Analysis of the efficacy of retrodiscal approach percutaneous epidural adhesiolysis with WHIP catheter® in patients with lumbar radiculopathy: A retrospective study.

Percutaneous epidural adhesiolysis (PEA) is an effective treatment for patients with lumbar radiculopathy unresponsive to single steroid injections. Various approaches and instruments have been developed to access these lesions. This study aimed to evaluate the utility of a retrodiscal approach for epidural adhesiolysis using a WHIP catheter®. This retrospective study was conducted at Bundang Seoul National University Hospital, reviewing cases from January to December 2022. Forty-seven patients diagnosed with lumbar radiculopathy, aged 20 to 80 years, who underwent PEA with the WHIP catheter® were included. Outcomes assessed Numeric Rating Scale (NRS) for pain, Patients' Global Impression of Change (PGIC) scores, and the incidence of procedure-related complications. Follow-up evaluations occurred at 1, 3, and 6 months post-procedure. Among 47 patients, 41 completed the study, showing significant pain reduction at all follow-up points: 1 month (N = 41, 1.32 ±â€…1.68, P < .001), 3 months (N = 31, 1.90 ±â€…2.14, P < .001), and 6 months (N = 30, 2.50 ±â€…2.30, P < .001). PGIC scores indicated that 40% of the patients reported substantial improvement at one-month post-procedure. The complications were minimal, with only one case of intradiscal injection and 2 cases of vascular uptake. The retrodiscal approach PEA using the WHIP catheter® demonstrated significant efficacy in pain reduction with minimal safety concerns for patients with lumbar radiculopathy. These findings suggest that this procedure is a viable option for patients who are unresponsive to conservative treatment. However, the retrospective nature of this study and its small sample size necessitate further prospective controlled studies to confirm our results and establish long-term outcomes.

Effect duration of lumbar sympathetic ganglion neurolysis in patients with complex regional pain syndrome: a prospective observational study.

Lumbar sympathetic ganglion neurolysis (LSGN) has been used for long-term pain relief in patients with complex regional pain syndrome (CRPS). However, the actual effect duration of LSGN has not been accurately measured. This prospective observational study measured the effect duration of LSGN in CRPS patients and investigated the relationship between temperature change and pain relief. After performing LSGN, the skin temperatures of both the maximum pain site and the plantar area in the affected and unaffected limbs were measured by infrared thermography, and pain intensity was assessed before and at 2 weeks, 1 month, and 3 months. The median time to return to baseline temperature was calculated using survival analysis. The skin temperature increased significantly at all-time points relative to baseline in both regions (maximum pain site: 1.4 °C ± 1.0 °C, plantar region: 1.28 °C ± 0.8 °C, all P < 0.001). The median time to return to baseline temperature was 12 weeks (95% confidence interval [CI] 7.7-16.3) at the maximum pain site and 12 weeks (95% CI 9.4-14.6) at the plantar area. Pain intensity decreased significantly relative to baseline, at all-time points after LSGN. In conclusion, the median duration of the LSGN is estimated to be 12 weeks.

Development of a Deep Learning Model for the Analysis of Dorsal Root Ganglion Chromatolysis in Rat Spinal Stenosis.

Objective: To create a deep learning (DL) model that can accurately detect and classify three distinct types of rat dorsal root ganglion neurons: normal, segmental chromatolysis, and central chromatolysis. The DL model has the potential to improve the efficiency and precision of neuron classification in research related to spinal injuries and diseases. Methods: H&E slide images were divided into an internal training set (80%) and a test set (20%). The training dataset was labeled by two pathologists using pre-defined grades. Using this dataset, a two-component DL model was developed with the first component being a convolutional neural network (CNN) that was trained to detect the region of interest (ROI) and the second component being another CNN used for classification. Results: A total of 240 lumbar dorsal root ganglion (DRG) pathology slide images from rats were analyzed. The internal testing results showed an accuracy of 93.13%, and the external dataset testing demonstrated an accuracy of 93.44%. Conclusion: The DL model demonstrated a level of agreement comparable to that of pathologists in detecting and classifying normal and segmental chromatolysis neurons, although its agreement was slightly lower for central chromatolysis neurons. Significance: DL in improving the accuracy and efficiency of pathological analysis suggests that it may have a role in enhancing medical decision-making.

