Widespread Pain

Small Fibre Neuropathy

Definition

Small fibre neuropathy is a neurological disease of the peripheral nerves, accompanied by pain due to dysfunction of the small nerves.

Aetiology

The aetiology of small fibre neuropathy is largely unknown. It is characterised by a reduction in the number of small C fibres and Aδ fibres.

Small fibre neuropathy is related to other diseases, such as diabetes, sarcoidosis, autoimmune diseases, connective tissue diseases, hypothyroidism, paraneoplastic syndromes, hyperlipidemia, statines, anti-retroviral treatment and infections.

Signs and symptoms

Patients complain of continuous pain in the hands and feet. This pain can be: burning (65.6%), sharp (16.4%), paroxysmal (4.5%), itchy (5.9 %), deep stabbing (4.5%), or accompanied by thermal allodynia (3%).

Autonomic disorders can occur (47.8%) such as hypo- or anhydrosis, and vasomotor dysfunction, including excessive blushing, orthostatic hypotension, urinary bladder and intestinal disorders.

Diagnostics

Physical Examination

A general physical examination and extensive neurological examination are very important for excluding other causes. Referral to an internist, pulmonologist or neurologist is frequently indicated.

The following tests should definitely be included in the neurological examination: (1) testing of all sensory qualities of the arms and legs (attention should be paid to symmetry and to the distal proximal gradient); (2) reflexes; and (3) strength tests.  Allodynia and hyperalgesia may present.

Additional Somatic Diagnostics

  • Electrophysiology (sensory and motor nerve conduction) evaluation in small fibre neuropathy is mandatory in order to exclude  axonal degeneration and demyelinisation.
  • QST is always indicated.
  • Skin biopsy

Additional Psycho-cognitive Diagnostics

  • RAND-36 (quality of life)
  • VAS-Pain (maximal, minimal, actual, average/week)
  • PCS (catastrophising)
  • HADS (fear and depression)

Multidisciplinary Treatment

Whether or not somatic treatment is indicated is based on the pain diagnosis.  Based on the findings of the pain questionnaires, additional diagnostics and/or multidisciplinary treatment consisting of various the non-somatic treatments may be necessary.

Non-somatic Treatment

Somatic Treatment

Pharmacological treatment:

  • Tricyclic antidepressants
  • Anticonvulsives: carbamazepine, oxcarbazepine, gabapentine and pregabaline.
  • Meticulous regulation of blood glucose levels

Interventional Pain Treatment