Cooled versus conventional radiofrequency treatment of the genicular nerves for chronic knee pain: 12-month and cost-effectiveness results from the multicenter COCOGEN trial.

BACKGROUND: Radiofrequency (RF) treatment of the genicular nerves reduces chronic knee pain in patients with osteoarthritis (OA) or persistent postsurgical pain (PPSP) after total knee arthroplasty (TKA). The objective of this study is to compare long-term outcomes of cooled and conventional RF and perform an economic evaluation. METHODS: The COCOGEN trial is a double-blinded, non-inferiority, pilot, randomized controlled trial that compared the effects up to 12 months of cooled and conventional RF in patients with chronic knee pain suffering from OA or PPSP after TKA following a 1:1 randomization rate. Outcomes were knee pain, functionality, quality of life, emotional health, medication use, and adverse events. A trial-based economic evaluation was performed with a 12-month societal perspective. Here, the primary outcome was the incremental costs per quality-adjusted life year (QALY). RESULTS: 41 of the 49 included patients completed the 12-month follow-up. One patient in the PPSP cooled RF group had substantial missing data at 12-month follow-up. The proportion of patients with ≥50% pain reduction at 12 months was 22.2% (4/18) in patients treated with conventional RF versus 22.7% (5/22) in patients treated with cooled RF (p>0.05). There was a statistically significant difference in the mean absolute numerical rating scale at 12 months after cooled RF and conventional RF in patients with PPSP (p=0.02). Differences between other outcomes were not statistically significant. The health economic analysis indicated that cooled RF resulted in lower costs and improved QALYs compared with conventional RF in PPSP but not in OA. There were no serious adverse events. CONCLUSIONS: Both RF treatments demonstrated in approximately 22% of patients a ≥50% pain reduction at 12 months. In patients with PPSP, contrary to OA, cooled RF seems to be more effective than conventional RF. Additionally, cooled RF has in patients with PPSP, as opposed to OA, greater effectiveness at lower costs compared with conventional RF. TRIAL REGISTRATION NUMBER: NCT03865849.

A Comparison of Precision and Safety using Three Recognized Ultrasound-Guided Approaches to Cervical Medial Branch Blocks: A Cadaver Study.

BACKGROUND: Ultrasound (US) guidance is widely used for needle positioning for cervical medial branch blocks (CMBB) and radiofrequency ablation, however, limited research is available comparing different approaches. OBJECTIVE: We aimed to assess the accuracy and safety of 3 different US-guided approaches for CMBB. STUDY DESIGN: A cadaveric study divided into ultrasound-guided needle placement and fluoroscopy evaluation stages. SETTING: Department of Pathology, Forensic, and Insurance Medicine, Semmelweis University. METHODS: Sonographically guided third occipital nerve (TON), C3, C4, C5 and C6 medial branch injections and radiology evaluations were performed.The 3 approaches compared were:1. ES (published by Eichenberger-Siegenthaler): US probe in the coronal plane to visualize the cervical articular pillars, needle approach out of the plane, from anterior to posterior.2. Fi (published by Finlayson): US probe in the transverse plane to visualize a cervical articular pillar and its lamina, needle approach in the plane, from posterior to anterior.3. FiM (Modified Finlayson approach): Needles are placed as in Fi, but then adjusted with a coronal view of the cervical articular pillars.Fluoroscopy images were taken and later evaluated, for "crude", "high precision" and "dangerous" placement. RESULTS: One hundred and fifty-five needle placements were assessed (10 were excluded, as no anterior-posterior fluoroscopy images were saved). Interobserver agreement on position of needle placement between the 5 observers was very high; the Fleiss' Kappa was 0.921. For crude placement, no significant differences were identified between various approaches; (77.6%, 79.5%, and 75.6% for the ES, Fi, and FiM respectively). However, for placement in predefined high-precision zones, ES resulted in significantly more success (ES: 42.9%, Fi: 22.7%, and FiM: 24.4%, P = 0.032). Fi and FiM resulted in no dangerous placements, while ES led to the potential compromise of the exiting nerve root and vertebral artery on three occasions. In 10% of the placements, the levels were identified wrongly, with no difference between the various approaches. LIMITATIONS: Feedback from a live patient, may prevent some existing nerve root injections, unlike in a cadaver. Though a higher number of needles were placed in this study than in most available publications, the number is still low at each individual medial branch level. CONCLUSION: Fi proved safer than ES. Fi was equally successful in targeting the articular pillar, however, ES proved the most successful in placing the needle in the center of the articular pillar. Adding another, (coronal) US view to check needle position in FiM did not improve safety or precision. Identifying CMB levels with the US is challenging with all approaches, therefore we still recommend using fluoroscopy for level identification. While there were pros and cons with either procedure, the efficacy findings of previous papers were not replicated on elderly cadavers with arthritic necks.