Effect of Nonsurgical Spinal Decompression on Intensity of Pain and Herniated Disc Volume in Subacute Lumbar Herniated Disc.

Objective: Nonsurgical spinal decompression therapy (NSDT) is a conservative treatment for the lumbosacral herniated intervertebral disc (L-HIVD). This study aimed to evaluate the clinical effectiveness of the NSDT and change in disc volume through magnetic resonance imaging (MRI) in subacute L-HIVD. Methods: Sixty patients with subacute L-HIVD were randomized into either the decompression group (group D, n = 30) or the nondecompression group (group N, n = 30). In group D, NSDT was performed ten times in eight weeks. In group N, pseudodecompression therapy (no force) was performed with the same protocol. Lower back and lower leg pain intensities and functional improvements were measured by the visual analog scale and the Korean Oswestry Disability Index (K-ODI). The change in the lumbosacral disc herniation index (HI) was evaluated through a follow-up MRI three months after the therapy. Results: The lower leg pain intensity in group D was lower than that in group N at two months (p=0.028). Additionally, there were significantly lower K-ODI scores in group D at two and three months (p=0.023, 0.019) than in group N. The change in HI after the therapy was -27.6 ± 27.5 (%) in group D and -7.1 ± 24.9 (%) in group N, with a significant difference (p=0.017). Approximately 26.9% of patients in group D and no patients in group N showed over 50% reduction in HI (p=0.031). Conclusion: NSDT may be a suitable treatment option for conservative treatment of subacute L-HIVD.

Efficacy and safety of 5% lidocaine patches for postoperative pain management in patients undergoing unilateral inguinal hernia repair: study protocol for a prospective, double-blind, randomized, controlled clinical trial.

BACKGROUND: Acute postoperative pain is a common complication of inguinal hernia repair. Pain management using local application of anesthetic agents over the skin surrounding the surgical incision may reduce the requirement for other pain medications. Targeted topical analgesics such as 5% lidocaine patches have been known to improve acute and chronic pain. However, the clinical effect of lidocaine patches on postoperative pain after inguinal hernia repair has not been studied, especially in patients undergoing surgery at day surgery units. METHODS/DESIGN: This is a single-center, prospective, double-blind, randomized, controlled clinical trial. Participants with unilateral inguinal hernia will be randomized to the lidocaine patch group or the placebo patch group. Based on the randomized allocation sequence, either lidocaine patches or placebo patches will be attached near each participant's surgical wound after open hernia repair under general anesthesia. Participants will be asked to follow up at our outpatient clinic on the first postoperative day and at 1 week after surgery. The primary outcome is pain intensity, which will be measured using the visual analog scale (VAS) at the time of discharge from the day surgery unit. The secondary outcomes are VAS score at 24 h and 1 week after surgery. We will collect and analyze the participants' clinical data (amount of intraoperative opioid use, time to recovery, and pain intensity at 30 min after surgery) and demographic characteristics (age, sex, body weight, and height). DISCUSSION: This trial may not only provide evidence on the efficacy of a 5% lidocaine patch for acute postoperative pain management after unilateral inguinal hernia repair, but also demonstrate the efficacy and safety of the patch for post-discharge pain management. TRIAL REGISTRATION: ClinicalTrials.gov NCT04754451. Registered on February 10, 2021.

Aspirin Cessation Before Interventional Procedures: Not Blindly Following Guidelines but Making Test-based Decisions.

