Brain Metabolite Changes in the Anterior Cingulate Cortex of Chronic Low Back Pain Patients and Correlations Between Metabolites and Psychological State

Alterations in metabolites in the anterior cingulate cortex and thalamus and their associations with pain and empathy in patients with chronic mild pain: a preliminary study

Proton magnetic resonance spectroscopy (1H-MRS) has shown inconsistent alterations in the brain metabolites of individuals with chronic pain. We used 3T 1H-MRS to investigate the brain metabolites in the anterior cingulate cortex and thalamus of 22 patients with chronic mild pain and no gait disturbance and 22 healthy controls. The chronic-pain group included patients with chronic low back pain and/or osteoarthritis but none suffering from hypersensitivity. There were no significant between group-differences in glutamate, glutamate plus glutamine (Glx), N-acetylaspartate, glycerophosphorylcholine (GPC), glutamine, creatine plus phosphocreatine, or myo-inositol in the anterior cingulate cortex, but the patients showed a significant decrease in GPC, but not other metabolites, in the thalamus compared to the controls. The GPC values in the patients' thalamus were significantly correlated with pain components on the Short-Form McGill Pain Questionnaire (SF-MPQ-2) and affective empathy components on the Questionnaire of Cognitive and Affective Empathy (QCAE). The GPC in the patients' anterior cingulate cortex showed significant correlations with cognitive empathy components on the QCAE. Myo-inositol in the controls' anterior cingulate cortex and Glx in the patients' thalamus each showed significant relationships with peripheral responsivity on the QCAE. These significances were not significant after Bonferroni corrections. These preliminary findings indicate important roles of GPC, myo-inositol, and Glx in the brain of patients with chronic mild pain.

Thalamic neurometabolite alterations in chronic low back pain: a common phenomenon across musculoskeletal pain conditions?

ABSTRACT

Recently, we showed that patients with knee osteoarthritis (KOA) demonstrate alterations in the thalamic concentrations of several metabolites compared with healthy controls: higher myo-inositol (mIns), lower N-acetylaspartate (NAA), and lower choline (Cho). Here, we evaluated whether these metabolite alterations are specific to KOA or could also be observed in patients with a different musculoskeletal condition, such as chronic low back pain (cLBP). Thirty-six patients with cLBP and 20 healthy controls were scanned using 1 H-magnetic resonance spectroscopy (MRS) and a PRESS (Point RESolved Spectroscopy) sequence with voxel placement in the left thalamus. Compared with healthy controls, patients with cLBP demonstrated lower absolute concentrations of NAA ( P = 0.0005) and Cho ( P < 0.05) and higher absolute concentrations of mIns ( P = 0.01) when controlling for age, as predicted by our previous work in KOA. In contrast to our KOA study, mIns levels in this population did not significantly correlate with pain measures (eg, pain severity or duration). However, exploratory analyses revealed that NAA levels in patients were negatively correlated with the severity of sleep disturbance ( P < 0.01), which was higher in patients compared with healthy controls ( P < 0.001). Additionally, also in patients, both Cho and mIns levels were positively correlated with age ( P < 0.01 and P < 0.05, respectively). Altogether, these results suggest that thalamic metabolite changes may be common across etiologically different musculoskeletal chronic pain conditions, including cLBP and KOA, and may relate to symptoms often comorbid with chronic pain, such as sleep disturbance. The functional and clinical significance of these brain changes remains to be fully understood.

Meta-analysis and open-source database for in vivo brain Magnetic Resonance spectroscopy in health and disease

Proton (1H) Magnetic Resonance Spectroscopy (MRS) is a non-invasive tool capable of quantifying brain metabolite concentrations in vivo. Prioritization of standardization and accessibility in the field has led to the development of universal pulse sequences, methodological consensus recommendations, and the development of open-source analysis software packages. One on-going challenge is methodological validation with ground-truth data. As ground-truths are rarely available for in vivo measurements, data simulations have become an important tool. The diverse literature of metabolite measurements has made it challenging to define ranges to be used within simulations. Especially for the development of deep learning and machine learning algorithms, simulations must be able to produce accurate spectra capturing all the nuances of in vivo data. Therefore, we sought to determine the physiological ranges and relaxation rates of brain metabolites which can be used both in data simulations and as reference estimates. Using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we've identified relevant MRS research articles and created an open-source database containing methods, results, and other article information as a resource. Using this database, expectation values and ranges for metabolite concentrations and T2 relaxation times are established based upon a meta-analyses of healthy and diseased brains.