Comparison of conventional and cooled radiofrequency treatment of the genicular nerves versus sham procedure for patients with chronic knee pain: protocol for a multicentre, double-blind, randomised controlled trial (COGENIUS).

INTRODUCTION: The prevalence of chronic knee pain is increasing. Osteoarthritis (OA) and persistent postsurgical pain (PPSP) are two important causes of knee pain. Chronic knee pain is primarily treated with medications, physiotherapy, life-style changes and intra-articular infiltrations. A radiofrequency treatment (RF) of the genicular nerves is a therapeutical option for refractory knee pain. This study investigates the effectiveness and cost-effectiveness of conventional and cooled RF in patients suffering from chronic, therapy resistant, moderate to severe knee pain due to OA and PPSP. METHODS AND ANALYSIS: The COGENIUS trial is a double-blinded, randomised controlled trial with 2-year follow-up. Patients and outcome assessors are blinded. Patients will be recruited and treated in Belgium and the Netherlands. All PPSP after a total knee prothesis and OA patients (grades 2-4) will undergo a run-in period of 1-3 months where conservative treatment will be optimised. After the run-in period, 200 patient per group will be randomised to conventional RF, cooled RF or a sham procedure following a 2:2:1 ratio. The analysis will include a comparison of the effectiveness of each RF treatment with the sham procedure and secondarily between conventional and cooled RF. All comparisons will be made for each indication separately. The primary outcome is the Western Ontario and McMaster Universities Osteoarthritis Index score at 6 months. Other outcomes include knee pain, physical functionality, health-related quality of life, emotional health, medication use, healthcare and societal cost and adverse events up to 24 months postintervention. ETHICS AND DISSEMINATION: Ethics approval was obtained from the Ethics Committee of the University of Antwerp (Number Project ID 3069-Edge 002190-BUN B3002022000025), the Ethics committee of Maastricht University (Number NL80503.068.22-METC22-023) and the Ethics committee of all participating hospitals. Results of the study will be published in international peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05407610.

Comparison of cooled versus conventional radiofrequency treatment of the genicular nerves for chronic knee pain: a multicenter non-inferiority randomized pilot trial (COCOGEN trial).

BACKGROUND: Radiofrequency (RF) treatment of the genicular nerves has the potential to reduce chronic knee pain due to osteoarthritis or persistent postsurgical pain, however, a direct comparison between the two main modalities used, conventional and cooled, is lacking. METHODS: This double blind, non-inferiority, pilot, randomized controlled trial compared the effects of cooled and conventional RF in chronic knee pain patients suffering from osteoarthritis or persistent postsurgical pain after total knee arthroplasty. Patients were randomized following a 1:1 rate. The primary outcome was the proportion of patients with ≥50% pain reduction at 3 months postintervention. Other outcomes were knee pain, functionality, quality of life, emotional health, and adverse events up to 6 months postintervention. Conventional RF treatment was tested for non-inferiority to cooled in reducing knee pain at 3 months follow-up. RESULTS: Forty-nine of 70 patients were included, of which 47 completed a 3-month follow-up. The primary outcome was achieved in 4 of 23 patients treated with conventional RF (17%) vs in 8 of 24 with cooled (33%) (p=0,21). Results from the non-inferiority comparison were inconclusive in relation to the non-inferiority margin. There was no statistically significant difference between secondary outcomes. There were no serious adverse events. CONCLUSIONS: Both conventional and cooled RF treatment reduced pain in the osteoarthritis and persistent postsurgical pain population. This pilot study did not demonstrate statistically significant differences in the proportion of patients experiencing ≥50% pain reduction between techniques. The non-inferiority analysis was inconclusive. These results warrant further research. TRIAL REGISTRATION NUMBER: NCT03865849.

Intercostal nerve block of the anterior cutaneous branches and the sensibility of the female breast.

INTRODUCTION: Better sensation in the reconstructed breast improves the quality of life. Sensory nerve coaptation is a valuable addition to autologous breast reconstruction. There are few publications concerning the sensory nerves of the breast and the nipple-areola complex and reports are contradictory, so it is unknown which nerve is best suited as a recipient for coaptation. The current study serves as a proof of concept. MATERIALS AND METHODS: The areas innervated by the anterior cutaneous branches (ACBs) of the intercostal nerves (ICNs) were studied on two separate occasions in two healthy women. First, the ACBs of ICNs 2-5 were individually blocked using ultrasound. Next, the ACBs of all levels were blocked simultaneously. Sensation was measured using Semmes-Weinstein monofilaments. The numbed areas corresponding to the ICNs were drawn in a raster of 2 × 2 cm. RESULTS: The largest area was supplied by the ACB of the 4th ICN, located in the upper (UIQ) and the lower (LIQ) inner quadrants of the breast. The 2nd-largest area was supplied by the ACB of the 3rd ICN. Blockage of ACBs 2-5 affected sensation in the nipple and the areola. CONCLUSIONS: Blockage of all levels 2-5 partially affected sensation in the nipple-areola complex, suggesting innervation by a nerve plexus consisting of both ACBs and lateral cutaneous branches (LCBs). ACB4 supplied the largest area of the breast in the UIQ and LIQ and could be best suited for sensory nerve coaptation to optimize sensation in the autologously reconstructed breast.

