Comparing the Efficacy of Dorsal Root Ganglion Stimulation With Conventional Medical Management in Patients With Chronic Postsurgical Inguinal Pain: Post Hoc Analyzed Results of the SMASHING Study.

OBJECTIVES: Approximately 10% of patients who undergo inguinal hernia repair or Pfannenstiel incision develop chronic (> three months) postsurgical inguinal pain (PSIP). If medication or peripheral nerve blocks fail, a neurectomy is the treatment of choice. However, some patients do not respond to this treatment. In such cases, stimulation of the dorsal root ganglion (DRG) appears to significantly reduce chronic PSIP in selected patients. MATERIALS AND METHODS: In this multicenter, randomized controlled study, DRG stimulation was compared with conventional medical management (CMM) (noninvasive treatments, such as medication, transcutaneous electric neurostimulation, and rehabilitation therapy) in patients with PSIP that was resistant to a neurectomy. Patients were recruited at a tertiary referral center for groin pain (SolviMáx, Eindhoven, The Netherlands) between March 2015 and November 2016. Suitability for implantation was assessed according to the Dutch Neuromodulation Association guidelines. The sponsor discontinued the study early owing to slow enrollment. Of 78 planned patients, 18 were randomized (DRG and CMM groups each had nine patients). Six patients with CMM (67%) crossed over to DRG stimulation at the six-month mark. RESULTS: Fifteen of the 18 patients met the six-month primary end point with a complete data set for a per-protocol analysis. Three patients with DRG stimulation had a negative trial and were lost to follow-up. The average pain reduction was 50% in the DRG stimulation and crossover group (from 6.60 ± 1.24 to 3.28 ± 2.30, p = 0.0029). Conversely, a 13% increase in pain was observed in patients with CMM (from 6.13 ± 2.24 to 6.89 ± 1.24, p = 0.42). Nine patients with DRG stimulation experienced a total of 19 adverse events, such as lead dislocation and pain at the implantation site. CONCLUSIONS: DRG stimulation is a promising effective therapy for pain relief in patients with PSIP resistant to conventional treatment modalities; larger studies should confirm this. The frequency of side effects should be a concern in a new study. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT02349659.

Ketamine therapy for chronic pain in The Netherlands: a nationwide survey.

OBJECTIVES: Ketamine is used to treat chronic refractory pain. However, there are no scientific guidelines for ketamine use in the Netherlands. The aim of this survey was to provide an overview of the use of ketamine for chronic pain in the Netherlands. METHODS: All pain clinics in the Netherlands were contacted. A digital survey, available from June 2019 to January 2020, was sent to 68 pain clinics. The survey was completed by one pain physician as a representative of the entire pain department. The survey included questions about ketamine treatment indications, administration, dose, duration, treatment repetition and the inpatient or outpatient setting. RESULTS: The survey was completed by 51 pain clinics (75.0%). Thirty-one clinics used ketamine for chronic pain treatment. The most common indication was Complex Regional Pain Syndrome (83.9%). Pain clinics administered ketamine via intravenous infusions (96.8%), iontophoresis (61.3%), subcutaneous (3.2%) or oral administration (3.2%). Intravenous ketamine treatment was offered in an inpatient setting in 14 pain clinics, in both an inpatient and outpatient setting in 11 pain clinics and in six pain clinics in an outpatient setting. In the outpatient setting, the median starting dose was 5 mg/h (IQR=17.5-5). The median maximum dose was 27.5 mg/h (IQR=100-11.9). The median infusion duration was 6 h (IQR=8-4). In the inpatient setting, the median starting dose was 5 mg/h (IQR=5-1.5) and the median maximum dose was 25 mg/h (IQR=25-14). Patients were admitted to hospital for a median of 4 days (IQR=5-1). CONCLUSIONS: The results of this Dutch nationwide survey study show that there are heterogeneous treatment protocols with different indications, treatment setting and dosing regimen for the treatment of chronic pain with ketamine. This study encourages the formulation of a broader consensus and the development of evidence based guidelines for ketamine treatment.

Long-Term Effects of Dexmedetomidine versus Propofol During the Implantation of a Neurostimulator-A Post-Trial Follow-Up Analysis.