Neuropathic Pain and Spinal Cord Injury: Management, Phenotypes, and Biomarkers

Chronic neuropathic pain after a spinal cord injury (SCI) continues to be a complex condition that is difficult to manage due to multiple underlying pathophysiological mechanisms and the association with psychosocial factors. Determining the individual contribution of each of these factors is currently not a realistic goal; however, focusing on the primary mechanisms may be more feasible. One approach used to uncover underlying mechanisms includes phenotyping using pain symptoms and somatosensory function. However, this approach does not consider cognitive and psychosocial mechanisms that may also significantly contribute to the pain experience and impact treatment outcomes. Indeed, clinical experience supports that a combination of self-management, non-pharmacological, and pharmacological approaches is needed to optimally manage pain in this population. This article will provide a broad updated summary integrating the clinical aspects of SCI-related neuropathic pain, potential pain mechanisms, evidence-based treatment recommendations, neuropathic pain phenotypes and brain biomarkers, psychosocial factors, and progress regarding how defining neuropathic pain phenotypes and other surrogate measures in the neuropathic pain field may lead to targeted treatments for neuropathic pain after SCI.

Meta-analysis and Open-source Database for In Vivo Brain Magnetic Resonance Spectroscopy in Health and Disease

Proton ( 1 H) Magnetic Resonance Spectroscopy (MRS) is a non-invasive tool capable of quantifying brain metabolite concentrations in vivo . Prioritization of standardization and accessibility in the field has led to the development of universal pulse sequences, methodological consensus recommendations, and the development of open-source analysis software packages. One on-going challenge is methodological validation with ground-truth data. As ground-truths are rarely available for in vivo measurements, data simulations have become an important tool. The diverse literature of metabolite measurements has made it challenging to define ranges to be used within simulations. Especially for the development of deep learning and machine learning algorithms, simulations must be able to produce accurate spectra capturing all the nuances of in vivo data. Therefore, we sought to determine the physiological ranges and relaxation rates of brain metabolites which can be used both in data simulations and as reference estimates. Using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we've identified relevant MRS research articles and created an open-source database containing methods, results, and other article information as a resource. Using this database, expectation values and ranges for metabolite concentrations and T 2 relaxation times are established based upon a meta-analyses of healthy and diseased brains.

Lipid and metabolic alteration involvement in physiotherapy for chronic nonspecific low back pain

BACKGROUND

Chronic nonspecific low back pain (cNLBP) is a common health problem worldwide, affecting 65-80% of the population and greatly affecting people's quality of life and productivity. It also causes huge economic losses. Manual therapy (MT) and therapeutic exercise (TE) are effective treatment options for cNLBP physiotherapy-based treatment. However, the underlying mechanisms that promote cNLBP amelioration by MT or TE are incompletely understood.

METHODS

Seventeen recruited subjects were randomly divided into an MT group and a TE group. Subjects in the MT group performed muscular relaxation, myofascial release, and mobilization for 20 min during each treatment session. The treatment lasted for a total of six sessions, once every two days. Subjects in the TE group completed motor control and core stability exercises for 30 min during each treatment session. The motor control exercise included stretching of the trunk and extremity muscles through trunk and hip rotation and flexion training. Stabilization exercises consisted of the (1) bridge exercise, (2) single-leg-lift bridge exercise, (3) side bridge exercise, (4) two-point bird-dog position with an elevated contralateral leg and arm, (5) bear crawl exercise, and (6) dead bug exercise. The treatment lasted for a total of six sessions, with one session every two days. Serum samples were collected from subjects before and after physiotherapy-based treatment for lipidomic and metabolomic measurements.

RESULTS

Through lipidomic analysis, we found that the phosphatidylcholine/phosphatidylethanolamine (PC/PE) ratio decreased and the sphingomyelin/ceramide (SM/Cer) ratio increased in cNLBP patients after MT or TE treatment. In addition, eight metabolites enriched in pyrimidine and purine differed significantly in cNLBP patients who received MT treatment. A total of nine metabolites enriched in pyrimidine, tyrosine, and galactose pathways differed significantly in cNLBP patients after TE treatment during metabolomics analysis.

CONCLUSION

Our study was the first to elucidate the alterations in the lipidomics and metabolomics of cNLBP physiotherapy-based treatment and can expand our knowledge of cNLBP physiotherapy-based treatment.

