Neuropathic Pain Group Research Articles

Evaluation of outcomes of clinical phenotyping-based treatment for bladder pain syndrome/interstitial cystitis.

Bladder pain syndrome/Interstitial cystitis (BPS/IC) is clinically of diverse types because different causes contribute to the development of their symptoms. It is important to classify patients into various groups based on the possible etiopathogenesis of their condition. Treatment may be tailored to each specific group according to the possible cause. Twenty-five patients diagnosed with BPS/IC were categorized into four different clinical phenotypes (CP) based on their history of symptoms, allergy, dysfunctional voiding, neuropathic pain, and the presence of Hunner's ulcer. Some patients could be classified into multiple groups. The patients were given oral pentosan polysulfate, and treatment specific to their CP. Patients in CP1, CP2, and CP3 groups received, respectively hydroxyzine, clonazepam, and amitriptyline. Patients with Hunner's lesions (HL) (CP4) underwent hydro distension and ablation of the lesion, followed by intravesical instillation of heparin and hydrocortisone. The patients were evaluated using the Apollo clinical scoring (ACS) system and their clinical scores were recorded at 1, 3, and 6 month(s). Among the 25 patients, 5, 7, 4, and 9 patients were classified into CP 1 - CP4 groups respectively, and were all subjected to ACS assessment. In CP1 group (allergy group), 80% (4/5) of patients responded well to the treatment and 20% (1/5) had unsatisfactory responses. In CP2 group (dysfunctional voiding group), 71.42% (5/7) patients had good, and 28.57% (2/7) had excellent responses. In CP3 group (neuropathic pain group), 28.57% (3/4) patients had excellent, and 75% (1/4) patients had good responses. In CP4 group (HL group), 33.33% (3/9) patients had unsatisfactory, 44.44% (4/9) achieved good, and 22.22% (2/9) had excellent responses. Overall, 16% (4/25) patients had unsatisfactory, 56% (14/25) attained good, and 28% (7/25) had an excellent response at the completion of the study. Using clinical phenotyping-based features indicative of etiology could potentially improve treatment outcomes by targeting the specific pathological processes contributing to the patients' symptoms.

Low back pain classifications and their associations with disability, quality-of-life, and sociodemographic factors: a comprehensive examination using the PainDETECT questionnaire

Background Low back pain (LBP) is a debilitating phenomenon that significantly impacts quality-of-life (QoL). The PainDETECT questionnaire (PD-Q) is a screening tool aimed at distinguishing nociceptive pain (NoP) and neuropathic pain (NeP) classifications. Associations between these classifications and patient-reported outcome measures (PROMs) and sociodemographic parameters are yet to be established. Objective The study aimed to determine the relationship between NeP as assessed by the PD-Q and pain, disability, QoL, and sociodemographic factors. Methods A retrospective analysis of an ongoing prospectively collected database was conducted involving 512 patients aged >18 years who presented to a tertiary spine clinic for LBP having completed the PainDETECT questionnaire, Oswestry Disability Index (ODI), EuroQol Five-Dimensional (EQ-5D) questionnaire, or answered questions regarding sociodemographic status. Results The NeP group had a higher mean numerical rating scale (NRS) score (7.96 ± 1.54 vs. 5.76 ± 2.27, p <.001) and lower age (55 ± 15.6 vs. 59 ± 17.8, p <.05) compared to the NoP group. When confounded for NRS, analysis of covariance demonstrated an 89.5% higher total ODI score (p <.001) and 50.5% lower EQ-5D utility score (p <.001) in the NeP compared to NoP group. Smokers and individuals with a no partner marital status were 2.373 (OR = 2.373, 95% CI = 1.319–4.266, p <.01) and 2.384 times (OR = 2.384, 95% CI = 1.390–4.092, p <.01) more likely to have NeP compared to NoP, respectively. Patients with NeP were also of lower income class compared to patients with NoP (Z = −2.45, p <.05). Conclusion NeP was associated with higher levels of disability and lower QoL. Smokers, individuals with a no partner marital status, and individuals with a lower income class were more likely to suffer NeP rather than NoP. These findings have illuminated a crucial notion: in patients with elevated NRS, the detrimental impact of NeP on patient wellbeing underscores the fundamental need to represent pain on a nociceptive-neuropathic continuum, permitting more accurate differentiation of pain components.

