Pulsed Radiofrequency in the Treatment of Persistent Pain After Inguinal Herniotomy: A Systematic Review

Comparing the Efficacy of Dorsal Root Ganglion Stimulation With Conventional Medical Management in Patients With Chronic Postsurgical Inguinal Pain: Post Hoc Analyzed Results of the SMASHING Study

OBJECTIVES

Approximately 10% of patients who undergo inguinal hernia repair or Pfannenstiel incision develop chronic (> three months) postsurgical inguinal pain (PSIP). If medication or peripheral nerve blocks fail, a neurectomy is the treatment of choice. However, some patients do not respond to this treatment. In such cases, stimulation of the dorsal root ganglion (DRG) appears to significantly reduce chronic PSIP in selected patients.

MATERIALS AND METHODS

In this multicenter, randomized controlled study, DRG stimulation was compared with conventional medical management (CMM) (noninvasive treatments, such as medication, transcutaneous electric neurostimulation, and rehabilitation therapy) in patients with PSIP that was resistant to a neurectomy. Patients were recruited at a tertiary referral center for groin pain (SolviMáx, Eindhoven, The Netherlands) between March 2015 and November 2016. Suitability for implantation was assessed according to the Dutch Neuromodulation Association guidelines. The sponsor discontinued the study early owing to slow enrollment. Of 78 planned patients, 18 were randomized (DRG and CMM groups each had nine patients). Six patients with CMM (67%) crossed over to DRG stimulation at the six-month mark.

RESULTS

Fifteen of the 18 patients met the six-month primary end point with a complete data set for a per-protocol analysis. Three patients with DRG stimulation had a negative trial and were lost to follow-up. The average pain reduction was 50% in the DRG stimulation and crossover group (from 6.60 ± 1.24 to 3.28 ± 2.30, p = 0.0029). Conversely, a 13% increase in pain was observed in patients with CMM (from 6.13 ± 2.24 to 6.89 ± 1.24, p = 0.42). Nine patients with DRG stimulation experienced a total of 19 adverse events, such as lead dislocation and pain at the implantation site.

CONCLUSIONS

DRG stimulation is a promising effective therapy for pain relief in patients with PSIP resistant to conventional treatment modalities; larger studies should confirm this. The frequency of side effects should be a concern in a new study.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02349659.

Pain specialist management of sexual pain: III-neuromodulation

INTRODUCTION

Some women with sexual pain do not respond to conservative multi-modal care modalities. Neuromodulation is a group of methods which alter nerve activity by delivering electrical energy or pharmaceutical agents directly to target neural structures. Multiple forms of neuromodulation may provide durable treatment options to fill the unmet therapeutic need of a certain population of women with chronic sexual pain.

OBJECTIVES

To provide a current review of neuromodulation treatments used for female sexual pain and introduce neuromodulation techniques which may be applied in novel ways to specific sexual pain phenotypes.

METHODS

Internet, PubMed and Cochrane Library were searched for relevant articles on female sexual pain within the clinical purview and scope of practice of pain management.

RESULTS

A thorough review of the literature was conducted to include basic science studies, clinical trials, systematic reviews, consensus statements, and case-reports. A sampling of information on real-world patient outcomes was included. The amount and quality of evidence for neuromodulation to treat female sexual pain is low-moderate. Descriptions of neuromodulation procedures for sexual pain were made and clinical studies reviewed. The effects of autonomic nervous system (ANS) dysregulation on the experience of pain were discussed with consideration of interventional procedures to facilitate restoration of ANS equilibrium.

CONCLUSION

Treating female sexual pain is complex. There are considerable numbers of women who have unsatisfactory sexual pain relief despite evidence-based interdisciplinary care. These women may benefit from referral to consider neuromodulation treatment options. Neuromodulation is a relatively new capability in the arsenal of pain management and other specialists that can be considered for women with treatment refractory sexual pain.

