Chemical neurolysis of the genicular nerves for chronic refractory knee pain: an observational cohort study.

OBJECTIVE: Evaluate outcomes of genicular nerve chemical neurolysis (GChN) in a real-world population with chronic knee pain. DESIGN: Restrospective, observational cohort study. SETTING: Tertiary academic medical center. SUBJECTS: Consecutive patients who had undergone GChN ≥3 months prior. METHODS: Standardized surveys were collected by telephone and included the numerical rating scale, opioid analgesic use, and Patient Global Impression of Change. Age, sex, body mass index, duration of pain, history of arthroplasty, lack of effect from previous radiofrequency ablation, percentage relief from a prognostic block, and volume of phenol used at each injection site were extracted from charts. Descriptive statistics were calculated, and logistic regression analyses were performed to identify factors influencing treatment outcome. RESULTS: At the time of follow-up after GChN (mean ± SD: 9.9 ± 6.1 months), 43.5% (95% CI = 33.5-54.1) of participants reported ≥50% sustained pain reduction. On the Patient Global Impression of Change assessment, 45.9% (95% CI = 35.5-56.7) of participants reported themselves to be "very much improved" or "much improved." Of 40 participants taking opioids at baseline, 11 (27.5%; 95% CI = 14.6-43.9) ceased use. Of participants with a native knee treated, 46.3% reported ≥50% pain reduction, whereas of participants with an arthroplasty in the treated knee, 33.3% reported this threshold of pain reduction (P = .326). Logistic regression analyses did not reveal associations between treatment success and any of the factors that we evaluated. CONCLUSIONS: GChN could provide a robust and durable treatment effect in a subset of individuals with chronic knee pain with complicating factors traditionally associated with poor treatment outcomes, such as those with pain refractory to radiofrequency ablation or those who have undergone arthroplasty.

The Effectiveness of Fluoroscopically Guided Genicular Nerve Radiofrequency Ablation for the Treatment of Chronic Knee Pain Due to Osteoarthritis: A Systematic Review.

ABSTRACT: The objective was to determine the effectiveness of fluoroscopically guided genicular nerve radiofrequency ablation for painful knee osteoarthritis. Primary outcome measure was improvement in pain after 6 mos. Secondary outcomes included the Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index. Two reviewers independently assessed publications before October 10, 2020. The Cochrane Risk of Bias Tool and Grades of Recommendation, Assessment, Development, and Evaluation system were used. One hundred ninety-nine publications were screened, and nine were included. Six-month success rates for 50% or greater pain relief after radiofrequency ablation ranged from 49% to 74%. When compared with intra-articular steroid injection, the probability of success was 4.5 times higher for radiofrequency ablation (relative risk = 4.58 [95% confidence interval = 2.61-8.04]). When radiofrequency ablation was compared with hyaluronic acid injection, the probability of treatment success was 1.8 times higher (relative risk = 1.88, 95% confidence interval = 1.38-2.57). The group mean Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index scores improved in participants receiving genicular radiofrequency ablation compared with intra-articular steroid injection and hyaluronic acid injection. According to Grades of Recommendation, Assessment, Development, and Evaluation, there is moderate-quality evidence that fluoroscopically guided genicular radiofrequency ablation is effective for reducing pain associated with knee osteoarthritis at minimum of 6 mos. Further research is likely to have an important impact on the current understanding of the long-term effectiveness of this treatment.

Technical considerations for genicular nerve radiofrequency ablation: optimizing outcomes.

Genicular nerve radiofrequency ablation has emerged as a treatment option for patients with painful knee osteoarthritis who have failed conservative management but who may not qualify or wish to avoid a surgical procedure. Radiofrequency ablation techniques targeting the genicular nerves have evolved as our understanding of the anatomy of the anterior knee joint capsule has become more defined. The article aims to review the basic anatomy of the anterior knee joint and both the traditional and revised approaches to nerve ablation.

Factors Associated With Implantable Pulse Generator Site Pain: A Multicenter Cross-Sectional Study.