The Roles of Imaging Biomarkers in the Management of Chronic Neuropathic Pain

Chronic neuropathic pain (CNP) affects around 10% of the general population and has a significant social, emotional, and economic impact. Current diagnosis techniques rely mainly on patient-reported outcomes and symptoms, which leads to significant diagnostic heterogeneity and subsequent challenges in management and assessment of outcomes. As such, it is necessary to review the approach to a pathology that occurs so frequently, with such burdensome and complex implications. Recent research has shown that imaging methods can detect subtle neuroplastic changes in the central and peripheral nervous system, which can be correlated with neuropathic symptoms and may serve as potential markers. The aim of this paper is to review available imaging methods used for diagnosing and assessing therapeutic efficacy in CNP for both the preclinical and clinical setting. Of course, further research is required to standardize and improve detection accuracy, but available data indicate that imaging is a valuable tool that can impact the management of CNP.

Evidence of persistent glial cell dysfunction in the anterior cingulate cortex of juvenile idiopathic arthritis children: a proton MRS study

BACKGROUND

This study aims to investigate whether the neurometabolites of the anterior cingulate cortex (ACC) were distinct in patients with active and inactive juvenile idiopathic arthritis (JIA) using the proton magnetic resonance spectroscopy.

METHODS

We measured the levels of total N-acetylaspartate (tNAA), choline (Cho), myo-inositol (ml), glutamate (Glu) and the complex of glutamate and glutamine (Glx) relative to total creatine (tCr) in ACC of each participant.

RESULTS

Compared with the healthy controls, a significant decrease of total Cho/tCr and Glx/tCr ratio in ACC occurred in active and inactive JIA group. The tCho/Cr level was negatively associated with the serum level of ESR in active JIA patients. There was no difference in NAA/tCr ratio among the three groups, which may imply that no neuron and axonal losses occurred in either active or inactive JIA patients.

CONCLUSIONS

The abnormal neurometabolites in tCho/tCr and Glx/tCr in ACC may indicate that persistent dysfunction of glial cell, while neither neuron nor axonal losses occurred in active and inactive JIA patients.

Neural correlates of co-occurring pain and depression: an activation-likelihood estimation (ALE) meta-analysis and systematic review

The relationship between pain and depression is thought to be bidirectional and the underlying neurobiology 'shared' between the two conditions. However, these claims are often based on qualitative comparisons of brain regions implicated in pain or depression, while focused quantitative studies of the neurobiology of pain-depression comorbidity are lacking. Particularly, the direction of comorbidity, i.e., pain with depression vs. depression with pain, is rarely addressed. In this systematic review (PROSPERO registration CRD42020219876), we aimed to delineate brain correlates associated with primary pain with concomitant depression, primary depression with concurrent pain, and equal pain and depression comorbidity, using activation likelihood estimation (ALE) meta-analysis. Neuroimaging studies published in English until the 28th of September 2021 were evaluated using PRISMA guidelines. A total of 70 studies were included, of which 26 reported stereotactic coordinates and were analysed with ALE. All studies were assessed for quality by two authors, using the National Institute of Health Quality Assessment Tool. Our results revealed paucity of studies that directly investigated the neurobiology of pain-depression comorbidity. The ALE analysis indicated that pain with concomitant depression was associated with the right amygdala, while depression with concomitant pain was related primarily to the left dorsolateral prefrontal cortex (DLPFC). We provide evidence that pain and depression have a cumulative negative effect on a specific set of brain regions, distinct for primary diagnosis of depression vs. pain.

Functional connectivity and neurotransmitter impairments of the salience brain network in chronic low back pain patients: a combined resting state functional MRI and 1H-MRS study

ABSTRACT

Functional re-organisation of the salience network (SN) has been proposed as one of the key pathomechanisms associated with central nociceptive processing in the chronic pain state. Being associated with an altered functional connectivity within the SN, these processes have been hypothesized to result from a loss of inhibitory function leading to node hyperexcitability and spontaneous pain. Combined resting-state (rs) BOLD fMRI and 1H-MR spectroscopy was applied to chronic back pain (CBP) patients and healthy subjects (HS) to assess deviations from functional integrity (weighted closeness centrality, wCC, derived from rs-fMRI), oscillatory BOLD characteristics (spectral power, SP), and neurotransmitter levels (GABA+, glutamate+glutamine) in two key SN nodes, anterior insular (aInsR) and anterior mid-cingulate (aMCC) cortices. In addition, examinations were repeated in CBP patients after a four week interdisciplinary multimodal pain treatment and in HS after four weeks to explore longitudinal, treatment-mediated changes in target variables. The aInsR and, to a lesser extent, the aMCC of patients exhibited significantly reduced wCC accompanied by a SP shift from a lower to a higher frequency band, indicating a desynchronization of their neuronal activity within the SN, possibly due to increased spontaneous activations. Without revealing neurotransmitter differences, patients alone showed significant positive associations between local GABA+ levels and wCC in aInsR, suggesting a stronger dependence of node synchronization on the inhibitory tone in the chronic pain state. However, this needs to be explored in future using MRS techniques that are more sensitive to detecting subtle neurotransmitter changes and also allow multifocal characterization of neurotransmitter tone.

