Burst and Tonic Spinal Cord Stimulation: Different and Common Brain Mechanisms

Burst Stimulation Evokes Increased Bladder and Urethral Pressure in Patients With Sacral Neuromodulation, Indicating Potential Activation of the Autonomic Nervous System: A Pilot Study

OBJECTIVES

Currently, sacral neuromodulation (SNM) outcomes are often suboptimal, and changing stimulation parameters might improve SNM efficacy. Burst stimulation mimics physiological burst firing of the nervous system and might therefore benefit patients treated with SNM. The purpose of the present pilot study was to evaluate the effect of various Burst SNM paradigms on bladder and urethral pressure in patients with overactive bladder (OAB) or nonobstructive urinary retention (NOUR).

MATERIALS AND METHODS

The bladder was filled to 50% of its capacity under general anesthesia in six patients with an implanted sacral lead for SNM purposes. Bladder pressure, and mid- and proximal urethral pressure were measured using conventional (Con-) SNM and various Burst SNM paradigms (10-20-40 Hz interburst frequency) with increasing amplitudes up to 5 mA for Con-SNM and 4 mA for Burst SNM.

RESULTS

Burst SNM caused a substantial increase in both bladder and urethral pressure. In contrast, Con-SNM caused a milder increase in urethral pressure, and only one patient showed a modest increase in bladder pressure. Furthermore, the pressure increase was higher in the proximal urethra than in the midurethra using Burst-SNM, whereas Con-SNM caused comparable increases in proximal and midurethra pressure.

CONCLUSIONS

Burst SNM induces bladder contraction compared with Con-SNM and induces higher pressure increases in bladder and proximal urethra than does Con-SNM in patients with OAB or NOUR, indicating a higher degree of autonomic nervous system stimulation. The observed responses could not be fully explained by the total charge of the Burst SNM paradigms, which suggests the importance of individual Burst SNM parameters, such as frequency and amplitude. Future studies should assess the feasibility and efficacy of Burst SNM in awake patients.

Closed-Loop Infraslow Brain-Computer Interface can Modulate Cortical Activity and Connectivity in Individuals With Chronic Painful Knee Osteoarthritis: A Secondary Analysis of a Randomized Placebo-Controlled Clinical Trial

Introduction. Chronic pain is a percept due to an imbalance in the activity between sensory-discriminative, motivational-affective, and descending pain-inhibitory brain regions. Evidence suggests that electroencephalography (EEG) infraslow fluctuation neurofeedback (ISF-NF) training can improve clinical outcomes. It is unknown whether such training can induce EEG activity and functional connectivity (FC) changes. A secondary data analysis of a feasibility clinical trial was conducted to determine whether EEG ISF-NF training can significantly alter EEG activity and FC between the targeted cortical regions in people with chronic painful knee osteoarthritis (OA). Methods. A parallel, two-arm, double-blind, randomized, sham-controlled clinical trial was conducted. People with chronic knee pain associated with OA were randomized to receive sham NF training or source-localized ratio ISF-NF training protocol to down-train ISF bands at the somatosensory (SSC), dorsal anterior cingulate (dACC), and uptrain pregenual anterior cingulate cortices (pgACC). Resting state EEG was recorded at baseline and immediate post-training. Results. The source localization mapping demonstrated a reduction (P = .04) in the ISF band activity at the left dorsolateral prefrontal cortex (LdlPFC) in the active NF group. Region of interest analysis yielded significant differences for ISF (P = .008), slow (P = .007), beta (P = .043), and gamma (P = .012) band activities at LdlPFC, dACC, and bilateral SSC. The FC between pgACC and left SSC in the delta band was negatively correlated with pain bothersomeness in the ISF-NF group. Conclusion. The EEG ISF-NF training can modulate EEG activity and connectivity in individuals with chronic painful knee osteoarthritis, and the observed EEG changes correlate with clinical pain measures.

Neurophysiological Oscillatory Mechanisms Underlying the Effect of Mirror Visual Feedback-Induced Illusion of Hand Movements on Nociception and Cortical Activation

Mirror Visual Feedback (MVF)-induced illusion of hand movements produces beneficial effects in patients with chronic pain. However, neurophysiological mechanisms underlying these effects are poorly known. In this preliminary study, we test the novel hypothesis that such an MVF-induced movement illusion may exert its effects by changing the activity in midline cortical areas associated with pain processing. Electrical stimuli with individually fixed intensity were applied to the left hand of healthy adults to produce painful and non-painful sensations during unilateral right-hand movements with such an MVF illusion and right and bilateral hand movements without MVF. During these events, electroencephalographic (EEG) activity was recorded from 64 scalp electrodes. Event-related desynchronization (ERD) of EEG alpha rhythms (8-12 Hz) indexed the neurophysiological oscillatory mechanisms inducing cortical activation. Compared to the painful sensations, the non-painful sensations were specifically characterized by (1) lower alpha ERD estimated in the cortical midline, angular gyrus, and lateral parietal regions during the experimental condition with MVF and (2) higher alpha ERD estimated in the lateral prefrontal and parietal regions during the control conditions without MVF. These preliminary results suggest that the MVF-induced movement illusion may affect nociception and neurophysiological oscillatory mechanisms, reducing the activation in cortical limbic and default mode regions.

Clinical outcomes of spinal cord stimulation in patients with intractable leg pain in Japan

BACKGROUND

Neuromodulation through spinal cord stimulation (SCS) is a therapeutic option for relieving leg pain and improving the chances of limb salvage in patients with intractable chronic limb-threatening ischemia (CLTI); however, there is no consensus on its indications.

OBJECTIVE

The aim of this study was to assess the clinical outcomes of SCS in patients with intractable leg pain caused by various diseases treated in the department of cardiovascular medicine in Japan.

METHODS

This was a retrospective study of patients who underwent SCS for pain management. Patients were considered eligible for the therapy if they met the following criteria: (1) intractable leg pain (numerical rating scale [NRS] score of 10), (2) no revascularization option, and (3) no septicemia.

RESULTS

Twenty patients (mean age: 77 years; men/women: 11/9) were included in this study. The NRS score of the patients significantly reduced from 10 ± 0 before procedure to 4 ± 3 at discharge (p < 0.001). The clinical response rate of the entire cohort was 65% (13/20) at 17 ± 14 months after implantation; however, patients with intractable CLTI showed a low response rate (45%), whereas those with subacute limb ischemia showed a high response rate (100%). A multivariable regression analysis showed that hemoglobin level was significantly associated with treatment response, even after adjusting for age and sex (p = 0.026). The area under the receiver operating characteristic curve for the correlation between hemoglobin level (cutoff, 11.4 g/dL) and clinical response to SCS was 0.824 (0.619-1).

CONCLUSIONS

SCS can reduce clinical symptoms in majority of patients with intractable leg pain. Although implantation of an SCS device has been shown to improve microvascular perfusion insufficiency, the correlation between hemoglobin level and the clinical effect of SCS indicates that a preserved microcirculatory vascular bed is essential for the therapy to be effective.

The deep and the deeper: Spinal cord and deep brain stimulation for neuropathic pain

Neuropathic pain occurs in people experiencing lesion or disease affecting the somatosensorial system. It is present in 7 % of the general population and may not fully respond to first- and second-line treatments in up to 40 % of cases. Neuromodulation approaches are often proposed for those not tolerating or not responding to usual pharmacological management. These approaches can be delivered surgically (invasively) or non-invasively. Invasive neuromodulation techniques were the first to be employed in neuropathic pain. Among them is spinal cord stimulation (SCS), which consists of the implantation of epidural electrodes over the spinal cord. It is recommended in some guidelines for peripheral neuropathic pain. While recent studies have called into question its efficacy, others have provided promising data, driven by advances in techniques, battery capabilities, programming algorithms and software developments. Deep brain stimulation (DBS) is another well-stablished neuromodulation therapy routinely used for movement disorders; however, its role in pain management remains limited to specific research centers. This is not only due to variable results in the literature contesting its efficacy, but also because several different brain targets have been explored in small trials, compromising comparisons between these studies. Structures such as the periaqueductal grey, posterior thalamus, anterior cingulate cortex, ventral striatum/anterior limb of the internal capsule and the insula are the main targets described to date in literature. SCS and DBS present diverse rationales for use, mechanistic backgrounds, and varying levels of support from experimental studies. The present review aims to present their methodological details, main mechanisms of action for analgesia and their place in the current body of evidence in the management of patients with neuropathic pain, as well their particularities, effectiveness, safety and limitations.

Causal interactions in brain networks predict pain levels in trigeminal neuralgia

Trigeminal neuralgia (TN) is a highly debilitating facial pain condition. Magnetic resonance imaging (MRI) is the main method for generating insights into the central mechanisms of TN pain in humans. Studies have found both structural and functional abnormalities in various brain structures in TN patients as compared with healthy controls. Whereas studies have also examined aberrations in brain networks in TN, no studies have to date investigated causal interactions in these brain networks and related these causal interactions to the levels of TN pain. We recorded fMRI data from 39 TN patients who either rested comfortably in the scanner during the resting state session or tracked their pain levels during the pain tracking session. Applying Granger causality to analyze the data and requiring consistent findings across the two scanning sessions, we found 5 causal interactions, including: (1) Thalamus → dACC, (2) Caudate → Inferior temporal gyrus, (3) Precentral gyrus → Inferior temporal gyrus, (4) Supramarginal gyrus → Inferior temporal gyrus, and (5) Bankssts → Inferior temporal gyrus, that were consistently associated with the levels of pain experienced by the patients. Utilizing these 5 causal interactions as predictor variables and the pain score as the predicted variable in a linear multiple regression model, we found that in both pain tracking and resting state sessions, the model was able to explain ∼36 % of the variance in pain levels, and importantly, the model trained on the 5 causal interaction values from one session was able to predict pain levels using the 5 causal interaction values from the other session, thereby cross-validating the models. These results, obtained by applying novel analytical methods to neuroimaging data, provide important insights into the pathophysiology of TN and could inform future studies aimed at developing innovative therapies for treating TN.

