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What is small fibre neuropathy? 

Small fibre neuropathy is a type of neuropathy affecting small myelinated Aδ and unmyelinated C nerve fibres of the peripheral nervous system which innervate cutaneous structures and contribute to maintenance of the autonomic nervous system. The function of Aδ and C fibres is to carry the sensation of temperature and pain as well as to help control the function of the sweat glands, gastrointestinal organs, blood vessels and heart.

The incidence and prevalence is not known but the number of patients with small fibre neuropathy has been increasing as the awareness of the condition has risen in the world.

Symptoms of small fibre neuropathy

Small fibre neuropathy typically causes a painful and burning sensation, often in the feet, but also in other parts of the body including the arms, face and trunk. 

The pain is usually constant but can vary throughout the day and it can be worse during rest or at night. The patients are sensitive to touch and may get pain from bed sheets touching their feet. 

Patients may also report transient electric shock-like pain lasting for seconds but many times during the day. Cramps can also occur. 

Patients also report: 

  • light-headedness
  • postural hypotension
  • presyncope
  • syncope
  • abnormal sweating
  • gastrointestinal and sexual dysfunction

 Patients with small fibre neuropathy may be misdiagnosed as having a plantar fasciitis, fibromyalgia or psychosomatic syndrome.

Skin biopsy test

Until recently there was no objective test to help establish the diagnosis of the small fibre neuropathy. 

This has significantly changed with the introduction of the measurement of intraepidermal nerve fibre density. The sensitivity and specificity of the intraepidermal nerve fibre density measurement has been shown to be high (78 - 92% and 65 - 90% respectively) in a number of clinical studies. The test is done by taking a skin biopsy.

A skin biopsy is typically conducted at two sites: 10 cm above the right outer ankle and 20cm below the right outer hip joint. 

The procedure involves using a local anaesthetic and then taking two 3mm punch skin biopsies. The biopsy sites are closed with steristrips and covered with a dressing, which should be removed in seven days. 

The biopsy site should not hurt but if necessary the patients can take paracetamol or ibuprofen. The cells from the biopsy are then looked at under a microscope. Neuropathologists investigating the biopsy will take particular note of the density of the nerve fibres in the skin, which is reduced in small fibre neuropathy.

Identifying the causes

If the skin biopsy confirms small fibre neuropathy, your consultant will look for the cause, which can only be identified in around 50% of cases. 

Small fibre neuropathy is associated with a number of common diseases such as diabetes or metabolic syndrome (hyperlipidemia, hypertension, obesity and abnormal glucose metabolism). 

It can be also seen in patients with abnormal thyroid function, vitamin B12 deficiency or chronic kidney disease. 

Other conditions associated with small fibre neuropathy include: 

  • immune disorders such as Sjogren’s syndrome and systemic lupus erythematosus rheumatoid arthritis
  • sarcoid
  • coeliac disease
  • paraproteinemia
  • amyloid
  • inflammatory bowel disease
  • paraneoplastic syndromes
  • infections such as hepatitis C or HIV
  • neurotoxic drug use (anti-retrovirals, antibiotics – Metronidazole, Nitrofurantoin, Linezolid, chemotherapy – Bortezomib, Flecainide, statins, alcohol, excess vitamin B6)

Small fibre neuropathy can be genetic as a part of Fabry disease but can also occur in sodium channelopathies associated with SCN9A and SCN10A gene mutations.  

 Management of small fibre neuropathy

Once the cause has been identified, the treatment should focus on treating the cause. There are no specific guidelines for management of pain associated with small fibre neuropathy although consensus guidelines for neuropathic pain have been adapted for pain management associated with small fibre neuropathy.

Treatment cost

The London Clinic offers affordable, competitive self-pay packages for certain treatments.

Patients have the option to spread the cost of treatment with Chrysalis Finance.

Please call +44 (0)20 3613 7502 to speak to our helpful team to find out more and to book an appointment.

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