General Surgery: Management of Postoperative Complications Following Ventral Hernia Repair and Inguinal Hernia Repair

Ventral and inguinal hernia repairs are some of the most commonly performed general surgery operations worldwide. This review focuses on the management of postoperative complications, which include surgical site infection, hernia recurrence, postoperative pain, and mesh-related issues. In each section, we aim to discuss classifications, risk factors, diagnostic modalities, and treatment options for common complications following hernia repair.

Ultrasound-guided microwave ablation in the treatment of inguinal neuralgia

Chronic groin pain can be due to a variety of causes and is the most common complication of inguinal hernia repair surgery. The etiology of pain after inguinal hernia repair surgery is often multifactorial though injury to or scarring around the nerves in the operative region, namely the ilioinguinal nerve, genital branch of the genitofemoral nerve, and the iliohypogastric nerve, is thought to be a key factor in causing chronic post-operative hernia pain or inguinal neuralgia. Inguinal neuralgia is difficult to treat and requires a multidisciplinary approach. Radiologists play a key role in the management of these patients by providing accurate image-guided injections to alleviate patient symptoms and identify the pain generator. Recently, ultrasound-guided microwave ablation has emerged as a safe technique, capable of providing durable pain relief in the majority of patients with this difficult to treat condition. The objectives of this paper are to review the complex nerve anatomy of the groin, discuss diagnostic ultrasound-guided nerve injection and patient selection for nerve ablation, and illustrate the microwave ablation technique used at our institution.

Chronic postoperative inguinal pain: A narrative review

Inguinodynia or chronic postoperative inguinal pain is a growing problem between patients who undergo surgical repair of an inguinal hernia. The change in results measurement proposed by many authors towards Patient Reported Outcome Measurement has underlined the importance of chronic postoperative inguinal pain, because of the great limitations in everyday life and the huge socioeconomic impact that it causes. In this article a narrative review of the available literature in PUBMED, EMBASE and Cochrane Library is performed and the most relevant aspects about epidemiology, etiology prevention, diagnosis and treatment of chronic postoperative inguinal pain are discussed. A new management algorithm is also proposed. The variability in its incidence and clinical presentation makes diagnosis of chronic postoperative inguinal pain a very challenging issue. There is no standardized therapy and an adequate etiological diagnosis is key point for a successful treatment. There are many treatment options that have to be sequentially used and adjusted to each patient and their clinical features.

Ilioinguinal Neuropathy

PURPOSE OF REVIEW

The purpose of this review is to present an overview of ilioinguinal (IL) neuralgia and evaluate the current literature.

RECENT FINDINGS

Treatment of IL neuralgia includes pharmacotherapies, perineural injections, radiofrequency ablation, cryoablation, neuromodulation, and neurectomy. The efficacy of these therapies varies considerably. IL neuralgia is a common pain disorder characterized by pain in the lower abdomen and upper thigh. While various modalities can be used in the treatment of IL neuralgia, the efficacy of these modalities is at times limited. Dorsal root ganglion stimulation exhibits promise in the treatment of IL neuralgia. More research is needed to better address the needs of patients suffering from this disorder.

Therapeutic Approaches for Peripheral and Central Neuropathic Pain

Neuropathic pain is a chronic secondary pain condition, which is a consequence of peripheral or central nervous (somatosensory) system lesions or diseases. It is a devastating condition, which affects around 7% of the general population. Numerous etiological factors contribute to the development of chronic neuropathic pain. It can originate from the peripheral part of the nervous system such as in the case of trigeminal or postherpetic neuralgia, peripheral nerve injury, painful polyneuropathies, or radiculopathies. Central chronic neuropathic pain can develop as a result of spinal cord or brain injury, stroke, or multiple sclerosis. As first-line pharmacological treatment options, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids are recommended. In trigeminal neuralgia, carbamazepine and oxcarbazepine are the first-choice drugs. In drug-refractory cases, interventional, physical, and psychological therapies are available. This review was structured based on a PubMed search of papers published in the field from 2010 until May 2019.

