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CC BY 4.0 · Arq Neuropsiquiatr 2025; 83(09): s00451811722
DOI: 10.1055/s-0045-1811722
Original Article

Assessment of possible small fiber Neuropathy in early-stage vitamin B12 deficiency using electrophysiological methods

Authors

  • Elif Simin Issi 

    1   Eskişehir City Hospital, Neurology Department, Eskişehir, Turkey.
    2   Afyonkarahisar Health Sciences University, Faculty of Medicine, Department of Neurology, Afyonkarahisar, Turkey.
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Abstract

Background

Small fiber neuropathy (SFN) affects thinly myelinated and unmyelinated fibers, often presenting with subtle clinical signs that are undetectable in routine nerve conduction studies. Vitamin B12 deficiency is a known risk factor for SFN, yet early-stage cases frequently remain undiagnosed. Sympathetic skin response (SSR) and cutaneous silent period (CSP) are noninvasive electrophysiological techniques used to assess autonomic and somatic small fiber function.

Objective

The present study aimed to evaluate the diagnostic utility of SSR and CSP in detecting possible subclinical small-fiber neuropathy (pSFN) in individuals with early-stage vitamin B12 deficiency.

Methods

The present observational study included 28 patients with vitamin B12 deficiency who had nonspecific complaints, Douleur Neuropathique en 4 Questions (DN4) scores < 4, and normal nerve conduction studies, along with 25 healthy controls. Electrophysiological testing involved SSR recordings from all extremities and CSP measurements from the right median and sural nerves.

Results

In the patient group, Median Nerve Cutaneous Silent Period (MN-CSP) and Tibialis Anterior -Sural Cutaneous Silent Period (TA-sural CSP) durations were significantly shorter, while termination and onset latencies were prolonged compared with controls. MN-CSP and TA-sural CSP durations demonstrated high diagnostic accuracy. Sympathetic skin response latencies were significantly prolonged in both hands and feet, indicating autonomic dysfunction. No significant differences were observed in SSR amplitudes.

Conclusion

Sympathetic skin response and CSP are valuable tools for detecting possible subclinical SFN in vitamin B12 deficiency. Sympathetic skin response effectively identified autonomic dysfunction, while CSP provided additional diagnostic value for somatic small fiber impairment. Combining SSR and CSP may enhance early detection of pSFN in vitamin B12 deficiency and allow timely intervention.

Keywords

Vitamin B 12 Deficiency - Small Fiber Neuropathy - Galvanic Skin Response - Reflex, Abnormal - Electrodiagnosis

Data Availability Statement

Data are available from the corresponding author upon reasonable request.


Editor-in-Chief: Hélio A. G. Teive. https://orcid.org/0000-0003-2305-1073


Associate Editor: Carlos Otto Heise. https://orcid.org/0000-0003-3956-3073




Publication History

Received: 21 April 2025

Accepted: 07 July 2025

Article published online:
19 September 2025

© 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit (https://creativecommons.org/licenses/by/4.0/)

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Bibliographical Record
Elif Simin Issi. Assessment of possible small fiber Neuropathy in early-stage vitamin B12 deficiency using electrophysiological methods. Arq Neuropsiquiatr 2025; 83: s00451811722.
DOI: 10.1055/s-0045-1811722