Fluoroscopy-Guided High-Intensity Focused Ultrasound Neurotomy of the Lumbar Zygapophyseal Joints: A Clinical Pilot Study.

OBJECTIVE: To investigate the safety and feasibility of a fluoroscopy-guided, high-intensity focused ultrasound system for zygapophyseal joint denervation as a treatment for chronic low back pain. METHODS: The clinical pilot study was performed on 10 participants diagnosed with lumbar zygapophyseal joint syndrome. Each participant had a documented positive response to a diagnostic block or a previous, clinically beneficial radiofrequency ablation. For a descriptive study, the primary outcome was the safety question. All device- or procedure-related adverse events were collected. Secondary outcome variables included the average numeric rating scale for pain, the Roland-Morris Disability Questionnaire, the Brief Pain Inventory, the Patient Global Impression of Change, the morphine equivalent dose, and the finding of the neurological examination. RESULTS: All participants tolerated the procedure well with no significant device- or procedure-related adverse events; there was one episode of transient pain during the procedure. The average numeric rating scale score for pain decreased from 6.2 at baseline to 2.1 (n = 10) after 1 month, 4.9 (n = 9) after 3 months, 3.0 (n = 8) after 6 months, and 3.0 (n = 6) after 12 months. The ratio of participants who were considered a treatment success was 90% at 1 month, 50% at 3 months, 60% at 6 months, and 40% at 12 months. CONCLUSIONS: The first clinical pilot study using a noninvasive, fluoroscopy-guided, high-intensity focused ultrasound lumbar zygapophyseal neurotomy resulted in no significant device- or procedure-related adverse events and achieved clinical success comparable with that of routine radiofrequency ablation.

Biceps Tendon Sheath Injection: An Anatomical Conundrum.

Objective: Long head biceps tendon peritendinous or sheath injections are routinely administered at or immediately distally to the bicipital groove. The main indication for injection remains the clinical diagnosis or treatment of biceps tendinopathy, although true inflammation of the tendon within the bicipital groove is rare. Because the tendon sheath is merely an extension of the joint cavity, it is plausible to assume that an injection into the sheath would result in intraarticular spread. Surprisingly, such an anatomical tenet has a vague confirmation in the published clinical literature. This experiment was undertaken to investigate patterns of injectate spread when peri-tendon injection at the bicipital groove is performed. Design: An experimental cadaveric study. Setting: An institutional clinical anatomy laboratory. Methods: Twelve ultrasound-guided methylene blue injections of the bicep tendon sheath were performed on cadaver specimens. Dissections and gross examination of staining of the internal joint surfaces were performed. Visual confirmation of the intra- and/or extra-articular spread of the injectate was performed. Results: In 11 specimens, injected contrast was found spreading onto the entire internal joint surface, including glenoid cartilage. One extraarticular injection was attributable to a technical issue. Conclusions: The experiment confirmed continuity of the joint capsule and the biceps tendon sheath. These results suggest a low diagnostic utility of peritendinous injections at the level of the bicep groove. Such injections would likely result in intraarticular deposit of the injectate. Nonetheless, this approach may be utilized as an alternative simplified access to the glenohumeral joint.

Using Activity Trackers to Quantify Postpartum Ambulation: A Prospective Observational Study of Ambulation after Regional Anesthesia and Analgesia Interventions.

BACKGROUND: Early postoperative ambulation is associated with enhanced functional recovery, particularly in the postpartum population, but ambulation questionnaires are limited by recall bias. This observational study aims to objectively quantify ambulation after neuraxial anesthesia and analgesia for cesarean delivery and vaginal delivery, respectively, by using activity tracker technology. The hypothesis was that vaginal delivery is associated with greater ambulation during the first 24 h postdelivery, compared to cesarean delivery. METHODS: Parturients having first/second cesarean delivery under spinal anesthesia or first/second vaginal delivery under epidural analgesia between July 2015 and December 2016 were recruited. Patients with significant comorbidities or postpartum complications were excluded, and participants received standard multimodal analgesia. Mothers were fitted with wrist-worn activity trackers immediately postdelivery, and the trackers were recollected 24 h later. Rest and dynamic postpartum pain scores at 2, 6, 12, 18, and 24 h and quality of recovery (QoR-15) at 12 and 24 h were assessed. RESULTS: The study analyzed 173 patients (cesarean delivery: 76; vaginal delivery: 97). Vaginal delivery was associated with greater postpartum ambulation (44%) compared to cesarean delivery, with means ± SD of 1,205 ± 422 and 835 ± 381 steps, respectively, and mean difference (95% CI) of 370 steps (250, 490; P < 0.0001). Although both groups had similar pain scores and opioid consumption (less than 1.0 mg of morphine), vaginal delivery was associated with superior QoR-15 scores, with 9.2 (0.6, 17.8; P = 0.02) and 8.2 (0.1, 16.3; P = 0.045) differences at 12 and 24 h, respectively. CONCLUSIONS: This study objectively demonstrates that vaginal delivery is associated with greater early ambulation and functional recovery compared to cesarean delivery. It also establishes the feasibility of using activity trackers to evaluate early postoperative ambulation after neuraxial anesthesia and analgesia.