Ultrasound-Guided Microwave Ablation for the Management of Inguinal Neuralgia: A Preliminary Study with 1-Year Follow-up

PURPOSE

To evaluate the feasibility and efficacy of ultrasound-guided microwave ablation for the treatment of inguinal neuralgia.

MATERIALS AND METHODS

A retrospective review of 12 consecutive ultrasound-guided microwave ablation procedures was performed of 10 consecutive patients (8 men, 2 women; mean age, 41 years [range, 15-64 years]), between August 2012 and August 2016. Inclusion criteria for inguinal neuralgia included clinical diagnosis of chronic inguinal pain (average, 17.3 months [range, 6-46 months]) refractory to conservative treatment and a positive nerve block. Pain response-reduction of pain level and duration and percent pain reduction using a 10-point visual analog scale (VAS) at baseline and up to 12 months after the procedure-was measured. Nine patients had pain after the inguinal hernia repair, and 1 patient had pain from the femoral artery bypass procedure. The microwave ablation procedure targeted the ilioinguinal nerve in 7 cases, the genitofemoral nerve in 4 cases, and the iliohypogastric nerve in 1 case.

RESULTS

Average baseline VAS pain score was 6.1 (standard deviation, 2.5). Improved pain levels immediately after the procedure and at 1, 6, and 12 months were statistically significant (P = .0037, .0037, .0038, .0058, respectively). Also, 91.7% (11/12) of the procedures resulted in immediate pain relief and at 1 month and 6 months. At 12 months, 83.3% (10/12) of patients had an average of 69% ± 31% pain reduction. Percent maximal pain reduction was 93% ± 14% (60%-100%), and the average duration of clinically significant pain reduction was 10.5 months (range, 0-12 months.). No complications or adverse outcomes occurred.

CONCLUSIONS

Ultrasound-guided microwave ablation is an effective technique for the treatment of inguinal neuralgia after herniorrhaphy.

The HerniaSurge Group. International guidelines for groin hernia management

INTRODUCTION

Worldwide, more than 20 million patients undergo groin hernia repair annually. The many different approaches, treatment indications and a significant array of techniques for groin hernia repair warrant guidelines to standardize care, minimize complications, and improve results. The main goal of these guidelines is to improve patient outcomes, specifically to decrease recurrence rates and reduce chronic pain, the most frequent problems following groin hernia repair. They have been endorsed by all five continental hernia societies, the International Endo Hernia Society and the European Association for Endoscopic Surgery.

