Assessing the modulation of cutaneous sensory fiber excitability using a fast perception threshold tracking technique.

Muscle Nerve

Department of Health Science and Technology, Center for Sensory-Motor Interaction (SMI), Aalborg University, Fredrik Bajers Vej 7 D3, 9220 Aalborg Ø, Denmark.

Published: October 2019

Introduction: Topical application of lidocaine-and-prilocaine (LP) cream attenuates the functionality of small cutaneous nerve fibers. The aim of this human study was to measure the underlying excitability modulation of small cutaneous nerve fibers using a novel and fast perception threshold tracking (PTT) technique.

Methods: Small sensory fibers were selectively blocked by 120-minute topical application of LP and confirmed by quantitative sensory testing. Excitability changes of small (activated by a specially designed pin electrode) and large (patch electrode) nerve fibers were assessed as the strength-duration relation and threshold electrotonus.

Results: The excitability assessed by the strength-duration relation and threshold electrotonus was significantly modulated for the small afferents (P < 0.05, Wilcoxon's test) but not the large afferents.

Discussion: This novel PTT technique was able to assess inhibition of membrane properties of small cutaneous fibers, suggesting the usefulness of the technique as a diagnostic method for assessing impairment of small fibers, as seen in many types of polyneuropathies.

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http://dx.doi.org/10.1002/mus.26520DOI Listing

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