples include:
Certain chemotherapy drugs
Some antiviral medications
Excessive alcohol consumption
Occupational toxin exposure
Reviewing medication history is therefore an important part of assessment.
Infections
SFN may occasionally develop following infections.
Examples include:
HIV
Hepatitis C
Some post-viral illnesses, including COVID-19 in a subset of patients
Research into post-infectious SFN continues to evolve, and the exact mechanisms remain under investigation.
Genetic Causes
Rare inherited conditions affecting nerve function may present as Small Fibre Neuropathy.
These are usually considered when symptoms begin at a young age, there is a family history of neuropathy or other neurological features suggest a genetic condition.
Sometimes No Cause Is Found
Despite thorough investigation, some people have idiopathic Small Fibre Neuropathy, meaning no underlying cause can currently be identified.
This does not mean the diagnosis is uncertain.
Rather, it reflects the current limits of medical knowledge.
Research continues to improve understanding of previously unexplained cases, and occasionally an underlying cause becomes apparent later, which is why periodic review may be recommended.
Why Finding the Cause Matters
Although symptom control is important, identifying the underlying cause offers the greatest opportunity to slow progression or improve symptoms.
For example:
Improving blood glucose control may reduce further nerve damage.
Vitamin B12 replacement can prevent ongoing deficiency-related injury.
Treating autoimmune disease may reduce immune-mediated nerve damage.
Stopping a toxic medication or correcting nutritional deficiencies may prevent progression.
For this reason, Rowan Health follows a structured screening pathway that investigates metabolic, nutritional, autoimmune, infectious, toxic, endocrine and genetic causes rather than assuming symptoms are "idiopathic" too early.
How It Is Diagnosed
There is no single test that diagnoses Small Fibre Neuropathy (SFN).
Instead, diagnosis combines a detailed clinical assessment, neurological examination, appropriate investigations and confirmation that the symptoms are consistent with damage to the small nerve fibres. An equally important part of the assessment is identifying the underlying cause, as many cases are associated with conditions that can be treated or managed.
Medical History
Your clinician will begin by building a detailed understanding of your symptoms and overall health.
This includes discussing:
The quality of your symptoms (burning, stabbing, electric shocks, tingling or numbness)
Where symptoms occur and whether they began in the feet or another part of the body
When symptoms started and how they have progressed
Any dizziness, sweating changes, digestive problems or other autonomic symptoms
Previous medical conditions, including diabetes, autoimmune disease or cancer
Current medications and possible toxin exposure
Family history of neuropathy or neurological disorders
Understanding these details helps distinguish small-fibre neuropathy from other neurological conditions and guides further investigations.
Neurological Examination
A physical examination helps assess which types of nerve fibres may be affected.
Your clinician may examine:
Pinprick sensation
Temperature sensation
Light touch
Skin colour and sweating patterns
Muscle strength
Tendon reflexes
Vibration sense
Joint position (proprioception)
In pure small-fibre neuropathy, muscle strength, vibration sensation and tendon reflexes are usually preserved because these functions depend on the larger nerve fibres. Any weakness or loss of reflexes suggests that additional nerve fibres may also be involved and requires further investigation.
Why Is My EMG Normal?
One of the most common questions people ask is:
"If my nerve tests are normal, how can I still have neuropathy?"
The answer lies in understanding that standard nerve conduction studies (NCS) and electromyography (EMG) assess only the large nerve fibres.
Small nerve fibres are simply too small to be measured by these tests.
As a result, people with pure small-fibre neuropathy usually have completely normal nerve conduction studies.
A normal EMG therefore does not exclude small-fibre neuropathy.
Instead, it helps exclude other neurological conditions affecting the larger nerve fibres, such as large fibre neuropathy, radiculopathy or motor nerve disorders.
Skin Biopsy: The Gold Standard Test
When the clinical picture suggests Small Fibre Neuropathy and routine nerve conduction studies are normal, the most widely accepted confirmatory investigation is a skin biopsy.
A tiny sample of skin is taken—usually from the lower leg—and examined under a microscope to measure the intraepidermal nerve fibre density (IENFD).
A reduced nerve fibre density supports the diagnosis of small-fibre neuropathy and can also help determine whether the pattern is length-dependent or non-length-dependent.
Looking for the Underlying Cause
Confirming the diagnosis is only one part of the assessment.
Equally important is identifying why the nerve fibres have become damaged.
Your clinician may follow a structured investigation pathway to screen for the most common and treatable causes of small-fibre neuropathy.
Depending on your medical history and symptoms, investigations may include:
Full blood count (FBC)
Kidney and liver function tests
HbA1c (and oral glucose tolerance testing where appropriate)
Vitamin B12 and folate
Thyroid function (TSH)
Autoimmune screening (ANA and related antibodies where indicated)
Serum protein electrophoresis and immunofixation
Lipid profile
Additional investigations such as coeliac screening, HIV or hepatitis testing, or chest imaging when clinically appropriate.