Identification of Key Genes and Pathways in Oxaliplatin-Induced Neuropathic Pain Through Bioinformatic Analysis.

The mechanism of Chemotherapy-induced neuropathic pain (NP) remains obscure. This study was aimed to uncover the key genes as well as protein networks that contribute to Oxaliplatin-induced NP. Oxaliplatin frequently results in a type of Chemotherapy-induced NP that is marked by heightened sensitivity to mechanical and cold stimuli, which can lead to intolerance and discontinuation of medication. We investigated whether these different etiologies lead to similar pathological outcomes by targeting shared genetic targets or signaling pathways. Gene expression data were obtained from the Gene Expression Comprehensive Database (GEO) for GSE38038 (representing differential expression in the spinal nerve ligation model rats) and GSE126773 (representing differential expression among the Oxaliplatin-induced NP model rats). Differential gene expression analysis was performed using GEO2R. Protein-protein interaction (PPI) analysis identified 260 co-differentially expressed genes (co-DEGs). Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed three shared pathways involved in both models: Kaposi sarcoma-associated herpesvirus (KSHV) infection, Epstein-Barr virus (EBV) infection, and AGE-RAGE signaling pathway in diabetic complications. Further bioinformatics analysis highlighted eight significantly up-regulated genes in the NP group: Mapk14, Icam1, Cd44, IL6, Cxcr4, Stat1, Casp3 and Fgf2. Our results suggest that immune dysfunction, inflammation-related factors or regulating inflammation factors may also be related to Oxaliplatin-induced NP. Additionally, we analyzed a dataset (GSE145222) involving chronic compression of DRGs (CCD) and control groups. CCD model is a classic model for studying NP. We assessed these hub genes' expression levels. In contrast with the control groups, the hub genes were up-regulated in CCD groups, the difference was statistically significant, except Stat1. Our research significantly contributes to elucidating the mechanisms underlying the occurrence as well as the progression of Oxaliplatin-induced NP. We have identified crucial genes and signaling pathways associated with this condition.

A Cross-Sectional Study on Neuropathic Pain Associated With Quality of Sleep in Spondylosis Patients.

Neuropathic pain (NP) is common in spondylosis patients. Cervical and lumbar spondylosis are more common in the elderly population. Spondylosis patients also suffer from poor quality of sleep (QOS). This study aims to find a correlation between NP and QOS in spondylosis patients. We conducted a cross-sectional study and analyzed data using the chi-square test to correlate the NP with QOS. The Pittsburgh Sleep Quality Index (PSQI) and the Leeds Assessment of Neuropathic Symptoms and Signs, Self-complete (S-LANSS) questionnaires were used to assess QOS and evaluate neuropathic pain, respectively. Spondylosis was diagnosed based on the history, clinical examination, and radiological findings. A total of 72 spondylosis patients, with a mean age of 47.35 years, were included in this study. Out of 72 subjects, 52 (72.2%) patients had neuropathic pain (NP group), and 20 (27.8%) patients had non-neuropathic pain (non-NP group). In the NP group, 41 patients (78.8%) had poor QOS, while 11 (21.2%) had good QOS. In the non-NP group, eight (40%) had poor QOS, and 12 (60%) had good QOS. This study concludes that neuropathic pain is associated with poor quality of sleep in spondylosis patients.

Differential relationships between physical activity and pain phenotypes in individuals with spinal cord injury

Background Chronic pain affects 70% of individuals with spinal cord injury (SCI) and leads to declines in health and quality of life. Neuropathic and nociceptive pain are phenotypes derived from different mechanisms that contribute to pain perception. The objective of this research was to investigate differential pain responses to moderate-to-vigorous physical activity (MVPA) in two chronic pain phenotypes: neuropathic and nociceptive pain. Methods Community-based physical activity levels were collected for one week in 17 individuals with SCI using a wrist-worn accelerometer, and daily pain ratings were assessed and categorized by phenotype. Physical activity levels were summarized to calculate minutes of MVPA. Correlational analyses were conducted to compare relationships between pain intensity and MVPA across individual participants and between pain phenotype groups. Results The neuropathic pain group revealed significant negative correlation between MVPA and pain intensity. In the nociceptive pain group, there was no significant correlation between MVPA and pain intensity. Further analysis revealed two subgroups of positive (N = 4) and negative (N = 3) correlations between MVPA and pain intensity. Pain location differed between the subgroups of nociceptive pain. Individuals with negative correlation experienced neck and upper back pain, whereas individuals with positive correlation experienced unilateral upper extremity pain. Conclusion Differential relationships exist between pain phenotypes and MVPA in individuals with SCI. Pain location differed between the subgroups of nociceptive pain, which we presume may indicate the presence of nociplastic pain in some individuals. These results may contribute to the advancement of personalized pain management by targeting non-pharmacological interventions for specific pain phenotypes. Trial registration: ClinicalTrials.gov identifier: NCT05236933..

