Radiofrequency Neurotomy Does Not Cause Fatty Degeneration of the Lumbar Paraspinal Musculature in Patients with Chronic Lumbar Pain-A Retrospective 3D-Computer-Assisted MRI Analysis Using iSix Software.

OBJECTIVE: The present study aimed (1) to analyze the relative paraspinal autochthonous intramuscular fat volume before and after radiofrequency neurotomy (RFN) and (2) to compare it to the contralateral non-treated side. DESIGN: Retrospective cohort study. SETTING: Inselspital, University Hospital Bern, University of Bern. SUBJECTS: Twenty patients (59.60 ± 8.49 years; 55% female) with chronic low back pain, treated with RFN (L2/3-L5/S1) due to symptomatic facet joint syndrome (FCS) between 2008 and 2017 were included. METHODS: All patients received a magnetic resonance imaging (MRI) of the lumbar spine before and at a minimum of 6 months after RFN. The absolute (cm3) and relative (%) paraspinal muscle and fat volume was analyzed three-dimensionally on standard T2-MRI sequences using a newly developed software (iSix, Osiris plugin). Both sides were examined and allocated as treated or non-treated side. RESULTS: A total of 31 treated and 9 non-treated sides (Level L2/3-L5/S1) were examined. There were no differences in the relative paraspinal intramuscular fat volume before and at a median of 1.4 [0.9 - 2.6] years after RFN (P = .726). We found no differences in the relative fat volume between the treated and non-treated side before (P = .481) and after (P = .578) RFN. CONCLUSIONS: Our study shows that there are no differences in the paraspinal muscle/fat distribution after RFN. RFN of the medial branches for FCS does not seem to cause fatty degeneration of the lumbar paraspinal muscles as a sign of iatrogenic muscle denervation.

[Multiprofessional treatment approach in chronic back pain]. / Multiprofessioneller Behandlungsansatz bei chronischen Rückenschmerzen.

International guidelines recommend involving various professions and disciplines at an early stage in the event of chronic back pain. In connection with this, terms such as multiprofessional or interprofessional interventions are often mentioned without a uniform idea of what they mean. This article is intended to provide an overview of multiprofessional interventions for patients with chronic back pain and the integration into a meaningful interdisciplinary and interprofessional multimodal treatment concept. This is illustrated in a biopsychosocial pillar model, which should be pursued for each patient individually.

Risk factors for chronic postsurgical pain in visceral surgery: a matched case-control analysis.

PURPOSE: Chronic postsurgical pain (CPSP) after abdominal visceral surgery is an underestimated long-term complication with relevant impact on health-related quality of life and socioeconomic costs. Early identification of affected patients is important. We aim to identify the incidence and risk factors for CPSP in this patient population. METHODS: Retrospective case-control matched analysis including all patients diagnosed with CPSP after visceral surgery in our institution between 2016 and 2019. One-to-two case-control matching was based on operation category (HPB, upper-GI, colorectal, transplantation, bariatric, hernia and others) and date of surgery. Potential risk factors for CPSP were identified using conditional multivariate logistic regression. RESULTS: Among a cohort of 3730 patients, 176 (4.7%) were diagnosed with CPSP during the study period and matched to a sample of 352 control patients. Independent risk factors for CPSP were age under 55 years (OR 2.64, CI 1.51-4.61), preexisting chronic pain of any origin (OR 3.42, CI 1.75-6.67), previous abdominal surgery (OR 1.99, CI 1.11-3.57), acute postoperative pain (OR 1.29, CI 1.16-1.44), postoperative use of non-steroidal anti-inflammatory drugs (OR 3.73, OR 1.61-8.65), opioid use on discharge (OR 3.78, CI 2.10-6.80) and length of stay over 3 days (OR 2.60, CI 1.22-5.53). Preoperative Pregabalin intake was protective (OR 0.02, CI 0.002-0.21). CONCLUSION: The incidence of CPSP is high and associated with specific risk factors, some of them modifiable. Special attention should be given to sufficient treatment of preexisting chronic pain and acute postoperative pain.