METHODS

An expert group of international surgeons (the HerniaSurge Group) and one anesthesiologist pain expert was formed. The group consisted of members from all continents with specific experience in hernia-related research. Care was taken to include surgeons who perform different types of repair and had preferably performed research on groin hernia surgery. During the Group's first meeting, evidence-based medicine (EBM) training occurred and 166 key questions (KQ) were formulated. EBM rules were followed in complete literature searches (including a complete search by The Dutch Cochrane database) to January 1, 2015 and to July 1, 2015 for level 1 publications. The articles were scored by teams of two or three according to Oxford, SIGN and Grade methodologies. During five 2-day meetings, results were discussed with the working group members leading to 136 statements and 88 recommendations. Recommendations were graded as "strong" (recommendations) or "weak" (suggestions) and by consensus in some cases upgraded. In the Results and summary section below, the term "should" refers to a recommendation. The AGREE II instrument was used to validate the guidelines. An external review was performed by three international experts. They recommended the guidelines with high scores. The risk factors for inguinal hernia (IH) include: family history, previous contra-lateral hernia, male gender, age, abnormal collagen metabolism, prostatectomy, and low body mass index. Peri-operative risk factors for recurrence include poor surgical techniques, low surgical volumes, surgical inexperience and local anesthesia. These should be considered when treating IH patients. IH diagnosis can be confirmed by physical examination alone in the vast majority of patients with appropriate signs and symptoms. Rarely, ultrasound is necessary. Less commonly still, a dynamic MRI or CT scan or herniography may be needed. The EHS classification system is suggested to stratify IH patients for tailored treatment, research and audit. Symptomatic groin hernias should be treated surgically. Asymptomatic or minimally symptomatic male IH patients may be managed with "watchful waiting" since their risk of hernia-related emergencies is low. The majority of these individuals will eventually require surgery; therefore, surgical risks and the watchful waiting strategy should be discussed with patients. Surgical treatment should be tailored to the surgeon's expertise, patient- and hernia-related characteristics and local/national resources. Furthermore, patient health-related, life style and social factors should all influence the shared decision-making process leading up to hernia management. Mesh repair is recommended as first choice, either by an open procedure or a laparo-endoscopic repair technique. One standard repair technique for all groin hernias does not exist. It is recommended that surgeons/surgical services provide both anterior and posterior approach options. Lichtenstein and laparo-endoscopic repair are best evaluated. Many other techniques need further evaluation. Provided that resources and expertise are available, laparo-endoscopic techniques have faster recovery times, lower chronic pain risk and are cost effective. There is discussion concerning laparo-endoscopic management of potential bilateral hernias (occult hernia issue). After patient consent, during TAPP, the contra-lateral side should be inspected. This is not suggested during unilateral TEP repair. After appropriate discussions with patients concerning results tissue repair (first choice is the Shouldice technique) can be offered. Day surgery is recommended for the majority of groin hernia repair provided aftercare is organized. Surgeons should be aware of the intrinsic characteristics of the meshes they use. Use of so-called low-weight mesh may have slight short-term benefits like reduced postoperative pain and shorter convalescence, but are not associated with better longer-term outcomes like recurrence and chronic pain. Mesh selection on weight alone is not recommended. The incidence of erosion seems higher with plug versus flat mesh. It is suggested not to use plug repair techniques. The use of other implants to replace the standard flat mesh in the Lichtenstein technique is currently not recommended. In almost all cases, mesh fixation in TEP is unnecessary. In both TEP and TAPP it is recommended to fix mesh in M3 hernias (large medial) to reduce recurrence risk. Antibiotic prophylaxis in average-risk patients in low-risk environments is not recommended in open surgery. In laparo-endoscopic repair it is never recommended. Local anesthesia in open repair has many advantages, and its use is recommended provided the surgeon is experienced in this technique. General anesthesia is suggested over regional in patients aged 65 and older as it might be associated with fewer complications like myocardial infarction, pneumonia and thromboembolism. Perioperative field blocks and/or subfascial/subcutaneous infiltrations are recommended in all cases of open repair. Patients are recommended to resume normal activities without restrictions as soon as they feel comfortable. Provided expertise is available, it is suggested that women with groin hernias undergo laparo-endoscopic repair in order to decrease the risk of chronic pain and avoid missing a femoral hernia. Watchful waiting is suggested in pregnant women as groin swelling most often consists of self-limited round ligament varicosities. Timely mesh repair by a laparo-endoscopic approach is suggested for femoral hernias provided expertise is available. All complications of groin hernia management are discussed in an extensive chapter on the topic. Overall, the incidence of clinically significant chronic pain is in the 10-12% range, decreasing over time. Debilitating chronic pain affecting normal daily activities or work ranges from 0.5 to 6%. Chronic postoperative inguinal pain (CPIP) is defined as bothersome moderate pain impacting daily activities lasting at least 3 months postoperatively and decreasing over time. CPIP risk factors include: young age, female gender, high preoperative pain, early high postoperative pain, recurrent hernia and open repair. For CPIP the focus should be on nerve recognition in open surgery and, in selected cases, prophylactic pragmatic nerve resection (planned resection is not suggested). It is suggested that CPIP management be performed by multi-disciplinary teams. It is also suggested that CPIP be managed by a combination of pharmacological and interventional measures and, if this is unsuccessful, followed by, in selected cases (triple) neurectomy and (in selected cases) mesh removal. For recurrent hernia after anterior repair, posterior repair is recommended. If recurrence occurs after a posterior repair, an anterior repair is recommended. After a failed anterior and posterior approach, management by a specialist hernia surgeon is recommended. Risk factors for hernia incarceration/strangulation include: female gender, femoral hernia and a history of hospitalization related to groin hernia. It is suggested that treatment of emergencies be tailored according to patient- and hernia-related factors, local expertise and resources. Learning curves vary between different techniques. Probably about 100 supervised laparo-endoscopic repairs are needed to achieve the same results as open mesh surgery like Lichtenstein. It is suggested that case load per surgeon is more important than center volume. It is recommended that minimum requirements be developed to certify individuals as expert hernia surgeon. The same is true for the designation "Hernia Center". From a cost-effectiveness perspective, day-case laparoscopic IH repair with minimal use of disposables is recommended. The development and implementation of national groin hernia registries in every country (or region, in the case of small country populations) is suggested. They should include patient follow-up data and account for local healthcare structures. A dissemination and implementation plan of the guidelines will be developed by global (HerniaSurge), regional (international societies) and local (national chapters) initiatives through internet websites, social media and smartphone apps. An overarching plan to improve access to safe IH surgery in low-resource settings (LRSs) is needed. It is suggested that this plan contains simple guidelines and a sustainability strategy, independent of international aid. It is suggested that in LRSs the focus be on performing high-volume Lichtenstein repair under local anesthesia using low-cost mesh. Three chapters discuss future research, guidelines for general practitioners and guidelines for patients.

