ABSTRACT Background Central sensitization and impaired conditioned pain modulation (CPM) response have been associated with chronic migraine. Consequently, migraine patients can present with allodynia. Occipital nerve stimulation (ONS) is a neuromodulation procedure used in patients with refractory chronic primary headache disorders such as cluster headaches and migraines. We report on long‐term outcome data on the effects of ONS on central sensitization. Efficacy outcomes for ONS typically employ standardized headache questionnaire measures. However, more objective tests of endogenous pain mechanisms, such as Quantitative Sensory Testing (QST), have not been utilized to measure whether reported outcomes are paralleled by QST changes following the long‐term implementation of ONS. Our group has published one‐year outcomes in central sensitization following ONS. Objective This prospective study aimed to evaluate whether QST detects a change in central sensitisation in patients with refractory chronic primary headache and provides more long‐term outcome data for patients receiving ONS. Methods Six patients, three new persistent daily headaches, two chronic migraines, and one chronic cluster headache were implanted between 2013 and 2015 with percutaneous leads placed bilaterally parallel to the greater occipital nerve; IPG was a Genesis/Prodigy St Jude Medical, Plano, TX, USA now Abbott systems. Baseline QST and questionnaires were completed and monitored for up to 12 months and then annual review for 10 years. Results Patients showed substantial reductions in headache‐related disability and quality of life measures. Patients demonstrated impaired/reduced CPM in all but one patient at baseline, and this reverted to an increased CPM at 12 months. Then, this was maintained at the 10‐year visit. Conclusion This is a long‐term prospective follow‐up investigating the effect on central sensitization following ONS implantation. Responders showed substantial reductions in headache‐related disability and improved conditioned pain modulation over a 10‐year period.
ABSTRACT Background Unreliable pain reporting predicts placebo responses in clinical trials and has been documented in chronic pain populations. The thermal Focused Analgesia Selection Test (FAST) quantifies Pain Reporting Reliability (PRR) by assessing consistency when rating repeated thermal stimuli of varying intensities presented in pseudo‐randomized order. However, FAST's validity as a pure measure of reporting reliability remains unclear. Methods We investigated whether PRR derived from the thermal FAST is confounded by individual differences in pain sensitivity (pain and tolerance thresholds), stimuli extending beyond individual pain ranges, and temporal trends. Fifty‐five healthy participants (32 women) completed the thermal FAST protocol comprising 49 stimuli across seven temperatures (43°C–50°C). Results Higher pain thresholds predicted lower PRR ( b = −4.66, 95% HDI [−9.18, −0.07]). Exploratory analysis suggests that rating variability was reduced when stimulation fell outside individual pain ranges (below‐range: b = −8.04, 95% HDI [−11.44, −4.72]; above‐range: b = −4.45, 95% HDI [−7.98, −0.90]). Greater coverage of FAST temperatures by individual pain ranges correlated with higher PRR ( ρ = 0.33). Thermode repositioning to prevent habituation at the stimulation site may have induced acute sensitization at the repositioned site as pain ratings increased by +33 and +19 VAS points at the first two stimuli following repositioning. Excluding these trials improved median PRR by 16% (from R 2 = 0.65 to 0.81). Conclusions PRR derived from the current thermal FAST implementation likely conflates reporting consistency with pain sensitivity, psychophysical range effects, and procedural artifacts and may therefore risk misclassifying pain phenotypes as reporting inconsistencies. We propose methodological refinements, particularly individualized stimulus calibration and optimized repositioning protocols, which should be evaluated in confirmatory studies and chronic pain populations.
ABSTRACT Background Preoperative risk stratification to identify patients who develop acute refractory pain after lumbar spine surgery is a first step to prevent unfavorable outcomes. In this study, we aimed to develop and internally validate a clinically relevant, multidimensional prediction rule for preoperative risk assessment. Methods This is a retrospective analysis of prospectively collected data conducted at an orthopedic hospital specialized in spine care. Baseline and outcome data on patients who underwent lumbar spine surgery between July 2012 and December 2022 were included in this study. 105 factors were considered as potential predictive factors for acute refractory pain after lumbar spine surgery. Multivariable logistic lasso regression analysis and multivariable logistic regression analysis were performed to develop a prediction model. Performance measures (ROC‐AUC and Nagelkerke's R 2 ) and a prediction rule for clinical use were presented. Results Data on 1156 patients was included in this analysis. The prevalence of patients developing acute refractory pain was 19.6% ( n = 228/1156). Multivariable logistic lasso regression identified 13 relevant predictive factors for acute refractory pain after lumbar spine surgery: age, prior hospital treatment for back pain, professional sports participation, duration of back pain, back pain before age 45, numeric pain rating scale for back pain, preoperative opioid use, circumferent surgery, instrumented surgery, anxiety, catastrophizing, return‐to‐work attitude, high score for psychosocial burden of low back pain. Five of these were selected by logistic regression. The discriminative ability of the multivariable logistic lasso regression model was ROC‐AUC of 0.69 (95% CI 0.66–0.73), and the multivariable logistic regression model 0.67 (95% CI 0.63–0.71). Nagelkerke's R 2 of the logistic regression model was 8.4%. Conclusion Multidimensional predictive factors for acute refractory pain were identified using a clinical prediction rule. This rule creates a patient profile which can help anesthesiologists to preoperatively determine the individual risk for developing acute refractory pain despite the use of a standardized multimodal analgesic treatment.
ABSTRACT Background Chronic low back pain (CLBP) is common and often refractory to existing treatments, necessitating long‐term opioid therapy, which has substantial risks. Mindfulness‐based (MBT) and cognitive behavioral (CBT) therapies are safe and can be effective for CLBP. Aims To better understand how MBT and CBT may help improve opioid‐treated CLBP: Methods This qualitative study involved a subgroup of participants with opioid‐treated CLBP who completed a 12‐month randomized clinical trial comparing the effects of MBT versus CBT. Participants who reported improvements at 12 months, compared to baseline, in main outcomes (assessed with validated “quantitative” questionnaires) and experience with the study intervention, and who attended the intervention sessions were invited to in‐depth exit interviews. The interviews achieved thematic saturation. Thematic analysis of transcribed interviews summarized qualitative findings. Results Fifty participants (26 MBT, 24 CBT) were interviewed. They were, on average, 58.5 (SD = 10.0) years old. Most were female (60.0%), non‐Hispanic (94.0%), and White (82.0%). At baseline, both groups were, on average, moderately‐to‐severely impacted by CLBP and treated with moderate‐to‐high daily opioid doses; at 12 months, they quantitatively reported improved pain, function and QoL scores and reduced daily opioid dose. In their qualitative responses, these participants corroborated the quantitative findings, reporting reductions in back pain (98.0% of interviewed participants), functional limitations (100.0%), and opioid dose (98.0%), with the majority attributing these changes to the study intervention they had received (98.0%, 94.0%, and 90.0%, respectively). Participants also reported the interventions helped them cope with emotional challenges and life stressors, and opioid‐related adverse effects. Participants did not raise concerns about interventions' safety. Qualitative themes identified intervention‐taught techniques participants most frequently used to manage their symptoms. Conclusion MBT and CBT can improve health and QoL and reduce opioid dose in adults with opioid‐treated refractory CLBP, calling for improved access to these safe treatments.