Telemedicine for chronic pain treatment during the COVID-19 pandemic: Do pain intensity and anxiousness correlate with patient acceptance?

INTRODUCTION: Recent recommendations for the treatment of chronic pain patients during the coronavirus disease 2019 (COVID-19) pandemic suggest using telemedicine instead of in-person consultations. Knowing whether patients with chronic pain are receptive to the use of telemedicine during a pandemic might improve tailored care. OBJECTIVE: The aims of the present study were to assess patients' acceptance of telemedicine during the COVID-19 pandemic in Switzerland and to examine the correlation of acceptance with pain intensity and anxiousness. METHODS: An anonymous survey was conducted from March 31, 2020, to July 30, 2020, with 61 patients referred to the Pain Center at the Bern University Hospital Inselspital in Bern, Switzerland. Collected data were analyzed descriptively, and correlations were calculated between acceptance of telemedicine and mean levels of current pain, psychological distress, and fear of COVID-19. RESULTS: Our main finding was an average level of acceptance of telemedicine, with a mean of 6.25 on a scale from 0 (not at all) to 10 (completely), with substantial variability and range (SD = 3.56). The acceptance of telemedicine correlated negatively with current mean pain level (r = -0.44), worries (r = -0.42), and fear of COVID-19 (r = -0.4), as well as positively with the general condition (r = 0.46). CONCLUSIONS: Using telemedicine for chronic pain treatment during the COVID-19 crisis was accepted to a sufficient degree by a considerable proportion of patients. However, the higher the mean levels of pain and anxiousness, the lower the acceptance, indicating that these severely burdened patients may suffer most from treatment restrictions. For this subgroup, telemedicine might not suffice and in-person visits should be considered.

[Diagnostic and therapeutic nerve blocks in pain therapy]. / Diagnostische und therapeutische Nervenblockaden in der Schmerztherapie.

Diagnostic and therapeutic nerve blocks in pain therapy Abstract. Nerve blocks are not only performed in anaesthesiology to enable surgery, but also in pain therapy to diagnose and treat localised pain. For diagnostic purposes a minimal dose of local anaesthetic is applied directly to the nerve. Ultrasound has recently become the most precise and practicable tool to localise the nerve. When the effect of the block lasts as long as the predicted duration of the local anaesthetic, this confirms that the blocked nerve conducts the pain. In such cases, repetitive therapeutic blocks with local anaesthetics can be used to desensitise the nerve. A structural lesion of the nerve caused by heat (radiofrequency ablation), cold (cryoneurolysis) or even surgical nerve dissection can lead to long-term pain reduction. However, there is only weak evidence supporting these therapies and a relevant risk of pain due to deafferentation, and depending on the nerve, there could be persistent motor or sensitivity disturbances. Any intervention in humans includes placebo and nocebo effects. Those effects should be taken into consideration by asking the patient about previous experiences and their expectations for the intervention. The knowledge of placebo and nocebo effects can then be used to make the patient more comfortable during the procedure, to improve therapeutic effects and to reduce side effects. Problematic psychosocial factors and signs of centralised sensitivity should be evaluated in advance in order to consider withholding the use of interventional procedures in sensitised patients.

A randomised controlled trial: can acupuncture reduce drug requirement during analgosedation with propofol and alfentanil for colonoscopy? A study protocol.