Neuromodulation and Habituation: A Literature Review and Conceptional Analysis of Sustaining Therapeutic Efficacy and Mitigating Habituation

Spinal cord stimulation (SCS) is a therapeutic modality for the treatment of various chronic pain conditions that has rapidly evolved over the past 50 years. Unfortunately, over time, patients implanted with SCS undergo a habituation phenomenon leading to decreased pain relief. Consequently, the discovery of new stimulation waveforms and SCS applications has been shown to prolong efficacy and reduce explantation rates. This article explores various SCS waveforms, their applications, and proposes a graded approach to habituation mitigation. We suspect the neural habituation phenomenon parallels that seen in pharmacology. Consequently, we urge further exploration of the early introduction of these stimulation strategies to abate spinal cord stimulation habituation.

Distinct Functional Connectivity Patterns for Intermittent Vs Constant Neuropathic Pain Phenotypes in Persistent Spinal Pain Syndrome Type 2 Patients

Background

Chronic low back pain (cLBP) has been associated with alterations in brain functional connectivity (FC) but based upon heterogeneous populations and single network analyses. Our goal is to study a more homogeneous cLBP population and focus on multiple cross-network (CN) connectivity analysis. We hypothesize that within this population: 1) altered CN FC, involving emotion and reward/aversion functions are related to their pain levels and 2) altered relationships are dependent upon pain phenotype (constant neuropathic vs intermittent pain).

Methods

In this case series, resting state fcMRI scans were obtained over a study duration of 60 months from 23 patients (13 constant neuropathic and 10 intermittent pain) with Persistent Spinal Pain Syndrome (PSPS Type 2) being considered for spinal cord stimulation (SCS) therapy at a single academic center. Images were acquired using a Discovery MR750 GE scanner. During the resting state acquisitions, they were asked to close their eyes and relax. The CN analysis was performed on 7 brain networks and compared to age-matched controls. Linear regression was used to test the correlation between CN connectivity and pain scores.

Results

CN FC involving emotion networks (STM: striatum network index) was significantly lower than controls in all patients, regardless of pain phenotype (P < 0.003). Pain levels were positively correlated with emotional FC for intermittent pain but negatively correlated for constant pain.

Conclusion

This is the first report of 1) altered CN FC involving emotion/reward brain circuitry in 2) a homogeneous population of cLBP patients with 3) two different pain phenotypes (constant vs intermittent) in PSPS Type 2 patients being considered for SCS. FC patterns were altered in cLBP patients as compared to controls and were characteristic for each pain phenotype. These data support fcMRI as a potential and objective tool in assessing pain levels in cLBP patients with different pain phenotypes.

Amygdala electrical stimulation for operant conditioning in rat navigation

There have been several attempts to navigate the locomotion of animals by neuromodulation. The most common method is animal training with electrical brain stimulation for directional cues and rewards; the basic principle is to activate dopamine-mediated neural reward pathways such as the medial forebrain bundle (MFB) when the animal correctly follows the external commands. In this study, the amygdala, which is the brain region responsible for fear modulation, was targeted for punishment training. The brain regions of MFB, amygdala, and barrel cortex were electrically stimulated for reward, punishment, and directional cues, respectively. Electrical stimulation was applied to the amygdala of rats when they failed to follow directional commands. First, two different amygdala regions, i.e., basolateral amygdala (BLA) and central amygdala (CeA), were stimulated and compared in terms of behavior responses, success and correction rates for training, and gene expression for learning and memory. Then, the training was performed in three groups: group R (MFB stimulation for reward), group P (BLA stimulation for punishment), and group RP (both MFB and BLA stimulation for reward and punishment). In group P, after the training, RNA sequencing was conducted to detect gene expression and demonstrate the effect of punishment learning. Group P showed higher success rates than group R, and group RP exhibited the most effective locomotion control among the three groups. Gene expression results imply that BLA stimulation can be more effective as a punishment in the learning process than CeA stimulation. We developed a new method to navigate rat locomotion behaviors by applying amygdala stimulation.

Temporary Spinal Cord Stimulation for Herpes Zoster With Myelitis: A Case Series

Introduction: Preventing the development of postherpetic neuralgia (PHN), the most prevalent and severe complication of herpes zoster (HZ), is vital. Recently, it has been suggested that using temporary spinal cord stimulation (tSCS) for 10-14 days can improve HZ-associated pain (ZAP) and prevent PHN. However, myelitis complicates HZ. Permanent SCS has been successful in treating neuropathic pain induced by postoperative transverse myelitis of the spine that has not responded to traditional multidisciplinary treatment. However, it is unknown whether tSCS can reduce ZAP complicated with myelitis. Methodology: Between January 2020 and April 2022, all patients with HZ who visited our pain clinic with spinal cord edema and who underwent tSCS were enrolled in this study; their medical records were retrospectively examined. Pain intensity was assessed at baseline (before initiating interventional procedures), just before tSCS, after tSCS removal, and one and three months after tSCS. Results: Twelve patients were enrolled. The mean Numerical Rating Scale (NRS) was 7.9 ± 1.6 at baseline (before interventional procedures), 6.8 ± 2.2 before tSCS (after interventional procedures), and 3.5 ± 2.4 after tSCS. Compared with before tSCS, the mean NRS decreased to 3.3 ± 2.3 after tSCS (P = 0.0004). The mean NRS changes with interventional procedures before and after tSCS were -1.2 ± 2.2 (P = 0.0945) and 3.3 ± 2.3 (P = 0.0004), respectively; the change after tSCS was significantly higher (between-group difference: -2.1 ± 3.7; P = 0.0324). Conclusions: Temporary SCS alleviated pain in cases of shingles with myelitis refractory to interventional therapy. Even in cases with myelitis, tSCS for ZAP remains an effective way to prevent PHN.

Combined behavioral and EEG evidence for the 70 Hz frequency selection of short-term spinal cord stimulation in disorders of consciousness

OBJECTIVES

This study investigated the prognostic effect of electroencephalography (EEG) instant effects of single spinal cord stimulation (SCS) on clinical outcome in disorders of consciousness (DOC) and the time-dependent brain response during the recovery of consciousness prompted by SCS.

METHODS

Twenty three patients with DOC underwent short-term SCS (stSCS) implantation operation. Then, all patients received the postoperative EEG test including EEG record before (T1) and after (T2) single SCS session. Subsequently, 2 weeks stSCS treatment was performed and revised coma recovery scale (CRS-R) and EEG data were collected. Finally, they were classified into effective and ineffective groups at 3-month follow-up (T6).

RESULTS

The parietal-occipital (PO) connectivity and clustering coefficients (CC) in the beta band of the effective group at the 1 week after the treatment (T5) were found to be higher than preoperative assessment (T0). Correlation analysis showed that the change in beta CC at T1/T2 was correlated with the change in CRS-R at T0/T6. In addition, the change in PO connectivity and CC in the beta at T0/T5 were also correlated with the change in CRS-R at T0/T5.

CONCLUSION

SCS may facilitate the recovery of consciousness by enhancing local information interaction in posterior brain regions. And the recovery can be predicted by beta CC in the EEG test.

Burst Spinal Cord Stimulation as Compared With L2 Dorsal Root Ganglion Stimulation in Pain Relief for Nonoperated Discogenic Low Back Pain: Analysis of Two Prospective Studies

INTRODUCTION

Chronic discogenic low back pain (CD-LBP) is caused by degenerated disks marked by neural and vascular ingrowth. Spinal cord stimulation (SCS) has been shown to be effective for pain relief in patients who are not responsive to conventional treatments. Previously, the pain-relieving effect of two variations of SCS has been evaluated in CD-LBP: Burst SCS and L2 dorsal root ganglion stimulation (DRGS). The aim of this study is to compare the effectivity in pain relief and pain experience of Burst SCS with that of conventional L2 DRGS in patients with CD-LBP.

MATERIALS AND METHODS

Subjects were implanted with either Burst SCS (n = 14) or L2 DRGS with conventional stimulation (n = 15). Patients completed the numeric pain rating score (NRS) for back pain and Oswestry disability index (ODI) and EuroQoL 5D (EQ-5D) questionnaires at baseline, and at three, six, and 12 months after implantation. Data were compared between time points and between groups.

RESULTS

Both Burst SCS and L2 DRGS significantly decreased NRS, ODI, and EQ-5D scores as compared with baseline. L2 DRGS resulted in significantly lower NRS scores at 12 months and significantly increased EQ-5D scores at six and 12 months.

CONCLUSIONS

Both L2 DRGS and Burst SCS resulted in reduction of pain and disability, and increased quality of life in patients with CD-LBP. L2 DRGS provided significantly increased pain relief and improvement in quality of life when compared with Burst SCS.

CLINICAL TRIAL REGISTRATION

The clinical trial registration numbers for the study are NCT03958604 and NL54405.091.15.