OBJECTIVE: The success of neurostimulation depends partly on the amount of coverage of the neurostimulation-induced paresthesia of the painful area. This is often achieved by asking feedback from patients intraoperatively. If sedation analgesia is used, it is important that the patient is comfortable during sedation and easily arousable. If the patient is not well sedated or experiences residual effects of the sedation during testing, this can directly influence the ideal placement of the leads and indirectly the long-term effect of the treatment. It is our hypothesis that the quality of the sedation is directly coupled to the adequacy of lead placement and in this way in the result of the treatment. Dexmedetomidine is known for its easy production of arousable sedation. The aim of the present study was to compare the long-term effect of using dexmedetomidine versus propofol during the implantation of a neurostimulator. MATERIALS AND METHODS: This is a post-trial follow-up analysis of the DexMedPro cohort. The primary outcome was global perceived effect (GPE). The secondary outcomes were the course of pain intensity, the emotional and physical functioning at the time of follow-up, and the course of neurostimulation treatment. In this study, we used the patient satisfaction with sedation as a measure for sedation quality. RESULTS: Regarding the GPE, no statistically significant differences were found between the experimental groups in either subscale (ie, recovery (p=0.82) and satisfaction with the neurostimulation treatment at follow-up (p=0.06)). The same was found regarding the secondary parameters. A correlation was found between patient satisfaction with sedation during the lead implantation (side effects and procedural recall) and satisfaction at follow-up. CONCLUSION: Regarding the long-term efficacy of neurostimulation treatment, no statistically significant differences were found between the dexmedetomidine and the propofol group. We observed a trend towards greater satisfaction with the neurostimulation treatment at follow-up in the dexmedetomidine group, compared to the propofol group.

Effect of intravenous low-dose S-ketamine on pain in patients with Complex Regional Pain Syndrome: A retrospective cohort study.

OBJECTIVE: The objective of this study was to assess the effectiveness of a low-dose intravenous S-ketamine treatment on refractory pain in patients with Complex Regional Pain Syndrome (CRPS). METHODS: In this retrospective study, patients with CRPS who received intravenous S-ketamine from March 2010 to April 2019 were included. According to our inpatient protocol, S-ketamine dose was increased until pain reduction was achieved or side effects were observed. Maximum dose was 14 mg/h and treatment duration was 7 days. Primary outcome parameters were pain scores (Numeric Rating Scale) at baseline (T0), end of infusion (T1), and approximately 4 weeks postinfusion (T2). Patients were categorized as responder/nonresponder at T1 and T2. Patients were considered a responder in case there was pain score reduction of greater than or equal to 2 points or if treatment was reported as successful. RESULTS: Forty-eight patients were included. Mean disease duration was 5 years (interquartile range [IQR] = 6 years). Median pain score significantly decreased from 8 (IQR = 2) at T0 to 6 (IQR = 4) at T1 (p < 0.001). At T1, 62% of the patients were responders. At T2, 48% of the patients remained a responder. A significant proportion of the responders at T1 turned into nonresponders at T2 (p = 0.03). CONCLUSION: In a group of patients with CRPS with refractory pain, low-dose intravenous S-ketamine treatment resulted in effective pain relief during infusion. Although a significant proportion of initial responders became nonresponders at follow-up, half of the patients were still a responder at ~ 4 weeks postinfusion. Further research is needed to investigate mechanisms responsible for pain relief by S-ketamine infusions and to ascertain possible predictors of response to the treatment.

The Relation Between Patients' Beliefs About Pain Medication, Medication Adherence, and Treatment Outcome in Chronic Pain Patients: A Prospective Study.