BACKGROUND: The number of colonoscopies tremendously increased in recent years and will further rise in the near future. Because of patients' growing expectation on comfort during medical procedures, it is not surprising that the demand for sedation also expands. Propofol in combination with alfentanil is known to provide excellent analgosedation, however, its use is associated with respiratory and cardiovascular depression. Acupuncture could be a technique to reduce drug requirement while providing the same level of sedation and analgesia. METHODS/DESIGN: The study will be performed as a single centre, randomised, placebo controlled trial. 153 patients scheduled for propofol/alfentanil sedation during colonoscopy will be randomly assigned to receive electroacupuncture (P6, ST36, LI4), sham acupuncture, or placebo acupuncture. Following endoscopy patients and gastroenterologists have to fill in questionnaires about their sedation experiences. Additionally, patients have to accomplish the Trieger test before and after the procedure. Patient monitoring includes time adapted HR, SpO2, ECG, NIBP, exCO2, OAA/S, and the Aldrete score. The primary outcome parameter is the dosage of propofol necessary for an adequate level of sedation to tolerate the procedure (OAA/S < 4). Effectiveness of sedation, classified by satisfaction levels measured by questionnaires is the secondary outcome parameter. DISCUSSION: Moderate to deep sedation using propofol is increasingly applied during colonoscopies with a high satisfaction level among patients despite well-known hemodynamic and respiratory side effects of this hypnotic agent. Acupuncture is known to attenuate gastrointestinal discomfort and pain. We hypothesize that the combination of conventional sedation techniques with acupuncture may result in equally satisfied patients with a lower risk of respiratory and hemodynamic events during colonoscopies. TRIAL REGISTRATION: This trial is registered in the Nederland's Trial Register NTR 4325 . The first patient was randomized on 13 February 2014.

Acceptance, Satisfaction, and Preference With Telemedicine During the COVID-19 Pandemic in 2021-2022: Survey Among Patients With Chronic Pain.

BACKGROUND: The COVID-19 pandemic has forced many health care providers to make changes in their treatment, with telemedicine being expanded on a large scale. An earlier study investigated the acceptance of telephone calls but did not record satisfaction with treatment or patients' preferences. This warranted a follow-up study to investigate acceptance, satisfaction, and preferences regarding telemedicine, comprising of phone consultations, among health care recipients. OBJECTIVE: The primary aim was to assess the acceptance and satisfaction of telemedicine during the subsequent months of 2021-2022, after the initial wave of the COVID-19 pandemic in Switzerland. Furthermore, we aimed to assess patients' preferences and whether these differed in patients who had already experienced telemedicine in the past, as well as correlations between acceptance and satisfaction, pain intensity, general condition, perception of telemedicine, and catastrophizing. Finally, we aimed to investigate whether more governmental restrictions were correlated with higher acceptance. METHODS: An anonymous cross-sectional web-based survey was conducted between January 27, 2021, and February 4, 2022, enrolling patients undergoing outpatient pain therapy in a tertiary university clinic. We conducted a descriptive analysis of acceptance and satisfaction with telemedicine and investigated patients' preferences. Further, we conducted a descriptive and correlational analysis of the COVID-19 stringency index. Spearman correlation analysis and a chi-square test for categorical data were used with Cramer V statistic to assess effect sizes. RESULTS: Our survey was completed by 60 patients. Telemedicine acceptance and satisfaction were high, with an average score of 7.6 (SD 3.3; on an 11-point Numeric Rating Scale from 0=not at all to 10=completely), and 8.8 (SD 1.8), respectively. Respondents generally preferred on-site consultations to telemedicine (n=35, 58% vs n=24, 40%). A subgroup analysis revealed that respondents who already had received phone consultation, showed a higher preference for telemedicine (n/N=21/42, 50% vs n/N=3/18, 17%; χ22 [N=60]=7.5, P=.02, Cramer V=0.354), as well as those who had been treated for more than 3 months (n/N=17/31, 55% vs n/N=7/29, 24%; χ22 [N=60]=6.5, P=.04, Cramer V=0.329). Acceptance of telemedicine showed a moderate positive correlation with satisfaction (rs{58}=0.41, P<.05), but there were no correlations between the COVID-19 stringency index and the other variables. CONCLUSIONS: Despite high acceptance of and satisfaction with telemedicine, patients preferred on-site consultations. Preference for telemedicine was markedly higher in patients who had already received phone consultations or had been treated for longer than 3 months. This highlights the need to convey knowledge of eHealth services to patients and the value of building meaningful relationships with patients at the beginning of treatment. During the COVID-19 pandemic, the modality of patient care should be discussed individually.