Current Waveforms in Spinal Cord Stimulation and Their Impact on the Future of Neuromodulation: A Scoping Review

BACKGROUND

Neuromodulation is a standard and well-accepted treatment for chronic refractory neuropathic pain. There has been progressive innovation in the field over the last decade, particularly in areas of spinal cord stimulation (SCS) and dorsal root ganglion stimulation. Improved outcomes using proprietary waveforms have become customary in the field, leading to an unprecedented expansion of these products and a plethora of options for the management of pain. Although advances in waveform technology have improved our fundamental understanding of neuromodulation, a scoping review describing new energy platforms and their associated clinical effects and outcomes is needed. The authors submit that understanding electrophysiological neuromodulation may be important for clinical decision-making and programming selection for personalized patient care.

OBJECTIVE

This review aims to characterize ways differences in mechanism of action and clinical outcomes of current spinal neuromodulation products may affect contemporary clinical decision-making while outlining a possible path for the future SCS.

STUDY DESIGN

The study is a scoping review of the literature about newer generation SCS waveforms.

MATERIALS AND METHODS

A literature report was performed on PubMed and chapters to include articles on spine neuromodulation mechanism of action and efficacy.

RESULTS

A total of 8469 studies were identified, 75 of which were included for the scoping review after keywords defining recent waveform technology were added.

CONCLUSIONS

Clinical data suggest that neuromodulation remains a promising tool in the treatment of chronic pain. The evidence for SCS for treating chronic pain seems compelling; however, more long-term and comparative data are needed for a comparison of waveforms when it comes to the etiology of pain. In addition, an exploration into combination waveform therapy and waveform cycling may be paramount for future clinical studies and the development of new technologies.

Bilateral T12 Dorsal Root Ganglion Stimulation for the Treatment of Low Back Pain With 20-Hz and 4-Hz Stimulation, a Retrospective Study

OBJECTIVES

Chronic low back pain (CLBP) is one of the most common chronic pain conditions that cause both individual suffering and a burden to society. For these patients, several interventional treatment options such as surgery, blocks, radiofrequency, and spinal cord stimulation are available. Lately, dorsal root ganglion stimulation (DRG-S) also has been mentioned as an option by targeting bilateral T12 dorsal ganglia. In this study, we present the outcome of 11 patients with CLBP treated with bilateral T12 DRG-S.

MATERIALS AND METHODS

Thirteen patients with CLBP with and without leg pain were treated with bilateral T12 DRG-S. Three of the patients also received a third lumbar lead owing to leg pain. Eleven of the patients had >50% pain relief during the peri- or/and postoperative testing and received a fully implantable neurostimulator. Pain intensity, general health status, quality of life, pain catastrophizing, mental status, sleeping disorder, physical activity, and patient satisfaction were followed using numeric rating scale (NRS), Patient-Reported Outcomes Measurement Information System 29 version 2.1, Pain Catastrophizing Score, Generalized Anxiety Disorder 7-item scale, Patient Health Questionnaire Depression Module, Insomnia Severity Index, and Patient Satisfaction Questionnaire at baseline before implantation and at three months and six months. The results were analyzed on the basis of six domains: pain relief, sleeping disorder, social ability, mental status, physical activity, and satisfaction. To be identified as a responder, the patients should show a significant improvement in the pain relief domain together with at least two other domains. All responders also were given the opportunity to test 4-Hz DRG-S and compare it with traditional 20-Hz stimulation.

RESULTS

All 11 patients were identified as responders at six months. Five of the patients had >80% pain relief, with an average NRS score reduction of 71% for the whole group. Significant improvement could be observed in three domains for one patient, four domains for three patients, five domains for six patients, and six domains for one patient. Seven patients chose to try 4-Hz stimulation. All seven identified 4-Hz stimulation as at least as good as or better than 20-Hz stimulation and chose to continue with 4-Hz stimulation.

CONCLUSIONS

Bilateral T12 DRG-S seems to be an effective treatment for chronic low back pain, with significant beneficial effect not only on pain but also on quality of life, pain catastrophizing, mental status, sleeping disorder, and physical activity. 4-Hz DRG-S gave a result comparable with or better than 20-Hz stimulation.

Correlation between spinal cord stimulation analgesia and cortical dynamics in pain management

AIM

Spinal cord stimulation (SCS) is an effective method to treat neuropathic pain. It is necessary to identify the responders of SCS analgesia before implantation. The aim of this study is to investigate the relationship between the cortical dynamics and SCS analgesia responders in pain management.

METHODS

Resting-state EEG recording was performed in patients who underwent short-term implantation of spinal cord stimulation for pain therapy. We then did spectral analysis to capture the pattern of cortical oscillation between neuromodulation therapy analgesia responders and nonresponders.

RESULTS

About 58.3% (14 out of 24) of participants were considered as analgesia responders, with average visual analogue scores reduction of 4.8 ± 1.0 after surgery, and 2.1 ± 0.7 for the nonresponder subgroup, respectively. The alpha oscillation was significantly enhanced in responder cohort compared with nonresponders. We also observed an increasing spectral power of gamma band in responders. Furthermore, the attenuation of pain severity was significantly correlated with the global alpha oscillation activity (r = 0.60, P = 0.002). Likely, positive and significant correlation was found between the pain relief and gamma activity (r = 0.58, P = 0.003).

CONCLUSIONS

Distinct pattern of neural oscillation is associated with the analgesic effect of spinal cord stimulation in pain management, enhancement of cortical alpha and gamma oscillation may be a predictor of analgesia responders.

Evaluation of Patient's Quality of Life before and after Implantation of Abbott's Proclaim™ XR Spinal Cord Stimulator with BurstDR™ Stimulation in Chronic Pain Syndrome

Background and Objectives: In case of the ineffectiveness of pharmacological and non-pharmacological treatments in managing chronic neuropathic pain, spinal cord stimulation (SCS) with BurstDR™ stimulation may reduce pain and increase the quality of life. The term "burst" refers to a series of stimulation impulses that are compressed into small packets and separated by intervals of latency. Materials and Methods: A group of 30 consecutive patients who received the BurstDR™ stimulator using the minimally invasive percutaneous method was selected. Patients selected for our study underwent numerous spinal surgeries before SCS implantation. In the study, analgesics and co-analgesics and their doses used by patients before and 6 months after SCS implantation were examined and compared. Using the visual analogue scale (VAS), pain was compared before and after the procedure. Patients` quality of life was assessed using the Oswestry Disability Index (ODI). Results: We observed a significant reduction in opioid daily doses by an average of 32.4% (±36.1%) and a reduction in paracetamol daily doses by an average of 40% (±33.4%). There was a reduction in pregabalin doses as well. Ketoprofen daily dose reduction was 85.4 mg. The mean VAS difference before and after procedure was 3.9 (±2.3), and the mean difference in ODI was 12.9 (±9), which benefits operative treatment. The VAS and ODI results were statistically significant as well. Conclusions: According to our research, BurstDR™ stimulation improves the quality of life by reducing doses of analgesics and the level of pain.

Patient profiling and outcome assessment in spinal cord stimulation for chronic back and/or leg pain (the PROSTIM study): a study protocol

Spinal cord stimulation (SCS) is a well-established treatment option in the multidisciplinary approach to chronic back and leg pain. Nevertheless, careful patient selection remains crucial to provide the most optimal treatment and prevent treatment failure. We report the protocol for the PROSTIM study, an ongoing prospective, multicentric and observational clinical study (NCT05349695) that aims to identify different patient clusters and their outcomes after SCS. Patients are recruited in different centers in Europe. Analysis focuses on identifying significant patient clusters based on different health domains and the changes in biopsychosocial variables 6 weeks, 3 and 12 months after implantation. This study is the first to include a biopsychosocial cluster analysis to identify significant patient groups and their response to treatment with SCS.

Should we Oppose or Combine Waveforms for Spinal Cord Stimulation in PSPS-T2 Patients? A Prospective Randomized Crossover Trial (MULTIWAVE Study)

Refractory persistent spinal pain syndrome after surgery (PSPS-T2) can be successfully addressed by spinal cord stimulation (SCS). While conventional stimulation generates paresthesia, recent systems enable the delivery of paresthesia-free stimulation. Studies have claimed non-inferiority/superiority of selected paresthesia-free stimulation compared with paresthesia-based stimulation, but the comparative efficacy between different waveforms still needs to be determined in a given patient. We designed a randomized controlled 3-month crossover trial to compare pain relief of paresthesia-based stimulation versus high frequency versus burst in 28 PSPS-T2 patients implanted with multiwave SCS systems. Our secondary objectives were to determine the efficacy of these 3 waveforms on pain surface, quality of life, functional capacity, psychological distress, and validated composite multidimensional clinical response index to provide holistic comparisons at 3-, 6-, 9-, and 15-month post-randomization. The preferred stimulation modality was documented during the follow-up periods. No difference between the waveforms was observed in this study (P = .08). SCS led to significant pain relief, quality of life improvement, improvement of multidimensional clinical response index, and of all other clinical outcomes at all follow-up visits. Forty-four percent of the patients chose to keep the paresthesia-based stimulation modality after the 15-month follow-up period. By giving the possibility to switch and/or to combine several waveforms, the overall rate of SCS responders further increased with 25%. In this study, high frequency or burst do not appear superior to paresthesia-based stimulation, wherefore paresthesia-based stimulation should still be considered as a valid option. However, combining paresthesia-based stimulation with paresthesia-free stimulation, through personalized multiwave therapy, might significantly improve SCS responses. PERSPECTIVE: This article assesses clinical SCS efficacy on pain relief, by comparing paresthesia-based stimulation and paresthesia-free stimulation (including high frequency and burst) modalities in patient presenting with PSPS-T2. Switching and/or combining waveforms contribute to increasing the global SCS responders rate.