OBJECTIVES: Implantable pulse generator (IPG) site pain following neuromodulation procedures is a recognized complication. The site of the IPG placement varies depending on the neuromodulation type and physician preference. The incidence of IPG site pain as a function of the site of IPG implantation has not been studied systematically. MATERIALS AND METHODS: We performed a multicenter cross-sectional survey of the incidence, severity, and quality of IPG site pain, location of the IPG, the pain management needs, functional impairment, and cosmetic appearance related to the IPG placement. Contingency table analysis was conducted for categorical variables, and logistic regression analysis and linear regression model was used. RESULTS: The survey response rate was 60.5% (n = 510). Overall, 31.0% of patients reported pain at the IPG site in the last 72 hours with 31.4% reporting moderate to severe pain and 7.6% reporting severe pain. Older age was inversely associated with IPG-related pain (OR = 0.97, 95% CI = 0.96-0.99, p = 0.001). IPG implantation site did not have a statistically significant interaction with IPG site pain (p > 0.05). The most important factor for IPG site-associated pain was having a spinal cord stimulator implanted as compared to a deep brain stimulator, or sacral nerve stimulator. Most subjects reported no functional impairment related to IPG site pain (91%), found the IPG site pain as expected (80%), and found IPG site cosmetic appearance as expected (96%). CONCLUSIONS: The incidence of IPG site pain is an important complication of invasive neuromodulation. The anatomic location of the IPG placement does not appear to affect the incidence or severity of IPG site pain. However, the presence of a pre-implant chronic pain disorder does appear to affect the frequency and severity of IPG site pain.

Physiologic vasomotor symptoms are associated with verbal memory dysfunction in breast cancer survivors.

OBJECTIVE: Vasomotor symptoms (VMS), sleep disturbance, and cognitive complaints are common among women with a history of breast cancer and contribute to decreased quality of life. Studies in healthy women showed an association between verbal memory performance and physiologic VMS measured with ambulatory skin conductance monitors but not with VMS by self-report. We hypothesized that we would find a similar association in women with breast cancer. METHODS: Participants included 30 female breast cancer survivors (mean age 52.7 y; 26.7% African-American) with moderate-to-severe VMS enrolled in a larger clinical trial of a nonhormonal intervention for VMS. At baseline, participants completed assessments of physiologic VMS, actigraphy-based assessments of sleep, questionnaires about mood, and two tests of verbal memory - Logical Memory (LM) and the California Verbal Learning Test (CVLT). Using baseline data, we conducted multivariate regression analyses to examine the association between VMS and memory, controlling for sleep and other factors. RESULTS: On average, women reported 46% of total physiologic VMS. A higher frequency of physiologic VMS - but not reported VMS - was significantly associated with lower scores on the California Verbal Learning Test short-delay free recall (r[28] = -0.41, P = 0.03), long-delay free recall (r[28] = -0.42, P = 0.03), and total clustering, (r[28] = -0.39, P = 0.04). These associations were independent of sleep, mood, and other factors. CONCLUSIONS: Independent of their effect on sleep, VMS may be a modifiable contributor to memory difficulties in women with breast cancer. These findings underscore the importance of objective measurement of VMS in cognitive studies. : Video Summary:http://links.lww.com/MENO/A623.

Video Summary:http://links.lww.com/MENO/A623.

Intrathecal Catheter as a Source of Infection Years After Implantation of an Intrathecal Drug Delivery System: A Case Report.

We describe a patient with an intrathecal drug delivery system (IDDS) for management of chronic back pain who developed worsening pain symptoms associated with an infected catheter tip, identified years after initial implantation. A 72-year-old woman had an IDDS initially implanted for management of chronic back pain. Years later, after suffering a vertebral compression fracture, workup revealed magnetic resonance imaging (MRI) findings suggestive of infection despite unremarkable laboratory findings. Her pain worsened, and after explantation of the IDDS, methicillin-resistant Staphylococcus aureus colonized the catheter tip. Worsening pain symptoms in a patient with intrathecal morphine pump must be met with a broad differential diagnosis.