Peripheral Nerve Stimulation for Chronic Shoulder Pain: A Proof of Concept Anatomy Study.

OBJECTIVES: Although spinal cord and dorsal root ganglia stimulation may be effective for managing regional pain syndromes, a more targeted approach is perhaps more appealing for discrete anatomical structures. Chronic shoulder pain is a common musculoskeletal problem with significant socioeconomic impact. A peripheral nerve stimulation of the axillary and suprascapular nerves may prove to be effective as a long-term solution for this indication. In anticipation of the future experimental research and clinical utilization, a sound methodology for the lead placement was developed, and its feasibility is tested in a cadaveric study. MATERIALS AND METHODS: Normal anatomy was corroborated with ultrasound scans of live models and cadaver specimens. A step-by-step ultrasound-guided implantation technique was designed. The procedure was completed targeting both the axillary and suprascapular nerves. The accuracy of the lead placement was confirmed by dissections. RESULTS: The implanted devices were found adjacent to the target nerves within 0.5-1 cm distance. CONCLUSIONS: The anatomical dissections confirmed the accuracy of ultrasound-guided placement of the lead. The described method is based on normal anatomy and appeared to be reproducible by following the outlined procedural steps.

Twelve-Month Follow-up of a Randomized Clinical Trial Comparing Intradiscal Biacuplasty to Conventional Medical Management for Discogenic Lumbar Back Pain.

Objective: This report conveys 12-month outcomes of subjects treated with intradiscal biacuplasty (IDB) and conservative medical management (CMM) for chronic low back pain of discogenic origin, and results for subjects who elected to receive IDB + CMM 6 months after CMM-alone. Methods: Sixty-three subjects were originally randomized to the IDB + CMM group (N = 29) or CMM-alone (N = 34). Six months following continuous CMM-alone treatment, participants in this study group were permitted to "cross-over" to IDB + CMM (N = 25), and followed for an additional 6 months. The original IDB + CMM study subjects were followed for a total of 12 months (N = 22). Results: Pain reduction at 12 months was statistically significant and clinically meaningful in the original IDB + CMM group compared to baseline. Functional and disability outcomes were also improved statistically and clinically. Fifty-five percent of the IDB + CMM patients responded to treatment with a mean VAS reduction of 2.2 points at 12 months. Furthermore, 50% and 64% of subjects reported clinically significant improvements in SF36-PF and in ODI, respectively. There was a 1.7-point reduction (improvement) on a 7-point PGIC scale, and a 0.13-point increase (improvement) in the EQ-5D Health Index. Fifty-percent of cross-over subjects responded to IDB + CMM intervention. Mean outcome scores for cross-over subjects were similar to those of the originally-treated subjects, and functional and disability endpoints were improved statistically and clinically compared to respective baseline values. Conclusions: The study demonstrated long-term clinical effectiveness of IDB + CMM for treating chronic lumbar discogenic pain. Furthermore, the cross-over study subjects experienced similar improvements in pain, function, disability, and satisfaction.

Ultrasound-Guided Superior Hypogastric Plexus Block: A Cadaveric Feasibility Study with Fluoroscopic Confirmation.