Ultrasound-controlled cryoneurolysis for peripheral mononeuropathies: a retrospective cohort study.

Aim: Cryoneurolysis is a potential therapy for peripheral mononeuropathies, but randomized studies of its effects on the duration of pain reduction are lacking. Methods: This retrospective cohort study evaluated the analgesic effects of cryoneurolysis on patients with refractory peripheral mononeuropathy. We included 24 patients who underwent ultrasound-guided cryoneurolysis between June 2018 and July 2022. The daily maximum pain level was recorded using a numerical rating scale before and 1, 3 and 6 months after the procedure. Results: At 1 month, 54.2% of patients reported pain reduction of at least 30%. This percentage was significantly lower at 3 and 6 months (13.8 and 9.1%, respectively). Conclusion: Our results suggest that repeated cryoneurolysis may be a viable treatment for refractory mononeuropathy. Further investigations are needed.

Getting started with taiji: investigating students expectations and teachers appraisals of taiji beginners courses.

In recent years, Taiji has been frequently investigated and considered as a stress management intervention. Although health care providers' appraisals and consumers' expectations are regarded as essential for treatment outcome, little attention has been drawn to this issue in Taiji research. In our study we have conducted two surveys to explore beginners' (n = 74) expectations and teachers' (n = 136) appraisals of their Taiji courses in general as well as more particularly related to stress management. Qualitative data analysis revealed that beginners mainly expected to learn a new method that is applicable in their daily life to foster peace of mind and to enhance their stress management. Congruently moderate-to-high improvements in stress management have also been found in quantitative analysis, whereby a lower educational level predicted higher expectations (P = 0.016). Taiji-teachers stated body- and mind-related benefits most frequently and appraised moderate-to-high improvements in stress management. Higher appraisals were predicted by a shorter teaching experience (P = 0.024). Our results inform about beginners' expectations and teachers' appraisals related to a Taiji-beginners course and highlight the role of educational background and teaching experience in shaping stress-management-related beginners' expectations and teachers' appraisals.

Does acupuncture needling induce analgesic effects comparable to diffuse noxious inhibitory controls?

Diffuse noxious inhibitory control (DNIC) is described as one possible mechanism of acupuncture analgesia. This study investigated the analgesic effect of acupuncture without stimulation compared to nonpenetrating sham acupuncture (NPSA) and cold-pressor-induced DNIC. Forty-five subjects received each of the three interventions in a randomized order. The analgesic effect was measured using pressure algometry at the second toe before and after each of the interventions. Pressure pain detection threshold (PPDT) rose from 299 kPa (SD 112 kPa) to 364 kPa (SD 144), 353 kPa (SD 135), and 467 kPa (SD 168) after acupuncture, NPSA, and DNIC test, respectively. There was no statistically significant difference between acupuncture and NPSA at any time, but a significantly higher increase of PPDT in the DNIC test compared to acupuncture and NPSA. PPDT decreased after the DNIC test, whereas it remained stable after acupuncture and NPSA. Acupuncture needling at low pain stimulus intensity showed a small analgesic effect which did not significantly differ from placebo response and was significantly less than a DNIC-like effect of a painful noninvasive stimulus.

The impact of chronic pain on creative ideation: An examination of the underlying attention-related psychophysiological mechanisms.

