Patients are diagnosed with small fibre neuropathy (SFN) when at least two of the following examinations are abnormal:

1. Clinical signs of small fibre impairment (pinprick and thermal sensory loss and/or allodynia and/or hyperalgesia), which distribution is consistent with peripheral neuropathy (length or non-length dependent neuropathy);
2. Abnormal warm and/or cooling threshold at the foot assessed by quantitative sensory testing (QST);
3. Reduced intraepidermal nerve fibres (IENF) density at the distal leg.

SFN are ruled out in the presence of:

1. any sign of large fibre impairment (light touch and/or vibratory and/or proprioceptive sensory loss and/or absent deep tendon reflexes);
2. any sign of motor fibre impairment (muscle waste and/or weakness);
3. any abnormality on sensorimotor nerve conduction study (NCS).

Reference:

1. Devigili G, Tugnoli V, Penza P, Camozzi F, Lombardi R, Melli G, Broglio L, Granieri E, Lauria G. The diagnostic criteria for small fibre neuropathy: from symptoms to neuropathology. Brain. 2008 Jul;131(Pt 7):1912-25. [Medline]

Created: Sep 15, 2009