Pericapsular nerve group (PENG) block: what have we learned in the last 5 years?

This educational article discusses the current understanding of the pericaspular nerve group block (PENG) of the hip regarding its mechanism of action and spread patterns, as well as plausible explanations for postblock quadriceps weakness. Finally, we will discuss the recent evidence of PENG block as an analgesic block in hip fractures and in different hip surgeries.

Innervation of thumb carpometacarpal joint: implications for diagnostic block and denervation procedures.

INTRODUCTION: Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint is a common disorder that negatively impacts hand function. Denervation of the thumb CMC joint has emerged as a viable treatment option. However, the innervation pattern of the thumb CMC joint is controversial. Therefore, the objective of this study was to identify the articular branches supplying the thumb CMC joint and to document their relationship to anatomical landmarks to provide the foundation for image-guided diagnostic block and denervation procedures. METHODS: In 10 formalin-embalmed upper limb specimens articular branches supplying the thumb CMC joint were dissected from their origin to termination. A frequency map documenting the number of articular branches was generated. The frequency map enabled visualization and comparison of the relative area of innervation of the thumb CMC joint by each articular branch. RESULTS: The thumb CMC joint received innervation from six nerves. These were the deep branch of ulnar nerve (DBUN), dorsal articular nerve (DAN) of the first interosseus space, thenar branch of median nerve (TBMN), palmar cutaneous branch of median nerve (PCBMN), lateral antebrachial cutaneous nerve (LACN) and superficial branch of the radial nerve (SBRN) and/or their branches. Each nerve was found to innervate different aspects of the joint. The DBUN and DAN were found to innervate the posteromedial aspect of the thumb CMC joint, the TBMN and PCBMN anterior/anteromedial aspects, LACN posterolateral/lateral/anterior aspects and SBRN posterolateral/anterolateral aspects. CONCLUSIONS: The thumb CMC joint was innervated by articular branches originating from the SBRN, DAN, LACN, PCBMN, TBMN and DBUN. The documented anatomical relationships provide the foundation to inform selective diagnostic block and denervation of the thumb CMC joint. Further investigations are needed to assess the clinical implications of the current study.

Infraspinatus Fascial Dysfunction as a Cause of Painful Anterior Shoulder Snapping: Its Visualization via Dynamic Ultrasound and Its Resolution via Diagnostic Ultrasound-Guided Injection.

This report presents the first case of painful anterior shoulder snapping due to a thickened, fibrotic bursa snapping between the subscapularis and the short head of the bicep during external and internal rotation of the humerus. A 46-year-old presented with a 10-month history of on-and-off anterolateral right shoulder pain and snapping. Direct treatment to the anterior suspected lesions partially and temporarily relieved the pain but did not reduce the snapping. Further musculoskeletal examination and dynamic ultrasound scanning showed dysfunction in the scapulothoracic movement and defects of the muscles that interact with the infraspinatus aponeurotic fascia. An ultrasound-guided diagnostic injection to the suspected lesions in the infraspinatus fascia and its muscles attachments improved the scapulothoracic movement, and the snapping and pain were eliminated immediately after the injection, which further shows that the defects in the infraspinatus fascia may be the root cause of the painful anterolateral snapping. The importance of the infraspinatus fascia and its related muscle in maintaining the harmony of the scapulothoracic movement and flexibility of the shoulder is considerable.

Spontaneous intracranial hypotension due to CSF-venous fistula: Evaluation of renal accumulation of contrast following decubitus myelography and maintained decubitus CT to improve fistula localization.