3D magnetic resonance spectroscopic imaging reveals links between brain metabolites and multidimensional pain features in fibromyalgia

BACKGROUND

Fibromyalgia is a centralized multidimensional chronic pain syndrome, but its pathophysiology is not fully understood.

METHODS

We applied 3D magnetic resonance spectroscopic imaging (MRSI), covering multiple cortical and subcortical brain regions, to investigate the association between neuro-metabolite (e.g. combined glutamate and glutamine, Glx; myo-inositol, mIno; and combined (total) N-acetylaspartate and N-acetylaspartylglutamate, tNAA) levels and multidimensional clinical/behavioural variables (e.g. pain catastrophizing, clinical pain severity and evoked pain sensitivity) in women with fibromyalgia (N = 87).

RESULTS

Pain catastrophizing scores were positively correlated with Glx and tNAA levels in insular cortex, and negatively correlated with mIno levels in posterior cingulate cortex (PCC). Clinical pain severity was positively correlated with Glx levels in insula and PCC, and with tNAA levels in anterior midcingulate cortex (aMCC), but negatively correlated with mIno levels in aMCC and thalamus. Evoked pain sensitivity was negatively correlated with levels of tNAA in insular cortex, MCC, PCC and thalamus.

CONCLUSIONS

These findings support single voxel placement targeting nociceptive processing areas in prior ¹ H-MRS studies, but also highlight other areas not as commonly targeted, such as PCC, as important for chronic pain pathophysiology. Identifying target brain regions linked to multidimensional symptoms of fibromyalgia (e.g. negative cognitive/affective response to pain, clinical pain, evoked pain sensitivity) may aid the development of neuromodulatory and individualized therapies. Furthermore, efficient multi-region sampling with 3D MRSI could reduce the burden of lengthy scan time for clinical research applications of molecular brain-based mechanisms supporting multidimensional aspects of fibromyalgia.

SIGNIFICANCE

This large N study linked brain metabolites and pain features in fibromyalgia patients, with a better spatial resolution and brain coverage, to understand a molecular mechanism underlying pain catastrophizing and other aspects of pain transmission. Metabolite levels in self-referential cognitive processing area as well as pain-processing regions were associated with pain outcomes. These results could help the understanding of its pathophysiology and treatment strategies for clinicians.

Magnetic Resonance Spectroscopy Assessment of Brain Metabolite Concentrations in Individuals With Chronic Whiplash-associated Disorder: A Cross-sectional Study

OBJECTIVES

Pathophysiologic mechanisms underpinning ongoing pain in whiplash-associated disorder (WAD) are not well understood, however, alterations in brain morphology and function have been observed in this population and in other chronic pain conditions. This study investigated metabolite profiles of brain regions in people with chronic WAD compared with controls.

MATERIALS AND METHODS

Thirty-eight individuals with chronic WAD (mean [SD] age, 39.5 [11.3] years, 23 female individuals) and 16 pain-free controls (38.9 [12.7] years, 11 female individuals) underwent multivoxel brain magnetic resonance spectroscopy. At the anterior cingulate cortex (ACC), primary motor cortex (1MC), and somatosensory cortex (SSC), ratios of metabolite concentrations were calculated for N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myo-inositol (Ins), and glutamate/glutamine (Glx). Chronic WAD group participants completed clinical questionnaires and cold and pressure pain threshold assessment. Data were analyzed with hypothesis testing and Spearman correlations (P≥0.05), with Benjamini-Hochberg corrections (5% false discovery rate).

RESULTS

No group differences were observed for NAA:Cr, NAA:Cho, Cr:Cho, Glx:NAA, Glx:Cr, Glx:Cho, Ins:NAA, Ins:Cr, Ins:Cho or Ins:Glx for left or right ACC, 1MC, or SSC following correction for multiple comparisons. No significant correlations were observed between metabolite ratios and any clinical variable.