Plancarte first described a fluoroscopy-guided superior hypogastric plexus block to manage pelvic pain in 1990. Modifications have since been described using different imaging modalities. Ultrasound-guided approach has been described in a clinical outcome study. However, the accuracy of an ultrasound-guided method has never been validated by alternative imaging. We conducted an experiment aiming to develop ultrasound-guided superior hypogastric plexus block using human cadavers in the supine position. Final needle position and spread of a radiopaque contrast was verified by fluoroscopy, a standard imaging tool. The needle approach to the L5 vertebral body was performed in the short axis as has been recommended. Injection of radiopaque contrast revealed unilateral and cephalad spread to the L5/S1 disk. Additional transabdominal long-axis scanning of the lumbosacral segment was and the needle trajectory was modified to aim for the apex of the L5/S1 disk. Bilateral spread was achieved by strict midline placement of the needle tip and real-time observation of injection. The modified ultrasound-guided technique resulted in a similar spread of injectate as the traditional fluoroscopy-guided technique that in a clinical scenario would offer complete block of the superior hypogastric plexus.

New horizons in neuromodulation.

Electrical stimulation of the nervous system is a method used for several centuries which just in the past decades received wide recognition as an effective and safe modality in the management of neuropathic pain and other maladies. Explosion of new technologies and discovery of new neuromodulation targets are two parallel and interconnected processes. Using a paraphrase from the famous novel of Samuel Sham, The House of God, one can say that there is no nervous tissue in the human body that cannot be reached with a stimulating lead directed by a good strong arm. Neuromodulation devices are being used for the stimulation of the entire nervous system, from the cutaneous terminals to brain centers. Autonomic regulation is also subject to stimulation via implanted devices. Future research and development is tightly related to the process of discovery, experimental courage, and philosophical exploration of neurobehavioral mechanisms.

"Sonology" of programmable intrathecal pumps.

OBJECTIVE: The study aims to demonstrate the unique sonographic features of the commercially available intrathecal drug delivery systems. METHODS: "Not-for-human-use" pumps were obtained, placed in a tray, and covered with an ultrasound phantom gel. The anterior surface of each pump was scanned and the sonographic features were observed and recorded. RESULTS: All systems have a centrally located reservoir port (RP) and a peripherally located catheter access port (CAP) that are observable on ultrasound. The RP of the SynchroMed II system (Medtronic, Minneapolis, MN, USA) appears as an anechoic depression and a break in the bright echogenic line of the superior pump surface. The CAP appears as smaller diameter conical depression outside the circular perimeter of the pump. The RP of the MedStream system (Codman & Shurtleff, Inc., Raynham, MA, USA) has a dome-shaped appearance. The CAP appears as a smaller dome-shaped object that is off center but still contained within the circular perimeter of the pump. Similarly, the RP of the Prometra system (Flowonix Medical Inc, Mt. Olive, NJ, USA) is a dome-shaped object. The CAP visually appears similar to the reservoir access port of the SynchroMed II system, namely a small depression and a break in the bright echogenic line of the pump surface, outside the perimeter of the pump. CONCLUSION: In all programmable intrathecal pumps, the RP can be readily identified sonographically. Potentially, the dome-shaped configuration of RP for the Prometra and MedStream systems make the access easier, when compared with SynchroMed II system. Ultrasound could potentially be utilized to localize the RP and CAP for all the systems as each of the three systems has a unique sonographic appearance.

Ultrasound-guided placement of a paddle lead onto peripheral nerves: surgical anatomy and methodology.

OBJECTIVES: Implanted peripheral nerve stimulation is one of the earliest developed methods of neuromodulation for the treatment of chronic neuropathic pain. It is traditionally performed by surgical exposure and implantation of a paddle lead. Ultrasound-guided percutaneous placement of cylindrical leads has been proposed as an alternative. However, those leads are fragile and prone to migration. Minimally invasive paddle lead implantation may improve long-term results while minimizing surgical insult. A feasibility laboratory study was performed. MATERIALS AND METHODS: Ultrasound-guided placements of a narrow paddle lead were performed in the upper and lower extremities of a human cadaver. Ultrasonography was used to record the lead position relative to the target nerves. Dissections were performed, and digital photography was completed. Anatomic images were analyzed. RESULTS: All experiments were successfully accomplished. Although ultrasound localization of the upper extremity nerves was straightforward and clear, all procedural steps were technically easier at the lower extremity. For the latter, fewer attempts were required to maintain the lead in the desired tissue plane. Ultrasound revealed an acoustic shadowing of the underlying nerves in both the short- and long-axis views by the inserted lead. All dissections revealed a parallel to the nerve lead placement with at least four contacts facing the nerve. The lead appeared to be more mechanically stable at the lower extremity. CONCLUSIONS: This anatomic study confirmed technical feasibility of percutaneous placement of a narrow paddle-type lead for the peripheral nerve stimulation that may potentially improve stimulation and reduce migrations.