Neuropathic pain is a feature in patients with symptomatic femoral acetabular impingement

Femoral acetabular impingement syndrome (FAIS) is a cause of hip pain thought to be nociceptive, although pain phenotypes e.g., burning, pain attacks, prickling, numbness etc., are reported, mimicking neuropathic pain. Although no lesion to the somatosensory system is identified, neuropathic pain (NeP) may explain why nociceptive-focussed treatments are not always successful. ObjectiveTo identify NeP in patients with FAIS and investigate if related to poorer outcomes. DesignA secondary analysis of the Femoral Acetabular Impingement Trial (FAIT). Outcome of interest: PainDETECT questionnaire; secondary outcomes of interest; International Hip Outcome Tool (iHOT33), Hospital Anxiety and Depression Scale (HADS) and VAS ‘average pain over a month’, at baseline and 8 months follow-up. Intervention (surgery or physiotherapy) were pooled. Results173 data sets at baseline; 123 at 8 months follow-up. Baseline painDETECT identified three groups: 69% nociceptive, 19% unclear and 12% neuropathic pain phenotypes. Baseline, median scores were higher for the neuropathic group compared to the nociceptive group demonstrating borderline anxiety (9.5(5.3 to 14.2), 5(3 to 8), higher normal values for depression (7.5(2.3 to 11.8), (4(2 to 9), higher average pain (7 (6 to 8), 5(4 to 6) and lower iHOT33 14.2(9 to 21.1), 38.4(26.2 to 55.7). Post treatment, there was a median change in the neuropathic score in both iHOT33 (40.8 (25 to 76.5) with a median difference of 24.13 (CI 95% 10.46 to 45.92) and average pain 4.5(1.5 to 7) with a median difference of 2 (CI 95% 1 to 5) but to a lesser amount than the nociceptive group, iHOT33 (64(38.2 to 86.6) with a median difference of 15.50 (CI 95% 6.41 to 21.82) and average pain 3(1 to 5.7) with a median difference of 1 (CI 95% 0.5 to 1). ConclusionNeP exists in symptomatic FAIS patients and is associated with increased average pain, and functional limitations. Nociceptive-targeted treatment improves hip function and pain but with less improvement in the NeP group when compared to the nociceptive group.Pain phenotyping before intervention may improve outcomes. Contribution of paper•Neuropathic pain is a feature in patients with Femoral Acetabular Impingement Syndrome (FAIS).•Neuropathic pain is related to borderline levels of anxiety, higher average pain and poorer hip function.•Nociceptive focused treatment improves hip function and average pain in patients with neuropathic pain but to a lesser extent than patients with nociceptive pain.

Evaluation of Washout Periods After Dorsal Root Ganglion Stimulation Trial

ObjectiveDorsal root ganglion stimulation (DRG-S) is a novel therapy to treat chronic pain. It has shown efficacy when delivered intermittently, suggesting a delayed washout effect exists. To measure the washout period, and to determine whether there are differences in washout times among different types of treated pain, we measured the time for pain to return at the end of the patients’ one-week DRG stimulation trials. Materials and MethodsPatients who completed a successful DRG-S trial were included. The times until 25% (t25) and 90% (t90) of baseline pain level returned were recorded. The patients were divided into neuropathic, nociceptive, and mixed pain groups for subgroup comparison. t25 and t90 were plotted in the entire cohort and subgroups using reverse Kaplan-Meier plots (failure curves) and compared using a log-rank test. ResultsIn total, 29 consecutive patients were included. Median t25 and t90 times were 7.1 and 19.5 hours, respectively. Median (interquartile range) times were longest for the nociceptive pain group (n = 17) and shortest for the neuropathic pain group (n = 6), with the mixed-pain group (n = 6) in between (t25: 7.1 [1.7–19.4], 3.40 [1.4–8.4], and 5.7 [0.8–17.6]; t90, 22.0 [10.7–71.0], 7.6 [3.6–19.8], and 20.9 [14.2–31.2], respectively). t90 times differed significantly by pain type (p = 0.040). ConclusionsThis study showed a prolonged washout period after cessation of DRG-S therapy. Washout times vary according to pain type. The observed effects are possibly due to long-term depression of pain signaling and could allow the implementation of alternative stimulation strategies with DRG-S. Further investigations evaluating DRG-S washout times are warranted.