BACKGROUND: Deciding whether to continue or discontinue aspirin prior to interventional procedures is a major concern for pain physicians. Many guidelines have been published on the discontinuation of aspirin before invasive procedures; however, the recommendations are inconsistent and do not consider individual platelet function. Furthermore, many studies have shown a high prevalence of aspirin resistance  in patients taking this medication. OBJECTIVES: To determine the necessity of discontinuing aspirin prior to interventional pain procedures in relation to individual platelet function. STUDY DESIGN: Multicenter, cross-sectional study. SETTING: University-affiliated hospitals. METHODS: We examined platelet function among patients scheduled for an interventional pain procedure by measuring their closure time using collagen/epinephrine cartridges in a commercial platelet-function analyzer. The patients were categorized into either an aspirin-taking or nonaspirin-taking group (Group A or Group N, respectively). The proportion of patients who showed normal/abnormal platelet function was calculated and compared between the groups. RESULTS: A total of 1,111 patients were included in this study. In Group A, 56.4% (102/181) showed normal platelet function, whereas 43.6% (79/181) showed abnormal platelet function. In Group N, 85.8% (798/930) and 14.2% (132/930) showed normal and abnormal platelet function, respectively. LIMITATION: The proportion of laboratory, not clinical aspirin resistance was evaluated. Factors affecting platelet function were not investigated exhaustively. CONCLUSION: The high prevalence of normal platelet function in patients taking aspirin suggests no necessity of discontinuation before procedures in such patients. Abnormal platelet function can occur even in patients who are not taking aspirin. Therefore, platelet function should be measured and considered on a case-by-case basis prior to interventional procedures, and discontinuation of aspirin should be decided based on these factors.

Efficacy and Safety of a New Sustained-release Pregabalin Formulation Compared With Immediate-release Pregabalin in Patients With Peripheral Neuropathic Pain: A Randomized Noninferiority Phase 3 Trial.

OBJECTIVE: This study investigated whether a new sustained-release (SR) pregabalin formulation is noninferior to immediate-release (IR) pregabalin in alleviating peripheral neuropathic pain in Korean patients. MATERIALS AND METHODS: This was a randomized, double-blind, active-controlled phase 3 study of patients with diabetic peripheral neuropathy or postherpetic neuralgia from 41 sites in South Korea in 2017-2018. Eligible patients were randomized (1:1) to receive once-daily SR pregabalin or twice-daily IR pregabalin (150 to 600 mg/d) in a double-dummy manner for 12 weeks according to a stratified permuted block randomization scheme. The primary endpoint was the Daily Pain Rating Scale score at the end of treatment, averaged from the last 7 available scores. RESULTS: A total of 319 of 371 (86.0%) randomized patients completed the 12-week treatment (SR pregabalin: n=154; IR pregabalin: n=165; per-protocol set: n=296). The least square mean difference between both groups for the primary endpoint was 0.06 (SE 0.19); (95% confidence interval -0.31 to 0.42), with the lower limit of the confidence interval above the pre-specified margin (-0.78; Pnoninferiority<0.0001). Drug-related treatment-emergent adverse events (TEAEs) were comparable between both groups. The incidence of drug-related TEAEs leading to treatment discontinuation was low (SR pregabalin: 2.7%; IR pregabalin: 1.1%). No serious drug-related TEAEs or deaths occurred. DISCUSSION: The results demonstrate that the new once-daily SR pregabalin formulation is noninferior to twice-daily IR pregabalin in reducing peripheral neuropathic pain and is well tolerated in Korean patients with diabetic peripheral neuropathy or postherpetic neuralgia after 12 weeks of treatment.

Comparison of Effect and Contrast Spreading in Transforaminal Epidural Injection Using the Retrodiscal Versus Subpedicular Approach: A Prospective, Randomized Trial.