CONCLUSIONS

The HerniaSurge Group has developed these extensive and inclusive guidelines for the management of adult groin hernia patients. It is hoped that they will lead to better outcomes for groin hernia patients wherever they live. More knowledge, better training, national audit and specialization in groin hernia management will standardize care for these patients, lead to more effective and efficient healthcare and provide direction for future research.

Pulsed radiofrequency or anterior neurectomy for anterior cutaneous nerve entrapment syndrome (ACNES) (the PULSE trial): study protocol of a randomized controlled trial

Background

Some patients with chronic abdominal pain suffer from an anterior cutaneous nerve entrapment syndrome (ACNES). This somewhat illusive syndrome is thought to be caused by the entrapment of end branches of the intercostal nerves residing in the abdominal wall. If ACNES is suspected, a local injection of an anesthetic agent may offer relief. If pain is recurrent following multiple-injection therapy, an anterior neurectomy entailing removal of the entrapped nerve endings may be considered. After 1 year, a 70% success rate has been reported. Research on minimally invasive alternative treatments is scarce. Pulsed radiofrequency (PRF) treatment is a relatively new treatment for chronic pain syndromes. An electromagnetic field is applied around the nerve in the hope of leading to pain relief. This randomized controlled trial compares the effect of PRF treatment and neurectomy in patients with ACNES.

Methods

Adult ACNES patients having short-lived success following injections are randomized to PRF or neurectomy. At the 8-week follow-up visit, unsuccessful PRF patients are allowed to cross over to a neurectomy. Primary outcome is pain relief after either therapy. Secondary outcomes include patient satisfaction, quality of life, use of analgesics and unanticipated adverse events. The study is terminated 6 months after receiving the final procedure.

Discussion

Since academic literature on minimally invasive techniques is lacking, well-designed trials are needed to optimize results of treatment for ACNES. This is the first large, randomized controlled, proof-of-concept trial comparing two therapy techniques in ACNES patients. The first patient was included in October 2015. The expected trial deadline is December 2017. If effective, PRF may be incorporated into the ACNES treatment algorithm, thus minimizing the number of patients requiring surgery.