Fluoroscopy-guided high-intensity focused ultrasound neurotomy of the lumbar zygapophyseal joints: a prospective, open-label study.

OBJECTIVE: The objective of this study is to investigate safety and effectiveness of a fluoroscopy-guided high-intensity focused ultrasound (HIFU) system for thermal ablation of the lumbar medial branch nerves. METHODS: This dual center prospective cohort study enrolled 30 participants with lumbar zygapophyseal joint syndrome. Each participant previously had a positive response to either a single diagnostic analgesic block or radiofrequency ablation (RFA). The primary effectiveness outcome was individual responder rate, defined as a reduction of two points or more on the pain intensity numerical rating scale without an increase in opioid intake, or a reduction in opioid intake without an increase in pain at 6 months after the intervention. The primary safety outcome was procedure-related or device-related adverse events (AEs). Secondary outcome variables included MRI evidence of tissue ablation, Oswestry Disability Index, 12-Item Short Form Health Survey, Brief Pain Inventory, and Patient Global Impression of Change. RESULTS: The individual responder rate was 89.7% at 2 days, 89.7% at 7 days, 72.4% at 14 days, 82.1% at 30 days, 59.3% at 90 days and 82.6% at 180 days. The average Numeric Rating Scale for pain severity decreased from 7.1 at baseline to 3.0 (N=29) after 2 days, 3.0 (N=29) after 7 days, 3.1 (N=29) after 14 days, 3.2 (N=28) after 30 days, 4.3 (N=27) after 90 days, and 3.3 (N=23) after 180 days. All participants tolerated the procedure well with no significant side effects or complications. CONCLUSIONS: Fluoroscopy-guided HIFU neurotomy achieved clinical responses comparable with RFA, and there were no significant device-related or procedure-related AEs. TRIAL REGISTRATION NUMBER: NCT04129034.

Fluoroscopy-guided high-intensity focused ultrasound ablation of the lumbar medial branch nerves: dose escalation study and comparison with radiofrequency ablation in a porcine model.

BACKGROUND: Radiofrequency ablation (RFA) is a common method for alleviating chronic back pain by targeting and ablating of facet joint sensory nerves. High-intensity focused ultrasound (HIFU) is an emerging, non-invasive, image-guided technology capable of providing thermal tissue ablation. While HIFU shows promise as a potentially superior option for ablating sensory nerves, its efficacy needs validation and comparison with existing methods. METHODS: Nine adult pigs underwent fluoroscopy-guided HIFU ablation of eight lumbar medial branch nerves, with varying acoustic energy levels: 1000 (N=3), 1500 (N=3), or 2000 (N=3) joules (J). An additional three animals underwent standard RFA (two 90 s long lesions at 80°C) of the same eight nerves. Following 2 days of neurobehavioral observation, all 12 animals were sacrificed. The targeted tissue was excised and subjected to macropathology and micropathology, with a primary focus on the medial branch nerves. RESULTS: The percentage of ablated nerves with HIFU was 71%, 86%, and 96% for 1000 J, 1500 J, and 2000 J, respectively. In contrast, RFA achieved a 50% ablation rate. No significant adverse events occurred during the procedure or follow-up period. CONCLUSIONS: These findings suggest that HIFU may be more effective than RFA in inducing thermal necrosis of the nerve.

Intense focused ultrasound preferentially stimulates subcutaneous and focal neuropathic tissue: preliminary results.

OBJECTIVE: Potential peripheral sources of pain from subcutaneous tissue can require invasive evocative tests for their localization and assessment. Here, we describe studies whose ultimate goal is development of a noninvasive evocative test for subcutaneous, painful tissue. DESIGN: We used a rat model of a focal and subcutaneous neuroma to test the hypothesis that intense focused ultrasound can differentiate focal and subcutaneous neuropathic tissue from control tissue. To do so, we first applied intense focused ultrasound (2 MHz, with individual pulses of 0.1 second in duration) to the rat's neuroma while the rat was under light anesthesia. We started with low values of intensity, which we increased until intense focused ultrasound stimulation caused the rat to reliably flick its paw. We then applied that same intense focused ultrasound protocol to control tissue away from the neuroma and assayed for the rat's response to that stimulation. RESULTS: Intense focused ultrasound of sufficient strength (I(SATA) of 600 +/- 160 W/cm(2) ) applied to the neuroma caused the rat to flick its paw, while the same intense focused ultrasound applied millimeters to a centimeter away failed to induce a paw flick. CONCLUSION: Successful stimulation of the neuroma by intense focused ultrasound required colocalization of the neuroma and intense focused ultrasound supporting our hypothesis.

