Clinical diagnosis and management of small fiber neuropathy: an update on best practice

ABSTRACT

Introduction

Small fiber neuropathy (SFN) is a heterogeneous group of disorders affecting thin myelinated Aδ and unmyelinated C fibers. Common symptoms include neuropathic pain and autonomic disturbances, and the typical clinical presentation is that of a length-dependent polyneuropathy, although other distributions could be present.

Area covered

This review focuses on several aspects of SFN including etiology, clinical presentation, diagnostic criteria and tests, management, and future perspectives.

Diagnostic challenges are discussed, encompassing the role of accurate and standardized assessment of symptoms and signs and providing clues for the clinical practice. The authors discuss the evidence in support of skin biopsy and quantitative sensory testing as diagnostic tests and present an overview of other diagnostic techniques to assess sensory and autonomic fibers dysfunction. The authors also suggest a systematic approach to the etiology including a set of laboratory tests and genetic examinations of sodium channelopathies and other rare conditions that might drive the therapeutic approach based on underlying cause or symptoms treatment.

Expert opinion

SFN provides a useful model for neuropathic pain whose known mechanisms and cause could pave the way toward personalized treatments.

KEYWORDS:

• Small fiber neuropathy
• skin biopsy
• quantitative sensory testing
• neuropathic pain
• autonomic disorders
• sodium channelopathy
• painful evoked potentials

Article highlights

• Small fiber neuropathy (SFN) is characterized by sensory and autonomic symptoms and signs associated with neural damage selectively or predominantly involving peripheral thin myelinated Aδ fibers and unmyelinated C nerve fibers.

• Skin biopsy and quantitative sensory testing are widely acknowledged as confirmatory diagnostic tests.

• Diagnostic criteria are available for clinical practice and research.

• Variants in genes encoding for sodium channels have been discovered as novel cause of SFN.

• Current symptomatic treatment for neuropathic pain is based on a “trial-and-error”approach, though new studies suggested that genotype might influence the response to specific drugs.

• Deep phenotyping and genotyping of patients could contribute to achieve concrete steps toward personalized management

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.