Translation and cross-cultural adaptation of Polish version of Neuropathic Pain Questionnaire (NPQ-PL) and its comparisons with different questionnaires.

The aim of this study was to assess the validity and reliability of the Polish version of the Neuropathic Pain Questionnaire (NPQ-PL), and to compare it to other diagnostic tools. Neuropathic pain is a burdensome condition, of which the exact prevalence is difficult to estimate. During initial screening, pain questionnaires are helpful in alerting clinicians about the need for further evaluation. The NPQ-PL has been developed following the guidelines for translation and cultural adaptation. A total of 140 patients with chronic pain (ChP), 90 with neuropathic pain (NP), and 50 with nociceptive pain (NoP), were enrolled into this study. The study group consisted of 60.71% women and 39.29% men; the mean age of patients (standard deviation, SD) was 53.22 years (15.81), and the average NPQ-PL score (SD) was 0.49 (1.27). Statistically significant relationships were found between higher age distribution and greater pain intensity in the NP group compared to the NoP group. There were also significant differences in pain levels between people of different ages, with the predominance in the elderly. Cronbach's alpha coefficient of the whole questionnaire was 0.85 and the intraclass correlation coefficient (ICC) for test-retest reliability was 0.635. Using receiver-operating characteristic (ROC) curve analysis, the area under the curve (AUC) was 0.97 and the best cut-off value was 0.002, which resulted in the highest sensitivity (93.3%) and specificity (96.0%). The NPQ-PL is a valid tool for discriminating between neuropathic and nociceptive pain. It can be used by physicians of various disciplines when assessing patients with ChP of various origins.

An assessment of the treatment of spinal cord stimulation: Postlaminectomy pain or neuropathic pain

Neuromodulation has a significant place, among the interventional methods, in the treatment of chronic pain. Spinal Cord Stimulation (SCS) is the most applied treatment method among neuromodulation methods. SCS procedure is a neuromodulation method used in the failed back surgery syndrome, neuropathic pain, and cancer pain. The 102 patients who applied SCS were included in the retrospective study from 2017-2022 in the University Algology Department. We asked about pain scores in line with visual analog scale degrees (VAS) before and after the SCS procedure, opioid use and compared the patient satisfaction with the procedure. We divided the patients into two groups as those with a diagnosis of post-laminectomy syndrome (Group 1) and those with a diagnosis of neuropathic pain (Group 2). VAS before SCS was 9.11±0.75 in Group 1 and 8.45±0.77 in Group two. After SCS, the decrease in pain intensity was much more distinct in post-laminectomy patients (Group 1), compared to the neuropathic pain patients (Group 2). The results were as follows: Group 1- 1.98±1.40, Group 2-4.08±0.71, p&lt;0.001. The decrease in using analgesics was observed to be much more significant in Group 2. (P&lt;0.05) Patient satisfaction was higher in Group 1 as well (p&lt;0.05). We hold the opinion that post-laminectomy patients benefit more from the SCS procedure than neuropathic pain patients. We observed that the decrease both in pain intensity and the use of opioid analgesics was statistically and overwhelmingly distinct in post-laminectomy patients. According to the results of our study, we think that SCS is an effective and safe treatment method both for post-laminectomy and neuropathic pain patients.

Mitochondrial dysfunction and disulfidptosis co-regulate neuronal cell in neuropathic pain based on bioinformatics analysis.