DISCUSSION

These results suggest that ongoing pain and disability in this population may not be underpinned by metabolite aberrations in the brain regions examined. Further research is required to progress our understanding of cortical contributions to neurophysiologic mechanisms in chronic WAD.

Differential Role of Anterior Cingulate Cortical Glutamatergic Neurons in Pain-Related Aversion Learning and Nociceptive Behaviors in Male and Female Rats

Pain is comprised of both sensory and affective components. The anterior cingulate cortex (ACC) is a key brain region involved in the emotional processing of pain. Specifically, glutamatergic transmission within the ACC has been shown to modulate pain-related aversion. In the present study, we use in vivo optogenetics to activate or silence, using channelrhodopsin (ChR2) and archaerhodopsin (ArchT) respectively, calmodulin-kinase IIα (CaMKIIα)-expressing excitatory glutamatergic neurons of the ACC during a formalin-induced conditioned place aversion (F-CPA) behavioral paradigm in both female and male adult Sprague-Dawley rats. Expression of c-Fos, a marker of neuronal activity, was assessed within the ACC using immunohistochemistry. Optogenetic inhibition of glutamatergic neurons of the ACC abolished F-CPA without affecting formalin-induced nociceptive behavior during conditioning. In male rats, optogenetic activation of ACC glutamatergic neurons decreased formalin-induced nociceptive behavior during conditioning without affecting F-CPA. Interestingly, the opposite effect was seen in females, where optogenetic activation of glutamatergic neurons of the ACC increased formalin-induced nociceptive behavior during conditioning. The abolition of F-CPA following optogenetic inhibition of glutamatergic neurons of the ACC was associated with a reduction in c-Fos immunoreactivity in the ACC in male rats, but not female rats. These results suggest that excitatory glutamatergic neurons of the ACC play differential and sex-dependent roles in the aversion learning and acute sensory components of pain.

Reduced Glutamate in the Medial Prefrontal Cortex Is Associated With Emotional and Cognitive Dysregulation in People With Chronic Pain

A decrease in glutamate in the medial prefrontal cortex (mPFC) has been extensively found in animal models of chronic pain. Given that the mPFC is implicated in emotional appraisal, cognition and extinction of fear, could a potential decrease in glutamate be associated with increased pessimistic thinking, fear and worry symptoms commonly found in people with chronic pain? To clarify this question, 19 chronic pain subjects and 19 age- and gender-matched control subjects without pain underwent magnetic resonance spectroscopy. Both groups also completed the Temperament and Character, the Beck Depression and the State Anxiety Inventories to measure levels of harm avoidance, depression, and anxiety, respectively. People with chronic pain had significantly higher scores in harm avoidance, depression and anxiety compared to control subjects without pain. High levels of harm avoidance are characterized by excessive worry, pessimism, fear, doubt and fatigue. Individuals with chronic pain showed a significant decrease in mPFC glutamate levels compared to control subjects without pain. In people with chronic pain mPFC glutamate levels were significantly negatively correlated with harm avoidance scores. This means that the lower the concentration of glutamate in the mPFC, the greater the total scores of harm avoidance. High scores are associated with fearfulness, pessimism, and fatigue-proneness. We suggest that chronic pain, particularly the stress-induced release of glucocorticoids, induces changes in glutamate transmission in the mPFC, thereby influencing cognitive, and emotional processing. Thus, in people with chronic pain, regulation of fear, worry, negative thinking and fatigue is impaired.

Cingulate glutamate levels associate with pain in chronic pancreatitis patients

Aims

Emerging evidence show that patients with chronic pancreatitis (CP) and abdominal pain have structural and functional alterations in the central nervous system. The aim was to investigate cerebral metabolic signatures in CP and the associations to various risk factors/clinical characteristics and patient outcomes.

Methods

Magnetic resonance spectroscopy was used to measure brain metabolites in the anterior cingulate cortex (ACC), insula, prefrontal cortex and the parietal region in patients with CP and healthy controls. Subgroup analyses based on disease characteristics (alcoholic etiology of CP, diabetes and opioid treatment) were performed. Finally, relations to abdominal pain symptoms and quality of life scores were explored.