PURPOSE: Presented here is a strategy of sequential lateral decubitus digital subtraction myelography (LDDSM) followed closely by lateral decubitus CT (LDCT) to facilitate cerebrospinal fluid (CSF)-venous fistula (CVF) localization. MATERIALS AND METHODS: This is a retrospective analysis of patients referred to our institution for evaluation of CSF leak. Patients with Type 1 and Type 2 leaks, and those not displaying MR brain stigmata of intracranial hypotension were excluded. All patients underwent consecutive LDDSM and LDCT. If the CVF was not localized on the first LDDSM-LDCT pair the patient returned for contralateral examinations. Images were reviewed for CVF and for accumulation of contrast within the renal pelvises expressed as a renal pelvis contrast score (RPCS) in Hounsfield units (HU). RESULTS: Twenty-two patients were included in this study. In 21 of 22 patients (95%) a CVF was identified yielding an RPCS for the LDDSM-LDCT pair ipsilateral to the CVF ranging from 71 to 423 with an average of 146 HU. An RPCS of the negative side LDDSM-LDCT pair contralateral to a CVF was available in 8 patients and averaged 51 HU. In 4 patients the initial bilateral LDDSM-LDCT pairs did not reveal the location of the CVF however in 3 of these 4 cases the CVF was revealed on a third LDDSM repeated ipsilateral to the higher RPCS. CONCLUSION: The strategy of sequential LDDSM-LDCT coupled with evaluation of renal accumulation of contrast agent appears to improve the rate of CVF localization and warrants further evaluation.

Ultrasound-Guided Interventions for Carpal Tunnel Syndrome: A Systematic Review and Meta-Analyses.

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment, and recently, ultrasound-guided perineural injection (UPIT) and percutaneous flexor retinaculum release (UPCTR) have been utilized to treat CTS. However, no systematic review or meta-analysis has included both intervention types of ultrasound-guided interventions for CTS. Therefore, we performed this review using four databases (i.e., PubMed, EMBASE, Scopus, and Cochrane) to evaluate the quality of evidence, effectiveness, and safety of the published studies on ultrasound-guided interventions in CTS. Among sixty studies selected for systemic review, 20 randomized treatment comparison or controlled studies were included in six meta-analyses. Steroid UPIT with ultrasound guidance outperformed that with landmark guidance. UPIT with higher-dose steroids outperformed that with lower-dose steroids. UPIT with 5% dextrose in water (D5W) outperformed control injection and hydrodissection with high-volume D5W was superior to that with low-volume D5W. UPIT with platelet-rich plasma outperformed various control treatments. UPCTR outperformed open surgery in terms of symptom improvement but not functional improvement. No serious adverse events were reported in the studies reviewed. The findings suggest that both UPIT and UPCTR may provide clinically important benefits and appear safe. Further treatment comparison studies are required to determine comparative therapeutic efficacy.

Anatomical Study of the Innervation of Triangular Fibrocartilage Complex and Distal Radioulnar and Radiocarpal Joints: Implications for Denervation.

PURPOSE: Open and percutaneous denervation is an emerging technique for joint pain. This study investigated the course and distribution of the articular branches innervating the triangular fibrocartilage complex (TFCC), distal radioulnar joint (DRUJ), and radiocarpal joint (RCJ) relative to bony and soft tissue landmarks to guide wrist denervation procedures. METHODS: Fourteen formalin-embalmed specimens were serially dissected to expose the origin, course, and distribution of articular branches innervating the TFCC, DRUJ, and RCJ. Bony and soft tissue landmarks to localize each articular branch were documented and visualized on a 3-dimensional reconstruction of the bones of the distal forearm and hand. RESULTS: The TFCC was innervated by articular branches from the posterior interosseus nerve (10 of 14 specimens), dorsal cutaneous branch of the ulnar nerve (14 of 14 specimens), palmar cutaneous branch of the ulnar nerve (12 of 14 specimens), and medial antebrachial cutaneous nerve (9 of 14 specimens). The DRUJ was innervated by the posterior interosseus nerve (9 of 14 specimens) and anterior interosseus nerve (14 of 14 specimens). The RCJ was innervated by the posterior interosseus nerve (14 of 14 specimens), superficial branch of the radial nerve (5 of 14 specimens), lateral antebrachial cutaneous nerve (14 of 14 specimens), and palmar cutaneous branch of the median nerve (10 of 14 specimens). CONCLUSIONS: Multiple nerves were found to innervate the TFCC, DRUJ, and RCJ. The relationship of anatomical landmarks to specific articular branches supplying the TFCC, DRUJ, and RCJ can inform selective denervation procedures based on the structural origin of pain. CLINICAL RELEVANCE: The detailed documentation of the spatial relationship of the nerve supply to the wrist provides clinicians with the anatomical basis to optimize current, and develop new denervation protocols to manage chronic wrist pain.