BACKGROUND: Lumbar transforaminal epidural injection (TFEI) effectively decreases low back pain and radicular pain in herniated intervertebral disc (HIVD) and spinal stenosis (SS). The precise delivery of drugs to the target is important for pain control and minimizing complications. OBJECTIVES: We aimed to evaluate the efficacy and complications of the subpedicular (SP) and retrodiscal (RD) approaches by analysis of contrast spread patterns into the pathologic target on the basis of a newly established specific criterion. We also investigated whether the severity of patients' spinal disease influenced this pattern. STUDY DESIGN: A prospective, randomized, observational study. SETTING: Interventional pain management center at a university-affiliated hospital. METHODS: Among patients who showed lumbar spinal stenosis or HIVD at the L4/5 level, participants were randomly assigned to undergo TFEI with the SP approach (SP group) or RD approach (RD group). Pain relief in terms of the visual analog scale (VAS) score and complications such as intravascular or intradiscal uptake were also analyzed. The contrast image was analyzed as the contrast media was injected, starting from 0.5 mL up to 3.0 mL. The spread patterns of contrast media were graded into 4 categories, which were newly defined in this study. RESULTS: Both groups demonstrated a significant decrease in pain relief (P value < 0.01) at 2 and 4 weeks after the procedures, but no significant difference was found between the 2 groups. In the intergroup analysis between the RD and SP groups, with a 1.5-mL contrast media injection, more patients in the RD group (17.2%) showed a grade 3 spread than those in the SP group (8.2%). In the subgroup analysis, the RD group showed superior spread (more grade 3 and 4) with 1.5-, 2-, and 2.5-mL contrast media injections (P values = 0.02, 0.03, and 0.04) in severe central stenosis, and 1.5- and 2-mL contrast media injections (P values = 0.01, 0.02) in severe foraminal stenosis. LIMITATIONS: The follow-up period was only 4 weeks after TFESI, and higher contrast injection was used for procedures. CONCLUSIONS: The RD approach for TFEI showed a better contrast spreading pattern than the SP approach, especially in patients with severe central and foraminal spinal stenosis. The RD approach might be more beneficial for patients with severe central and foraminal spinal stenosis in the short-term follow-up.

Effect of epidural polydeoxyribonucleotide in a rat model of lumbar foraminal stenosis.

BACKGROUND: We aimed to investigate the effect of epidural polydeoxyribonucleotide (PDRN) on mechanical allodynia and motor dysfunction in a rat model of lumbar foraminal stenosis (LFS). METHODS: This study was conducted in two stages, using male Sprague-Dawley rats. The rats were randomly divided into eight groups. In the first stage, the groups were as follows: vehicle (V), sham (S), and epidural PDRN at 5 (P5), 8 (P8), and 10 (P10) mg/kg; and in the second stage, they were as follows: intraperitoneal PDRN 8 mg/kg, epidural 3,7-dimethyl-1-propargilxanthine (DMPX) (0.1 mg/kg), and DMPX (0.1 mg/kg). The LFS model was established, except for the S group. After an epidural injection of the test solutions, von Frey and treadmill tests were conducted for 3 weeks. Subsequently, histopathologic examinations were conducted in the V, S, P5, and P10 groups. RESULTS: A total of 65 rats were included. The P8 and P10 groups showed significant recovery from mechanical allodynia and motor dysfunction at all time points after drug administration compared to the V group. These effects were abolished by concomitant administration of DMPX. On histopathological examination, no epineurial inflammation or fibrosis was observed in the epidural PDRN groups. CONCLUSIONS: Epidural injection of PDRN significantly improves mechanical allodynia and motor dysfunction in a rat model of LFS, which is mediated by the spinal adenosine A2A receptor. The present data support the need for further research to determine the role of epidural PDRN in spinal stenosis treatment.

Transforaminal Epidural Steroid Injection for Zoster-Related Pain: The Golden Period for the Best Outcome.

BACKGROUND: Zoster-related pain (ZRP) has many negative effects on a patient's quality of life. The transforaminal steroid injection (TFESI), which reduces neural inflammation and pain, has been advocated by pain physicians. Many reports demonstrated that early administration of TFESI showed better efficacy; however, the golden period during which TFESI is most effective remains unclear. OBJECTIVES: This multicentre retrospective cohort study aimed to identify the golden period by which TFESI yields the best outcome in patients with ZRP. STUDY DESIGN: Multicenter, retrospective cohort study. SETTING: University-affiliated hospitals. METHODS: After performing the TFESI in patients with ZRP, the patients were classified into two groups: the effective group (E) and the not effective group (N) based on the changes in the pain intensity 3 months after the TFESI. The receiver operating characteristic (ROC) curve analysis was used to assess the cut-off time point for predicting TFESI effectiveness. Furthermore, a logistic regression analysis was performed to identify patients' factors associated with a successful treatment outcome. RESULT: Of the 302 patients, 186 and 116 patients were classified into the E and N group, respectively. ROC curve analysis showed that the best cut-off time point for TFESI was 12 weeks (95% confidence interval [CI]; 10-14 weeks) after the onset of HZ. The only variable associated with a favorable outcome was a symptom duration of ? 12 weeks compared with > 12 weeks (Odd ratio, 0.107; 95% CI, 0.055-0.205; P < 0.001). Other patient variables were not significantly associated with the effectiveness of TFESI. TFESI was most effective when administered within 12 weeks of the onset of herpes zoster. LIMITATION: This study was not a prospective randomized controlled trial (RCT) and the follow-up period was only 3 months after TFESI. CONCLUSION: TFESI is more effective when administered within 12 weeks of onset of herpes zoster.