Rapid ultrasonic stimulation of inflamed tissue with diagnostic intent.

Previous studies have observed that individual pulses of intense focused ultrasound (iFU) applied to inflamed and normal tissue can generate sensations, where inflamed tissue responds at a lower intensity than normal tissue. It was hypothesized that successively applied iFU pulses will generate sensation in inflamed tissue at a lower intensity and dose than application of a single iFU pulse. This hypothesis was tested using an animal model of chronic inflammatory pain, created by injecting an irritant into the rat hind paw. Ultrasound pulses were applied in rapid succession or individually to rats' rear paws beginning at low peak intensities and progressing to higher peak intensities, until the rats withdrew their paws immediately after iFU application. Focused ultrasound protocols consisting of successively and rapidly applied pulses elicited inflamed paw withdrawal at lower intensity and estimated tissue displacement values than single pulse protocols. However, both successively applied pulses and single pulses produced comparable threshold acoustic dose values and estimates of temperature increases. This raises the possibility that temperature increase contributed to paw withdrawal after rapid iFU stimulation. While iFU-induction of temporal summation may also play a role, electrophysiological studies are necessary to tease out these potential contributors to iFU stimulation.

Pulsed radiofrequency of suprascapular nerve for chronic shoulder pain: a randomized double-blind active placebo-controlled study.

BACKGROUND: The suprascapular nerve block is frequently implemented to treat chronic shoulder pain. Although effective the nerve blockade provides only a short-term relief, and more compelling apaproaches have been investigated. Pulsed radiofrequency (pRF) has been anecdotally reported as safe and reliable method. However, formal efficacy study has not been published. Ostensibly evidence-based validation of a new method is necessary for both scholastic and practical purposes. METHODS: This study was designed as a randomized active placebo-control double-blind trial. Because of encountered difficulties in recruitment and high rate of dropout, the study was redesigned as to allow a smaller sample size and statistical analyses were performed utilizing the last observation carry forward method. Lidocaine injections alone or with combination of the pRF were performed. Participants were followed up during 6 months, and multiple subjective and objective outcome variables were recorded. RESULTS: Thirteen of 22 participants completed 6 months follow-up. Dropout rate was higher in the lidocaine group. A significant linear trend (P < 0.05) for improvement on the numeric rating scale, Shoulder Pain and Disability Index and Constant-Murley score was observed in the pRF group, but not in the lidocaine group. Patients in the pRF group were on average more satisfied than the lidocaine group at 1 month (P = 0.041) and at 3 months (P = 0.035). DISCUSSION: Considering limitations of the study design and statistics, it seems plausible to attribute better results in the pRF group to unique properties of this physical modality.

Validation of self-reported pain reduction after diagnostic blockade.

OBJECTIVE: The criterion commonly used to determine whether radiofrequency neurotomy may be recommended is based on patient-reported, short-term pain relief following facet block injections. This study evaluated the concordance between two commonly used outcomes for pain relief: the pain numerical rating scale (NRS) and the global perceived improvement (GPI) scale. DESIGN: This is a retrospective cohort study. METHODS: Data were obtained from a consecutive cohort of patients through a review of the electronic medical records, with the following inclusion criteria: medial branch facet blocks at either cervical or lumbar spinal regions. OUTCOME MEASURES: Pain NRS (baseline, postprocedure, and hourly up to 6 hours) and GPI scale are expressed as percent improvement at 6 hours, relative to baseline. RESULTS: The percent improvement in pain NRS corresponded to 49%, 43%, 34%, 21%, and 36% for baseline vs immediately post-block, 1 hour, 3 hours, 6 hours and average of all postscores, respectively. Average GPI reported at 6 hours was 44%, and differed significantly only to the baseline vs 6 hours percent improvement on the NRS (P < 0.01). Multiple regression analysis indicated that there were no demographic or baseline factors that accounted for the discrepancy between GPI vs NRS. CONCLUSIONS: Asking patients about their pain relief in retrospect can be misleading. It is possible that patients' report on the GPI is weighed by their total experience of pain reduction and retrospective recall. Therefore, when choosing to address percent improvement on NRS measures, it is important to take into account multiple instances of NRS measures following treatment.

