Longitudinal effect of transcranial direct current stimulation on knee osteoarthritis patients measured by functional infrared spectroscopy: a pilot study.

Luca Pollonini,Hongyu Miao,Hyochol Ahn

doi:10.1117/1.nph.7.2.025004

Luca Pollonini, Hongyu Miao + Show 1 more

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https://doi.org/10.1117/1.nph.7.2.025004

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Abstract

.Significance: Knee osteoarthritis (OA) is a common joint disease causing chronic pain and functional alterations (stiffness and swelling) in the elderly population. OA is currently treated pharmacologically with analgesics, although neuromodulation via transcranial direct current stimulation (tDCS) has recently generated a growing interest as a safe side-effect free treatment alternative or a complement to medications for chronic pain conditions. Although a number of studies have shown that tDCS has a beneficial effect on behavioral measures of pain, the mechanistic action of neuromodulation on pain sensitivity and coping at the central nervous system is not well understood.Aim: We aimed at observing longitudinal changes of cortical hemodynamics in older adults with knee OA associated with a two-week-long tDCS self-treatment protocol.Approach: Hemodynamics was measured bilaterally in the motor and somatosensory cortices with functional near-infrared spectroscopy (fNIRS) in response to thermal pain induced ipsilaterally to the knee primarily affected by OA.Results: We found that both oxyhemoglobin- and deoxyhemoglobin-related functional activations significantly increased during the course of the tDCS treatment, supporting the notion that tDCS yields an increased cortical excitability. Concurrently, clinical measures of pain decreased with tDCS treatment, hinting at a potential spatial dissociation between cortically mediated pain perception and suppression and the prevalence of neuromodulatory effects over cortical pain processing.Conclusions: fNIRS is a valid method for objectively tracking pain in an ambulatory setting and it could potentially be used to inform strategies for optimized tDCS treatment and to develop innovative tDCS protocols.

Highlights

Knee osteoarthritis (OA) is the most common type of joint disease in older adults, affecting more than 14 million people in the United States alone.[1,2,3,4,5,6] OA manifests symptomatically in the form NeurophotonicsApr–Jun 2020 Vol 7(2)Pollonini, Miao, and Ahn: Longitudinal effect of transcranial direct current stimulation. . .of chronic knee pain and disability, which are typically treated pharmacologically with analgesics
In support of this theory, neuroimaging using functional magnetic resonance imaging have shown that pain-related brain activation in people with knee OA and alterations in pain-related brain mechanisms have been associated with OA-related clinical pain,[12,13,14,15,16] possibly explaining the limited success of treatment locally targeting the pain in the area of the knee
We present a pilot study designed to observe the longitudinal changes in the cortical hemodynamic response to thermal pain measured with functional near-infrared spectroscopy concomitant to a two-week-long transcranial direct current stimulation (tDCS) treatment protocol self-administered by older adults with knee OA, which, to our knowledge, is an unprecedented effort

Summary

Introduction

Knee osteoarthritis (OA) is the most common type of joint disease in older adults, affecting more than 14 million people in the United States alone.[1,2,3,4,5,6] OA manifests symptomatically in the form NeurophotonicsApr–Jun 2020 Vol 7(2)Pollonini, Miao, and Ahn: Longitudinal effect of transcranial direct current stimulation. . .of chronic knee pain and disability, which are typically treated pharmacologically with analgesics. Recent studies have shown that pharmacological intervention alone is a suboptimal strategy for the management of knee OA in older adults since pain is only partially responsive and these drugs often produce significant adverse events, such as constipation, nausea, and drowsiness.[7,8,9] Another challenge underscored by several studies is the poor correspondence between measures of OA disease severity and measures of clinical pain, hinting that pain processing at the central nervous level in the brain may play a significant role in addition to localized joint pathophysiology.[10,11] In support of this theory, neuroimaging using functional magnetic resonance imaging (fMRI) have shown that pain-related brain activation in people with knee OA and alterations in pain-related brain mechanisms have been associated with OA-related clinical pain,[12,13,14,15,16] possibly explaining the limited success of treatment locally targeting the pain in the area of the knee. There exists the need and the opportunity to investigate alternative and/or complementary strategies for pharmacological interventions for the treatment of OArelated pain

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