OBJECTIVES: Nonadherence to prescribed pain medication is common in chronic noncancer pain patients. Beliefs about pain medication have been reported to be associated with nonadherence behavior in cross-sectional studies. The aim of this study was to prospectively investigate the relationship between patients' beliefs about pain medication and their medication adherence and treatment outcome. METHODS: Chronic noncancer pain patients completed a baseline questionnaire including the 47-item Pain Medication Attitudes Questionnaire, consisting of 7 subscales with regards to beliefs on prescribed medication. After 11 weeks, medication underuse and overuse were assessed by self-report. In addition, patient satisfaction with regards to the effect of prescribed pain medication and satisfaction as regards prescribed medication and care, and the burden of side effects were assessed. RESULTS: A total of 133 participants completed the baseline questionnaire, and 99 patients completed the follow-up questionnaire. Concerns over side effects at baseline were positively associated with underuse and the presence of side effects after 11 weeks. The perceived need was positively associated with overuse, whereas concerns over addiction were negatively associated with overuse. Concerns over tolerance were negatively associated with patient satisfaction with medication effects after 11 weeks. Concerns over tolerance and mistrust in the prescribing doctor were negatively associated with satisfaction about medication and care. CONCLUSION: Attitudes and concerns toward pain medication are associated with adherence patterns and outcome parameters. To improve medication adherence and therapy outcome, patient beliefs about pain medication should be taken into account by providing tailored education, adequate follow-up, or alternate therapy.

Survey on sedation-analgesia regimens, in particular the use of dexmedetomidine, among Dutch implanters of spinal cord neurostimulators.

BACKGROUND AND AIMS: During implantation of most spinal cord neurostimulators, patients need to be cooperative to give feedback during lead placement, and also be comfortable. Sedation and analgesia can support these conditions. This survey aimed to provide an overview of the sedation-analgesia regimens currently used among Dutch pain specialists. The survey focused on the sedative agent "dexmedetomidine" due to its attractive pharmacological profile and its promising results during awake procedures. METHODS: A 27-item survey was sent to the 65 pain specialists involved in neurostimulation in the Netherlands. The survey consisted of questions related to different aspects of sedation and analgesia during neurostimulation, e.g. the current regimen, the opinion on and experience with dexmedetomidine as a sedative agent, and preferences regarding different aspects of sedation (i.e. production of arousable sedation, pain management, quality of patient's feedback and overall preference). RESULTS: Of 65 pain specialists, 45 (69%) completed the survey. Most commonly used sedative was propofol (91%) and most common used analgesic was remifentanil (78%). Of the 45 respondents, 21 (47%) considered the use of dexmedetomidine, whereas 13 (29%) had experience with dexmedetomidine during neurostimulation. The most frequently mentioned positive property of dexmedetomidine was the easy production of arousable sedation. Most respondents who used dexmedetomidine preferred dexmedetomidine sedation over propofol sedation regarding all aspects of sedation. CONCLUSIONS: The most commonly used sedation-analgesia regimen is the combination of propofol-remifentanil during the implantation of a neurostimulator among Dutch pain specialists. Only a small percentage of respondents had experience with the use of dexmedetomidine, despite its reported advantages. IMPLICATIONS: When implanting a spinal cord neurostimulator, dexmedetomidine could be considered as a sedative, given its allowance for and preservation of a state of easy arousable sedation.

Dexmedetomidine vs propofol as sedation for implantation of neurostimulators: A single-center single-blinded randomized controlled trial.

BACKGROUND: During the lead implantation of most spinal cord neurostimulators, the patient has to be comfortable and without pain. However, the patient is expected to provide feedback during electrical mapping. Titrating sedatives and analgesics for this double goal can be challenging. In comparison with our standard sedative agent propofol, the pharmacological profile of dexmedetomidine is more conducive to produce arousable sedation. The latter, however, is associated with hemodynamic side effects. We investigated whether dexmedetomidine is preferable over propofol during neurostimulator implantation. METHODS: This single-center single-blinded randomized controlled trial included 72 patients with an indication for a neurostimulator, randomized to sedation with either propofol (0.5 mg/kg for 10 minutes, followed by 2.0 mg/kg/h) or dexmedetomidine (1 µg/kg for 10 minutes, followed by 0.6 µg/kg/h). The primary outcome was patient satisfaction with the sedation. The secondary outcomes were patient's and operator's comfort, number of titration adjustments, standard intraoperative hemodynamic and respiratory parameters and side effects. RESULTS: Data of 69 patients (dexmedetomidine n = 35; propofol n = 34) were analyzed. Those receiving dexmedetomidine were more satisfied with the sedation than those receiving propofol; i.e. with sedation delivery (median 100.0 vs 83.3, P < .01), procedural recall (median 95.8 vs 83.3, P = .03), and sedation side effects (median 90.0 vs 83.3, P = .01). Fewer changes in the dexmedetomidine titration were necessary to maintain arousable sedation. Over time, mean arterial pressure and heart rate were significantly lower in the dexmedetomidine group. Hemodynamic side effects were comparable across groups. CONCLUSIONS: Dexmedetomidine sedation resulted in higher patient satisfaction and allowed for better arousable sedation than sedation with propofol. Although differences in hemodynamic parameters were found between the groups, these differences were not regarded as clinically relevant.