Effect of low-dose lidocaine on objective upper extremity strength and immediate pain relief following cervical interlaminar epidural injections: a double-blinded randomized controlled trial.

BACKGROUND: Low-dose lidocaine is a common diluent for analgesia following cervical interlaminar epidural steroid injection (CIESI). Concerns with this practice exist. A single-arm cohort reported that 20% of patients develop postprocedural upper extremity weakness when using lidocaine as a diluent. Furthermore, a high-cervical spinal block with unintended intrathecal or subdural administration is possible. OBJECTIVE: Determine if low-dose lidocaine as a diluent during CIESI causes clinically meaningful (1) upper extremity weakness and (2) immediate pain relief when compared with saline. DESIGN: Double-blinded randomized control trial. METHODS: Patients with cervical radicular pain scheduled for CIESI were enrolled. Participants received lidocaine (CIESI-L) or saline (CIESI-S) as a diluent for the epidural injectate. Myotomal strength was measured with dynamometry before and between 20 and 30 min after CIESI. Pre-pain and post-pain scores were obtained. Primary and secondary outcomes were post-CIESI weakness of ≥20% (minimal clinically important difference (MCID)) in >1 myotome and ≥50% pain reduction on the numerical scale. RESULTS: 120 participants (64 females (53%), mean age, 56 (SD 13.7) years) completed the study and were analyzed (CIESI-L n=60; CIESI-S n=60). There was no significant between-group difference in the proportion of participants with postprocedural weakness, CIESI-L 41.7% (95% CI, 29.8% to 54.5%), CIESL-S 50% (95% CI, 37.5% to 62.5%). Between-group comparison showed no significant difference in pain reduction, relative risk 1.53 (95% CI, 0.82 to 2.86). CONCLUSION: Low-dose lidocaine as a diluent in CIESI does not significantly increase the risk of post-CIESI myotomal weakness when compared with saline, but also does not substantially increase the likelihood of immediate, meaningful pain relief. TRIAL REGISTRATION DETAILS: ClinicalTrials.gov (NCT03127137); December 26, 2017.

Patient-reported outcomes after cryoballoon ablation are equivalent between moderate sedation and general anesthesia.

INTRODUCTION: Moderate sedation (MS) during cryoballoon ablation (CBA) avoids risks of general anesthesia (GA) and improves electrophysiology (EP) lab throughput. However, one barrier to the use of MS is the potential for patient discomfort. The objective of this study was to compare patient-reported outcome measures following CBA for paroxysmal atrial fibrillation (pAF) under MS and GA. METHODS AND RESULTS: Consecutive patients undergoing a first CBA for pAF under GA or MS were prospectively enrolled. The sedation method was assigned based on patient and provider preference, and perceived airway risk. The primary outcomes were quality of recovery (measured using a validated 40 question survey; QoR-40) and likelihood to recommend (LTR) the procedure and sedation method (measured by Likert scale). Secondary outcomes were acute pulmonary vein (PV) isolation rate, procedure, fluoroscopy and ablation times, and complication rates. Forty-seven GA and 53 MS patients were included. The mean age was 64.9 ± 9.4 years and mean CHA2 DS2 -VASc score was 2.0 ± 1.4. QoR-40 scores were 184.6 ± 16.4 for GA and 187.6 ± 10.2 for MS (P = .28). LTR responses were similar between groups. Mean procedure times were 148.2 ± 56.0 minutes for GA and 129.4 ± 31.4 minutes for MS (P = .038). Fluoroscopy and ablation times were similar between groups. A total of 100% (409/409) of PVs were acutely isolated. One hemopericardium occurred in the MS group requiring pericardiocentesis. CONCLUSION: MS for CBA offers an alternative to GA that is safe and well-tolerated by patients with comparable success rates and improved EP lab throughput.