Trial registration

Nederlands Trial Register (Dutch Trial Register), NTR5131 (http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5131). Registered on 15 April 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2110-5) contains supplementary material, which is available to authorized users.

Diagnosis and Surgical Management of Male Pelvic, Inguinal, and Testicular Pain

Pain occurs in the male genitourinary organs as for any organ system in response to traumatic, infectious, or irritative stimuli. A knowledge and understanding of chronic genitourinary pain can be of great utility to practicing nonurologists. This article provides insight into the medical and surgical management of subacute and chronic pelvic, inguinal, and scrotal pain. The pathophysiology, diagnosis, and medical and surgical treatment options of each are discussed.

Minimally invasive procedures for neuropathic pain

Neuropathic pain is "pain arising as a direct consequence of a lesion or disease affecting the somatosensory system". The prevalence of neuropathic pain ranges from 7 to 11% of the population and minimally invasive procedures have been used to both diagnose and treat neuropathic pain. Diagnostic procedures consist of nerve blocks aimed to isolate the peripheral nerve implicated, whereas therapeutic interventions either modify or destroy nerve function. Procedures that modify how nerves function include epidural steroid injections, peripheral nerve blocks and sympathetic nerve blocks. Neuroablative procedures include radiofrequency ablation, cryoanalgesia and neurectomies. Currently, neuromodulation with peripheral nerve stimulators and spinal cord stimulators are the most evidence-based treatments of neuropathic pain.

Successful management of a refractory case of postoperative herniorrhaphy pain with extended duration pulsed radiofrequency

Chronic postsurgical pain (CPSP) is a distressful condition following hernia surgery. A 25-year-old, 55 kg male patient presented with severe pain on the right side of the lower abdomen that radiated to the testicle and the inner side of the thigh. Patient was symptomatic since 5 months following inguinal herniorrhaphy surgery. The pain was not relieved with pharmacological and interventional nerve blocks. An ultrasound-guided ilioinguinal-iliohypogastric (II-IH) block with extended duration (42°C, four cycles of 120 s each) pulsed radiofrequency (PRF) and a diagnostic genital branch of genitofemoral nerve (GGFN) block provided pain relief. After 1-month, an extended duration PRF in GGFN resulted in complete resolution of symptoms. During a regular follow-up of 9 months, patient reported an improved quality-of-life. We believe the successful management of CPSP following hernia repair with single extended duration PRF of II-IH and GGFN has not been described in the literature.

Management of Postherniorrhaphy Chronic Neuropathic Groin Pain: A Role for Dorsal Root Ganglion Stimulation

Chronic neuropathic groin pain is a sequela of hernia surgery that occurs at unacceptably high rates, causing widespread impacts on quality of life. Although the medical community is beginning to recognize the role of surgical technique in the initiation and maintenance of postherniorrhaphy neuropathic pain, little information exists regarding pain management strategies for this condition. This review presents a summary of the pain condition state, its treatment options, and treatment recommendations. Both literature review and clinical experience were used to develop a proposed a treatment algorithm for the treatment of postherniorrhaphy pain. The development of chronic pain may be prevented via a number of perioperative measures. For pain that is already established, some surgical approaches including inguinal neurectomy can be effective, in addition to standard pharmacological treatments and local infiltrations. An unmet need may still exist with these options, however, leaving a role for neuromodulation for the treatment of intractable cases. A pain management algorithm for iterative interventions including stimulation of the dorsal root ganglion (DRG) is described. It is expected that cross-disciplinary awareness of surgeons for nonsurgical pain management options in the treatment of chronic neuropathic postherniorrhaphy pain will contribute to better clinical outcomes.