Clinical Course and Impact of Complex Regional Pain Syndrome Confined to the Knee.

OBJECTIVE: Although complex regional pain syndrome (CRPS) of the knee is comparable to CRPS of the ankle/foot at time of diagnosis, no reports are available concerning the course of knee CRPS. Therefore, this study investigated the clinical course in terms of the symptoms and signs, health-related quality of life (HR-QoL), and work status of patients diagnosed with CRPS of the knee. DESIGN: Observational, descriptive study. SETTING: Single-center study. SUBJECTS: Patients with CRPS of the knee. METHODS: Patients self-reported their past and current CRPS symptoms, HR-QoL, and work status; all underwent a physical examination. A comparison was made of changes in symptoms over time between patients with CRPS of the knee and those with CRPS of more distal locations. RESULTS: In total, 32 patients were enrolled. The follow-up time was 11.5 ± 6.29 years since diagnosis, and symptoms and signs showed a significant decrease over time. Twelve patients (37.5%) rated their health as (generally) positive. Patients who were still able to work (31.3%) stated that their physical health gave them at least some problems in the performance of their job. A change in symptoms occurred significantly less often in CRPS of the knee. CONCLUSIONS: CRPS of the knee changes in terms of symptoms over time, but significantly less than CRPS of other locations. A change in work status was reported in 82% of the patients due to their CRPS, and in 91%, the pain interfered with their daily life. CRPS of the knee is a painful condition with persistent symptoms causing a diminished HR-QoL.

Adding steroids to lidocaine in a therapeutic injection regimen for patients with abdominal pain due to anterior cutaneous nerve entrapment syndrome (ACNES): a single blinded randomized clinical trial.

Background and aims Anterior cutaneous nerve entrapment syndrome (ACNES) may result in chronic abdominal pain. Therapeutic options include local injection therapy. Data on the efficacy of adding corticosteroids to these injections is lacking. Methods Patients ≥18 years with ACNES were randomized to receive an injection of lidocaine with (LC-group) or without (LA-group) the addition of methylprednisolone into the point of maximal abdominal wall pain. Pain was recorded using a numeric rating scale (NRS: 0-10) and a verbal rating scale (VRS: 0=no pain, 5=unbearable pain) at baseline and 6 weeks after the start of a bi-weekly injection regimen consisting of a total of three injections. A minimal 50% reduction on NRS and/or two points on VRS were considered successful responses. Results Between February 2014 and August 2016, 136 patients (median age 46 year, range 18-79, 75% females) were randomized (68 vs. 68). The proportion of patients demonstrating a successful response after 6 weeks did not significantly differ between groups (LA 38%, LC 31%, p=0.61). At 12 weeks, the number of patients still experiencing a minimal 50% pain relief had decreased but no group difference was observed (LA 20%, LC 18%, p=0.80). Minor side effects included temporary increase of pain, tenderness at injection sites or transient malaise (LA23/68, LC 29/68, p=0.46). Conclusions Adding corticosteroids to a lidocaine does not increase the proportion of ACNES patients with a successful response to injection therapy. Lidocaine alone can provide long term pain relief after one or multiple injections, in approximately 1 of 5 patients.

Dorsal Column Stimulation vs. Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome Confined to the Knee: Patients' Preference Following the Trial Period.