Management of Quebec Platelet Disorder for Cervical Facet Injections in the Outpatient Setting: A Case Report.

Quebec platelet disorder (QPD) is a condition that causes delayed-onset bleeding after hemostatic challenges. While there are interventional spine procedure (ISP) guidelines for managing patients on blood thinners or with common bleeding disorders, there are none for approaching patients with unique coagulopathies. We report a patient with QPD and extensive history of postprocedural bleeding complications (PPBCs) who presented with chronic cervical facet pain. After consulting a hematologist and administering antifibrinolytic agent with platelet transfusions, the patient underwent medial branch nerve blocks (MBNBs) followed by radiofrequency ablation (RFA) without experiencing PPBCs. A comprehensive team approach is critical to maximize patient safety when performing an ISP in such a population.

Simultaneous noninvasive recording of electrocardiogram and skin sympathetic nerve activity (neuECG).

neuECG, the simultaneous noninvasive recording of ECG and skin sympathetic nerve activity (SKNA), directly records sympathetic nerve activity over a long period of time. It can be used to measure sympathetic tone in healthy subjects and in subjects with non-cardiovascular diseases. The electrical activity that can be measured on the surface of the skin originates from the heart, the muscle or nerve structures. Because the frequency content of nerve activity falls in a higher frequency range than that of the ECG and myopotential, it is possible to use high-pass or band-pass filtering to specifically isolate the SKNA. neuECG is voltage calibrated and does not require invasive procedures to impale electrodes in nerves and thus has advantages over microneurography. Here, we present a protocol that takes <10 min to set up. The neuECG can be continuously recorded over a 24-h period or longer. We also describe methods to efficiently analyze neuECG from humans using commercially available hardware and software to facilitate adoption of this technology in clinical research.

Low-Pressure Lumbar Provocation Discography According to Spine Intervention Society/International Association for the Study of Pain Standards Does Not Cause Acceleration of Disc Degeneration in Patients With Symptomatic Low Back Pain: A 7-Year Matched Cohort Study.

STUDY DESIGN: Retrospective matched cohort study. OBJECTIVE: To determine if low-pressure lumbar provocation discography (PD) results in long-term accelerated disc degeneration, internal disc disruption, or disc herniation in patients with symptomatic low back pain (LBP). SUMMARY OF BACKGROUND DATA: Study of subjects without clinically-significant LBP suggests that high-pressure PD may accelerate disc degeneration. METHODS: Consecutive patients with symptomatic LBP who underwent magnetic resonance imaging (MRI), PD, and repeat MRI more than 7 years later, but did not undergo subsequent spinal fusion surgery, were included. Punctured discs were matched (1:2 to 1:4) to corresponding discs in a control cohort by age, BMI, Pfirrmann score (±2), and presence of disc herniation; control cohort inclusion required MRIs for symptomatic LBP, separated by more than 7 years. The primary outcome of the study was a progression in Pfirrmann score category (I-II, III-IV, V). MRI disc-to-CSF T2 signal-intensity ratio, disc height, disc herniations, high intensity zones (HIZs), and Modic changes were assessed. RESULTS: Baseline and follow-up MRIs were available for 77 discs exposed to PD, and for 260 discs in the matched control cohort. There was no difference in the proportion of punctured discs that advanced in Pfirrmann score category in the PD group (17%, 95% CI 9-27%) compared with corresponding discs in the Control group (21%, 95% CI 17-27%), P = 0.3578, or in non-punctured discs in the PD group (35%, 95% CI 21-51%) compared with corresponding discs in the Control group (34%, 95% CI 27-42%), P = 0.1169. There were no differences in disc-to-CSF T2 signal-intensity ratio, presence of disc herniations, HIZs, or Modic changes following puncture in the PD versus matched cohort discs or in the non-punctured PD cohort discs versus corresponding control cohort discs (P > 0.05). CONCLUSION: Patients with symptomatic LBP who underwent low-pressure PD, but who did not undergo a subsequent spinal fusion surgery, developed disc degeneration and new disc herniations at a similar rate to corresponding discs in matched control patients. LEVEL OF EVIDENCE: 3.