Identifying an underlying cause is important because treatment may help prevent further nerve damage and, in some cases, improve symptoms.
Additional Investigations
In selected cases, further tests may be recommended.
These can include:
Quantitative sensory testing (QST)
Autonomic function testing
Corneal confocal microscopy (in specialist centres)
Genetic testing where an inherited neuropathy is suspected
Additional neurological investigations if another diagnosis is considered
The choice of investigations depends on your symptoms, examination findings and overall clinical picture.
A Structured Diagnostic Approach
Because many different conditions can cause burning pain or altered sensation, diagnosing small-fibre neuropathy involves more than confirming nerve damage alone.
A comprehensive assessment aims to:
Confirm that symptoms are consistent with small-fibre neuropathy.
Exclude disorders affecting the larger nerve fibres.
Identify any underlying, potentially treatable cause.
Recognise associated autonomic dysfunction where present.
Develop an individualised management plan based on your symptoms and overall health.
This structured approach helps ensure that treatment focuses not only on symptom relief but also on addressing the factors contributing to nerve damage whenever possible.
HOW IS IT USUALLY MANAGED?
Management depends on the diagnosis, symptom severity, underlying mechanisms and each person's individual circumstances.
Treatment for Small Fibre Neuropathy (SFN) focuses on two equally important goals:
Identifying and treating the underlying cause whenever possible.
Managing symptoms and improving quality of life.
Because SFN can result from many different medical conditions, treatment should always be individualised. Successfully treating the underlying cause may slow progression, prevent further nerve damage and, in some cases, improve symptoms.
Treating the Underlying Cause
Whenever an underlying cause is identified, this becomes the priority.
Examples include:
Optimising blood glucose control in diabetes or prediabetes.
Correcting vitamin B12 or folate deficiency.
Treating autoimmune diseases such as Sjögren syndrome.
Managing thyroid disorders.
Treating coeliac disease where appropriate.
Reviewing medications or toxin exposure that may contribute to nerve damage.
Addressing these factors offers the best opportunity to prevent further nerve injury and improve long-term outcomes.
Managing Neuropathic Pain
Although treating the underlying cause is essential, many people also require medication to reduce neuropathic pain.
Current guidelines recommend several first-line medications, including:
Gabapentin
Pregabalin
Duloxetine
Amitriptyline or nortriptyline
The most appropriate treatment depends on several factors, including other medical conditions, kidney or liver function, sleep disturbance and potential side effects.
Treatment is usually started at a low dose and increased gradually until symptoms improve or side effects limit further increases.
Topical Treatments
For pain affecting a limited area, topical treatments may be used.
These may include:
Lidocaine preparations
Capsaicin preparations
Because these treatments act locally, they may be appropriate for some people who cannot tolerate systemic medication.
Medications That Are Usually Avoided
Long-term opioid medication is not routinely recommended for chronic Small Fibre Neuropathy pain.
Current evidence suggests that, for most people, the potential risks outweigh the long-term benefits.
Instead, treatment focuses on addressing the underlying cause, optimising neuropathic pain medication and improving function.
Looking Beyond Pain
Small Fibre Neuropathy may affect much more than pain sensation.
Depending on your symptoms, management may also include support for:
Sleep disturbance
Fatigue
Balance problems
Autonomic symptoms
Digestive symptoms
Exercise tolerance
Daily function
Addressing these aspects of health can significantly improve quality of life even when pain remains present.
Monitoring Progress
Regular review helps assess both symptom control and disease progression.
Your clinician may monitor:
Pain intensity
Burning or tingling sensations
Sleep quality
Daily function
Medication effectiveness
Side effects
Development of any new neurological symptoms
Monitoring also helps determine whether treatment should be adjusted or whether further investigations are required.
LIVING WELL WITH THE CONDITION
Impact on Daily Life
Living with Small Fibre Neuropathy can be challenging because symptoms often fluctuate and may not always be visible to others.
Burning pain, altered sensation and autonomic symptoms can affect sleep, mobility, work and everyday activities. Many people also find that symptoms worsen in the evening or after prolonged standing, making it difficult to predict how they will feel from one day to the next.
For some, reaching a diagnosis can take considerable time. Because routine nerve conduction studies are often normal, many people are initially reassured that "nothing is wrong," despite experiencing genuine neurological symptoms. Receiving an explanation for why this occurs is often an important step in understanding the condition and moving forward with appropriate care.
Although symptoms may not disappear completely, many people achieve meaningful improvements through identifying the underlying cause, optimising treatment and adopting strategies that support long-term nerve health and overall wellbeing.
HOW ROWAN HEALTH SUPPORTS YOU
At Rowan Health, we look beyond the diagnosis to understand why your small nerve fibres may have become affected and how your symptoms impact your daily life.
Following a comprehensive assessment, we develop a personalised care plan tailored to your diagnosis, symptom pattern and underlying causes. Our aim is to improve symptom control, support nerve health and enhance your long-term function and quality of life.