Surgical options after a failed neurectomy in anterior cutaneous nerve entrapment syndrome

BACKGROUND

Injection treatment followed by an anterior neurectomy in patients insufficiently responding to an injection regimen is successful long term in three-quarters of patients with anterior cutaneous nerve entrapment syndrome (ACNES). The efficacy of secondary surgery, including re-exploration or a posterior neurectomy in patients reporting recurrent pain after initially successful surgery or following an immediately failed anterior neurectomy is unknown.

METHODS

A database of ACNES patients receiving surgery between 2004 and 2012 in the SolviMáx institution was analysed. Adult patients with residual pain after an anterior neurectomy (failures) or with recurrent pain after initially successful surgery (recurrences) were selected. Following a re-exploration or a posterior neurectomy, pain was scored using a pain intensity numeric rating scale (PI-NRS 0-10) and a six-point verbal category rating scale (VRS). Success was defined as a ≥50 % PI-NRS reduction and/or ≥2 point VRS reduction.

RESULTS

ACNES patients undergoing an anterior neurectomy (n = 181) were analysed during the 8-year study period. At follow-up, 51 patients reported unacceptable pain levels following an anterior neurectomy, whereas 20 developed recurrent abdominal wall pain. Of these 71 unsuccessful patients, 41 underwent secondary surgery, including a re-exploration (n = 10), or a posterior neurectomy (n = 31). After a 25-month median follow-up, secondary surgical treatment regimens proved successful in 66 % (27/41). Patients with recurrent pain did better (14/15) than patients who were immediate failures after the anterior neurectomy (13/26, p = 0.01).

CONCLUSIONS

Secondary surgery including re-explorations and posterior neurectomies are successful in two-thirds of ACNES patients with persistent pain or recurrence of pain after an anterior neurectomy.

Pain control following inguinal herniorrhaphy: current perspectives

Inguinal hernia repair is one of the most common surgeries performed worldwide. With the success of modern hernia repair techniques, recurrence rates have significantly declined, with a lower incidence than the development of chronic postherniorrhaphy inguinal pain (CPIP). The avoidance of CPIP is arguably the most important clinical outcome and has the greatest impact on patient satisfaction, health care utilization, societal cost, and quality of life. The etiology of CPIP is multifactorial, with overlapping neuropathic and nociceptive components contributing to this complex syndrome. Treatment is often challenging, and no definitive treatment algorithm exists. Multidisciplinary management of this complex problem improves outcomes, as treatment must be individualized. Current medical, pharmacologic, interventional, and surgical management strategies are reviewed.

Pulsed radiofrequency reduced complete Freund's adjuvant-induced mechanical hyperalgesia via the spinal c-Jun N-terminal kinase pathway

Pulsed radiofrequency (PRF) treatment involves the pulsed application of a radiofrequency electric field to a nerve. The technology offers pain relief for patients suffering from chronic pain who do not respond well to conventional treatments. We tested whether PRF treatment attenuated complete Freund's adjuvant (CFA) induced inflammatory pain. The profile of spinal c-Jun N-terminal kinases (JNKs) phosphorylation was evaluated to elucidate the potential mechanism. Injection of CFA into the unilateral hind paw of rats induced mechanical hyperalgesia in both the ipsilateral and contralateral hind paws. We administered 500-kHz PRF treatment in 20-ms pulses, at a rate of 2 Hz (2 pulses per second) either to the sciatic nerve in the mid-thigh, or to the L4 anterior primary ramus just distal to the intervertebral foramen in both the CFA group and no-PRF group rats. Tissue samples were examined at 1, 3, 7, and 14 days following PRF treatments. Behavioral studies showed that PRF applied close to the dorsal root ganglion (DRG) significantly attenuated CFA-induced mechanical hyperalgesia compared to no-PRF group (P < .05). And western blotting revealed significant attenuation of the activation of JNK in the spinal dorsal horn compared to no-PRF group animals (P < .05). Application of PRF close to DRG provides an effective treatment for CFA-induced persistent mechanical hyperalgesia by attenuating JNK activation in the spinal dorsal horn.