Model-based analysis of subthreshold mechanisms of spinal cord stimulation for pain

Objective.Spinal cord stimulation (SCS) is a common treatment for chronic pain. For decades, SCS maximized overlap between stimulation-induced paresthesias and the patient's painful areas. Recently developed SCS paradigms relieve pain at sub-perceptible amplitudes, yet little is known about the neural response to these new waveforms or their analgesic mechanisms of action. Therefore, in this study, we investigated the neural response to multiple forms of paresthesia-free SCS.Approach.We used computational modeling to investigate the neurophysiological effects and the plausibility of commonly proposed mechanisms of three paresthesia-free SCS paradigms: burst, 1 kHz, and 10 kHz SCS. Specifically, in C- and Aβ-fibers, we investigated the effects of different SCS waveforms on spike timing and activation thresholds, as well as how stochastic ion channel gating affects the response of dorsal column axons. Finally, we characterized membrane polarization of superficial dorsal horn neurons.Main results.We found that none of the SCS waveforms activate nor modulate spike timing in C-fibers. Spike timing was modulated in Aβ-fibers only at suprathreshold amplitudes. Ion channel stochasticity had little effect on Aβ-fiber activation thresholds but produced heterogeneous spike timings at suprathreshold amplitudes. Finally, local cells were preferentially polarized in their axon terminals, and the magnitude of this polarization was dependent on cellular morphology and position relative to the stimulation electrodes.Significance.Overall, the mechanisms of action of subparesthetic SCS remain unclear. Our results suggest that no SCS waveforms directly activate C-fibers, and modulation of spike timing is unlikely at subthreshold amplitudes. We conclude that potential subthreshold neuromodulatory effects of SCS on local cells are likely to be presynaptic in nature, as axons are preferentially depolarized during SCS.

Blockage of pain by electrical spinal cord stimulation

BACKGROUND

Electrical spinal cord stimulation (SCS) is an alternative to conventional medication for chronic pain relief. Several hypotheses exist concerning the neurophysiological, vascular, and neurochemical mechanism behind SCS.

METHODS

The excitation and blockade effects of the three common SCS waveforms (tonic, burst, and high-frequency stimulation) on the nerve fibers bypassing the region of the electrodes are analyzed in a computational study. The simulations are based on the model of Hodgkin and Huxley which is fitted to spike durations of 1 ms.

RESULTS

SCS is a FDA approved technique for pain relief, but the mechanisms of action are still under investigation. The first element in the chain of mechanisms is the generation and the block of spikes in nerve fibers close to the stimulating electrode. For these "primary fibers" computer simulations showed that conventional SCS generates sharply synchronized spikes whereas the spread of the spiking times by burst stimulation is expected to cause the suppression of paresthesia. This rather uniform spread of spiking times (in comparison to tonic stimulation) is a consequence of more pulses (5 vs. 1), longer pulses, and increasing intensities within each train of 5 pulses.

CONCLUSIONS

High-frequency stimulation can block the conduction of spikes but the distance of the fiber to the lead is a critical factor.

Efficacy of the latest new stimulation patterns of spinal cord stimulation for intractable neuropathic pain compared to conventional stimulation: study protocol for a clinical trial

BACKGROUND

Spinal cord stimulation (SCS) is one of the neuromodulation therapies for chronic neuropathic pain. The conventional paresthesia-based SCS involves the application of tonic stimulation that induces a sense of paresthesia. Recently, new SCS stimulation patterns without paresthesia have been developed. Differential target multiplexed (DTM) stimulation and fast-acting subperception therapy (FAST) stimulation are the latest paresthesia-free SCS patterns.

METHODS

A single-center, open-label, crossover, randomized clinical trial to investigate the superiority of SCS using the latest new stimulation patterns over conventional tonic stimulation for neuropathic pain is planned. This study consists of two steps: SCS trial (first step) and SCS system implantation (second step). In the SCS trial, participants will be randomly assigned to 4 groups receiving stimulation, including tonic, DTM, and FAST. Each stimulation will then be performed for 2 days, and a visual analog scale (VAS) for pain will be evaluated before and after each stimulation pattern. A stimulation-off period for 1 day is set between each stimulation pattern to wash out the residual previous stimulation effects. Pain improvement is defined as more than 33% reduction in the pain VAS. The primary analysis will compare pain improvement between the new stimulation patterns and the conventional tonic stimulation pattern in the SCS trial. The secondary outcomes will be evaluated as follows: (1) the relationships between causative disease and improvement rate by each stimulation pattern; (2) comparison of pain improvement between the DTM and FAST stimulation patterns in all cases and by causative disease; (3) changes in assessment items preoperatively to 24 months after the implantation; (4) preoperative factors associated with long-term effects defined as continuing for more than 12 months; and (5) adverse events related to this study 3 months after the implantation.

DISCUSSION

This study aims to clarify the effectiveness of the latest new stimulation patterns compared to the conventional tonic stimulation. In addition, which stimulation pattern is most effective for which kind of causative disease will be clarified.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT) 1,042,220,094. Registered on 21 November 2022, and last modified on 6 January 2023. jRCT is an approved member of the Primary Registry Network of WHO ICTRP.

Investigation of the intraoperative cortical responses to spinal motor mapping in a patient with chronic pain

Intraoperative neurophysiological monitoring (IONM) in spinal cord stimulation (SCS) surgery for chronic pain is shown to provide effective guidance during device placement. Electromyography (EMG) is used to determine the laterality of the paddle. In some SCS cases, laterality cannot be obtained via EMG due to patient physiology. Electroencephalography (EEG) is already used in IONM to monitor cortical responses. Here, we show proof-of-concept of assessing the responses of epidurally evoked EMGs simultaneously with EEGs to determine laterality during IONM using a high-resolution (HR) SCS paddle. An 8-column HR-SCS paddle was acutely placed at T9-T10 interspace in patients with failed back surgery syndrome. EMG signals from 18 muscle groups were recorded simultaneously with 60-channel EEG signals at various stimulation amplitudes (0-10 mA). Particular attention was paid to regions associated with pain including the somatosensory cortex (S1), prefrontal cortex (PFC), and motor cortex (M1). When left and right lateral contacts were stimulated at low amplitudes (1-2 mA), significant changes were seen in θ, α, and β powers in the contralateral PFC but not in M1 or S1. There was a significant correlation between M1 and contralateral contacts in α power. At higher currents (7-8 mA), right-sided contacts resulted in α power change. We found significant differences in α, θ, and β powers in PFC for contralateral stimulation of the lateral SCS contacts at low amplitudes and in α power at higher amplitudes. The changes in PFC suggest the potential of EEG for understanding a cortical mechanism of action of SCS and provide insight into the pathophysiology of chronic pain.NEW & NOTEWORTHY Here, we present proof of concept of assessing the responses of epidurally evoked electromyography simultaneously with scalp electroencephalography to determine whether both laterality and insights into pain mechanisms can be elucidated. With stimulation, significant changes were seen in θ, α, and β band power in the contralateral prefrontal cortex and in α power in the motor cortex. We provide insight into the mechanism of action of SCS in preventing pain in this patient.

Towards chronic non-invasive stimulation: what can you learn from pain research?

This scientific commentary refers to 'Long-term analgesic effect of trans-spinal direct current stimulation compared to non-invasive motor cortex stimulation in complex regional pain syndrome, by Hodaj et al. (https://doi.org/10.1093/braincomms/fcad191).

BurstDR spinal cord stimulation rebalances pain input and pain suppression in the brain in chronic neuropathic pain

OBJECTIVE

Chronic pain is processed by at least three well-known pathways, two pain provoking pathways including a medial 'suffering' and lateral 'painfulness' pathway. A third descending pain pathway modulates pain but is predominantly inhibitory. Chronic pain can be seen as an imbalance between the two pain-provoking and the pain inhibitory pathways. If this assumption is correct, then the imbalance between pain input and pain suppression should reverse and normalize in response to successful, i.e., pain reducing burstDR spinal cord stimulation, one of the current treatment options for neuropathic pain.

MATERIALS AND METHODS

Fifteen patients, who received spinal cord stimulation for failed back surgery were included in this study, using source localized electrical brain activity and connectivity recording via EEG to identify the purported imbalance.

RESULTS

BurstDR spinal cord stimulation induces a significant change in EEG activity in both the left and right somatosensory cortex (SSC) for both θ and γ oscillations. In the dorsal anterior cingulate cortex (dACC), we observed a significant drop in both α and β oscillations. This reduction is accompanied by a change in pain intensity and suffering. BurstDR spinal cord stimulation is also associated with a reduction in θ at the pregenual anterior cingulate cortex (pgACC). Analyzing effective connectivity indicates that for the θ band, more information is sent from the pgACC to the left and right SSC. For α, increased information is sent from the pgACC to the dACC and both the left and right SSC. This is associated with a reduced θ-γ coupling in the SSC and reduced α-β coupling in dACC.

CONCLUSION

This study suggests that chronic pain is indeed an imbalance between the ascending and descending pathways in the brain and that burst spinal cord stimulation can normalize this imbalance in the brain.

Differential target multiplexed spinal cord stimulation using a paddle-type lead placed at the appropriate site for neuropathic pain after spinal cord injury in patients with past spinal surgical histories: study protocol for an exploratory clinical trial

BACKGROUND

Neuropathic pain after spinal cord injury (SCI), both traumatic and non-traumatic, is refractory to various treatments. Spinal cord stimulation (SCS) is one of the neuromodulation therapies for neuropathic pain, although SCS has insufficient efficacy for neuropathic pain after SCI. The reasons are presumed to be inappropriate locations of SCS leads and conventional tonic stimulation itself does not have a sufficient analgesic effect for the pain. In patients with past spinal surgical histories, the cylinder-type leads are likely to be placed on the caudal side of the SCI because of surgical adhesions. Differential target multiplexed (DTM) stimulation is one of the latest new stimulation patterns that is superior to conventional stimulation.

