Small fiber neuropathy (SFN) is characterized by the dysfunction of small-caliber sensory and/or autonomic nerve fibers. As small fibers can be affected in several pathological conditions, it is thought that SFN may represent an early stage of other neuropathies. This study was designed to better understand the clinical course of idiopathic SFN.

This retrospective study included 16 patients diagnosed with SNF, all of whom were initially seen between 2008 and 2014. At follow-up, ranging from 2.5 to 14 years, all participants underwent skin biopsy of the distal proximal lower extremity to identify intraepidermal nerve fibers (IENFDs). In addition, the subjects were asked to complete the Quality-of-Life Scale from the American Chronic Pain Association.

Of the 16 patients, eight initially presented with burning sensations, eight with pain and eight with reduced vibration sense. Skin biopsies of all patients revealed a decrease in IENFD. Follow-up exams involving 12 patients found that, in nine patients, clinical and electrophysiologic studies had not progressed. Three patients progressed or converted to axonal demyelinating sensorimotor neuropathy or demonstrated increased tibial-evoked potentials.

This study of patients diagnosed with small fiber neuropathy found that, at follow-up, 75% were stable and had not progressed to involvement of large fibers.