When to Seek Medical Advice
Although Small Fibre Neuropathy usually develops gradually, certain symptoms require urgent medical assessment.
Seek prompt medical advice if you develop:
Rapid progression of symptoms over days or weeks.
New muscle weakness.
Difficulty walking due to weakness rather than pain.
Difficulty swallowing or speaking.
Breathing difficulties.
Severe dizziness or repeated fainting.
Unexplained weight loss.
Symptoms suggesting an underlying cancer or inflammatory neurological condition.
These features are not typical of isolated Small Fibre Neuropathy and require urgent neurological assessment.
If your symptoms are severe, rapidly worsening or causing immediate concern, contact NHS 24 on 111. In a medical emergency, call 999 or attend your nearest Accident & Emergency department.
FAQs
Is Small Fibre Neuropathy the same as peripheral neuropathy?
Small Fibre Neuropathy is a type of peripheral neuropathy that specifically affects the smallest sensory and autonomic nerve fibres. Other forms of peripheral neuropathy may involve the larger nerve fibres responsible for muscle strength, vibration and position sense.
Why was my EMG normal?
Standard nerve conduction studies (NCS) and electromyography (EMG) assess the larger nerve fibres.
Because Small Fibre Neuropathy affects the smallest nerve fibres, these tests are usually normal. A normal EMG does not exclude Small Fibre Neuropathy.
What is the best test for Small Fibre Neuropathy?
When the clinical picture suggests SFN and large fibre neuropathy has been excluded, skin biopsy measuring intraepidermal nerve fibre density (IENFD) is considered the gold-standard confirmatory investigation.
Can Small Fibre Neuropathy be cured?
Treatment depends on the underlying cause.
In some cases, correcting the cause—such as vitamin B12 deficiency or impaired glucose regulation—may prevent further nerve damage and improve symptoms. When no reversible cause is identified, treatment focuses on symptom control and maintaining quality of life.
Does Small Fibre Neuropathy always get worse?
Not necessarily.
The course varies between individuals and depends largely on the underlying cause. Some people remain stable for many years, while others experience gradual progression. Early diagnosis and management may help reduce the risk of further nerve damage.
Can Small Fibre Neuropathy affect more than sensation?
Yes.
Because small nerve fibres also regulate many automatic body functions, some people experience dizziness, altered sweating, digestive symptoms, dry eyes or mouth, bladder symptoms or changes in heart rate alongside sensory symptoms.
Is Small Fibre Neuropathy associated with other conditions?
Yes.
Small Fibre Neuropathy may occur alongside several medical conditions, including diabetes, autoimmune diseases, hypermobile Ehlers-Danlos syndrome (hEDS), Hypermobility Spectrum Disorder (HSD), Postural Orthostatic Tachycardia Syndrome (POTS), fibromyalgia and ME/CFS. Identifying these associated conditions is an important part of assessment because they may influence both diagnosis and management.
How can Rowan Health help?
Our assessment aims to identify both the presence of Small Fibre Neuropathy and the factors contributing to it. Following a comprehensive evaluation, we develop a personalised management plan designed to improve symptom control, support nerve health and optimise your long-term wellbeing.
Sources & references
England JD, Gronseth GS, Franklin G, et al. Practice Parameter: Evaluation of Distal Symmetric Polyneuropathy. Neurology. 2009.
Lauria G, Hsieh ST, Johansson O, et al. European Federation of Neurological Societies/Peripheral Nerve Society Guideline on the use of skin biopsy in the diagnosis of small fibre neuropathy. European Journal of Neurology. 2010.
Faber CG, Hoeijmakers JGJ, Ahn HS, et al. Small Fibre Neuropathy. Nature Reviews Disease Primers. 2024.
Devigili G, Cazzato D, Lauria G. Clinical diagnosis and management of small fibre neuropathy. Current Opinion in Neurology.
Tesfaye S, Boulton AJM, et al. Diabetic Neuropathies: Update on Definitions, Diagnostic Criteria, Estimation of Severity and Treatments. Diabetes Care.
Peripheral Nerve Society. Clinical guidelines for peripheral neuropathies.
Clinical Review
Clinical content reviewed by
Rowan Health
Last reviewed:
4 August 2026
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Chronic & Complex Conditions >
Symptoms and Mechanisms
Peripheral Neuropathy (coming soon)
Neuropathic Pain (coming soon)
Burning Feet (coming soon)
Tingling and Numbness (coming soon)
Autonomic Dysfunction (coming soon)
Understanding Chronic Pain (coming soon)
Fatigue (coming soon)
Brain Fog (coming soon)
Treatment and Support
What Is Integrative Medicine? >
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At Rowan Health, we provide a comprehensive assessment to understand whether Small Fibre Neuropathy may be contributing to your symptoms and to identify any underlying conditions that may require further investigation.
Following a comprehensive evaluation, we develop a personalised care plan tailored to your diagnosis, symptom pattern and individual needs. Our aim is to improve symptom control, support nerve health and enhance your long-term function and quality of life alongside your conventional medical care.