BACKGROUND: Attentional deficits in patients with chronic pain are common and well studied. Yet, few studies have examined the effects of chronic pain on more complex cognitive abilities that rely on well-functioning attentional systems. With the current study, we aimed to investigate whether the impact of chronic pain on attention affects creative ideation as measured with an adaptation of the alternate uses task (AUT). METHODS: Performance in the AUT was compared between 33 patients suffering from chronic pain and 33 healthy matched controls. While solving the task, EEG was recorded to measure the degree of internally directed attention assessed by means of task-related power (TRP) changes. RESULTS: The results revealed that patients with chronic pain generated less creative ideas than healthy controls. This lack of performance was accompanied by lower event-related synchronization (ERS), especially in right parietal sites. Furthermore, these ERS differences explained one-third of the inter-group variance in AUT performance. CONCLUSIONS: These results suggest that performance decrements in creative ideation in patients with chronic pain may be at least partly attributable to attentional impairments associated with chronic pain. SIGNIFICANCE: Chronic pain negatively affects attention and more complex cognitive abilities. However, the underlying psychophysiological mechanisms and the role of attention as a source of these impairments in more complex abilities are poorly understood. By analyzing task-related power changes in the EEG, the role of internal attention in creative ideation could be determined, revealing the functional relationship between chronic pain, attention, and a more complex cognitive ability.

The effect of chronic pain on voluntary and involuntary capture of attention: An event-related potential study.

Although the interrupting effect of chronic pain on voluntary-directed attention is well-documented, research on the impact of chronic pain on involuntary-directed attention remains incomplete. This study aimed to investigate the influence of chronic pain on involuntary as well as voluntary allocation of attention as, respectively, indexed by the P3a and P3b components in the event-related potential derived from the electroencephalogram. Both involuntary and voluntary captures of attention were compared between 33 patients with chronic pain and 33 healthy controls using an auditory three-stimulus oddball task (with standard, target, and unexpected distractor tones). The results revealed a reduced P3a amplitude as well as a reduced P3b amplitude in patients with chronic pain compared to healthy controls, indicating a detrimental effect of chronic pain on involuntary and voluntary attention, respectively. This study extends the picture of the impairing effects of chronic pain on attentional allocation to a current task and attentional allocation to information outside the focus of attention. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Guilt is effectively induced by a written auto-biographical essay but not reduced by experimental pain.

Introduction: The aim of the present study was (1) to validate the method of guilt-induction by means of a written auto-biographical essay and (2) to test whether experimental pain is apt to alleviate the mental burden of guilt, a concept receiving support from both empirical research and clinical observation. Methods: Three independent groups of healthy male participants were recruited. Group allocation was not randomized but within group pain/sham administration was counterbalanced over the two test-days. Groups were tested in the following consecutive order: Group A: guilt induction, heat-pain/sham, N = 59; Group B: guilt induction, cold-pressure-pain/sham, N = 43; Group C: emotionally neutral induction, heat-pain/sham, N = 39. Guilt was induced on both test-days in group A and B before pain/sham administration. Visual analog scale (VAS) guilt ratings immediately after pain/sham stimulation served as the primary outcome. In a control group C the identical heat-pain experiment was performed like in group A but a neutral emotional state was induced. Results: A consistently strong overall effect of guilt-induction (heat-pain: p < 0.001, effect size r = 0.71; CPT-pain p < 0.001, r = 0.67) was found when compared to the control-condition (p = 0.25, r = 0.08). As expected, heat- and cold-pressure-stimuli were highly painful in all groups (p < 0.0001, r = 0.89). However, previous research supporting the hypothesis that pain is apt to reduce guilt was not replicated. Conclusion: Although guilt-induction was highly effective on both test-days no impact of pain on behavioral guilt-ratings in healthy individuals could be identified. Guilt induction per se did not depend on the order of testing. The result questions previous experimental work on the impact of pain on moral emotions.

The effect of brief electrical and manual acupuncture stimulation on mechanical experimental pain.