A Novel Technical Protocol for Improved Capture of the Genicular Nerves by Radiofrequency Ablation.

BACKGROUND: Fluoroscopically guided cooled genicular nerve radiofrequency ablation (RFA) is an increasingly performed procedure for chronic, refractory knee pain due to osteoarthritis. Traditionally, partial sensory denervation has been accomplished through ablation of the superomedial, superolateral, and inferomedial genicular nerves. However, recent cadaveric studies have demonstrated additional sensory nerves and significant anatomic variation that impact current protocols. OBJECTIVE: We describe an updated cooled genicular nerve radiofrequency ablation protocol that accounts for varied nerve location of the superomedial, superolateral, and inferomedial genicular nerves, as well as capture of the terminal articular branches of the nerves to the vastus intermedius, vastus lateralis, and vastus medialis. Furthermore, we describe an adjusted technique for inferomedial genicular nerve capture that mitigates the risk of pes anserine tendon injury. DESIGN: Technical report and brief literature review. METHODS: Cadaveric studies relating to the sensory innervation of the anterior knee joint were reviewed, and a more accurate and comprehensive cooled genicular nerve radiofrequency ablation (CRFA) protocol is proposed. CONCLUSIONS: Based on recent, rigorous anatomic dissections of the knee, the proposed genicular nerve CRFA protocol will provide more complete sensory denervation and potentially improve clinical outcomes. Prospective studies will be needed to confirm the hypothesis that this protocol will result in improved effectiveness and safety of genicular nerve RFA.

Randomized prospective trial of cooled versus traditional radiofrequency ablation of the medial branch nerves for the treatment of lumbar facet joint pain.

BACKGROUND AND OBJECTIVES: No previous study has assessed the outcomes of cooled radiofrequency ablation (C-RFA) of the medial branch nerves (MBN) for the treatment of lumbar facet joint pain nor compared its effectiveness with traditional RFA (T-RFA). This study evaluated 6-month outcomes for pain, function, psychometrics, and medication usage in patients who underwent MBN C-RFA versus T-RFA for lumbar Z-joint pain. METHODS: In this blinded, prospective trial, patients with positive diagnostic MBN blocks (>75% relief) were randomized to MBN C-RFA or T-RFA. The primary outcome was the proportion of 'responders' (≥50% Numeric Rating Scale (NRS) reduction) at 6 months. Secondary outcomes included NRS, Oswestry Disability Index (ODI), and Patient Global Impression of Change. RESULTS: Forty-three participants were randomized to MBN C-RFA (n=21) or T-RFA (n=22). There were no significant differences in demographic variables (p>0.05). A ≥50% NRS reduction was observed in 52% (95% CI 31% to 74%) and 44% (95% CI 22% to 69%) of participants in the C-RFA and T-RFA groups, respectively (p=0.75). A ≥15-point or ≥30% reduction in ODI score was observed in 62% (95% CI 38% to 82%) and 44% (95% CI 22% to 69%) of participants in the C-RFA and T-RFA groups, respectively (p=0.21). CONCLUSIONS: When using a single diagnostic block paradigm with a threshold of >75% pain reduction, both treatment with both C-RFA and T-RFA resulted in a success rate of approximately 50% when defined by both improvement in pain and physical function at 6-month follow-up. While the success rate was higher in the C-RFA group, this difference was not statistically significant. TRIAL REGISTRATION NUMBER: NCT02478437.

Management of a Cancer Patient with an Intrathecal Drug Delivery System and an Acute Brain Abscess.

Surgical-site infection, spinal cord abscess, and catheter tip granuloma are known but rare complications of intrathecal drug delivery systems (IDDS). To date, there are no published cases of brain abscess in a patient with an IDDS. In this study, we report a case of a cancer patient with an IDDS for management of cancer pain who developed a brain abscess with profound mental status changes and clinical management challenges.