Observational case-control study of small-fiber neuropathies, with regards on smoking and vitamin D deficiency and other possible causes

Maxime Fouchard; Emilie Brenaut; Steeve Genestet; Anne-Sophie Ficheux; Pascale Marcorelles; Laurent Misery

doi:10.3389/fmed.2022.1051967

Observational case-control study of small-fiber neuropathies, with regards on smoking and vitamin D deficiency and other possible causes

Front Med (Lausanne). 2023 Jan 12:9:1051967. doi: 10.3389/fmed.2022.1051967. eCollection 2022.

Authors

Maxime Fouchard^{1

2}, Emilie Brenaut^{1

2}, Steeve Genestet^{3

4}, Anne-Sophie Ficheux², Pascale Marcorelles^{2

4

5}, Laurent Misery^{1

2

4}

Affiliations

¹ Department of Dermatology, CHU Brest, Brest, France.
² Univ Brest, LIEN, Brest, France.
³ Department of Neurology, CHU Brest, Brest, France.
⁴ Breton Competence Center of Rare Neuromuscular Diseases and Neuropathies With Cutaneous-Mucosal Symptoms, CHRU de Brest, Brest, France.
⁵ Department of Pathology, CHU Brest, Brest, France.

Abstract

Introduction: Small fiber neuropathies (SFNs) are disorders of skin nerve endings inducing pruritus, burning pain, numbness, and paresthesia. The aims of this study were to search for putative etiologies of SFN and their occurrence in a cohort of patients and to compare patients with SFN to a group of patients without SFN to highlight potential factors associated with SFN.

Methods: This study was observational, retrospective, and monocentric. All patients with symptoms of SFN who underwent skin biopsies with intraepidermal nerve density counts were included. Patients with a count lower than 5 percentiles were considered to be in the SFN group. Other patients were considered to be the control group.

Results: A total of 162 patients with SFN and 161 controls were included. No cause was identified for 108 patients (61.7%). The established causes were autoimmune diseases (9.1%), diabetes or glucose intolerance (8%), medication (4%), liver disease (3.4%), and monoclonal gammopathy of undetermined significance (2.9%). Current or former smokers were more numerous in the SFN group (26.5%) than in the control group (16.1%), while vitamin D amounts were significantly lower in the SFN group than in the control group.

Discussion: Hence, tobacco smoking and vitamin D deficiency might be new putative causes of SFN.

Keywords: pain; pruritus; small-fiber neuropathy; smoking; vitamin D.