A Modified Posterolateral Approach for Radiofrequency Denervation of the Medial Branch of the Cervical Segmental Nerve in Cervical Facet Joint Pain Based on Anatomical Considerations.

The cervical facet joints, also called the zygapophyseal joints, are a potential source of neck pain (cervical facet joint pain). The cervical facet joints are innervated by the cervical medial branches (CMBs) of the cervical segmental nerves. Cervical facet joint pain has been shown to respond to multisegmental radiofrequency denervation of the cervical medial branches. This procedure is performed under fluoroscopic guidance. Currently, three approaches are described and used. Those three techniques of radiofrequency treatment of the CMBs, classified on the base of the needle trajectory toward the anatomical planes, are as follows: the posterolateral technique, the posterior technique, and the lateral technique. We describe the three techniques with their advantages and disadvantages. Anatomical studies providing a topographic anatomy of the course of the CMBs are reviewed. We developed a novel approach based on the observed strengths and weaknesses of the three currently used approaches and based on recent anatomical findings. With this fluoroscopic-guided approach, there is always bone (the facet column) in front of the needle, which makes it safer, and the insertion point is easier to determine without the risk of positioning the radiofrequency needle too dorsally.

The Role of Spectral Tissue Sensing During Lumbar Transforaminal Epidural Injection.

Spectral tissue sensing (STS) exploits the scattering and absorption of light by tissue. The main objective of the present study was to determine whether STS can discriminate between correct and incorrect placement of the needle tip during lumbar transforaminal epidural injection. This was a single-blind prospective observational study in 30 patients with lumbar radicular pain scheduled for lumbar transforaminal epidural injection. Spectral tissue sensing data from the needle tip were acquired along the needle trajectory at 4 predefined measurement points and compared with ultrasound, fluoroscopy, and digital subtraction angiography images. Spectral tissue sensing data contained the full spectra. The lipid and hemoglobin content at the different measurement points was also calculated, and partial least-squares discriminant analysis was used to estimate the sensitivity and specificity of STS. Spectral tissue sensing identified correct needle placement with a sensitivity of 57% and a specificity of 82%, and intraforaminal versus extraforaminal locations were identified with a sensitivity of 80% and a specificity of 71%.

Optical detection of peripheral nerves: an in vivo human study.

BACKGROUND AND OBJECTIVES: A critical challenge encountered in interventional pain medicine procedures is to accurately and efficiently identify transitions to peripheral nerve targets. Current methods, which include ultrasound guidance and nerve stimulation, are not perfect. In this pilot study, we investigated the feasibility of identifying tissue transitions encountered during insertions toward peripheral nerve targets using optical spectroscopy. METHODS: Using a custom needle stylet with integrated optical fibers, ultrasound-guided insertions toward peripheral nerves were performed in 20 patients, with the stylet positioned in the cannula of a 20-gauge stimulation needle. Six different peripheral nerves were represented in the study, with 1 insertion per patient. During each insertion, optical reflectance spectra were acquired with the needle tip in subcutaneous fat, skeletal muscle, and at the nerve target region. Differences in the spectra were quantified with 2 parameters that provide contrast for lipid and hemoglobin, respectively. RESULTS: The transition of the needle tip from subcutaneous fat to muscle was associated with lower lipid parameter values (P = 0.003) and higher hemoglobin parameter values (P = 0.023). The transition of the needle tip from the muscle to the nerve target region was associated with higher lipid parameter values (P = 0.008). CONCLUSIONS: The results indicate that the spectroscopic information provided by the needle stylet could potentially allow for reliable identification of transitions from subcutaneous fat to skeletal muscle and from the muscle to the nerve target region during peripheral nerve blocks.

Optical detection of vascular penetration during nerve blocks: an in vivo human study.