Non-Particulate Steroids (Betamethasone Sodium Phosphate, Dexamethasone Sodium Phosphate, and Dexamethasone Palmitate) Combined with Local Anesthetics (Ropivacaine, Levobupivacaine, Bupivacaine, and Lidocaine): A Potentially Unsafe Mixture.

PURPOSE: Particulate steroids used in epidural steroid injections have been suspected as a cause of post-procedural embolic events. Some particulate steroids have been suspended only when the transforaminal approach is used for an epidural block of the spine. In contrast, non-particulate steroids are generally accepted for safety during epidural steroid injections. However, the safety of using a mixture of non-particulate steroids and local anesthetics is unknown. This study analyzed whether mixtures of commonly used non-particulate steroids and local anesthetics form crystals in solution. METHODS: We mixed non-particulate steroids (betamethasone sodium phosphate, dexamethasone sodium phosphate, and dexamethasone palmitate) and local anesthetics (ropivacaine, levobupivacaine, bupivacaine, and lidocaine) at different ratios. We used fluorescence microscopy to observe whether crystals formed in mixed solutions; we also measured the pH of each steroid, local anesthetic, and the mixtures. RESULTS: Ropivacaine or levobupivacaine and betamethasone sodium phosphate produced large crystals (>50 µm). Ropivacaine or levobupivacaine and dexamethasone sodium phosphate produced small crystals (<10 µm). Lidocaine and all non-particulate steroids produced no identifiable crystals; dexamethasone palmitate and all local anesthetics did not form significant particulates. Betamethasone sodium phosphate and dexamethasone sodium phosphate demonstrated basic pH, while all local anesthetics demonstrated acidic pH. Mixtures showed a wide pH range. CONCLUSION: Non-particulate steroids can form crystals upon combination with local anesthetics. Crystal formation may be caused by alkalinization of steroids. The mixing of ropivacaine or levobupivacaine and betamethasone sodium phosphate may require caution during an epidural steroid injection. Lidocaine or bupivacaine is recommended as a local anesthetic. Dexamethasone palmitate is a candidate for a mixture, but additional studies on its safety and effectiveness are needed.

The influence of moderate or deep neuromuscular block status on anesthetic depth monitoring system during total intravenous anesthesia using propofol and remifentanil: A randomized trial.

The neuromuscular block state may affect the electroencephalogram-derived index representing the anesthetic depth. We applied an Anesthetic Depth Monitoring for Sedation (ADMS) to patients undergoing laparoscopic cholecystectomy under total intravenous anesthesia, and evaluated the requirement of propofol according to the different neuromuscular block state. Adult patients scheduled to undergo laparoscopic cholecystectomy were enrolled and randomly assigned to either the moderate (MB) or deep neuromuscular block (DB) group. The UniCon sensor of ADMS was applied to monitor anesthetic depth and the unicon value was maintained between 40 and 50 during the operation. According to the group assignment, intraoperative rocuronium was administered to maintain proper neuromuscular block state, moderate or deep block state. The unicon value, electromyography (EMG) index, and total dose of propofol and rocuronium were analyzed. At similar anesthetic depth, less propofol was used in the DB group compared to the MB group (6.19 ± 1.36 in the MB mg/kg/h group vs 4.93 ± 3.02 mg/kg/h in the DM group, p = 0.042). As expected, more rocuronium were used in the DB group than in the MB group (0.8 ± 0.2 mg/kg in the MB group vs 1.2 ± 0.2 mg/kg in the DB group, p = 0.023) and the EMG indices were lower in the DB group than in the MB group, at several time points as follows: at starting operation (p < 0.001); at 15 (p = 0.019), 45 (p = 0.011), and 60 min (p < 0.001) after the initiation of the operation; at the end of operation (p = 0.003); and at 5 min after the administration of sugammadex (p < 0.001). At similar anesthetic depth, patients under the deep neuromuscular block state required less propofol with lower intraoperative EMG indices compared to those under the moderate neuromuscular block state during general anesthesia.