Neuropathic pain (NP) affects approximately 6.9-10% of the world's population and necessitates the development of novel treatments. Mitochondria are essential in the regulation of cell death. Neuroimmune mechanisms are implicated in various forms of cell death associated with NP. However, the specific involvement of mitochondrial dysfunction and disulfidptosis in NP remains uncertain. Further research is required to gain a better understanding of their combined contribution. Our comprehensive study employs a variety of bioinformatic analysis methods, including differential gene analysis, weighted gene co-expression network analysis, machine learning, functional enrichment analysis, immune infiltration, sub-cluster analysis, single-cell dimensionality reduction and cell-cell communication to gain insight into the molecular mechanisms behind these processes. Our study rationally defines a list of key gene sets for mitochondrial dysfunction and disulfidptosis. 6 hub mitochondrial genes and 3 disulfidptosis-related genes (DRGs) were found to be associated with NP. The key genes were predominantly expressed in neurons and were lowly expressed in the NP group compared to SHAM. In addition, our macrophages used the APP (Amyloid precursor protein)-CD74 (MHC class II invariant chain) pathway to interact with neurons. These results suggest that NP is interconnected with the mechanistic processes of mitochondrial dysfunction and disulfidptosis, which may contribute to clinically targeted therapies.

Validity Test of an Alternative Method of Quantitative Pain Assessment (MAPKN) in Assessing Intensity of Nociceptive Pain, Mixed Pain, and Neuropathic Pain

Pain is a health problem phenomenon that most often brings patients to see a doctor. Pain intensity is the most often domain which assessed in clinical and research settings. Loeser suggests that four elements need to be considered when evaluating patients with pain. Based on the biopsychosocial approach and the concept of pain from Loeser, a pain assessment was made and called "Alternative Method of Quantitative Pain Assessment (MAPKN)". This study was conducted on 415 pain patients consisting of 163 nociceptive pain, 119 mixed pain, and 133 neuropathic pain. In the nociceptive pain group, MAPKN showed sensitivity 92.59%, specificity 96.43%, AUC 0,959 and a p value &lt;0.001. In the mixed pain group, MAPKN showed sensitivity 98.17%, specificity 80.00%, AUC 0,836 and a p -value of 0.001. In the neuropathic pain group, MAPKN showed sensitivity 92.06%, specificity of 85.71%, AUC 0,951 and a p&lt;0.001. The AUC value of 0.959 (96%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the nociceptive pain group is excellent (&gt;90%-100%). AUC value of 0.836 (83%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the mixed pain group is good (&gt; 80%-90%). The AUC value of 0.951 (95%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the neuropathic pain group is excellent (&gt;90%-100%). This is in accordance with research conducted by Eka Pranata 2004 that MAPKN has strong discriminant validity in assessing pain intensity. MAPKN is valid and has excellent diagnostic value in assessing nociceptive and neuropathic pain intensity, MAPKN is valid and has good diagnostic value in assessing mixed pain intensity.&#x0D;

White matter microstructural alterations in patients with neuropathic pain after spinal cord injury: a diffusion tensor imaging study.

Through contrastive analysis, we aimed to identify the white matter brain regions that show microstructural changes in patients with neuropathic pain (NP) after spinal cord injury (SCI). We categorized patients with SCI into NP (n = 30) and non-NP (n = 15) groups. We extracted diffusion tensor maps of fractional anisotropy (FA) and mean (MD), axial (AD), and radial (RD) diffusivity. A randomization-based method in tract-based spatial statistics was used to perform voxel-wise group comparisons among the FA, MD, AD, and RD for nonparametric permutation tests. Atlas-based analysis located significantly different regions (p < 0.05) in the appointed brain atlas. Compared to the non-NP group, the NP group showed higher FA in the posterior body and splenium of the corpus callosum and higher AD in the corpus callosum, internal capsule, corona radiata, posterior thalamic radiation, sagittal stratum, external capsule, cingulum, fornix/stria terminalis, superior longitudinal fasciculus, and uncinate fasciculus. The results demonstrated that compared with the non-NP group, NP pathogenesis after SCI was potentially related to higher values in FA that are associated with microstructural changes in the posterior body and splenium of the corpus callosum, which could be regarded as central sensitization or network hyperexcitability.