METHODS

A single-center, open-label, randomized, two-way crossover trial is planned to investigate the efficacy of SCS using DTM stimulation placing a paddle lead at the appropriate site for neuropathic pain after SCI in patients with spinal surgical histories. The paddle-type lead delivers energy more efficiently than a cylinder-type lead. This study consists of two steps: SCS trial (first step) and SCS system implantation (second step). The primary outcome is rates of achieving pain improvement with more than 33% reduction 3 months after SCS system implantation. The secondary outcomes are to be evaluated as follows: (1) effectiveness of DTM and tonic stimulations during the SCS trial; (2) changes of assessment items from 1 to 24 months; (3) relationships between the result of the SCS trial and the effects 3 months after SCS system implantation; (4) preoperative factors associated with a long-term effect, defined as continuing for more than 12 months; and (5) whether gait function improves from 1 to 24 months.

DISCUSSION

A paddle-type lead placed on the rostral side of SCI and using DTM stimulation may provide significant pain relief for patients with intractable neuropathic pain after SCI in patients with past spinal surgical histories.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCT) jRCT 1042220093. Registered on 21 November 2022, and last modified on 6 January 2023. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.

Neurotechnology for Pain

Neurotechnologies for treating pain rely on electrical stimulation of the central or peripheral nervous system to disrupt or block pain signaling and have been commercialized to treat a variety of pain conditions. While their adoption is accelerating, neurotechnologies are still frequently viewed as a last resort, after many other treatment options have been explored. We review the pain conditions commonly treated with electrical stimulation, as well as the specific neurotechnologies used for treating those conditions. We identify barriers to adoption, including a limited understanding of mechanisms of action, inconsistent efficacy across patients, and challenges related to selectivity of stimulation and off-target side effects. We describe design improvements that have recently been implemented, as well as some cutting-edge technologies that may address the limitations of existing neurotechnologies. Addressing these challenges will accelerate adoption and change neurotechnologies from last-line to first-line treatments for people living with chronic pain.

Functional Connectivity Magnetic Resonance Imaging Sequences in Patients With Postsurgical Persistent Spinal Pain Syndrome Type 2 With Implanted Spinal Cord Stimulation Systems: A Safety, Feasibility, and Validity Study

BACKGROUND

Chronic pain has been associated with alterations in brain connectivity, both within networks (regional) and between networks (cross-network connectivity). Functional connectivity (FC) data on chronic back pain are limited and based on heterogeneous pain populations. Patients with postsurgical persistent spinal pain syndrome (PSPS) type 2 are good candidates for spinal cord stimulation (SCS) therapy. We hypothesize that 1) FC magnetic resonance imaging (fcMRI) scans can be safely obtained in patients with PSPS type 2 with implanted therapeutic SCS devices and that 2) their cross-network connectivity patterns are altered and involve emotion and reward/aversion functions.

MATERIALS AND METHODS

Resting-state (RS) fcMRI (rsfcMRI) scans were obtained from nine patients with PSPS type 2 implanted with therapeutic SCS systems and 13 age-matched controls. Seven RS networks were analyzed, including the striatum.

RESULTS

Cross-network FC sequences were safely obtained on a 3T MRI scanner in all nine patients with PSPS type 2 with implanted SCS systems. FC patterns involving emotion/reward brain circuitry were altered as compared with controls. Patients with a history of constant neuropathic pain, experiencing longer therapeutic effects of SCS, had fewer alterations in their connectivity patterns.

CONCLUSIONS

To our knowledge, this is the first report of altered cross-network FC involving emotion/reward brain circuitry in a homogeneous population of patients with chronic pain with fully implanted SCS systems, on a 3T MRI scanner. All rsfcMRI studies were safe and well tolerated by all nine patients, with no detectable effects on the implanted devices.

Modeling Electric Fields in Transcutaneous Spinal Direct Current Stimulation: A Clinical Perspective

Clinical findings suggest that transcutaneous spinal direct current stimulation (tsDCS) can modulate ascending sensitive, descending corticospinal, and segmental pathways in the spinal cord (SC). However, several aspects of the stimulation have not been completely understood, and realistic computational models based on MRI are the gold standard to predict the interaction between tsDCS-induced electric fields and anatomy. Here, we review the electric fields distribution in the SC during tsDCS as predicted by MRI-based realistic models, compare such knowledge with clinical findings, and define the role of computational knowledge in optimizing tsDCS protocols. tsDCS-induced electric fields are predicted to be safe and induce both transient and neuroplastic changes. This could support the possibility to explore new clinical applications, such as spinal cord injury. For the most applied protocol (2-3 mA for 20-30 min, active electrode over T10-T12 and the reference on the right shoulder), similar electric field intensities are generated in both ventral and dorsal horns of the SC at the same height. This was confirmed by human studies, in which both motor and sensitive effects were found. Lastly, electric fields are strongly dependent on anatomy and electrodes' placement. Regardless of the montage, inter-individual hotspots of higher values of electric fields were predicted, which could change when the subjects move from a position to another (e.g., from the supine to the lateral position). These characteristics underlines the need for individualized and patient-tailored MRI-based computational models to optimize the stimulation protocol. A detailed modeling approach of the electric field distribution might contribute to optimizing stimulation protocols, tailoring electrodes' configuration, intensities, and duration to the clinical outcome.

Spinal cord stimulation for low back pain

BACKGROUND

Spinal cord stimulation (SCS) is a surgical intervention used to treat persistent low back pain. SCS is thought to modulate pain by sending electrical signals via implanted electrodes into the spinal cord. The long term benefits and harms of SCS for people with low back pain are uncertain.

OBJECTIVES

To assess the effects, including benefits and harms, of SCS for people with low back pain.

SEARCH METHODS

On 10 June 2022, we searched CENTRAL, MEDLINE, Embase, and one other database for published trials. We also searched three clinical trials registers for ongoing trials.

SELECTION CRITERIA

We included all randomised controlled trials and cross-over trials comparing SCS with placebo or no treatment for low back pain. The primary comparison was SCS versus placebo, at the longest time point measured in the trials. Major outcomes were mean low back pain intensity, function, health-related quality of life, global assessment of efficacy, withdrawals due to adverse events, adverse events, and serious adverse events. Our primary time point was long-term follow-up (≥ 12 months).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 13 studies with 699 participants: 55% of participants were female; mean age ranged from 47 to 59 years; and all participants had chronic low back pain with mean duration of symptoms ranging from five to 12 years. Ten cross-over trials compared SCS with placebo. Three parallel-group trials assessed the addition of SCS to medical management. Most studies were at risk of performance and detection bias from inadequate blinding and selective reporting bias. The placebo-controlled trials had other important biases, including lack of accounting for period and carryover effects. Two of the three parallel trials assessing SCS as an addition to medical management were at risk of attrition bias, and all three had substantial cross-over to the SCS group for time points beyond six months. In the parallel-group trials, we considered the lack of placebo control to be an important source of bias. None of our included studies evaluated the impact of SCS on mean low back pain intensity in the long term (≥ 12 months). The studies most often assessed outcomes in the immediate term (less than one month). At six months, the only available evidence was from a single cross-over trial (50 participants). There was moderate-certainty evidence that SCS probably does not improve back or leg pain, function, or quality of life compared with placebo. Pain was 61 points (on a 0- to 100-point scale, 0 = no pain) at six months with placebo, and 4 points better (8.2 points better to 0.2 points worse) with SCS. Function was 35.4 points (on a 0- to 100-point scale, 0 = no disability or best function) at six months with placebo, and 1.3 points better (3.9 points better to 1.3 points worse) with SCS. Health-related quality of life was 0.44 points out of 1 (0 to 1 index, 0 = worst quality of life) at six months with placebo, and 0.04 points better (0.16 points better to 0.08 points worse) with SCS. In that same study, nine participants (18%) experienced adverse events and four (8%) required revision surgery. Serious adverse events with SCS included infections, neurological damage, and lead migration requiring repeated surgery. We could not provide effect estimates of the relative risks as events were not reported for the placebo period. In parallel trials assessing SCS as an addition to medical management, it is uncertain whether, in the medium or long term, SCS can reduce low back pain, leg pain, or health-related quality of life, or if it increases the number of people reporting a 50% improvement or better, because the certainty of the evidence was very low. Low-certainty evidence suggests that adding SCS to medical management may slightly improve function and slightly reduce opioid use. In the medium term, mean function (0- to 100-point scale; lower is better) was 16.2 points better with the addition of SCS to medical management compared with medical management alone (95% confidence interval (CI) 19.4 points better to 13.0 points better; I2 = 95%; 3 studies, 430 participants; low-certainty evidence). The number of participants reporting opioid medicine use was 15% lower with the addition of SCS to medical management (95% CI 27% lower to 0% lower; I2 = 0%; 2 studies, 290 participants; low-certainty evidence). Adverse events with SCS were poorly reported but included infection and lead migration. One study found that, at 24 months, 13 of 42 people (31%) receiving SCS required revision surgery. It is uncertain to what extent the addition of SCS to medical management increases the risk of withdrawals due to adverse events, adverse events, or serious adverse events, because the certainty of the evidence was very low.