Efficacy and Safety of the Controlled-release Pregabalin Tablet (GLA5PR GLARS-NF1) and Immediate-release Pregabalin Capsule for Peripheral Neuropathic Pain: A Multicenter, Randomized, Double-blind, Parallel-group, Active-controlled, Phase III Clinical Trial.

PURPOSE: This study compared the efficacy and safety of controlled-release pregabalin (GLA5PR GLARS-NF1 tablets) with those of an immediate-release pregabalin capsule after 12 weeks' administration to patients with peripheral neuropathic pain. METHODS: In this multicenter, randomized, double-blind, active-controlled, parallel-group, Phase III study, the primary outcome was to confirm that a single treatment with the study drug (after the evening meal) is clinically noninferior to the control drug (BID regimen) at improving the mean Daily Pain Rating Scale score for treating peripheral neuropathic pain. Secondary outcomes were the Daily Sleep Interference Scale, Medical Outcomes Study Sleep Scale, Hospital Anxiety and Depression scale, and frequency of rescue medication use. The safety and tolerability of GLA5PR GLARS-NF1 tablets were also evaluated. The total daily dose of pregabalin is 150-600 mg. FINDINGS: Of the 352 randomized subjects, 261 (n = 130, study group; n = 131, control group) were analyzed. The difference in adjusted mean Daily Pain Rating Scale scores between the groups was -0.11 (95% confidence interval, -0.05 to 0.30), indicating that the study group is noninferior to the control group. There was no statistically significant difference in Daily Sleep Interference Scale, Medical Outcomes Study Sleep Scale, and Hospital Anxiety and Depression scale scores between the groups at treatment termination. Logistic regression analysis revealed no significant difference in the use of rescue medication between the groups (P = 0.217). The overall adverse event profile of the groups was similar, and no serious adverse drug reactions were observed. IMPLICATIONS: GLA5PR GLARS-NF1 tablets can be effectively and safely administered to patients with peripheral neuropathic pain. Furthermore, we found that sleep, anxiety, and depression were improved with pain control. Owing to the once-daily administration, treatment effects can be maximized by improved treatment compliance. ClinicalTrials.gov identifier: NCT03221907.

Topical agents: a thoughtful choice for multimodal analgesia.

For over a thousand years, various substances have been applied to the skin to treat pain. Some of these substances have active ingredients that we still use today. However, some have been discontinued due to their harmful effect, while others have been long forgotten. Recent concerns regarding the cardiovascular and renal risk from nonsteroidal anti-inflammatory drugs, and issues with opioids, have resulted in increasing demand and attention to non-systemic topical alternatives. There is increasing evidence of the efficacy and safety of topical agents in pain control. Topical analgesics are great alternatives for pain management and are an essential part of multimodal analgesia. This review aims to describe essential aspects of topical drugs that physicians should consider in their practice as part of multimodal analgesia. This review describes the mechanism of popular topical analgesics and also introduces the most recently released and experimental topical medications.

Recombinant zoster vaccine (Shingrix®): a new option for the prevention of herpes zoster and postherpetic neuralgia.

