A prospective open label 2-8 year extension of the randomised controlled ICON trial on the long-term efficacy and safety of occipital nerve stimulation in medically intractable chronic cluster headache.

BACKGROUND: We demonstrated in the randomised controlled ICON study that 48-week treatment of medically intractable chronic cluster headache (MICCH) with occipital nerve stimulation (ONS) is safe and effective. In L-ICON we prospectively evaluate its long-term effectiveness and safety. METHODS: ICON participants were enrolled in L-ICON immediately after completing ICON. Therefore, earlier ICON participants could be followed longer than later ones. L-ICON inclusion was stopped after the last ICON participant was enrolled in L-ICON and followed for ≥2 years by completing six-monthly questionnaires on attack frequency, side effects, subjective improvement and whether they would recommend ONS to others. Primary outcome was the change in mean weekly attack frequency 2 years after completion of the ICON study compared to baseline. Missing values for log-transformed attack-frequency were imputed for up to 5 years of follow-up. Descriptive analyses are presented as (pooled) geometric or arithmetic means and 95% confidence intervals. FINDINGS: Of 103 eligible participants, 88 (85%) gave informed consent and 73 (83%) were followed for ≥2 year, 61 (69%) ≥ 3 year, 33 (38%) ≥ 5 years and 3 (3%) ≥ 8.5 years. Mean (±SD) follow-up was 4.2 ± 2.2 years for a total of 370 person years (84% of potentially 442 years). The pooled geometric mean (95% CI) weekly attack frequency remained considerably lower after one (4.2; 2.8-6.3), two (5.1; 3.5-7.6) and five years (4.1; 3.0-5.5) compared to baseline (16.2; 14.4-18.3). Of the 49/88 (56%) ICON ≥50% responders, 35/49 (71%) retained this response and 15/39 (38%) ICON non-responders still became a ≥50% responder for at least half the follow-up period. Most participants (69/88; 78% [0.68-0.86]) reported a subjective improvement from baseline at last follow-up and 70/88 (81% [0.70-0.87]) would recommend ONS to others. Hardware-related surgery was required in 44/88 (50%) participants in 112/122 (92%) events (0.35 person-year-1 [0.28-0.41]). We didn't find predictive factors for effectiveness. INTERPRETATION: ONS is a safe, well-tolerated and long-term effective treatment for MICCH. FUNDING: The Netherlands Organisation for Scientific Research, the Dutch Ministry of Health, the NutsOhra Foundation from the Dutch Health Insurance Companies, and Medtronic.

Electrical neurostimulation for the treatment of chronic pruritus: A systematic review.

Approximately one fifth of the world population experiences continuous itch for 6 weeks or more during their life, that is chronic itch. It is diverse in its aetiologies, and it is notoriously hard to treat. Because itch and pain have largely overlapping pathophysiology and the demonstrated efficacy of neurostimulation in treatment of selected chronic pain conditions, we conducted a systematic review to investigate whether neurostimulation could be an effective treatment for chronic itch. We identified two randomized controlled trials and 17 open label studies or case reports investigating various neurostimulation modalities for the treatment of refractory itch of various aetiologies. Transcutaneous electrical nerve stimulation (TENS) was the most investigated modality (n = 17), and in the largest number of conditions. Other modalities were cutaneous field stimulation (n = 2), painscrambler (n = 1), transcranial direct current stimulation (n = 1) and peripheral nerve field stimulation (n = 1). Atopic dermatitis was the most studied condition (n = 5). Despite the large heterogeneity in used stimulation paradigms and outcome parameters, all studies reported a positive effect of at least one neurostimulation modality. Our review indicates that electrical neurostimulation could be considered for the treatment of refractory chronic itch of selected aetiologies, such as atopic dermatitis or burn pruritus. However, better understanding of the mechanisms of action of the neurostimulation modalities and regimens in various pruritic conditions is necessary.

Safety and efficacy of occipital nerve stimulation for attack prevention in medically intractable chronic cluster headache (ICON): a randomised, double-blind, multicentre, phase 3, electrical dose-controlled trial.