Cryoanalgesia for shoulder pain: a motor-sparing approach to rotator cuff disease.

INTRODUCTION: Rotator cuff disease is a common cause of musculoskeletal pain and disability, and the management can be challenging. Joint denervation emerges as a new technique, but the literature on shoulder neural ablation procedure is largely limited to pulsed radiofrequency due to the concern of motor impairment. We described a novel motor-sparing approach of cryoablation for the management of shoulder pain based on the recent literature on the innervation of shoulder. METHODS: Four patients with a history of rotator cuff disease refractory to conservative therapy and not amenable to surgery underwent a ultrasound-guided cryoablation of the capsular branches of the shoulder joint after a positive diagnostic injection. The target articular branches were based on the anatomical landmarks described in recent publication. They were the acromial, superior and inferior branches of the suprascapular nerve, the anterior branch of the axillary nerve, the nerve to the subscapularis, which were all located around the superior, posterior and anterior glenoid. The lateral pectoral nerve articular branch was targeted at the coracoclavicular space. RESULTS: All four patients experienced at least 60% pain relief with improvement in function for 6-12 months following the procedure without any clinical evidence of motor impairment. No adverse effect was observed. DISCUSSION: Based on the current understanding of the glenohumeral joint articular branches and their relationship to the bony landmark, targeting the articular branches only was feasible and led to good outcomes. Further large prospective cohort study is needed.

Anatomical study of the medial branches of the lumbar dorsal rami: implications for image-guided intervention.

INTRODUCTION: Fluoroscopic-guided radiofrequency ablation of the lumbar medial branches is commonly performed to manage chronic low back pain originating from the facet joints. A detailed understanding of the course of medial branches in relation to bony and soft tissue landmarks is paramount to optimizing lumbar denervation procedures, particularly parallel placement of the radiofrequency electrode. The objectives of this study were to investigate the relationship of medial branches to anatomical landmarks and discuss the implications for lumbar denervation. METHODS: Ten cadaveric specimens were meticulously dissected. The origin, course, and relationship of lumbar medial branches to bony and soft tissue landmarks were documented. RESULTS: The medial branches followed the lateral neck of superior articular process deep to the intertransversarii mediales muscle at each lumbar vertebral level. In all specimens, the medial branches coursed laterally on the anterior half of the neck and transitioned from parasagittal-to-medial on the posterior half to reach the mamillo-accessory notch. The mamillo-accessory ligament was found to not occlude the nerve on the posterior quarter of the lateral neck but rather at the mamillo-accessory notch located at the posterior margin of the superior articular process. DISCUSSION: A detailed understanding of the relationship of medial branches to anatomical landmarks is essential to optimizing needle placement for lumbar denervation procedures. The current study suggests that a parasagittal placement, with increased cranial-to-caudal angulation of the electrode, may improve parallel tip alignment with the targeted medial branch and represent a potential alternative to the traditional technique.

Frequency and characteristics of patient exclusion criteria in Canadian multidisciplinary pain treatment facilities: a cross-sectional study.

PURPOSE: A multidisciplinary approach is recommended for patients with complex chronic pain (CP). Many multidisciplinary pain treatment facilities (MTPFs) use patient exclusion criteria but little is known about their characteristics. The objective of this study was to describe the frequency and characteristics of exclusion criteria in public Canadian MTPFs. METHODS: We conducted a cross-sectional study in which we defined an MPTF as a clinic staffed with professionals from three disciplines or more (including at least one medical specialty) and whose services were integrated within the facility. We disseminated a web-based questionnaire in 2017-2018 to the administrative leads of MPTFs across the country. They were invited to complete the questionnaire about the characteristics of their facilities. Data were analyzed using descriptive statistics and correlation measures. RESULTS: A total of 87 MTPFs were included in the analyses. Half of them (52%) reported using three exclusion criteria or more. There was no significant association between the number of exclusion criteria and wait time for a first appointment or number of new consultations in the past year. Fibromyalgia and migraine were the most frequently excluded pain syndromes (10% and 7% of MPTFs, respectively). More than one MPTF out of four excluded patients with mental health disorders (30%) and/or substance use disorders (29%), including MPTFs with specialists in their staff. CONCLUSIONS: Multidisciplinary pain treatment facility exclusion criteria are most likely to affect CP patients living with complex pain issues and psychosocial vulnerabilities. Policy efforts are needed to support Canadian MPTFs in contributing to equitable access to pain management.