Postherpetic neuralgia (PHN) is a challenging condition for pain management specialists. The prevention of herpes zoster (HZ) and subsequent PHN in individuals aged 50 years and older, via the development of new vaccines, is an ongoing research project. The live zoster vaccine (LZV, Zostavax®) was the first proof of concept that vaccination could prevent HZ, but LZV cannot be used in various immunecompromised patients. This led to the development of a new non-live recombinant zoster vaccine (RZV, Shingrix®). This RZV has shown promising results in many clinical trials, with high reactogenicity and similar systemic adverse effects compared to those of LZV. The National Advisory Committee on Immunization has recommended LZV as a standard vaccine for HZ prevention in adults ≥ 50 years of age, but no studies directly comparing the safety and efficacy of RZV and LZV vaccines have been conducted. This article reviews the brief history, efficacy, and safety of the two vaccines and discusses the advantage of RZV over LZV based on the available literature.

Increased calcium-mediated cerebral processes after peripheral injury: possible role of the brain in complex regional pain syndrome.

BACKGROUND: Among various diseases that accompany pain, complex regional pain syndrome (CRPS) is one of the most frustrating for patients and physicians. Recently, many studies have shown functional and anatomical abnormalities in the brains of patients with CRPS. The calcium-related signaling pathway is important in various physiologic processes via calmodulin (CaM) and calcium-calmodulin kinase 2 (CaMK2). To investigate the cerebral mechanism of CRPS, we measured changes in CaM and CaMK2 expression in the cerebrum in CRPS animal models. METHODS: The chronic post-ischemia pain model was employed for CRPS model generation. After generation of the animal models, the animals were categorized into three groups based on changes in the withdrawal threshold for the affected limb: CRPS-positive (P), CRPS-negative (N), and control (C) groups. Western blot analysis was performed to measure CaM and CaMK2 expression in the rat cerebrum. RESULTS: Animals with a decreased withdrawal threshold (group P) showed a significant increment in cerebral CaM and CaMK2 expression (P = 0.013 and P = 0.021, respectively). However, groups N and C showed no difference in CaM and CaMK2 expression. CONCLUSIONS: The calcium-mediated cerebral process occurs after peripheral injury in CRPS, and there can be a relationship between the cerebrum and the pathogenesis of CRPS.

Psychological Characteristics in Patients with Chronic Complex Regional Pain Syndrome: Comparisons with Patients with Major Depressive Disorder and Other Types of Chronic Pain.

OBJECTIVE: This study investigated psychological characteristics of patients with chronic complex regional pain syndrome (CRPS) and examined relationships between psychosocial factors and pain severity. METHODS: In total, 76 patients with CRPS, 95 patients with other types of chronic pain, 171 healthy controls, and 66 patients with major depressive disorder (MDD) were included. Minnesota Multiphasic Personality Inventory (MMPI-2) profiles and scores on the Beck Depression Inventory and State-Trait Anxiety Inventory were calculated. Pain intensity was measured using a visual analog scale (VAS). RESULTS: Patients with CRPS scored higher on the Hypochondriasis (Hs), Depression (D), Hysteria (Hy), Paranoia (Pa), and Psychasthenia (Pt) scales of the MMPI-2 compared to healthy controls. The CRPS group scored lower on the D, Psychopathic deviate (Pd), Pa, Pt, Schizophrenia (Sc), and Social introversion (Si) scales compared to the MDD group. Although CRPS patients reported higher levels of pain than patients with other types of pain, the MMPI profiles of the two pain groups did not differ significantly. Linear regression analyses revealed that pain severity was significantly associated with depression and scores on the Masculinity-Femininity (Mf) scale. CONCLUSION: This is the first comparative study of the psychological characteristics of chronic CRPS patients, healthy controls, and patients with MDD. The neurotic profiles of CRPS patients were more psychologically adaptable than were those of patients with MDD; however, this profile was shared by both pain groups. The present findings further showed that, although pain severity was not a major contributor to depression, patients with CRPS should be evaluated for depressive symptoms.

Pulsed Radiofrequency Ablation of the C2 Dorsal Root Ganglion Using a Posterior Approach for Treating Cervicogenic Headache: A Retrospective Chart Review.