Different Pain Types at Coccygodynia and its Relation with Vitamin D Level

Background; Coccygodynia is a musculoskeletal disease that affects quality of life. The main complaint of coccygodynia is nociceptive and/or neuropathic pain. Vitamin D deficiency has been associated with the development of pain in various diseases. &#x0D; Aims; In this study we aimed investigate the pain types (nociceptive, neuropathic, mixed) and the relationship between pain types and Vitamin D level in patients with coccygodynia. &#x0D; Study design; Observational study&#x0D; Materials and Methods; A total of 54 patients diagnosed with coccygodynia were included. Pain intensity, disablity and pain type were evaluated by Visual Analogue Scale (VAS), the Oswestry Disability Index (ODI), and the PainDETECT questionnaire, respectively. All participants had their vitamin D levels measured. &#x0D; Results; Neuropathic pain was detected in 27.8% of the patients with coccygodynia. Vitamin D was determined to be insufficient or deficient in 81.5% of the patients. A statistical significant correlation was found between neuropathic pain and prolongation of coccygodynia and increased ODI values (p&lt;0.05). The Vitamin D values were determined to show statistically similar distribution in the nociceptive, mixed type, and neuropathic pain groups (p=0.532). &#x0D; Conclusion; The frequency of neuropathic pain in coccygodynia increases with increasing disability and disease duration. Although vitamin deficiency or insufficiency is common in coccygodynia, it is not associated with the type of pain.

A Silver Lining of Neuropathic Pain: Predicting Favorable Functional Outcome in Spinal Cord Injury.

Neuropathic pain (NP) is a common and severe problem following spinal cord injury (SCI). However, its relationship with functional outcome remains unclear. A retrospective explorative analysis was performed on SCI patients admitted to a tertiary academic medical center between January 2018 and June 2022. The candidate predictor variables, including demographics, clinical characteristics and complications, were analyzed with logistic and linear regression. Spinal Cord Independence Measure (SCIM) scores at discharge and mean relative functional gain (mRFG) of SCIM were as outcome parameters. A total of 140 SCI patients included for the final analysis. Among them, 44 (31.43%) patients were tetraplegics, and 96 (68.57%) patients were paraplegics; 68 (48.57%) patients developed NP, and 72 (51.43%) patients did not. Logistic and linear regression analyses of SCIM at discharge both showed that NP [OR=3.10, 95% CI (1.29,7.45), P=0.01; unstandardized β=11.47, 95% CI (4.95,17.99), P<0.01; respectively] was significantly independent predictors for a favorable outcome (SCIM at discharge ≥ 50, logistic regression results) and higher SCIM total score at discharge (linear regression results). Besides, NP [unstandardized β=15.67, 95% CI (8.94,22.41), P<0.01] was also independently associated with higher mRFG of SCIM scores. Furthermore, the NP group had significantly higher mRFG, SCIM total scores and subscales (self-care, respiration and sphincter management, and mobility) at discharge compared to the non-NP group. However, there were no significant differences in mRFG, SCIM total score or subscales at discharge among the NP subgroups in terms of locations (at level pain, below level pain, and both) or timing of occurrence (within and after one month after SCI). This study also showed that incomplete injury, lumbar-sacral injury level and non-anemia were significantly independent predictors for a favorable outcome, and higher mRFG of SCIM scores (except for non-anemia). NP appears independently associated with better functional recovery in SCI patients, suggesting the bright side of this undesirable complication. These findings may help to alleviate the psychological burden of NP patients and ultimately restore their confidence in rehabilitation.

Effect of medial opening wedge distal tibial tuberosity osteotomy on possible neuropathic pain in patients with osteoarthritis of the knee

BackgroundThere is a paucity of literature regarding the changes and features of neuropathic pain (NP) in knee osteoarthritis (OA) following medial opening wedge distal tibial tuberosity osteotomy (OWDTO). This study aimed to investigate the effect of OWDTO on NP in knee OA; we hypothesized that OWDTO improves knee symptoms and functions and also meets patient satisfaction in those with knee OA with possible NP or without NP. MethodsFifty-two consecutive patients who underwent OWDTO were categorized into the unlikely NP and possible NP groups using the painDETECT questionnaire. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) score and the Knee Society Score 2011 (KSS 2011) were compared between the groups preoperatively and at the 1-year follow-up. ResultsThe number of patients having possible NP significantly decreased from 12 (23.1%) preoperatively to one (1.9%) postoperatively (p < 0.001). The patient with postoperative possible NP also had possible NP preoperatively. All preoperative sub-scores of WOMAC were significantly higher in the possible NP group than in the unlikely NP group (p = 0.018, 0.013, 0.004, and 0.005, respectively); however, the postoperative scores did not differ between the two groups. Regarding the KSS 2011, the preoperative scores for symptom and functional activities were significantly lower in the possible NP group than in the unlikely NP group (p = 0.031 and 0.024, respectively). ConclusionsOWDTO is an effective surgery for patients with possible NP; it improves symptoms and knee function as well as meets patient satisfaction.Level of Evidence: Level IV, therapeutic case series.

