Remote Photoplethysmography for Evaluation of Cutaneous Sensory Nerve Fiber Function.

Alise Aglinska,Uldis Rubins,Andris Grabovskis,Zbignevs Marcinkevics

doi:10.3390/s21041272

Abstract

About 2% of the world’s population suffers from small nerve fiber dysfunction, neuropathy, which can result in severe pain. This condition is caused by damage to the small nerve fibers and its assessment is challenging, due to the lack of simple and objective diagnostic techniques. The present study aimed to develop a contactless photoplethysmography system using simple instrumentation, for objective and non-invasive assessment of small cutaneous sensory nerve fiber function. The approach is based on the use of contactless photoplethysmography for the characterization of skin flowmotions and topical heating evoked vasomotor responses. The feasibility of the technique was evaluated on volunteers (n = 14) using skin topical anesthesia, which is able to produce temporary alterations of cutaneous nerve fibers function. In the treated skin region in comparison to intact skin: neurogenic and endothelial component of flowmotions decreased by ~61% and 41%, the local heating evoked flare area decreased by ~44%, vasomotor response trend peak and nadir were substantially reduced. The results indicate for the potential of the remote photoplethysmography in the assessment of the cutaneous nerve fiber function. It is believed that in the future this technique could be used in the clinics as an affordable alternative to laser Doppler imaging technique.

Highlights

Small fiber peripheral neuropathy is a chronic nerve disorder, which occurs when damage to the peripheral nerves predominantly or entirely affects the small myelinated (Aδ) fibers or unmyelinated C fibers, which are involved in various somatic and autonomic functions [1], but mainly the sensory functions account for its manifestation such as thermal perception and nociception [2]
The present study aimed to evaluate the feasibility of remote photoplethysmography for the assessment of small cutaneous sensory nerve fiber function on healthy young volunteers, using novel skin topical anesthesia protocol
These results indicate that topical application EMLA gel to the skin significantly diminishes neurogenic and endothelial cutaneous flowmotions in remote photoplethysmography signal

Summary

Introduction

Small fiber peripheral neuropathy is a chronic nerve disorder, which occurs when damage to the peripheral nerves predominantly or entirely affects the small myelinated (Aδ) fibers or unmyelinated C fibers, which are involved in various somatic and autonomic functions [1], but mainly the sensory functions account for its manifestation such as thermal perception and nociception [2]. The exact prevalence of painful peripheral small fibers neuropathy is not known, as the disorder is associated with many diseases, including diabetes, infections, autoimmune and endocrine disorders, but it can occur due to genetic alterations. Among potential body sites suitable for diagnostics of chronic disease, the most promising is human skin, which is the largest organ, strategically located at the interface with the external environment with its complex diffuse neuro-immuno-endocrine system [11], which is able to represent the situation in the whole body [12,13], potentially serving as an early diagnostic marker [13]. The challenging part is the fact that the structure of the skin is rather complicated [15], optical properties are not uniform [16]

Methods

Results

Discussion

Conclusion