OBJECTIVE: To evaluate the efficacy and complications of C2 dorsal root ganglion (DRG) pulsed radiofrequency ablation (RFA) for cervicogenic headache (CEH) and to identify factors related to the outcome of the procedure in this retrospective analysis. BACKGROUND: Although conventional high-temperature C2 DRG RFA was effective in patients with CEH in previous studies, the effect of pulsed RFA on C2 DRG in cases of CEH has not yet been evaluated. METHODS: We examined the electronic medical records of consecutive patients who underwent C2 DRG block for CEH from January 2012 to May 2018 at a pain center. Consequent C2 DRG pulsed RFA was performed for patients in whom the headache recurred after an initial period of relief 24 hours after the C2 DRG block. A successful outcome was defined as at least 50% pain relief at 6 months after C2 DRG pulsed RFA. We also examined variables associated with the outcome and prognostic factors of CEH. RESULTS: Fluoroscopy-guided C2 DRG block was performed in 114 patients with CEH. Forty-five patients received C2 DRG pulsed RFA and 40.0% among them (18/45, success group) had ≥50% pain relief after 6 months. There were no post-procedure complications throughout the study period. Significantly more patients in the success group than in the failure group had a definite positive response (≥50% pain relief) to a previous C2 DRG block (P < .001). CONCLUSION: C2 DRG pulsed RFA may be an effective treatment for patients with CEH, particularly for patients who have previously experienced definite pain reduction after C2 DRG block. However, the limitations of our study design and small number of patients preclude firm conclusions.

Radiation exposure to the eyes and thyroid during C-arm fluoroscopy-guided cervical epidural injections is far below the safety limit.

BACKGROUND: The aim of this study was to evaluate radiation exposure to the eye and thyroid in pain physicians during the fluoroscopy-guided cervical epidural block (CEB). METHODS: Two pain physicians (a fellow and a professor) who regularly performed C-arm fluoroscopy-guided CEBs were included. Seven dosimeters were used to measure radiation exposure, five of which were placed on the physician (forehead, inside and outside of the thyroid protector, and inside and outside of the lead apron) and two were used as controls. Patient age, sex, height, and weight were noted, as were radiation exposure time, absorbed radiation dose, and distance from the X-ray field center to the physician. RESULTS: One hundred CEB procedures using C-arm fluoroscopy were performed on comparable patients. Only the distance from the X-ray field center to the physician was significantly different between the two physicians (fellow: 37.5 ± 2.1 cm, professor: 41.2 ± 3.6 cm, P = 0.03). The use of lead-based protection effectively decreased the absorbed radiation dose by up to 35%. CONCLUSIONS: Although there was no difference in radiation exposure between the professor and the fellow, there was a difference in the distance from the X-ray field during the CEBs. Further, radiation exposure can be minimized if proper protection (thyroid protector, leaded apron, and eyewear) is used, even if the distance between the X-ray beam and the pain physician is small. Damage from frequent, low-dose radiation exposure is not yet fully understood. Therefore, safety measures, including lead-based protection, should always be enforced.

Kambin's Triangle Approach versus Traditional Safe Triangle Approach for Percutaneous Transforaminal Epidural Adhesiolysis Using an Inflatable Balloon Catheter: A Pilot Study.

Spinal stenosis is a common condition in elderly individuals. Many patients are unresponsive to the conventional treatment. If the transforaminal epidural block does not exert a sufficient treatment effect, percutaneous transforaminal epidural adhesiolysis (PTFA) through the safe-triangle approach using an inflatable balloon catheter can reduce the patients' pain and improve their functional capacity. We aimed to evaluate the safety and efficacy of the Kambin's-triangle approach for PTFA using an inflatable balloon catheter and compare this approach to the traditional safe-triangle approach. Thirty patients with chronic unilateral L5 radiculopathy were divided into two groups: the safe-triangle-approach and Kambin's-triangle-approach groups, with 15 patients each. The success rate of the procedure was assessed. Pain and dysfunction were assessed using the Numerical Rating Scale and Oswestry Disability Index, respectively, before the procedure and at 1 and 3 months after the procedure. The success rate of the procedure was high in both the groups, with no significant difference between the groups. The Numerical Rating Scale and Oswestry Disability Index scores significantly decreased 3 months after the procedure in both the groups, with no significant difference between the groups. For patients in whom the safe-triangle approach for PTFA is difficult, the Kambin's-triangle approach could be an alternative.