RéSUMé: OBJECTIF: Une approche multidisciplinaire est recommandée pour les patients souffrant de douleur chronique (DC) complexe. De nombreux centres multidisciplinaires de traitement de la douleur (CMTD) utilisent des critères d'exclusion des patients, mais on ne sait que peu de choses sur leurs caractéristiques. L'objectif de cette étude était de décrire la fréquence et les caractéristiques des critères d'exclusion dans les CMTD publics canadiens. MéTHODE: Nous avons mené une étude transversale dans laquelle nous avons défini un CMTD comme une clinique composée de professionnels de trois disciplines ou plus (y compris au moins une spécialité médicale) et dont les services étaient intégrés à l'établissement. En 2017-2018, nous avons fait parvenir un questionnaire en ligne aux responsables administratifs des CMTD partout au pays. Ils ont été invités à remplir le questionnaire sur les caractéristiques de leurs établissements. Les données ont été analysées à l'aide de statistiques descriptives et de mesures de corrélation. RéSULTATS: Au total, 87 CMTD ont été inclus dans les analyses. La moitié d'entre eux (52 %) ont déclaré utiliser trois critères d'exclusion ou plus. Il n'y avait pas d'association significative entre le nombre de critères d'exclusion et le temps d'attente pour un premier rendez-vous ou le nombre de nouvelles consultations au cours de la dernière année. La fibromyalgie et la migraine étaient les syndromes douloureux les plus fréquemment exclus (10 % et 7 % des CMTD, respectivement). Plus d'un CMTD sur quatre excluait les patients atteints de troubles de santé mentale (30 %) et/ou de troubles liés à l'utilisation de substances (29 %), y compris les CMTD comptant des spécialistes dans leur personnel. CONCLUSION: Les critères d'exclusion des centres multidisciplinaires de traitement de la douleur sont plus susceptibles d'affecter les patients atteints de douleur chronique vivant avec des problèmes de douleur complexes et des vulnérabilités psychosociales. Des efforts au niveau des politiques sont nécessaires pour aider les CMTD canadiens à favoriser un accès équitable à la prise en charge de la douleur.

Novel approach for pericapsular radiofrequency ablation of sacrococcygeal junction for patients with coccydynia.

INTRODUCTION: Coccydynia is a multifactorial complex clinical challenge. A multimodal approach with both conservative measures and procedural interventions is often recommended. We described a novel approach of radiofrequency (RF) ablation for the management of coccydynia. METHODS: Three patients with known history of coccydynia refractory to conservative therapy were referred to our clinic. All received different types of RF ablation before: one with anterior bipolar lesion with no analgesia benefit, one with posterior stripped lesion with good benefit but only after 8 weeks of pain flare and one received anterior monopolar lesion with 50% pain reduction for 2-3 months. All subjects underwent a novel RF ablation to the anterior surface of the sacrococcygeal and intercoccygeal joints with two bipolar lesions using multi-tined needles under fluoroscopy guidance. One bipolar lesion was between two needles: one in the sacrococcygeal and another in the intercoccygeal (between first and second coccyx) joints. Another bipolar lesion was between needles on both side of the sacrococcygeal joint. RESULTS: All experienced at least 65% pain relief for 6 months. The sitting endurance increased from less than 5 min to an average of 70 min. No adverse effect was observed in two and in the patient who used to have pain flare after lesioning, the pain flare lasted only for 2 weeks. DISCUSSION: The configuration of the two bipolar lesions with multi-tined needles in this case series stimulates the thinking of new approach for the ablation technique for pain from coccyx. Further prospective large case cohort study is needed.

Positive airway pressure therapy for chronic pain in patients with obstructive sleep apnea-a systematic review.