AUTHORS' CONCLUSIONS

Data in this review do not support the use of SCS to manage low back pain outside a clinical trial. Current evidence suggests SCS probably does not have sustained clinical benefits that would outweigh the costs and risks of this surgical intervention.

A prospective study of BurstDR™ spinal cord stimulation for non-operated discogenic low back pain

INTRODUCTION

Chronic discogenic low back pain (CD-LBP) is caused by degeneration of the disc due to trauma to the annulus or by unprovoked degeneration, resulting in chronic pain. Spinal cord stimulation (SCS) employing the BurstDR™ waveform has been shown to be an effective treatment in a variety of chronic pain conditions. The aim of this prospective case study was to determine the effect of BurstDR™ SCS on pain relief, disability, and patient satisfaction in a population with CD-LBP.

METHODS

Seventeen subjects with CD-LBP received a SCS trial with BurstDR™ stimulation. Patients with >50% pain relief after a trial period of 2 weeks were permanently implanted (n = 15). Patients then rated LBP and leg pain using the numeric rating scale (NRS), Oswestry disability index (ODI), patient global impression of change (PGIC), EQ-5D quality of life, and painDETECT for neuropathic pain at baseline following trial, 3, 6, and 12 months after permanent implantation.

RESULTS

Treatment with BurstDR™ SCS resulted in significant reduction of LBP as the NRS was reduced from 71.7 ± 7.3 at baseline to 42.5 ± 18.1 at 12 months. Average pain relief at 12 months was 42.5%. In patients with leg pain (n = 8), pain was significantly reduced from 66.9 ± 8.2 to 11.7 ± 10.4 at 12 months. PainDETECT scores for neuropathic pain significantly reduced from 18.9 ± 4.8 at baseline, and 14.8 ± 3.2 at 12 months. Baseline ODI score significantly reduced from 41.2 ± 12.8 to 25.8 ± 8.6 at 12 months. PGIC scores remained low from 2.6 ± 1.6 at 3 months, 2.5 ± 1.0 at 6 months, and 2.5 ± 1.3 at 12 months. EQ-5D-5L rates remained constant from baseline 56.10 ± 23.9 to 68.6 ± 12.9 at 12 months.

CONCLUSION

BurstDR™ SCS resulted in significant reduction of back pain, leg pain, and quality of life in patients with CD-LBP and decreased the level of disability and generated positive patient satisfaction scores.

Mechanism of Action of Peripheral Nerve Stimulation for Chronic Pain: A Narrative Review

The use of stimulation of peripheral nerves to test or treat various medical disorders has been prevalent for a long time. Over the last few years, there has been growing evidence for the use of peripheral nerve stimulation (PNS) for treating a myriad of chronic pain conditions such as limb mononeuropathies, nerve entrapments, peripheral nerve injuries, phantom limb pain, complex regional pain syndrome, back pain, and even fibromyalgia. The ease of placement of a minimally invasive electrode via percutaneous approach in the close vicinity of the nerve and the ability to target various nerves have led to its widespread use and compliance. While most of the mechanism behind its role in neuromodulation is largely unknown, the gate control theory proposed by Melzack and Wall in the 1960s has been the mainstay for understanding its mechanism of action. In this review article, the authors performed a literature review to discuss the mechanism of action of PNS and discuss its safety and usefulness in treating chronic pain. The authors also discuss current PNS devices available in the market today.

"Neuro-Fiber Mapping": An Original Concept of Spinal Cord Neural Network Spatial Targeting Using Live Electrostimulation Mapping to (Re-)Explore the Conus Medullaris Anatomy

Spinal cord (SC) anatomy is often assimilated to a morphologically encapsulated neural entity, but its functional anatomy remains only partially understood. We hypothesized that it could be possible to re-explore SC neural networks by performing live electrostimulation mapping, based on "super-selective" spinal cord stimulation (SCS), originally designed as a therapeutical tool to address chronic refractory pain. As a starting point, we initiated a systematic SCS lead programming approach using live electrostimulation mapping on a chronic refractory perineal pain patient, previously implanted with multicolumn SCS at the level of the conus medullaris (T12-L1). It appeared possible to (re-)explore the classical anatomy of the conus medullaris using statistical correlations of paresthesia coverage mappings, resulting from 165 different electrical configurations tested. We highlighted that sacral dermatomes were not only located more medially but also deeper than lumbar dermatomes at the level of the conus medullaris, in contrast with classical anatomical descriptions of SC somatotopical organization. As we were finally able to find a morphofunctional description of "Philippe-Gombault's triangle" in 19th-century historical textbooks of neuroanatomy, remarkably matching these conclusions, the concept of "neuro-fiber mapping" was introduced.

Exploring electroencephalographic infraslow neurofeedback treatment for chronic low back pain: a double-blinded safety and feasibility randomized placebo-controlled trial

Chronic low back pain (CLBP) is a disabling condition worldwide. In CLBP, neuroimaging studies demonstrate abnormal activities in cortical areas responsible for pain modulation, emotional, and sensory components of pain experience [i.e., pregenual and dorsal anterior cingulate cortex (pgACC, dACC), and somatosensory cortex (SSC), respectively]. This pilot study, conducted in a university setting, evaluated the feasibility, safety, and acceptability of a novel electroencephalography-based infraslow-neurofeedback (EEG ISF-NF) technique for retraining activities in pgACC, dACC and SSC and explored its effects on pain and disability. Participants with CLBP (n = 60), recruited between July'20 to March'21, received 12 sessions of either: ISF-NF targeting pgACC, dACC + SSC, a ratio of pgACC*2/dACC + SSC, or Placebo-NF. Descriptive statistics demonstrated that ISF-NF training is feasible [recruitment rate (7 participants/month), dropouts (25%; 20-27%), and adherence (80%; 73-88%)], safe (no adverse events reported), and was moderate to highly acceptable [Mean ± SD: 7.8 ± 2.0 (pgACC), 7.5 ± 2.7 (dACC + SCC), 8.2 ± 1.9 (Ratio), and 7.7 ± 1.5 (Placebo)]. ISF-NF targeting pgACC demonstrated the most favourable clinical outcomes, with a higher proportion of participants exhibiting a clinically meaningful reduction in pain severity [53%; MD (95% CI): - 1.9 (- 2.7, - 1.0)], interference [80%; MD (95% CI): - 2.3 (- 3.5, - 1.2)], and disability [73%; MD (95% CI): - 4.5 (- 6.1, - 2.9)] at 1-month follow-up. ISF-NF training is a feasible, safe, and an acceptable treatment approach for CLBP.

Heterogeneous Cortical Effects of Spinal Cord Stimulation

OBJECTIVES

The understanding of the cortical effects of spinal cord stimulation (SCS) remains limited. Multiple studies have investigated the effects of SCS in resting-state electroencephalography. However, owing to the large variation in reported outcomes, we aimed to describe the differential cortical responses between two types of SCS and between responders and nonresponders using magnetoencephalography (MEG).

MATERIALS AND METHODS

We conducted 5-minute resting-state MEG recordings in 25 patients with chronic pain with active SCS in three sessions, each after a one-week exposure to tonic, burst, or sham SCS. We extracted six spectral features from the measured neurophysiological signals: the alpha peak frequency; alpha power ratio (power 7-9 Hz/power 9-11 Hz); and average power in the theta (4-7.5 Hz), alpha (8-12.5 Hz), beta (13-30 Hz), and low-gamma (30.5-60 Hz) frequency bands. We compared these features (using nonparametric permutation t-tests) for MEG sensor and cortical map effects across stimulation paradigms, between participants who reported low (< 5, responders) vs high (≥ 5, nonresponders) pain scores, and in three representative participants.

RESULTS

We found statistically significant (p < 0.05, false discovery rate corrected) increased MEG sensor signal power below 3 Hz in response to burst SCS compared with tonic and sham SCS. We did not find statistically significant differences (all p > 0.05) between the power spectra of responders and nonresponders. Our data did not show statistically significant differences in the spectral features of interest among the three stimulation paradigms or between responders and nonresponders. These results were confirmed by the MEG cortical maps. However, we did identify certain trends in the MEG source maps for all comparisons and several features, with substantial variation across participants.

CONCLUSIONS

The considerable variation in cortical responses to the various SCS treatment options necessitates studies with sample sizes larger than commonly reported in the field and more personalized treatment plans. Studies with a finer stratification between responders and nonresponders are required to advance the knowledge on SCS treatment effects.

A Review of Effects of Spinal Cord Stimulation on Spectral Features in Resting-State Electroencephalography

BACKGROUND

Spinal cord stimulation (SCS) is an effective therapy for patients with refractory chronic pain syndromes. Although studies have shown that SCS has both spinal and supraspinal effects, the current understanding of cortical effects is still limited. Neuroimaging techniques, such as magnetoencephalography (MEG) and electroencephalography (EEG), combined here as M/EEG, can reveal modulations in ongoing resting-state cortical activity. We aim to provide an overview of available literature on resting-state M/EEG in patients with chronic pain who have been treated with SCS.

MATERIALS AND METHODS

We searched multiple online data bases for studies on SCS, chronic pain, and resting-state M/EEG. Primary outcome measures were changes in spectral features, combined with brain regions in which these changes occurred.

RESULTS

We included eight studies reporting various SCS paradigms (tonic, burst, high-dose, and high-frequency stimulation) and revealing heterogeneity in outcome parameters. We summarized changes in cortical activity in various frequency bands: theta (4-7 Hz), alpha (7-12 Hz), beta (13-30 Hz), and gamma (30-44 Hz). In multiple studies, the somatosensory cortex showed modulation of cortical activity under tonic, burst, and high-frequency stimulation. Changes in connectivity were found in the dorsal anterior cingulate cortex, dorsolateral prefrontal cortex, and parahippocampus.