OBJECTIVE: Although manual and electrical stimulation are frequently used in acupuncture analgesia, studies comparing both stimulation modalities are contradictory. This blinded, placebo-controlled cross-over study investigates effects of brief manual and electrical acupuncture stimulation on pressure pain detection thresholds (PPDT) compared with nonpenetrating sham acupuncture (NPSA). INTERVENTIONS: Forty-five healthy volunteers received electrically and manually stimulated acupuncture and NPSA at large intestine 4 and 11 in randomized order. PPDT was assessed using pressure algometry at the second toe before; during; and 0, 2, and 5 minutes after each intervention. Stimulus intensity during stimulation was rated on a 0-10 numeric rating scale (NRS). RESULTS: PPDT rose from 316 kPa (standard deviation [SD] 149) to 398 kPa (SD 157) and 405 kPa (SD 184) immediately after acupuncture with manual and electrical stimulation, respectively, and to 380 kPa (SD 175) and 367 kPa (SD 168) after NPSA with simulated manual and electrical stimulation, respectively. During the intervention, electroacupuncture produced a higher PPDT increase than any other procedure (P<0.001). Immediately after, both acupuncture procedures were significantly more effective than NPSA (P<0.001) but did not mutually differ (P=0.082). NRS ratings differed significantly: manual acupuncture 4.1, electroacupuncture 2.7, manual NPSA 2.5, electro-NPSA 1.2 (P<0.001 except for electroacupuncture vs manual NPSA, P=0.271). CONCLUSION: Electroacupuncture produced higher PPDT elevation than manual acupuncture, and acupuncture in general showed significantly greater analgesic effect than NPSA. These effects seem to be short lasting (<5 minutes) in the context of only brief acupuncture. The superiority of acupuncture to NPSA provides further evidence for acupuncture-specific analgesic effects.

Factors determining the success of radiofrequency denervation in lumbar facet joint pain: a prospective study.

BACKGROUND AND AIMS: Radiofrequency denervation (RF) of the lumbar facet joints has been shown to be effective in well-selected patients. However, long-term success varies between studies. We evaluated the influence of selected psychosocial and constitutional factors on the outcome of RF, expressed as the duration of pain relief. METHODS: This prospective observational study included 44 patients who received RF denervations at the University Hospital of Berne. Success was defined as at least 50% pain reduction 7-21 days, 6 months and 1 year after RF therapy. The Cox-regression analysis was performed to evaluate the influence of the following factors on the duration of success: age, sex, depression, work inability and previous surgery. RESULTS: Complete follow-up was available for 41 patients. The success rate 7-21 days after the denervation was 76%. It decreased to 32% at 6 months and to 22% at 1 year. The median success duration was 17 weeks (95% CI 10-26). The Cox-regression analysis showed a significant shorter duration of success for patients with depression (hazard ratio [HR] 2.97, 95% CI 1.32-6.65), previous surgery (HR 2.39, 95% CI 1.10-5.21) and number of treated joints (HR 1.95 for each increase in the number of joints, 95% CI 1.14-3.33). In bivariate analyses, only depression was kept to be significant. CONCLUSIONS: Depression seems to be related with a short duration of success. Based on these findings, a comprehensive study is warranted to evaluate whether psychosocial factors have to be considered when recruiting patients for radiofrequency denervation.

[Drug therapy of acute and chronic abdominal pain]. / Medikamentöse Schmerzbehandlung akuter und chronischer Abdominalschmerzen.

For drug therapy a differentiation of acute and chronic pain is essential. In emergency situations of acute abdominal pain a fast diagnosis is mandatory. Analgesia should be provided as soon as possible. The different groups of analgesics should be used according to their known effects, side effects and contraindications. Postoperative pain after abdominal surgery has to be considered as a special condition of acute abdominal pain. Main treatment options are non opioid analgesics and opioids. Opioids can be administered intravenously via patient controlled analgesia (PCA) devices. In major abdominal surgery neuroaxial analgesia, preferentially administered via an epidural catheter provides excellent pain relief with positive impact on gastrointestinal motility and patients' recovery. Because of difficulties to allocate chronic abdominal pain to a specific organ, causal treatment often turns out to be difficult. Peripheral and central sensitization, as well as an alteration of the endogenous pain modulation comes to the fore in these chronic pain conditions. Co-analgesics like anticonvulsants and antidepressants are utilized to reduce sensitization and improve the endogenous pain modulating system. Non drug approaches and alternative treatment options might be useful. In contrast, orally or transcutaneously administered opioids are the principal corner stone for the treatment of cancer pain.