BACKGROUND: Occipital nerve stimulation (ONS) has shown promising results in small uncontrolled trials in patients with medically intractable chronic cluster headache (MICCH). We aimed to establish whether ONS could serve as an effective treatment for patients with MICCH. METHODS: The ONS in MICCH (ICON) study is an investigator-initiated, international, multicentre, randomised, double-blind, phase 3, electrical dose-controlled clinical trial. The study took place at four hospitals in the Netherlands, one hospital in Belgium, one in Germany, and one in Hungary. After 12 weeks' baseline observation, patients with MICCH, at least four attacks per week, and history of being non-responsive to at least three standard preventive drugs, were randomly allocated (at a 1:1 ratio using a computer-generated permuted block) to 24 weeks of occipital nerve stimulation at either 100% or 30% of the individually determined range between paraesthesia threshold and near-discomfort (double-blind study phase). Because ONS causes paraesthesia, preventing masked comparison versus placebo, we compared high-intensity versus low-intensity ONS, which are hypothesised to cause similar paraesthesia, but with different efficacy. In weeks 25-48, participants received individually optimised open-label ONS. The primary outcome was the weekly mean attack frequency in weeks 21-24 compared with baseline across all patients and, if a decrease was shown, to show a group-wise difference. The trial is closed to recruitment (ClinicalTrials.gov NCT01151631). FINDINGS: Patients were enrolled between Oct 12, 2010, and Dec 3, 2017. We enrolled 150 patients and randomly assigned 131 (87%) to treatment; 65 (50%) patients to 100% ONS and 66 (50%) to 30% ONS. One of the 66 patients assigned to 30% ONS was not implanted and was therefore excluded from the intention-to-treat analysis. Because the weekly mean attack frequencies at baseline were skewed (median 15·75; IQR 9·44 to 24·75) we used log transformation to analyse the data and medians to present the results. Median weekly mean attack frequencies in the total population decreased from baseline to 7·38 (2·50 to 18·50; p<0·0001) in weeks 21-24, a median change of -5·21 (-11·18 to -0·19; p<0·0001) attacks per week. In the 100% ONS stimulation group, mean attack frequency decreased from 17·58 (9·83 to 29·33) at baseline to 9·50 (3·00 to 21·25) at 21-24 weeks (median change from baseline -4·08, -11·92 to -0·25), and for the 30% ONS stimulation group, mean attack frequency decreased from 15·00 (9·25 to 22·33) to 6·75 (1·50 to 16·50; -6·50, -10·83 to -0·08). The difference in median weekly mean attack frequency between groups at the end of the masked phase in weeks 21-24 was -2·42 (95% CI -5·17 to 3·33). In the masked study phase, 129 adverse events occurred with 100% ONS and 95 occurred with 30% ONS. None of the adverse events was unexpected but 17 with 100% ONS and eight with 30% ONS were labelled as serious, given they required brief hospital admission for minor hardware-related issues. The most common adverse events were local pain, impaired wound healing, neck stiffness, and hardware damage. INTERPRETATION: In patients with MICCH, both 100% ONS intensity and 30% ONS intensity substantially reduced attack frequency and were safe and well tolerated. Future research should focus on optimising stimulation protocols and disentangling the underlying mechanism of action. FUNDING: The Netherlands Organisation for Scientific Research, the Dutch Ministry of Health, the NutsOhra Foundation from the Dutch Health Insurance Companies, and Medtronic.

Effectiveness of Epiduroscopy for Patients with Failed Back Surgery Syndrome: A Systematic Review and Meta-analysis.

INTRODUCTION: Low-back or leg pain in patients suffering from failed back surgery syndrome (FBSS) is often severe, having a major impact on functionality and quality of life. Despite conservative and surgical treatments, pain can be persistent. An alternative treatment option is epiduroscopy, a minimally invasive procedure based on mechanical adhesiolysis of epidural fibrosis. As epidural fibrosis is speculated to be a major contributor in the pathophysiologic process of FBSS, this review evaluates the effectiveness of epiduroscopy in FBSS patients. METHODS AND MATERIALS: A systematic literature search was performed in PubMed, Embase, and Cochrane databases. Critical appraisal was performed using validated tools. Meta-analysis was performed using generic inverse variance analysis. RESULTS: From the 286 identified articles, nine studies were included. The visual analogue scale (VAS) average was 7.6 at baseline, 4.5 at 6, and 4.3 at 12 months. The Oswestry Disability Index (ODI) average was 61.7% at baseline, 42.8% at 6, and 46.9% at 12 months. An average of 49% of patients experienced significant pain relief at 6 and 37% at 12 months. Meta-analysis showed a pooled VAS mean difference of 3.4 (2.6 to 4.1; 95% confidence interval [CI]) and 2.8 (1.6 to 4.0; 95% CI) and pooled ODI mean difference of 19.4% (12.5 to 26.4%; 95% CI) and 19.8% (13.8 to 25.9%; 95% CI) at 6 and 12 months, respectively. CONCLUSION: Current literature demonstrates a clinically relevant reduction in pain and disability scores at 6 to 12 months after mechanical adhesiolysis in FBSS patients. The quality of evidence is moderate, and the level of recommendation is weak. Practitioners should consider the benefits of epiduroscopy after weighing the risks for individual patients with FBSS.