Ultrasound-guided intrathecal pump access and prevention of the pocket fill.

OBJECTIVE: Intrathecal pump drug refill may result in significant adverse outcome and complications. Thus far, 351 reports from around the world have been received by Medtronic Inc. related to occurrence of pocket fill, including eight lethal events. Ultrasound-assisted pump port access has been previously described, but did not result in wide acceptance in routine practice due to cumbersome and unreliable setup. This study outlines the methodology of real-time ultrasound-guided pump refill. DESIGN: Preclinical feasibility study. SETTING: University of Washington Body Willed Program laboratory. INTERVENTIONS: Using unembalmed cadaver model clinical scenarios of either inverted or deeply implanted pump were replicated. Sonographic images of those conditions were studied and an ultrasound-guided technique for accessing the pump injection port was developed. The ability to correctly identify pump versus pocket fill using ultrasonography was evaluated. OUTCOME MEASUREMENTS: Positive and negative predictive value of correct needle placement, assessment of learning curve for inexperienced user, description of ultrasonography of inverted pump. RESULTS: Both positive and negative predictive values reached 100%. Mastering the technique easy and uneventful. Inverted pump has a distinctive sonographic appearance. CONCLUSIONS: Ultrasound-guided intrathecal pump access is a feasible and simple technique that may improve maintenance, routine device care, and prevent serious complications related to erroneous subcutaneous injections of concentrated medications. Clinical validation will be necessary in the future.

Ultrasound-guided caudad epidural access for the lumbosacral neurostimulation: case report and technical note.

OBJECTIVES: This is a case report and description of a new ultrasound-guided caudad epidural needle placement for percutaneous stimulation of the lumbosacral roots. MATERIALS AND METHODS: Case report. RESULTS: Using ultrasonography pertinent spinal and neuroaxial anatomy was visualized. In-plane approach with continuous monitoring of the needle advancement was utilized. The needle was seamlessly placed in the epidural space on the first attempt. CONCLUSIONS: Spinal sonography is a promising imaging method to facilitate percutaneous caudad epidural access.

A Retrospective Cohort Study of Healthcare Utilization Associated with Paravertebral Blocks for Chronic Pain Management in Ontario.

Background: Injections, particularly paravertebral blocks (PVBs), are frequently performed procedures in Ontario, Canada, for the management of chronic pain, despite limited evidence and risk of complications. Aim: This study examines usage patterns of PVBs to evaluate their effects on healthcare utilization and opioid prescribing. Methods: A retrospective cohort study in Ontario using administrative data. Ontario residents receiving their initial PVBs between July 1, 2013 and March 31, 2018 were included. Changes in use of other interventions, physician visits, and opioids were compared to the 12-month periods before and after index PVBs. Data use was authorized under section 45 of Ontario's Personal Health Information Protection Act. Results: 47,723 patients received their initial PVBs in the study period. The rate of index PVBs increased from 1.61 per 10,000 population (2013) to 2.26 per 10,000 (2018). Initial PVBs were performed most commonly by family physicians (N = 25,042), followed by anesthesiologists (N = 14,195). 23,386 patients (49%) received 1 to 9 repeat PVBs in the 12 months after index PVB; 12,474 patients (26.15%) received 10 or more. Use of other nonimage guided interventional pain procedures per patient (mean±SD) increased from 2.19 ± 9.35 to 31.68 ± 52.26 in the year before and after index PVB. Relevant physician visits per patient (mean±SD) also increased from 2.92 ± 3.61 to 9.64 ± 11.77. Mean opioid dosing did not change significantly between the year before and the year after index PVB. Conclusion: PVBs are associated with increases in healthcare utilization and no change in opioid use patterns.