EEG frequency band analysis in chronic neuropathic pain: A linear and nonlinear approach to classify pain severity

Background and objectiveChronic neuropathic pain (NP) is a chronic pain condition that severely impacts a patient's life. Pain management has proved to be inefficient due to a lack of a simple clinical tool that may identify and monitor NP. A low-cost, noninvasive tool that provides relevant information on NP is the electroencephalogram (EEG). However, the commonly used linear EEG features have proved to be limited in characterizing NP pathophysiology. This study sought to determine whether nonlinear EEG features such as approximate entropy (ApEn) would better differentiate pain severity than absolute band power. MethodsA non-parametric statistical approach based on the Brief Pain Inventory (BPI), along with linear and nonlinear EEG features, is proposed in this study. For this purpose, thirty-six chronic NP patients were recruited, and 22 channels were registered. Additionally, a control database of 13 participants with no NP was used as a reference, where 19 channels were registered. For both groups, EEG was recorded for 10 min in a resting state: 5 min with eyes open (EO) and 5 min with eyes closed (EC). Absolute band power and ApEn EEG features in the five clinical frequency bands (delta, theta, alpha, beta, and gamma) were estimated for all channels in both groups. As a result, 220-dimensional and 190-dimensional feature vectors were obtained for experimental and control classes respectively. For the experimental class, NP patients were grouped according to their BPI evaluation in three groups: low, moderate, and high pain. Finally, feature vectors were compared between groups using Kruskal Wallis and post-hoc Dunn's tests. ResultsApEn revealed significant statistical difference (p <=0.0001) in most frequency bands and conditions among the groups. In contrast, power had less significant differences between groups, particularly with EO. Furthermore, NP groups were notably clustered using only ApEn in theta, alpha, and beta bands. ConclusionsThe results indicate that ApEn effectively characterizes the different severities of chronic NP rather than the commonly used linear features. ApEn and other nonlinear techniques (e.g., spectral entropy, Shannon entropy) might be a more suitable methodology to monitor chronic NP experience.

Prevalence and predisposing factors of neuropathic pain in patients with rotator cuff tears

BackgroundThe management of pain in patients with rotator cuff tears can be challenging. Neuropathic pain is reportedly associated with pain occurrence in musculoskeletal diseases. However, to date, few studies have reported on the prevalence of neuropathic pain in patients with rotator cuff tears or identified the factors associated with neuropathic pain in a multicenter study. MethodsA total of 391 patients (205 males and 186 females; median age, 67.7 years; range, 27–92 years) with rotator cuff tears were included in this study. The prevalence of neuropathic pain in rotator cuff tears was investigated using the Japanese version of the painDETECT questionnaire for all patients. In addition, factors significantly associated with the occurrence of neuropathic pain were examined using multivariate logistic regression analysis. ResultsTwenty-eight patients (7.2%) were classified into the neuropathic pain group (score ≥19), 97 (24.8%) into the uncertainty regarding neuropathy group (score 13–18), and 266 (68.0%) into the nociceptive pain group (score ≤12). According to the multivariate logistic regression analysis, the independent predictors of neuropathic pain were the VAS score (most severe pain during the past 4 weeks; odds ratio, 1.55; 95% confidence interval [CI], 1.23–2.09) and UCLA shoulder score (odds ratio, 0.81; 95% CI, 0.65–0.97). ConclusionsBased on the study findings, the prevalence of neuropathic pain in patients with rotator cuff tear was 7.2%. It is important to investigate the presence or absence of neuropathic pain when treating patients with painful rotator cuff tears, because neuropathy associated with rotator cuff tears may adversely affect patient outcomes.