Evaluating Dorsal Root Ganglion Stimulation in a Prospective Dutch Cohort.

OBJECTIVES: Dorsal root ganglion (DRG) stimulation is a recent neuromodulation option that has delivered safe, effective pain relief for a number of etiologies. This prospective observational study was intended to establish the effectiveness of this treatment in a typical real-world clinical context. MATERIALS AND METHODS: Participants with chronic, intractable pain of the trunk or lower limbs were recruited from multiple pain clinics in the Netherlands. Subjects were trialed and implanted with DRG stimulation systems. Pain, function, mood, and quality of life, ratings were collected through 12 months postimplant. RESULTS: Of the 66 subjects enrolled, failed back surgery syndrome, peripheral nerve injury, and complex regional pain syndrome formed the largest etiologies. Permanent implants were placed in 86.2% subjects (56/65). After 12 months of treatment, average pain ratings in subjects' primary area of pain decreased from 8.0 cm at baseline to 4.1 cm, and 49% of subjects had ≥50% reduction in pain (visual analog scale). In addition, functional capacity was increased, and mood and quality of life improved. No confirmed lead migrations were observed, and there was a low rate of infection. CONCLUSIONS: DRG stimulation significantly reduced the severity of subjects' pain and enabled participatory changes that improved quality of life through 12-months postimplant.

Dorsal Column Stimulation vs. Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome Confined to the Knee: Patients' Preference Following the Trial Period.

BACKGROUND AND OBJECTIVES: Patients with complex regional pain syndrome (CRPS) confined to the knee are often therapy resistant. Neurostimulation is an accepted treatment for CRPS. Although results with dorsal column (DC) stimulation in patients with CRPS confined to the knee are often disappointing, the availability of dorsal root ganglion (DRG) stimulation may provide new opportunities for this complaint. Therefore, this study explores patients' preference for DC stimulation vs. DRG stimulation in treating chronic pain due to CRPS confined to the knee. METHODS: A prospective, observational crossover cohort study was conducted comparing 2 methods of neurostimulation, in randomized order, in patients with CRPS confined to the knee. After receiving DC and DRG stimulation during a trial period of 16 days, patients were asked which of the 2 methods they preferred. Patients with a successful trial period with one or both stimulation methods received a fully implantable system. RESULTS: Twelve patients were included. After finishing the trial period, 10 patients (83.3%) preferred DRG stimulation and 2 (16.7%) preferred DC stimulation (P = 0.04). CONCLUSION: To our knowledge, this is the first study to compare these 2 neurostimulation methods in patients with CRPS confined to the knee. Results show that the probability of the preference for either neurostimulation treatment significantly deviates from chance in favor of DRG stimulation.

Dexmedetomidine as a Sedative in the Awake Implantation of a Neuromodulative System.

OBJECTIVE: During implantation of a neuromodulative system, high patient satisfaction is closely associated with the equilibrium between an effective analgesia and sedation regimen, and the possibility for the patient to be awake and cooperative during procedure. This study assessed the efficacy of the sedative dexmedetomidine to achieve this balance, with patient satisfaction as the primary outcome. METHODS: Ten patients undergoing implantation of a dorsal column and dorsal root ganglion stimulator received dexmedetomidine (1 mcg/kg over 10 minutes, followed by 0.6 mcg/kg/hour) in combination with remifentanil at a set dose (3 mcg/kg/hour). Sedation was titrated to a Ramsay Sedation Score of 3. Recorded were as follows: patient satisfaction score, patient comfort score, operator comfort score, pain score, rescue medication and number of adjustments of dexmedetomidine intra-operatively, as well as sedation level, hemodynamic (blood pressure and heart rate), and respiratory characteristics (SpO2 ). RESULTS: Scores were high on patient satisfaction (median 8.5; IQR 2.0), patient comfort (3.0; IQR 1.25), and operator comfort (4.0; IQR 1.0). In all patients, intra-operative heart rate and mean arterial pressure were lower compared with baseline values. No respiratory depression or other complications related to anesthesia were reported. Moments of incident pain were effectively treated in 6 patients requiring an extra bolus of remifentanil. CONCLUSION: In this study group, dexmedetomidine combined with remifentanil provided a high level of patient satisfaction and comfort, as well as operator comfort, without any clinically relevant adverse events. All patients were highly cooperative and instructable; incident pain needs to be closely monitored.

The Dorsal Root Ganglion as a Therapeutic Target for Chronic Pain.