[Increase in New Approvals of Strong Opioid Medications in Switzerland]. / Starker Anstieg der Neuzulassungen von Opioiden in der Schweiz.

Increase in New Approvals of Strong Opioid Medications in Switzerland Abstract. Consumption of pain medication, especially opioids, has risen sharply since 2000, both worldwide and in Switzerland. However, it is unknown whether this increased use is associated with an increase in new approvals of pain medications. An analysis of new approvals of painkillers in Switzerland showed a significant increase from the year 2000 onwards. The majority of new registrations were strong opioid preparations, while the trend in new registrations of non-opioid painkillers was decreasing. Furthermore, the treatment duration of newly approved strong opioids increased significantly from the year 2000 onwards, which may lead to a higher risk of overdoses or dependence.

Effect of electroacupuncture on sedation requirements during colonoscopy: a prospective placebo-controlled randomised trial.

INTRODUCTION: Propofol provides excellent sedation during colonoscopy. However, its application, namely when used together with an opioid, is associated with cardiopulmonary depression. Acupuncture is used nowadays for the treatment of pain and anxiety, and also to induce sedation. We hypothesised that electroacupuncture (EA) during colonoscopy would have sedative effects, thereby reducing propofol requirements to achieve an adequate level of sedation. METHOD: The study was designed and conducted as a single centre, patient and observer blinded, sham- and placebo-controlled randomised trial. Patients scheduled for elective colonoscopy under deep propofol/alfentanil sedation were randomly assigned to receive unilateral EA, sham-acupuncture (SA) or placebo-acupuncture (PA) at ST36, PC6 and LI4. The primary outcome parameter was the total dosage of propofol. Secondary outcomes included the patients' and endoscopists' satisfaction levels evaluated by questionnaires. RESULTS: The dosage of propofol required (median [IQR]) was not significantly different between the three groups (EA group 147 µg/kg/min [109-193] vs SA group 141 µg/kg/min [123- 180] vs PA group 141 µg/kg/min [112-182]; P=0.776). There was also no significant difference in alfentanil consumption (P=0.634). Global satisfaction (median [IQR]) among patients (EA group 6.6 [6.0-7.0] vs SA group 6.8 [6.0-7.0] vs PA group 6.5 [6.0-7.0]; P=0.481) and endoscopists (6.0 [5.0-6.0] for all groups; P=0.773) did not significantly differ between the three groups. There was no significant difference in the number of cardiorespiratory events. CONCLUSION: For colonoscopy, the applied mode of EA did not show any propofol-sparing sedative effect compared with sham or placebo acupuncture. TRIAL REGISTRATION: The trial is registered in the Netherland's Trial Registry (NTR4325).

Reference values of conditioned pain modulation.

Background and aims Endogenous pain modulation can be studied in humans by conditioned pain modulation (CPM): pain induced by a test stimulus is attenuated by a distantly applied noxious conditioning stimulus. The detection of impaired CPM in individual patients is of potential importance to understand the pathophysiology and predict outcomes. However, it requires the availability of reference values. Methods We determined reference values of CPM in 146 pain-free subjects. Pressure and electrical stimulation were the test stimuli. For electrical stimuli, we recorded both pain threshold and threshold for the nociceptive withdrawal reflex. Cold pressor test was the conditioning stimulus. The 5th, 10th and 25th percentiles for the three tests were computed by quantile regression analyses. Results The average thresholds increased after the conditioning stimulus for all three tests. However, a subset of subjects displayed a decrease in thresholds during the conditioning stimulus. This produced negative values for most of the computed percentiles. Conclusions This study determined percentile reference values of CPM that can be used to better phenotype patients for clinical and research purposes. The negative value of percentiles suggests that a slightly negative CPM effect can be observed in pain-free volunteers. Implications Pain facilitation rather than inhibition during the conditioning stimulus occurs in some pain-free volunteers and may not necessarily represent an abnormal finding.