Contexte: Les injections, en particulier les blocs paravertébraux (BPV), sont des procédures fréquemment effectuées en Ontario, Canada, pour la prise en charge de la douleur chronique, malgré des données probantes limitées et le risque de complications.Objectif: Cette étude examine les modes d'utilisation des BPV afin d'évaluer leurs effets sur l'utilisation des soins de santé et la prescription d'opioïdes.Méthodes: Étude de cohorte rétrospective utilisant les données administratives en Ontario. Les résidents de l'Ontario ayant reçu leur BPV initial entre le 1er juillet 2013 et le 31 mars 2018 ont été inclus. Les changements dans l'utilisation des autres interventions, les visites aux médecins et les opioïdes ont été comparés 12 mois avant et 12 mois après les BPV de référence. L'utilisation des données a été autorisée en vertu de la Loi sur la protection des renseignements personnels sur la santé de l'Ontario.Résultats: 47 723 patients ont reçu leur BPV initial au cours de la période étudiée. Le taux de BPV est passé de 1,61 pour 10 000 habitants (2013) à 2,26 pour 10 000 (2018). Les BPV de référence étaient effectués le plus souvent par des médecins de famille (N = 25 042), suivis par les anesthésistes (N = 14 195). 23 386 patients (49 %) ont reçu de 1 à 9 BPV répétés dans les 12 mois suivant le BPV de référence ; 12 474 patients (26,15 %) en ont reçu 10 ou plus. L'utilisation d'autres procédures interventionnelles pour la douleur non guidées par l'image par patient (moyenne ± ET) est passée de 2,19 ± 9,35 à 31,68 ± 52,26 l'année précédant et suivant le BPV. Les visites médicales pertinentes par patient (moyenne ± ET) ont également augmenté de 2,92 ± 3,61 à 9,64 ± 11,77. La dose moyenne d'opioïdes n'a pas changé de manière significative entre l'année précédant et suivant le BPV de référence.Conclusion: Les BPV sont associés à une augmentation de l'utilisation des soins de santé et ne sont associés à aucun changement dans les modes d'utilisation des opioïdes.

Tolerability and Feasibility of X-ray Guided Non-Invasive Ablation of the Medial Branch Nerve with Focused Ultrasound: Preliminary Proof of Concept in a Pre-clinical Model.

Four to six million patients a year in the United States suffer from chronic pain caused by facet joint degeneration. Thermal ablation of the affected facet joint's sensory nerve using radiofrequency electrodes is the therapeutic standard of care. High-intensity focused ultrasound (HIFU) is a novel technology enabling image-guided non-invasive thermal ablation of tissue. Six pigs underwent fluoroscopy-guided HIFU of the medial branch nerve and were followed up for 1 wk (two pigs), 1 mo (two pigs) and 3 mo (two pigs). At the end of each follow-up period, the animals were sacrificed, and targeted tissue was excised and evaluated with computed tomography scans as well as by macro- and micropathology. No significant adverse events were recorded during the procedure or follow-up period. All targets were successfully ablated. X-Ray-guided HIFU is a feasible and promising alternative to radiofrequency ablation of the lumbar facet joint sensory nerve.

In vivo measurements of medial branch nerve depth and adjacent osseous structures for ablation of facet-related back pain: Predictors for patient candidacy.

BACKGROUND: Medial branch (MB) targeting during RF ablation for facetogenic back pain is usually performed with flouroscopic guidance yet no specific measurements on the target depth have been published. In order to understand candidacy for other potential ablation methods, we sought to determine the actual MB depth and measurements of adjacent osseous structures. METHODS: CT scans without contrast of the lumbar spine performed in the supine position were retrospectively analyzed in 100 patients. Axial slices less than or equal to 2.5 mm with sagittal and coronal reformations were evaluated. The following distances were measured bilaterally at the L2-L5 levels: The depth from the skin to the MB nerve (anatomic target for RF ablation) at a 15° angulation, the smallest width of the pedicle, and the length, height and width of the transverse process. Age, gender, weight, height, and BMI were correlated with the above measurements. RESULTS: The average distance and 95% CI from skin-to-MB in mm at a 15°angle to the skin increased as the lumbar level increased measuring 64.4 (62.4-66.5) at L2, 72.0 (69.7-74.3) at L3, 79.2 (76.9-81.6) at L4, and 79.1 (76.7-81.5) at L5. The average thickness of the pedicles also increased as the lumbar level increased measuring 9.2 mm at L2 and 16.1 mm at L5. Body weight, lumbar level, and female gender were associated with increased MB depth. Taller stature was associated with more superficial MB depth. We eliminated mild interaction effects between height, weight, and gender by substituting BMI for height and weight without affecting r2. Linear regression revealed the following equation: MB Depth (mm) = 2.2*BMI + 4.9*lumbar vertebral level + 3.6 (if female) - 5.4, which fit the data well (P<0.001, r2 = 0.60). CONCLUSIONS: Our results demonstrate that the MB resides 107 mm or less in depth when measured at a 15° angulation from the skin in > 95% of patients and the distance increases as the lumbar level increases.