PURPOSE: Obstructive sleep apnea (OSA) is prevalent in patients with chronic non-cancer pain. OSA may lead to low sleep quality and an increase in pain sensitivity. Patients reporting greater sleep impairment tend to experience higher pain intensity and vice versa. Positive airway pressure (PAP) is the current gold standard treatment for OSA. This review aims to evaluate the efficacy of PAP therapy in patients with comorbid chronic pain and OSA in influencing pain outcomes like pain intensity, tolerance, threshold, and sensitivity. METHODS: We performed a systematic literature search for studies published after 1990, utilizing the following databases: Medline, Medline In-Process/ePubs, Embase, Cochrane CENTRAL, and the Cochrane Database of Systematic Reviews. Search terms included "chronic pain," "sleep disorders," and "positive airway pressure." RESULTS: Of 1982 initial studies, ten studies met the study inclusion criteria. Seven of these studies examined the effect of PAP therapy on chronic pain, of which five demonstrated improved pain outcomes, specifically, headache pain. The effect of PAP therapy on chronic non-headache pain was found to be inconclusive. When examining the three studies that did not involve chronic pain patients, PAP therapy effectively increased pain threshold and tolerance in two studies (p = 0.03 and p = 0.01). CONCLUSION: An association exists between PAP therapy and decreased chronic headache outcomes in patients with OSA. Additionally, research shows that PAP therapy may increase pain tolerance and threshold. Future high-quality evidence is required to further investigate the association between PAP and non-headache chronic pain.

Hip Ablation Techniques.

Radiofrequency ablation (RFA) is still an emergent technique for the management of chronic hip pain. Although the ablation technique for facet articular branches of lumbar and cervical spine was already established, the literature on the targets and technique of needle placement for hip denervation are evolving. This article summarizes the current understanding of the anatomy of the articular branches, sonoanatomy, and the suggested techniques for the RFA of the hip. It also reviews the literature on the clinical studies.

Overview of Innervation of Knee Joint.

Image-guided diagnostic block and radiofrequency ablation of the knee joint to manage pain require detailed understanding of joint innervation in relation to soft tissue and bony landmarks. In this article, the origin, course, and relationship to anatomic landmarks of articular nerves supplying the knee joint are discussed. The innervation pattern of the anterior and posterior aspects of the knee joint capsule is relatively consistent, with some variation in supply by the saphenous, anterior division of obturator, and common fibular nerves. To improve nerve capture rates for diagnostic block and radiofrequency ablation, multiple target sites could be beneficial.

Knee Ablation Approaches.

Genicular nerve radiofrequency ablation has quickly become one of the most promising interventions for chronic knee pain secondary to osteoarthritis, with consistent improvements in pain and function. Although there are multiple techniques using slightly variable lesion locations, cannulas, lesion types, and imaging modalities, the clinical effectiveness targeting the anterior branches of the superior medial, superolateral, and inferior medial has reproducibly demonstrated clinically and statistically significant improvements up to 24 months after the procedure with minimal adverse events. This article summarizes the current knowledge of the sensory innervation of the knee joint, the principles of radiofrequency ablation, and the current literature on clinical outcomes.

Posterior hip pericapsular neurolysis (PHPN) for inoperable hip fracture: an adjunct to anterior hip pericapsular neurolysis.

BACKGROUND: The development of anterior hip neurolysis has made an appreciable impact on the management of patients with inoperable hip fracture. Nonetheless, suboptimal analgesic benefit was still observed in some patients. We therefore developed a novel posterior hip pericapsular neurolysis (PHPN) to complement anterior hip neurolysis in inoperable hip fracture. METHODS: In this retrospective review, we analyzed patients who responded suboptimally (defined as composite pain score moderate or higher on hip flexion 80°) to the anterior hip neurolysis from July 2019 to March 2021. The patients received additional PHPN if the composite pain score was suboptimal. The percentage of patients with dynamic composite pain scores on hip flexion to 80° and on gentle hip external and internal rotation on post-intervention day 5 was then evaluated. RESULTS: Among the 70 patients who were reviewed in the study period, 20 patients who partially responded to anterior hip neurolysis received an addition of diagnostic posterior hip pericapsular block. Eighteen patients were the positive responders and PHPN was then performed. Among the PHPN recipients, a high percentage with satisfactory dynamic pain control was observed with 78% on hip flexion 80° and 83% on hip external/internal rotation on day 5 following the intervention. No procedural adverse event was noted. CONCLUSIONS: While most patients responded satisfactorily to anterior hip neurolysis, we concluded PHPN could be an effective adjunct to manage suboptimal pain control after anterior hip neurolysis in inoperable hip fracture. TRIAL REGISTRATION NUMBER: NTWC/REC/21061.