CONCLUSIONS

The large heterogeneity observed in outcome measures is probably caused by the large variety in study designs, stimulation paradigms, and spectral features studied. Paresthesia-free paradigms have been compared with tonic stimulation in multiple studies. These studies suggest modulation of medial, lateral, and descending pathways for paresthesia-free stimulation, whereas tonic stimulation predominantly modulates lateral and descending pathways. Moreover, multiple studies have reported an increased alpha peak frequency, increased alpha power, and/or decreased theta power when SCS was compared with baseline, indicating modulation of thalamocortical pathways. Further studies with well-defined groups of responders and nonresponders to SCS are recommended to independently study the cortical effects of pain relief and SCS.

Physical Therapy Considerations and Recommendations for Patients Following Spinal Cord Stimulator Implant Surgery

OBJECTIVES

Spinal cord stimulation (SCS) is an established therapy option in interventional pain medicine. Recent advances in technology have allowed for greater compliance with treatment and improved efficacy in pain control. This article was proposed to fill the gap in the literature addressing this specific patient population and to facilitate further research. Even though there is a lack of consensus among societies and experts on exact parameters of physical therapy (PT) considerations and postoperative limitations in patients with SCS, we propose rehabilitative care for this population should be standardized. As the number of patients with SCS implants grow, it is vital to understand how to appropriately approach patients with implantable devices when additional treatments such as PT are prescribed.

MATERIALS AND METHODS

A literature search was performed on the use of PT following SCS implantation. Presently, there is no literature to date which addresses the use of PT in this patient population. The lack of data is the largest hurdle in the creation of formal SCS therapy guidelines. The authors therefore proposed recommendations for rehabilitation based upon a detailed understanding of SCS hardware alongside well-studied physiotherapy concepts.

RESULTS

Considerations when initiating PT in the SCS patient population should include: 1) biomechanics and quality of SCS output; 2) therapeutic exercise and spinal manipulation in association with risk for lead migration and fracture; 3) the application of therapeutic modalities and risk for injury to the patient and/or damage to the SCS componentry; and 4) integration of a biopsychosocial, person-centered approach.

CONCLUSIONS

PT treatment protocol in patients with a recently implanted SCS device should be person-centered addressing individual needs, values, and goals. Further research is needed to fully appreciate the impact of an interprofessional approach to management of SCS patients, particularly following stimulator implantation.

Spinal Cord Stimulation in Chronic Low Back Pain Syndrome: Mechanisms of Modulation, Technical Features and Clinical Application

Chronic low-back pain (CLBP) is a common disease with several negative consequences on the quality of life, work and activity ability and increased costs to the health-care system. When pharmacological, psychological, physical and occupational therapies or surgery fail to reduce CLBP, patients may be a candidate for Spinal Cord Stimulation (SCS). SCS consists of the transcutaneous or surgical implantation of different types of electrodes in the epidural space; electrodes are then connected to an Implanted Pulse Generator (IPG) that generates stimulating currents. Through spinal and supraspinal mechanisms based on the “gate control theory for pain transmission”, SCS reduces symptoms of CLBP in the almost totality of well-selected patients and its effect lasts up to eight years in around 75% of patients. However, the evidence in favor of SCS still remains weak, mainly due to poor trial methodology and design. This narrative review is mainly addressed to those professionals that may encounter patients with CLBP failing conventional treatments. For this reason, we report the mechanisms of pain relief during SCS, the technical features and some clinical considerations about the application of SCS in patients with CLBP.

Combining Awake Anesthesia with Minimal Invasive Surgery Optimizes Intraoperative Surgical Spinal Cord Stimulation Lead Placement

Spinal cord stimulation (SCS) is an effective and validated treatment to address chronic refractory neuropathic pain in persistent spinal pain syndrome-type 2 (PSPS-T2) patients. Surgical SCS lead placement is traditionally performed under general anesthesia due to its invasiveness. In parallel, recent works have suggested that awake anesthesia (AA), consisting of target controlled intra-venous anesthesia (TCIVA), could be an interesting tool to optimize lead anatomical placement using patient intra-operative feedback. We hypothesized that combining AA with minimal invasive surgery (MIS) could improve SCS outcomes. The goal of this study was to evaluate SCS lead performance (defined by the area of pain adequately covered by paraesthesia generated via SCS), using an intraoperative objective quantitative mapping tool, and secondarily, to assess pain relief, functional improvement and change in quality of life with a composite score. We analyzed data from a prospective multicenter study (ESTIMET) to compare the outcomes of 115 patients implanted with MIS under AA (MISAA group) or general anesthesia (MISGA group), or by laminectomy under general anesthesia (LGA group). All in all, awake surgery appears to show significantly better performance than general anesthesia in terms of patient pain coverage (65% vs. 34–62%), pain surface (50–76% vs. 50–61%) and pain intensity (65% vs. 35–40%), as well as improved secondary outcomes (quality of life, functional disability and depression). One step further, our results suggest that MISAA combined with intra-operative hypnosis could potentialize patient intraoperative cooperation and could be proposed as a personalized package offered to PSPS-T2 patients eligible for SCS implantation in highly dedicated neuromodulation centers.

The effects of low intensity focused ultrasound on neuronal activity in pain processing regions in a rodent model of common peroneal nerve injury

BACKGROUND

Non-invasive, external low intensity focused ultrasound (liFUS) offers promise for treating neuropathic pain when applied to the dorsal root ganglion (DRG).

OBJECTIVE

We examine how external liFUS treatment applied to the L5 DRG affects neuronal changes in single-unit activity from the primary somatosensory cortex (SI) and anterior cingulate cortex (ACC) in a common peroneal nerve injury (CPNI) rodent model.

METHODS

Male Sprague Dawley rats were divided into two cohorts: CPNI liFUS and CPNI sham liFUS. Baseline single-unit activity (SUA) recordings were taken 20 min prior to treatment and for 4 h post treatment in 20 min intervals, then analyzed for frequency and compared to baseline. Recordings from the SI and ACC were separated into pyramidal and interneurons based on waveform and principal component analysis.

RESULTS

Following CPNI surgery, all rats (n = 30) displayed a significant increase in mechanical sensitivity. In CPNI liFUS rats, there was a significant increase in pyramidal neuron spike frequency in the SI region compared to the CPNI sham liFUS animals beginning at 120 min following liFUS treatment (p < 0.05). In the ACC, liFUS significantly attenuated interneuron firing beginning at 80 min after liFUS treatment (p < 0.05).

CONCLUSION

We demonstrate that liFUS changed neuronal spiking in the SI and ACC regions 80 and 120 min after treatment, respectively, which may in part correlate with improved sensory thresholds. This may represent a mechanism of action how liFUS attenuates neuropathic pain. Understanding the impact of liFUS on pain circuits will help advance the use of liFUS as a non-invasive neuromodulation option.

Study protocol: Effects of active versus passive recharge burst spinal cord stimulation on pain experience in persistent spinal pain syndrome type 2: a multicentre randomized trial (BURST-RAP study)

Background

Spinal cord stimulation (SCS) has shown to be an effective treatment for patients with persistent spinal pain syndrome type 2 (PSPS Type 2). The method used to deliver electrical charge in SCS is important. One such method is burst stimulation. Within burst stimulation, a recharge pattern is used to prevent buildup of charge in stimulated tissues. Two variations of burst waveforms are currently in use: one that employs active recharge and one that uses passive recharge. It has been suggested that differences exist between active and passive recharge paradigms related to both efficacy of pain relief and their underlying mechanism of action. Active recharge has been shown to activate both the medial spinal pathway, engaging cortical sensorimotor areas involved in location and intensity of pain, and lateral pathway, reaching brain areas involved with cognitive-emotional aspects of pain. Passive recharge has been suggested to act via modulation of thalamic neurons, which fire in a similar electrical pattern, and thereby modulate activity in various cortical areas including those related to motivational and emotional aspects of pain. The objective of this randomized clinical trial is to assess and compare the effect of active versus passive recharge Burst SCS on a wide spectrum of pain in PSPS Type 2 patients.

Methods

This multicentre randomized clinical trial will take place in 6 Dutch hospitals. PSPS Type 2 patients (n=94) will be randomized into a group receiving either active or passive recharge burst. Following a successful trial period, patients are permanently implanted. Patients complete the Pain Catastrophizing Scale (PCS) (primary outcome at 6 months), Numeric Pain Rating Scale (NRS), Patient Vigilance and Awareness Questionnaire (PVAQ), Hospital Anxiety and Depression Scale (HADS), Quality of Life (EQ-5D), Oswestery Disability Index (ODI), Patient Global Impression of Change (PGIC) and painDETECT questionnaires (secondary outcomes) at baseline, after trial, 1, 3, 6 and 12 months following implantation.

Discussion

The BURST-RAP trial protocol will shed light on possible clinical differences and effectivity of pain relief, including emotional-motivational aspects between active and passive burst SCS in PSPS Type 2 patients.

Trial registration

ClinicalTrials.gov registration: NCT05421273. Registered on 16 June 2022. Netherlands Trial Register NL9194. Registered on 23 January 2021.