BACKGROUND AND OBJECTIVES: Patients with complex regional pain syndrome (CRPS) confined to the knee are often therapy resistant. Neurostimulation is an accepted treatment for CRPS. Although results with dorsal column (DC) stimulation in patients with CRPS confined to the knee are often disappointing, the availability of dorsal root ganglion (DRG) stimulation may provide new opportunities for this complaint. Therefore, this study explores patients' preference for DC stimulation vs. DRG stimulation in treating chronic pain due to CRPS confined to the knee. METHODS: A prospective, observational crossover cohort study was conducted comparing 2 methods of neurostimulation, in randomized order, in patients with CRPS confined to the knee. After receiving DC and DRG stimulation during a trial period of 16 days, patients were asked which of the 2 methods they preferred. Patients with a successful trial period with one or both stimulation methods received a fully implantable system. RESULTS: Twelve patients were included. After finishing the trial period, 10 patients (83.3%) preferred DRG stimulation and 2 (16.7%) preferred DC stimulation (P = 0.04). CONCLUSION: To our knowledge, this is the first study to compare these 2 neurostimulation methods in patients with CRPS confined to the knee. Results show that the probability of the preference for either neurostimulation treatment significantly deviates from chance in favor of DRG stimulation.

Spinal Cord Stimulation in Patients With Complex Regional Pain Syndrome: A Possible Target for Immunomodulation?

OBJECTIVE: Complex regional pain syndrome (CRPS) is characterized by continued pain disproportional to the inciting event, sensory abnormalities, vasomotor and sudomotor disturbances, and motor and trophic changes. Inflammatory involvement has been demonstrated in past CRPS studies resulting in pain, swelling, and warmth. Currently, it is unknown whether spinal cord stimulation (SCS) has immunomodulatory properties. The aim of this study was to determine whether SCS has immunomodulatory properties in CRPS patients. METHODS: The primary outcome parameters are cytokines (IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, IL-15, IL-17, TNF-α, IFN-γ), chemokines (IP-10 and Eotaxin), and growth factors (VEGF, PDGFbb, and basic FGF) from interstitial fluid of artificial skin blisters before (T0-baseline without SCS) and after SCS therapy (T1-40 Hz standard frequency stimulation and T2-preferred frequency stimulation). Secondary outcome parameters were baseline demographics, CRPS signs, symptoms, and phenotype (inflammatory, vasomotor, dystonia, or neuropathic). Results were analyzed by means of a MANOVA repeated measures design. RESULTS: After SCS, the expression of both pro- and anti-inflammatory cytokines decreased over time in both the CRPS affected extremity and the contralateral extremity. The levels of IP-10, Eotaxin, VEGF, and PDGFbb were also significantly reduced bilaterally. There were no significant changes in IL-6 and TNF-α before and after SCS. The sensory signs, symptoms, and phenotype improved after SCS. DISCUSSION: SCS in CRPS patients attenuates T-cell activation, improves peripheral tissue oxygenation and decreases anti-angiogenetic activity which results in diminished endothelial dysfunction and improved bloodflow. The possible immunomodulatory effects of SCS opens new therapeutic possibilities in diseases with the involvement of the immune system and vasomotor disturbances, and requires further research on these mechanisms of action.

Elevated Plasma Levels of sIL-2R in Complex Regional Pain Syndrome: A Pathogenic Role for T-Lymphocytes?

The immune system has long been thought to be involved in the pathophysiology of complex regional pain syndrome (CRPS). However, not much is known about the role of the immune system and specifically T-cells in the onset and maintenance of this disease. In this study, we aimed to evaluate T-cell activity in CRPS by comparing blood soluble interleukin-2 receptor (sIL-2R) levels between CRPS patients and healthy controls. CRPS patients had statistically significant elevated levels of sIL-2R as compared to healthy controls (median sIL-2R levels: 4151 pg/ml (Q3 - Q1 = 5731 pg/ml - 3546 pg/ml) versus 1907 pg/ml (Q3 - Q1: 2206 pg/ml - 1374 pg/ml), p < 0.001, resp.). Furthermore, sIL-2R level seems to be a good discriminator between CRPS patients and healthy controls with a high sensitivity (90%) and specificity (89.5%). Our finding indicates increased T-cell activity in patients with CRPS. This finding is of considerable relevance as it could point towards a T-cell-mediated inflammatory process in this disease. This could pave the way for new anti-inflammatory therapies in the treatment of CRPS. Furthermore, sIL-2R could be a promising new marker for determining inflammatory disease activity in CRPS.