Simple screening model for identifying the risk of sleep apnea in patients on opioids for chronic pain.

BACKGROUND: There is an increased risk of sleep apnea in patients using opioids for chronic pain. We hypothesized that a simple model comprizing of: (1) STOP-Bang questionnaire and resting daytime oxyhemoglobin saturation (SpO2); and (2) overnight oximetry will identify those at risk of moderate-to-severe sleep apnea in patients with chronic pain. METHOD: Adults on opioids for chronic pain were recruited from pain clinics. Participants completed the STOP-Bang questionnaire, resting daytime SpO2, and in-laboratory polysomnography. Overnight oximetry was performed at home to derive the Oxygen Desaturation Index. A STOP-Bang score ≥3 or resting daytime SpO2 ≤95% were used as thresholds for the first step, and for those identified at risk, overnight oximetry was used for further screening. The Oxygen Desaturation Index from overnight oximetry was validated against the Apnea-Hypopnea Index (≥15 events/hour) from polysomnography. RESULTS: Of 199 participants (52.5±12.8 years, 58% women), 159 (79.9%) had a STOP-Bang score ≥3 or resting SpO2 ≤95% and entered the second step (overnight oximetry). Using an Oxygen Desaturation Index ≥5 events/hour, the model had a sensitivity of 86.4% and specificity of 52% for identifying moderate-to-severe sleep apnea. The number of participants who would require diagnostic sleep studies was decreased by 38% from Step 1 to Step 2 of the model. CONCLUSION: A simple model using STOP-Bang questionnaire and resting daytime SpO2, followed by overnight oximetry, can identify those at high risk of moderate-to-severe sleep apnea in patients using opioids for chronic pain. TRIAL REGISTRATION NUMBER: NCT02513836.

Peripheral nerve block anesthesia/analgesia for patients undergoing primary hip and knee arthroplasty: recommendations from the International Consensus on Anesthesia-Related Outcomes after Surgery (ICAROS) group based on a systematic review and meta-analysis of current literature.

BACKGROUND: Evidence-based international expert consensus regarding the impact of peripheral nerve block (PNB) use in total hip/knee arthroplasty surgery. METHODS: A systematic review and meta-analysis: randomized controlled and observational studies investigating the impact of PNB utilization on major complications, including mortality, cardiac, pulmonary, gastrointestinal, renal, thromboembolic, neurologic, infectious, and bleeding complications.Medline, PubMed, Embase, and Cochrane Library including Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, NHS Economic Evaluation Database, were queried from 1946 to August 4, 2020.The Grading of Recommendations Assessment, Development, and Evaluation approach was used to assess evidence quality and for the development of recommendations. RESULTS: Analysis of 122 studies revealed that PNB use (compared with no use) was associated with lower ORs for (OR with 95% CIs) for numerous complications (total hip and knee arthroplasties (THA/TKA), respectively): cognitive dysfunction (OR 0.30, 95% CI 0.17 to 0.53/OR 0.52, 95% CI 0.34 to 0.80), respiratory failure (OR 0.36, 95% CI 0.17 to 0.74/OR 0.37, 95% CI 0.18 to 0.75), cardiac complications (OR 0.84, 95% CI 0.76 to 0.93/OR 0.83, 95% CI 0.79 to 0.86), surgical site infections (OR 0.55 95% CI 0.47 to 0.64/OR 0.86 95% CI 0.80 to 0.91), thromboembolism (OR 0.74, 95% CI 0.58 to 0.96/OR 0.90, 95% CI 0.84 to 0.96) and blood transfusion (OR 0.84, 95% CI 0.83 to 0.86/OR 0.91, 95% CI 0.90 to 0.92). CONCLUSIONS: Based on the current body of evidence, the consensus group recommends PNB use in THA/TKA for improved outcomes. RECOMMENDATION: PNB use is recommended for patients undergoing THA and TKA except when contraindications preclude their use. Furthermore, the alignment of provider skills and practice location resources needs to be ensured. Evidence level: moderate; recommendation: strong.