Can radiological findings detect neuropathic pain in patients with osteoarthritis of the knee undergoing surgery?

The mechanism underlying neuropathic pain (NP) in osteoarthritis (OA) of the knee is not completely understood. This study aimed to investigate whether possible NP in patients with knee OA undergoing knee surgery is associated with specific radiological findings. This study included 197 patients who underwent knee surgery for symptomatic knee OA. Clinical evaluation was performed using the Central Sensitization Inventory (CSI), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and PainDETECT questionnaire. Radiological evaluation was performed using the hip-knee-ankle (HKA) angle, posterior tibial slope (PTS), varus and valgus laxities, and magnetic resonance imaging OA Knee Score (MOAKS). Radiological findings were compared between patients with possible and unlikely NP. Logistic regression analysis was performed to identify the predictive factors for NP. There were 163 and 34 patients with unlikely NP and with possible NP, respectively. The percentage of patients with CSI score ≥ 40 was significantly higher in the possible NP group than in the unlikely NP group (17.6% vs. 6.1%). Patients with possible NP had worse WOMAC scores than patients with unlikely NP. There were no significant positive associations between the possible NP and radiological findings in knee OA. Regression analysis showed no predictive factors for possible NP. Possible NP is not associated with specific radiological findings in knee OA. Patients with possible NP may mediate CS and experience more severe symptoms, including decreased knee function and lower quality of life, than patients with unlikely NP.

Effect of neuropathic pain on sphenopalatine ganglion block responses in persistent idiopathic facial pain

ABSTRACT Objectives Management of persistent idiopathic facial pain (PIFP) can be challenging. Sphenopalatine ganglion (SPG) has been the target for the interventional treatment of many facial pain syndromes. However, possible factors that may affect SPG block success are unknown. It was aimed to investigate the effect of neuropathic pain on SPG block outcomes in PIFP, which includes a heterogeneous patient group. Methods All of the patients underwent fluoroscopy-guided SPG block with an injection of 40 mg of 2% lidocaine and 8 mg of dexamethasone. The patients were assigned to 2 groups according to existence of neuropathic pain determined with the DN4 questionnaire score: 19 patients with neuropathic pain (Group 1) and 15 patients without neuropathic pain (Group 2). Preprocedural and postprocedural Visual Analog Scale (VAS) scores were compared between the 2 groups. Results The mean age of the patients was 47.65 ± 6.50 years. The average pain duration was 52.95 ± 34.81 weeks. A significantly greater decrease was detected in the VAS scores at 1 week (p = 0.036) and 1 month (p < 0.001) in Group 1 when compared to Group 2. Moreover, the proportion of patients with >50% improvement in the VAS scores at 1 week (p = 0.012) and 1 month (P = 0.017) was significantly lower in Group 1 than in Group 2. Discussion SPG block appears as a safe, effective, and rapid method to treat PIFP, especially in cases with neuropathic pain. Neuropathic pain may be a predictor for pain relief in interventional procedures targeting SPG in the treatment of PIFP.

A Hidden Markov Model reveals magnetoencephalography spectral frequency-specific abnormalities of brain state power and phase-coupling in neuropathic pain

Neuronal populations in the brain are engaged in a temporally coordinated manner at rest. Here we show that spontaneous transitions between large-scale resting-state networks are altered in chronic neuropathic pain. We applied an approach based on the Hidden Markov Model to magnetoencephalography data to describe how the brain moves from one activity state to another. This identified 12 fast transient (~80 ms) brain states including the sensorimotor, ascending nociceptive pathway, salience, visual, and default mode networks. Compared to healthy controls, we found that people with neuropathic pain exhibited abnormal alpha power in the right ascending nociceptive pathway state, but higher power and coherence in the sensorimotor network state in the beta band, and shorter time intervals between visits of the sensorimotor network, indicating more active time in this state. Conversely, the neuropathic pain group showed lower coherence and spent less time in the frontal attentional state. Therefore, this study reveals a temporal imbalance and dysregulation of spectral frequency-specific brain microstates in patients with neuropathic pain. These findings can potentially impact the development of a mechanism-based therapeutic approach by identifying brain targets to stimulate using neuromodulation to modify abnormal activity and to restore effective neuronal synchrony between brain states.