The design of a theory-based intervention to improve medication adherence in chronic pain patients.

OBJECTIVE: Non-adherence to pain medication is common in chronic pain patients and may result in unfavorable treatment outcomes. Interventions to improve adherence behavior often fail to significantly change medication use. In this report, we describe the application of a theoretical psychological model of behavior change in order to design an intervention to improve medication adherence in chronic pain patients. METHODS: This study applies the Behavior Change Wheel framework and the Behavior Change Techniques Taxonomy to design a theory-based intervention to improve pain medication use. Available literature was used to extract determinants of adherence in chronic pain patients. RESULTS: Selected target behaviors to improve medication adherence are: share agreement on follow up policy, monitor medication adherence, provide patient education routinely, discuss attitudes and concerns towards pain medication, develop medication taking habits and use medication reminders. The intervention consists of three components in which relevant behavior change techniques are applied: (1) changes in the electronic patient data management systems to enable medical staff to apply target behaviors; (2) bi-annual education of medical staff to commit the team to the proposed intervention and provide feedback; (3) routine and mandatory education of chronic pain patients following prescription of pain medication. CONCLUSIONS: To improve medication adherence in chronic pain patients, most interventions should be focused on providers of pain therapy. Prescribing chronic pain medication should be seen as part of a larger treatment regimen including adequate follow-up, adherence monitoring and patient education during the course of treatment.

Dexmedetomidine as a Sedative in the Awake Implantation of a Neuromodulative System.

OBJECTIVE: During implantation of a neuromodulative system, high patient satisfaction is closely associated with the equilibrium between an effective analgesia and sedation regimen, and the possibility for the patient to be awake and cooperative during procedure. This study assessed the efficacy of the sedative dexmedetomidine to achieve this balance, with patient satisfaction as the primary outcome. METHODS: Ten patients undergoing implantation of a dorsal column and dorsal root ganglion stimulator received dexmedetomidine (1 mcg/kg over 10 minutes, followed by 0.6 mcg/kg/hour) in combination with remifentanil at a set dose (3 mcg/kg/hour). Sedation was titrated to a Ramsay Sedation Score of 3. Recorded were as follows: patient satisfaction score, patient comfort score, operator comfort score, pain score, rescue medication and number of adjustments of dexmedetomidine intra-operatively, as well as sedation level, hemodynamic (blood pressure and heart rate), and respiratory characteristics (SpO2 ). RESULTS: Scores were high on patient satisfaction (median 8.5; IQR 2.0), patient comfort (3.0; IQR 1.25), and operator comfort (4.0; IQR 1.0). In all patients, intra-operative heart rate and mean arterial pressure were lower compared with baseline values. No respiratory depression or other complications related to anesthesia were reported. Moments of incident pain were effectively treated in 6 patients requiring an extra bolus of remifentanil. CONCLUSION: In this study group, dexmedetomidine combined with remifentanil provided a high level of patient satisfaction and comfort, as well as operator comfort, without any clinically relevant adverse events. All patients were highly cooperative and instructable; incident pain needs to be closely monitored.

Efficacy of Dexmedetomidine as a Sole Sedative Agent in Small Diagnostic and Therapeutic Procedures: A Systematic Review.

Dexmedetomidine is an upcoming agent with sedative, anxiolytic, and analgesic properties. This review summarizes empirical evidence for the efficacy of dexmedetomidine as a sole sedative agent, and its effectiveness for small diagnostic and therapeutic procedure, in comparison with other frequently used sedatives. All randomized controlled trials on the effect of dexmedetomidine were reviewed. Pain level, patient satisfaction, operator satisfaction, procedure duration, recovery time, and hemodynamic and respiratory characteristics were examined. A total of 1993 patients (1,621 adults; 372 children) from 35 studies were included. In the adult studies, dexmedetomidine yielded significantly lower pain levels compared to the other sedatives (in 31.25% of the included studies) and significantly more patient satisfaction (68.2%). In studies on children, more favorable results concerning respiratory safety and the level of adequate sedation were found compared to the control sedatives. Implications for future studies are discussed.

