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

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.

Methods and strategies of tDCS for the treatment of pain: current status and future directions

“…Over the last years, clinical studies targeting anodal M1 for pain control have had significant results. Different conditions have been considered as fibromyalgia [17,[48][49][50][51][52][53][54][55][56][57], neuropathic pain [58][59][60][61][62][63][64][65][66][67][68][69][70], migraine [71][72][73][74][75][76], low back pain (LBP) [77][78][79][80][81], musculoskeletal conditions [16,[82][83][84][85][86][87], myofascial pain syndrome [88,89], post-operative pain [90][91][92][93], among others (See Table 1).…”

Feasibility, Acceptability, and Efficacy of Home-Based Transcranial Direct Current Stimulation on Pain in Older Adults with Alzheimer’s Disease and Related Dementias: A Randomized Sham-Controlled Pilot Clinical Trial

“…Our findings also suggest that the chronic pain experienced by individuals with ADRD involves central processing mechanisms since tDCS was able to impact pain intensity. Indeed, tDCS is a neuromodulation method potentially affecting pain processing pathways as shown in our studies using neuroimaging and conditioned pain modulation (CPM) measures [ 48 , 80 , 81 , 82 ]. We found significant changes in hemodynamic brain activity measured with functional near-infrared spectroscopy (fNIRS) [ 80 , 81 , 82 ], and simultaneously observed a significant increase in CPM in the active group as opposed to the sham group after tDCS [ 48 ], which coincides with tDCS studies using functional magnetic resonance imaging (fMRI) in both healthy subjects [ 83 , 84 ] and chronic pain patients [ 85 , 86 ].…”

“…Indeed, tDCS is a neuromodulation method potentially affecting pain processing pathways as shown in our studies using neuroimaging and conditioned pain modulation (CPM) measures [ 48 , 80 , 81 , 82 ]. We found significant changes in hemodynamic brain activity measured with functional near-infrared spectroscopy (fNIRS) [ 80 , 81 , 82 ], and simultaneously observed a significant increase in CPM in the active group as opposed to the sham group after tDCS [ 48 ], which coincides with tDCS studies using functional magnetic resonance imaging (fMRI) in both healthy subjects [ 83 , 84 ] and chronic pain patients [ 85 , 86 ]. In relation to ADRD, recent evidence suggests that there might be a link between pathological processes of ADRD and chronic pain [ 87 ].…”

Time Dependent Effect of the Combination of Transcranial Direct Current Stimulation and Transcutaneous Electrical Nerve Stimulation in Knee Osteoarthritis Patients

“…Thus, the time dependent effect of tDCS in KOA patients can also be explored. A study has explored the longitudinal effect of tDCS in knee OA patients via functional infrared spectroscopy and showed significant increase in the levels of oxyhemoglobin-and deoxyhemoglobin-related functional activations with the application of tDCS suggesting increase in cortical excitability along with the decrease in pain with its neuromodulatory effect on the cortical pain processing [26]. Keeping in view of the potential neuromodulatory effect of tDCS, the present study aims to find out the time dependent effect of the combination of tDCS with TENS in knee OA patients hypothesizing that the combination of the interventions may produce better treatment outcomes and can improve the clinical and mechanistic effects in knee OA patients.…”