Pain relief associated with decreased oxyhemoglobin level in left dorsolateral prefrontal cortex.

Shun Miyashiro,Fusako Koshikawa,Etsuro Ito,Masashi Hori,Rei Shima,Masaru Nagaoka,Toshizumi Muta,Yurika Yamada,Haruyuki Ishikawa,Kotaro Oka,Tetsuri Abe,Manabu Sakakibara

doi:10.1371/journal.pone.0256626

Shun Miyashiro, Fusako Koshikawa + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0256626

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Abstract

Pain in the elbow, shoulder, knee, lower back, and various other joints is relieved by adhesion of pyramidal thorn patches. To elucidate the pain relief mechanism induced by the patches, we established a quantitative method for estimating the pain reduction and investigated the brain regions that change in association with pain relief. We first attempted to quantify the pain relief using transcutaneous electric stimulation (TCES) and a visual analog scale (VAS), and then applied near-infrared spectroscopy (NIRS) to the prefrontal cortex, including the dorsolateral prefrontal cortex (DLPFC) and the orbitofrontal cortex (OFC). We also examined the salivary oxytocin levels, which are thought to reflect oxytocin secretion levels from the posterior pituitary in the brain. Application of pyramidal thorn patches to pain regions decreased the pain degree estimated using TCES and VAS. Oxyhemoglobin levels were likely to be decreased in the left DLPFC on the basis of NIRS measurements during patch treatment, suggesting that the left DLPFC is involved in pain relief. On the other hand, the salivary oxytocin levels varied widely. A potential reason for the varying salivary oxytocin levels is its utilization in the pain region as an analgesic agent. Our results suggest that the left DLPFC will become a target brain region for pain therapy.

Highlights

Pain relief is highly sought after, especially by those with chronic pain
The Near-infrared spectroscopy (NIRS) data suggested that the left dorsolateral prefrontal cortex (DLPFC) was inactivated by pain relief resulting from the thorn patch treatment
This finding is consistent with previous findings that compression at myofascial trigger points, known as ischemic compression, relieves musculoskeletal pain at the neck and that compression decreases the activity in the prefrontal cortex as observed by NIRS [35]

Summary

Introduction

Pain relief is highly sought after, especially by those with chronic pain. Recognition of the limitations of commercially available analgesic drugs has led to an increased use of complementary and integrative health approaches (e.g., natural products, deep breathing, meditation, massage, etc.) for various types of pain, such as back pain, neck pain, and joint pain [1]. Left dorsolateral frontal cortex in pain relief specific roles of this author are articulated in the ‘author contributions’ section

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