Results

Thirty-one patients with CP (mean age 58.5 ± 9.2 years) and 23 healthy controls (54.6 ± 7.8 years) were included. Compared to healthy controls, patients had increased glutamate/creatine (glu/cre) levels in the ACC (1.24 ± 0.17 vs. 1.13 ± 0.21, p = .045) and reduced parietal N-acetylaspartate/creatine (NAA/cre) levels (1.44 ± 0.18 vs. 1.54 ± 0.12, p = .027). Patients with alcoholic etiology of CP had significant lower levels of parietal NAA/cre as compared to patients without alcoholic etiology and healthy controls (p < .006). Patients with a high level of ACC glu/cre reported more severe abdominal pain than their counterparts with a low level of ACC glu/cre (pain score 4.1 ± 2.7 vs.1.9 ± 2.3, p = .039).

Conclusions

Cerebral spectroscopy revealed novel and complementary information on central pain mechanisms and alcohol mediated toxic effects in patients with CP. Our data suggest that cingulate glutamate levels associate with the patients clinical pain symptoms, while parietal NAA levels more likely associate with an alcoholic etiology of CP.

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Patients with chronic pancreatitis have altered brain metabolites.

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Increased cingulate glutamate levels associate with clinical pain symptoms.

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Decreased parietal N-acetylaspartate levels likely relate to alcoholic etiology.

The effects of transcranial direct current stimulation on metabolite changes at the anterior cingulate cortex in neuropathic pain: a pilot study

Background

Neuropathic pain (NP) in individuals with spinal cord injury (SCI) is both common and highly refractory to treatment. Primary motor cortex stimulation can relieve pain by interrupting the transmission of noxious information of descending pain modulatory systems including the anterior cingulate cortex (ACC). Previous research has shown that transcranial direct current stimulation (tDCS) can produce pain relief in individuals with NP. However, the underlying mechanisms for these effects are not yet understood. Research findings suggest the possibility that changes in brain metabolite concentrations produced by tDCS might explain some of these effects. For example, previous research has shown that SCI-related NP is associated with elevated levels of glutamine combined glutamate (Glx) per creatine (Glx/Cr). In addition, decreased N-acetylaspartate (NAA) has been observed in the ACC in individuals with chronic pain.

Methods

We used magnetic resonance spectroscopy (MRS) to study changes in NAA and Glx levels in the ACC after tDCS treatment. Ten patients with SCI with NP were given five daily anodal tDCS sessions, and an MRS evaluation was performed before and after treatment.

Results

The results showed treatment-related reductions in pain, and increases in both Glx/Cr and NAA/Cr in the ACC. The observed increase in NAA/Cr is consistent with the possibility that tDCS improves the descending pain modulation system by increasing the neuronal activity in the ACC.

Conclusion

The findings suggest the possibility that tDCS’s beneficial effects on neuropathic pain may be due, at least in part, to the changes it produces in Glx/Cr and NAA/Cr levels in the ACC. Additional research with larger samples sizes and a control group to evaluate this possibility is warranted.

Peripheral and Central Metabolites Affecting Depression, Anxiety, Suicidal Ideation, and Anger in Complex Regional Pain Syndrome Patients Using a Magnetic Resonance Spectroscopy: A Pilot Study

OBJECTIVE

This study investigated peripheral and central metabolites affecting depression, anxiety, suicidal ideation, and anger in complex regional pain syndrome (CRPS) patients.

METHODS

Metabolite levels were determined in the right and left thalamus and insula, in 12 CRPS patients using magnetic resonance spectroscopy (MRS).

RESULTS

There were positive correlations between valine (Val)/tNAA (N-acetylaspartate+N-acetylaspartylglutamate) and the anxiety, and a negative correlation between glutamine (Gln)/NAA and the depression. There were positive correlations between alanine (Ala)/Gln and the depression and suicidal ideation, between glutamate (Glu)/Gln and the depression and suicidal ideation, between N-acetylaspartylglutamate (NAAG)/Gln and the depression. There was a positive correlation between Ala/NAAG and the trait anger and a negative correlation between creatine (Cr)/N-acetylaspartate (NAA) and the trait anger. There was a negative correlation between Cr/Glx (Glu+Gln) and the trait anger. High hemoglobin and alkaline phosphatase were associated with low pain levels, but CO2 and chloride showed positive correlations with pain levels in CRPS patients. Peripheral glucose, CO2 and chloride were associated with depression, anxiety, anger and suicidal ideation.

CONCLUSION

The specific central and peripheral metabolites were associated with psychological disorders including depression, anxiety, suicidal ideation and anger in CRPS patients, showing pathological interactions between a painful body and mind.