Chronic neuropathic pain is a widespread problem with negative personal and societal consequences. Despite considerable clinical neuroscience research, the goal of developing effective, reliable, and durable treatments has remained elusive. The critical role played by the dorsal root ganglion (DRG) in the induction and maintenance of chronic pain has been largely overlooked in these efforts, however. It may be that, by targeting this site, robust new options for pain management will be revealed. This review summarizes recent advances in the knowledge base for DRG-targeted treatments for neuropathic pain:• Pharmacological options including the chemical targeting of voltage-dependent calcium channels, transient receptor potential channels, neurotrophin production, potentiation of opioid transduction pathways, and excitatory glutamate receptors.• Ablation or modulation of the DRG via continuous thermal radiofrequency and pulsed radiofrequency treatments.• Implanted electrical neurostimulator technologies.• Interventions involving the modification of DRG cellular function at the genetic level by using viral vectors and gene silencing methods.

Occipital nerve stimulation in medically intractable, chronic cluster headache. The ICON study: rationale and protocol of a randomised trial.

BACKGROUND: About 10% of cluster headache patients have the chronic form. At least 10% of this chronic group is intractable to or cannot tolerate medical treatment. Open pilot studies suggest that occipital nerve stimulation (ONS) might offer effective prevention in these patients. Controlled neuromodulation studies in treatments inducing paraesthesias have a general problem in blinding. We have introduced a new design in pain neuromodulation by which we think we can overcome this problem. METHODS/DESIGN: We propose a prospective, randomised, double-blind, parallel-group international clinical study in medically intractable, chronic cluster headache patients of high- versus low-amplitude ONS. Primary outcome measure is the mean number of attacks over the last four weeks. After a study period of six months there is an open extension phase of six months. Alongside the randomised trial an economic evaluation study is performed. DISCUSSION: The ICON study will show if ONS is an effective preventive therapy for patients suffering medically intractable chronic cluster headache and if there is a difference between high- and low-amplitude stimulation. The innovative design of the study will, for the first time, assess efficacy of ONS in a blinded way.

A multicenter, prospective trial to assess the safety and performance of the spinal modulation dorsal root ganglion neurostimulator system in the treatment of chronic pain.

OBJECTIVES: This multicenter prospective trial was conducted to evaluate the clinical performance of a new neurostimulation system designed to treat chronic pain through the electrical neuromodulation of the dorsal root ganglia (DRG) neurophysiologically associated with painful regions of the limbs and/or trunk. MATERIALS AND METHODS: Thirty-two subjects were implanted with a novel neuromodulation device. Pain ratings during stimulation were followed up to six months and compared with baseline ratings. Subjects also completed two separate reversal periods in which stimulation was briefly stopped in order to establish the effects of the intervention. RESULTS: At all assessments, more than half of subjects reported pain relief of 50% or better. At six months postimplant, average overall pain ratings were 58% lower than baseline (p < 0.001), and the proportions of subjects experiencing 50% or more reduction in pain specific to back, leg, and foot regions were 57%, 70%, and 89%, respectively. When stimulation was discontinued for a short time, pain returned to baseline levels. Discrete coverage of hard-to-treat areas was obtained across a variety of anatomical pain distributions. Paresthesia intensity remained stable over time and there was no significant difference in the paresthesia intensity perceived during different body postures/positions (standing up vs. lying down). CONCLUSIONS: Results of this clinical trial demonstrate that neurostimulation of the DRG is a viable neuromodulatory technique for the treatment of chronic pain. Additionally, the capture of discrete painful areas such as the feet combined with stable paresthesia intensities across body positions suggest that this stimulation modality may allow more selective targeting of painful areas and reduce unwanted side-effects observed in traditional spinal cord stimulation (SCS).

Anti-inflammatory actions of acupuncture.

Acupuncture has a beneficial effect when treating many diseases and painful conditions, and therefore is thought to be useful as a complementary therapy or to replace generally accepted pharmacological intervention. The attributive effect of acupuncture has been investigated in inflammatory diseases, including asthma, rhinitis, inflammatory bowel disease, rheumatoid arthritis, epicondylitis, complex regional pain syndrome type 1 and vasculitis. Large randomised trials demonstrating the immediate and sustained effect of acupuncture are missing. Mechanisms underlying the ascribed immunosuppressive actions of acupuncture are reviewed in this communication. The acupuncture-controlled release of neuropeptides from nerve endings and subsequent vasodilative and anti-inflammatory effects through calcitonine gene-related peptide is hypothesised. The complex interactions with substance P, the analgesic contribution of beta-endorphin and the balance between cell-specific pro-inflammatory and anti-inflammatory cytokines tumour necrosis factor-alpha and interleukin-10 are discussed.