BACKGROUND AND OBJECTIVES: Complications resulting from vascular penetration during nerve blocks are rare but potentially devastating events that can occur despite meticulous technique. In this in vivo human pilot study, we investigated the potential for detecting vascular penetration with optical reflectance spectroscopy during blocks of the sympathetic chain and the communicating ramus at lumbar levels. METHODS: A custom-designed needle stylet with integrated optical fibers was used in combination with a commercial needle shaft. The needle stylet was connected to a console that delivered broadband light to tissue and spectrally resolved light that was scattered near the stylet tip. A total of 18 insertions were performed on 10 patients; testing for vascular penetration at the nerve target region was performed with aspiration and with radio-opaque contrast injections, visualized fluoroscopically. Optical absorption by hemoglobin was quantified with a blood parameter that was calculated from each spectrum. The blood parameter provided a measure of the difference between spectra acquired from the nerve target region and reference spectra acquired from blood extracted from a volunteer. RESULTS: In 2 insertions, vascular penetration was detected. Pronounced optical absorption by hemoglobin was observed to be associated with both of these events and absent in all other cases. The difference between the blood parameters obtained when vascular penetration was detected, and all other blood parameters were statistically significant (P = 0.006), with a diagnostic odds ratio of 35.4 (confidence interval, 2.21 to ∞). CONCLUSIONS: The results from this study suggest that optical spectroscopy has the potential to detect intravascular needle placement, which may in turn increase the safety of nerve blocks.

Optical detection of the brachial plexus for peripheral nerve blocks: an in vivo swine study.

BACKGROUND AND OBJECTIVES: Accurate identification of nerves is critical to ensure safe and effective delivery of regional anesthesia during peripheral nerve blocks. Nerve stimulation is commonly used, but it is not perfect. Even when nerve stimulation is performed in conjunction with ultrasound guidance, determining when the needle tip is at the nerve target region can be challenging. In this in vivo pilot study, we investigated whether close proximity to the brachial plexus and penetration of the axillary artery can be identified with optical reflectance spectroscopy, using a custom needle stylet with integrated optical fibers. METHODS: Ultrasound-guided insertions to place the needle tip near the brachial plexus at the axillary level were performed at multiple locations in 2 swine, with the stylet positioned in the cannula of a 20-gauge stimulation needle. During each insertion, optical reflectance spectra were acquired with the needle tip in skeletal muscle, at the surface of muscle fascia, and at the nerve target region; confirmation of the final needle position was provided by nerve stimulation. In addition, an insertion to the lumen of the axillary artery was performed in a third swine. Differences in the spectra were quantified with lipid and hemoglobin parameters that provide contrast for optical absorption by the respective chromophores. RESULTS: The transition of the needle tip from skeletal muscle to the nerve target region was associated with higher lipid parameter values (P < 0.001) and lower hemoglobin parameter values (P < 0.001). The transition of the needle tip from muscle fascia to the nerve target region was associated with higher lipid parameter values (P = 0.001). Intraluminal access of the axillary artery was associated with an elevated hemoglobin parameter. CONCLUSIONS: Spectroscopic information obtained with the optical needle is distinct from nerve stimulation and complementary to ultrasound imaging, and it could potentially allow for reliable identification of the injection site during peripheral nerve blocks.

Somatic and psychologic predictors of long-term unfavorable outcome after surgical intervention.

OBJECTIVE: To identify somatic and psychologic predictors of pain, functional limitations, global perceived recovery, and quality of life 6 months after surgical intervention. SUMMARY BACKGROUND DATA: Recent studies have indicated that chronic pain after surgical intervention is more common than previously assumed. Several demographic and somatic predictors of long-term unfavorable outcome have been identified, but little is known about the contribution of psychologic risk factors. METHODS: A prospective cohort study, including 625 patients undergoing elective surgery at the University Hospital Maastricht, The Netherlands, was conducted between February and August 2003. Psychologic questionnaires were completed preoperatively and acute postoperative pain was recorded until 4 days after the operation. Six months later, all patients received follow-up questionnaires to assess pain, functional limitations, global perceived recovery, and quality of life. Multivariable logistic regression analyses were used to estimate relative risk of poor outcome in terms of pain, functional limitations, and global recovery. Multivariable linear regression analysis was used to assess associations with quality of life at 6 months. RESULTS: The most important somatic predictors of unfavorable outcome were duration of the operation and high levels of acute postoperative pain. Patients reporting high levels of pain 4 days after the operation and patients undergoing an operation of longer than 3 hours were at risk for increased pain, increased functional limitations, poor global recovery, and reported lower levels of quality of life 6 months after the operation. Psychologic variables that influenced long-term outcome were preoperative fear of surgery and optimism. Fear of the long-term consequences of the operation was associated with more pain, poor global recovery, and worse quality of life 6 months later, whereas optimism was associated with better recovery and higher quality of life. CONCLUSIONS: This study was the first to identify the joint contribution of somatic and psychologic factors to chronic pain, functional limitations, and quality of life 6 months after surgical interventions. It replicates previous findings that intense acute postoperative pain is a risk factor for long-term adverse outcome and also identified additional risk factors, namely, long duration of the operation, ASA status, and preoperative fear of surgery.