Source localized infraslow neurofeedback training in people with chronic painful knee osteoarthritis: A randomized, double-blind, sham-controlled feasibility clinical trial

Persistent pain is a key symptom in people living with knee osteoarthritis (KOA). Infra-slow Neurofeedback (ISF-NF) training is a recent development focusing on modulating cortical slow-wave activity to improve pain outcomes. A parallel, two-armed double-blinded, randomized sham-controlled, feasibility clinical trial aimed to determine the feasibility and safety of a novel electroencephalography-based infraslow fluctuation neurofeedback (EEG ISF-NF) training in people with KOA and determine the variability of clinical outcomes and EEG changes following NF training. Eligible participants attended nine 30-min ISF-NF training sessions involving three cortical regions linked to pain. Feasibility measures were monitored during the trial period. Pain and functional outcomes were measured at baseline, post-intervention, and follow-up after 2 weeks. Resting-state EEG was recorded at baseline and immediate post-intervention. Participants were middle-aged (61.7 ± 7.6 years), New Zealand European (90.5%), and mostly females (62%) with an average knee pain duration of 4 ± 3.4 years. The study achieved a retention rate of 91%, with 20/22 participants completing all the sessions. Participants rated high levels of acceptance and “moderate to high levels of perceived effectiveness of the training.” No serious adverse events were reported during the trial. Mean difference (95% CI) for clinical pain and function measures are as follows for pain severity [active: 0.89 ± 1.7 (−0.27 to 2.0); sham: 0.98 ± 1.1 (0.22–1.7)], pain interference [active: 0.75 ± 2.3 (−0.82 to 2.3); Sham: 0.89 ± 2.1 (−0.60 to 2.4)], pain unpleasantness [active: 2.6 ± 3.7 (0.17–5.1); sham: 2.8 ± 3 (0.62–5.0)] and physical function [active: 6.2 ± 13 (−2.6 to 15); sham: 1.6 ± 12 (−6.8 to 10)]. EEG sources demonstrated frequency-specific neuronal activity, functional connectivity, and ISF ratio changes following NF training. The findings of the study indicated that the ISF-NF training is a feasible, safe, and acceptable intervention for pain management in people with KOA, with high levels of perceived effectiveness. The study also reports the variability in clinical, brain activity, and connectivity changes following training.

Tinnitus and the triple network model: a perspective

Tinnitus is defined as the conscious awareness of a sound without an identifiable external sound source, and tinnitus disorder as tinnitus with associated suffering. Chronic tinnitus has been anatomically and phenomenologically separated into three pathways: a lateral “sound” pathway, a medial “suffering” pathway, and a descending noise-canceling pathway. Here, the triple network model is proposed as a unifying framework common to neuropsychiatric disorders. It proposes that abnormal interactions among three cardinal networks—the self-representational default mode network, the behavioral relevance-encoding salience network and the goal-oriented central executive network—underlie brain disorders. Tinnitus commonly leads to negative cognitive, emotional, and autonomic responses, phenomenologically expressed as tinnitus-related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, encoding the behavioral relevance of the sound stimulus. Chronic tinnitus can also become associated with the self-representing default mode network and becomes an intrinsic part of the self-percept. This is likely an energy-saving evolutionary adaptation, by detaching tinnitus from sympathetic energy-consuming activity. Eventually, this can lead to functional disability by interfering with the central executive network. In conclusion, these three pathways can be extended to a triple network model explaining all tinnitus-associated comorbidities. This model paves the way for the development of individualized treatment modalities.

High-definition transcranial infraslow pink noise stimulation for chronic low back pain: protocol for a pilot, safety and feasibility randomised placebo-controlled trial

INTRODUCTION

Chronic low back pain (CLBP) is a common disabling health condition. Current treatments demonstrate modest effects, warranting newer therapies. Brain imaging demonstrates altered electrical activities in cortical areas responsible for pain modulation, emotional and sensory components of pain experience. Treatments targeting to change electrical activities of these key brain regions may produce clinical benefits. This pilot study aims to (1) evaluate feasibility, safety and acceptability of a novel neuromodulation technique, high-definition transcranial infraslow pink noise stimulation (HD-tIPNS), in people with CLBP, (2) explore the trend of effect of HD-tIPNS on pain and function, and (3) derive treatment estimates to support sample size calculation for a fully powered trial should trends of effectiveness be present.

METHODS AND ANALYSIS

A pilot, triple-blinded randomised two-arm placebo-controlled parallel trial. Participants (n=40) with CLBP will be randomised to either sham stimulation or HD-tIPNS (targeting somatosensory cortex and dorsal and pregenual anterior cingulate cortex). Primary outcomes include feasibility and safety measures, and clinical outcomes of pain (Brief Pain Inventory) and disability (Roland-Morris disability questionnaire). Secondary measures include clinical, psychological, quantitative sensory testing and electroencephalography collected at baseline, immediately postintervention, and at 1-week, 1-month and 3 months postintervention. All data will be analysed descriptively. A nested qualitative study will assess participants perceptions about acceptability of intervention and analysed thematically.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from Health and Disability Ethics Committee (Ref:20/NTB/67). Findings will be reported to regulatory and funding bodies, presented at conferences, and published in a scientific journal.

TRIAL REGISTRATION NUMBER

ACTRN12620000505909p.

Passive Recharge Burst Spinal Cord Stimulation Provides Sustainable Improvements in Pain and Psychosocial Function: 2-year Results From the TRIUMPH Study

STUDY DESIGN

Prospective, international, multicenter, single-arm, post-market study.

OBJECTIVE

The aim of this study was to assess long-term safety and effectiveness of spinal cord stimulation using a passive recharge burst stimulation design for chronic intractable pain in the trunk and/or limbs. Herein we present 24-month outcomes from the TRIUMPH study (NCT03082261).

SUMMARY OF BACKGROUND DATA

Passive recharge burst spinal cord stimulation (B-SCS) uniquely mimics neuronal burst firing patterns in the nervous system and has been shown to modulate the affective and attentional components of pain processing.

METHODS

After a successful trial period, subjects received a permanent SCS implant and returned for follow-up at 6, 12, 18, and 24 months.

RESULTS

Significant improvements in physical, mental, and emotional functioning observed after 6 months of treatment were maintained at 2 years. Pain catastrophizing scale (PCS) scores dropped below the population norm. Health-related quality of life on EQ-5D improved across all domains and the mean index score was within one standard deviation of norm. Pain reduction (on NRS) was statistically significant (P < 0.001) at all timepoints. Patient reported pain relief, a stated percentage of improvement in pain, was consistent at all timepoints at 60%. Patients reported significant improvements across all measures including activity levels and impact of pain on daily life. At 24 months, 84% of subjects were satisfied and 90% would recommend the procedure. Subjects decreased their chronic pain medication intake for all categories; 38% reduced psychotropic and muscle relaxants, 46% reduced analgesic, anti-convulsant and NSAIDs, and 48% reduced opioid medication. Adverse events occurred at low rates without unanticipated events.

CONCLUSION

Early positive results with B-SCS were maintained long term. Evidence across multiple assessment tools show that B-SCS can alleviate pain intensity, psychological distress, and improve physical function and health-related quality of life.Level of Evidence: 3.

Spinal Cord Stimulation as Treatment for Cancer and Chemotherapy-Induced Pain

Neuropathic pain is a rampant disease exacting a significant toll on patients, providers, and health care systems around the globe. Neuromodulation has been successfully employed to treat many indications including failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), phantom limb pain (PLP), radiculopathies, and intractable pelvic pain, among many others. Recent studies have also demonstrated efficacy for cancer-related pain and chemotherapy induced neuropathy with these techniques. Spinal cord stimulation (SCS) is the most commonly employed technique and involves implantation of percutaneous or paddle leads targeting the dorsal columns of the spinal cord with the goal of disrupting the pain signals traveling to the brain. Tonic, high frequency, and burst waveforms have all been shown to reduce pain and disability in chronic pain patients. Closed-loop SCS systems that automatically adjust stimulation parameters based on feedback (such as evoked compound action potentials) are becoming increasingly used to help ease the burden placed on patients to adjust their programming to their pain and position. Additionally, dorsal root ganglion stimulation (DRGS) is a newer technique that allows for dermatomal coverage especially in patients with pain in up to two dermatomes. Regardless of the technique chosen, neuromodulation has been shown to be cost-effective and efficacious and should be given full consideration in patients with chronic pain conditions.

Pain and the Triple Network Model

Acute pain is a physiological response that causes an unpleasant sensory and emotional experience in the presence of actual or potential tissue injury. Anatomically and symptomatically, chronic pathological pain can be divided into three distinct but interconnected pathways, a lateral “painfulness” pathway, a medial “suffering” pathway and a descending pain inhibitory circuit. Pain (fullness) can exist without suffering and suffering can exist without pain (fullness). The triple network model is offering a generic unifying framework that may be used to understand a variety of neuropsychiatric illnesses. It claims that brain disorders are caused by aberrant interactions within and between three cardinal brain networks: the self-representational default mode network, the behavioral relevance encoding salience network and the goal oriented central executive network. A painful stimulus usually leads to a negative cognitive, emotional, and autonomic response, phenomenologically expressed as pain related suffering, processed by the medial pathway. This anatomically overlaps with the salience network, which encodes behavioral relevance of the painful stimuli and the central sympathetic control network. When pain lasts longer than the healing time and becomes chronic, the pain- associated somatosensory cortex activity may become functionally connected to the self-representational default mode network, i.e., it becomes an intrinsic part of the self-percept. This is most likely an evolutionary adaptation to save energy, by separating pain from sympathetic energy-consuming action. By interacting with the frontoparietal central executive network, this can eventually lead to functional impairment. In conclusion, the three well-known pain pathways can be combined into the triple network model explaining the whole range of pain related co-morbidities. This paves the path for the creation of new customized and personalized treatment methods.