Inter-rater reliability of diagnostic criteria for sacroiliac joint-, disc- and facet joint pain.

BACKGROUND/OBJECTIVE: Several diagnostic criteria sets are described in the literature to identify low back pain subtypes, but very little is known about the inter-rater reliability of these criteria. We conducted a study to determine the reliability of diagnostic tests that point towards SI joint-, disc- or facet joint pain. METHODS: Inter-rater reliability study alongside three randomized clinical trials. Multidisciplinary pain center of general hospital. Patients aged 18 or more with medical history and physical examination suggestive of sacroiliac joint-, disc- and facet joint pain on lumbar level. Making use of nowadays most common used diagnostic criteria, a physical examination is taken independently by three physicians (two pain physicians and one orthopedic surgeon). Inter-rater reliability (Kappa (κ) measure of agreement) and significance (p) between raters are presented. Strengths of agreement, indicated with κ values above 0,20, are presented in order of agreement. RESULTS: One hundred patients were included. None of the parameters from the physical investigation had κ values of more than 0.21 (fair) in all pairs of raters. Between two raters (C and D), there was an almost perfect agreement on three parameters, more specifically ``Abnormal sensory and motor examination, hyperactive or diminished reflexes'', ``Sitting exam shows no reflex, motor or sensory signs in the legs'' and ``Straight leg raising (Laségue) negative between 30 and 70 degrees of flexion''. The ``Drop test positive'' parameters had moderate strength of agreement between raters A and D and fair strength between raters A and B. The ``Digital interspinous pressure test positive'' had moderate strength of agreement between raters C and D and fair strength of agreement between raters A and B as well as raters B and C. Three other parameters had a fair strength of agreement between two raters, all other parameters had a slight or poor strength of agreement. Inter-rater reliability, confidence intervals and significance of pooled items for SI joint-, disc- and facet joint pain are represented; κ values for the pooled parameters of the physical examination suggestive of SI joint pain stayed below 0.20 between all raters. The same applies for the pooled parameters of the physical examination suggestive of facet joint or disc pain. CONCLUSIONS: The poor reliability of the diagnostic parameters seriously limits their predictive validity, and as such their use in patients with low back pain for more than 3 months.

Phenotypic Variation in Complex Regional Pain Syndrome: Comparison Between Presentation in Knee Alone or in Ankle/Foot.

OBJECTIVE: To compare the phenotypes of patients with complex regional pain syndrome (CRPS) of the knee to those with CRPS of the ankle/foot. SETTING: A retrospective study. SUBJECTS: Patients with CRPS of the knee and patients with CRPS of the ankle/foot. METHODS: We used electronic patient databases to identify patients with CRPS of the knee and patients with CRPS of the ankle/foot. The following variables were recorded: age, gender, duration of complaints, initial injury, and symptoms and signs. Frequency distributions and statistical significant differences between the groups were determined. RESULTS: Included were 50 patients with CRPS of the knee and 64 patients with CRPS of the ankle/foot. These patients were all diagnosed with CRPS according to the criteria used at the time of diagnosis. No significant differences were found in demographic characteristics. A few symptoms and signs appeared to be proportionally more prevalent in patients with CRPS of the ankle/foot. However, patients with CRPS of the knee suffered significantly longer from the disease than patients with CRPS of the ankle/foot. CONCLUSIONS: Some signs and symptoms appeared to be statistically significantly more prevalent in CRPS of the ankle/foot than in CRPS confined to the knee. We conclude that the phenotypes of CRPS confined to the knee and CRPS of the ankle/foot are comparable, but not identical. This can be a reason why CRPS in patients with pain of the knee, that is disproportionate to the initial trauma, is sometimes not recognized.

The Value of Medication-Specific Education on Medication Adherence and Treatment Outcome in Patients with Chronic Pain: A Randomized Clinical Trial.

OBJECTIVE: Non-adherence to pain medication is common and may jeopardize the effect of prescribed therapy in chronic pain patients. We investigated the effect of medication-specific education on pain medication adherence. METHODS: One hundred eligible chronic pain patients were randomized into a control or intervention group. They were assessed during an intake (T0) and two follow-up visits after 4 (T1) and 10 weeks (T2). Immediately after T1, patients in the intervention group additionally watched a video and received written information about the medication prescribed. At T1 and T2, medication adherence according to self-reporting including the Morisky Medication Adherence Scale, prescription knowledge, pain intensity numeric rating scale (NRS), concerns about medication, and patient satisfaction were recorded. RESULTS: Experimental group (control versus intervention) did not significantly contribute to the prediction of medication adherence at T2 (P = 0.38). The non-adherence rates were 31% and 43% at T1 and 53% and 49% at T2 in the control and intervention group, respectively. Changes in patients' knowledge of the prescription were attributable to the intervention (P < 0.01). No other significant differences were identified. CONCLUSIONS: Medication-specific education did increase knowledge of the prescribed therapy but did not improve adherence or treatment outcome parameters. There was no association between medication adherence and pain treatment outcome.

Randomized Sham-controlled Double-Blind Multicenter Clinical Trial to Ascertain the Effect of Percutaneous Radiofrequency Treatment for Sacroiliac Joint Pain: Three-month Results.

OBJECTIVES: To investigate the effect of a percutaneous radiofrequency (RF) heat lesion compared with a sham procedure, applied to the lateral branches of L5, S1, S2, S3, and S4 nerve roots. MATERIALS AND METHODS: Sixty patients aged 18 years and above with a medical history and physical examination suggestive for sacroiliac joint pain and a reduction of 2 or more on a numerical rating scale (NRS, 0 to 10) after a sacroiliac joint test block were included in this study. Treatment group: percutaneous RF heat lesion at the lateral branches of S1, S2, S3, and S4 nerve roots and the posterior ramus dorsalis of L5; sham group: same procedure as the treatment group except for the RF heat lesion. PRIMARY OUTCOME MEASURE: pain reduction (NRS). Secondary outcome measure: Global Perceived Effect. RESULTS: No statistically significant differences in pain level over time between the groups (Group×Period) (F1,58=0.353; P=0.56) nor within the treatment Group (F1,58=0.212; P=0.65) were found. The Period factor, however, yielded a significant difference (F1,58=61.67; P<0.001), that is, when pooled together the mean pain level of the patients was significantly reduced at T1 compared with T0. In the crossover group, 42.1% experienced a reduction in NRS of 2 or more at 1 month (P=0.65). No statistically significant difference in satisfaction over time between the groups was found (F1,50=2.1; P=0.15). The independent factors Group (F1,50=2.02; P=0.16) and Period (F1,50=0.95; P=0.33) also showed no statistically significant difference. The same applies to recovery: no statistically significant Group×Period effect (F1,51=0.09; P=0.77) was found, neither an effect of Group (F1,51=0.004; P=0.95) nor of Period (F1,51=0.27; P=0.60). DISCUSSION: The hypothesis of no difference in pain reduction or in Global Perceived Effect between the treatment and sham group cannot be rejected. LEVEL OF EVIDENCE: Level 1A.

The prevalence of autoantibodies in complex regional pain syndrome type I.

Autoimmunity has been suggested as one of the pathophysiologic mechanisms that may underlie complex regional pain syndrome (CRPS). Screening for antinuclear antibodies (ANA) is one of the diagnostic tests, which is usually performed if a person is suspected to have a systemic autoimmune disease. Antineuronal antibodies are autoantibodies directed against antigens in the central and/or peripheral nervous system. The aim of this study was to compare the prevalence of these antibodies in CRPS patients with the normal values of those antibodies in the healthy population. Twenty seven (33%) of the 82 CRPS patients of whom serum was available showed a positive ANA test. This prevalence is significantly higher than in the general population. Six patients (7.3%) showed a positive result for typical antineuronal antibodies. This proportion, however, does not deviate from that in the general population. Our findings suggest that autoantibodies may be associated with the pathophysiology of CRPS, at least in a subset of patients. Further research is needed into defining this subset and into the role of autoantibodies in the pathogenesis of CRPS.