European randomized controlled trial evaluating differential target multiplexed spinal cord stimulation and conventional medical management in subjects with persistent back pain ineligible for spine surgery: 24-month results.

BACKGROUND: Differential target multiplexed spinal cord stimulation (DTM SCS) was shown to be superior to conventional SCS for treating chronic low back pain (CLBP) in subjects with persistent spinal pain syndrome with previous spinal surgery (PSPS-T2) or ineligible for it (PSPS-T1). This study reports 24-month efficacy and safety of DTM SCS vs. conventional medical management (CMM) in PSPS-T1 subjects across four European countries. METHODS: This is a prospective, multicenter, open-label, randomized, controlled trial with optional crossover. Subjects randomized 1:1 to DTM SCS or CMM. Primary endpoint was responder rate (% subjects reporting ≥50% CLBP relief) at 6 months. A superiority test compared responder rates between treatments. CLBP and leg pain levels, functional disability, quality of life (QoL), patient satisfaction and global impression of change were evaluated for 24 months. A Composite Responder Index (CRI) was obtained using CLBP relief, disability and QoL. Incidence of study-related adverse events evaluated safety. RESULTS: A total of 55 and 57 subjects were randomized to DTM SCS and CMM respectively. DTM SCS was superior, with CLBP responder rates ≥80% and CLBP relief >5.6 cm (>70% reduction) through the 24-month follow-up. Improvements with DTM SCS in other outcomes were sustained. The CRI was >80% for DTM SCS through 24 months. Opioid medication intake decreased in subjects treated with DTM SCS. Most patients treated with DTM SCS felt satisfied and improved at the end of the study. Safety was congruent with other studies. CONCLUSION: DTM SCS is efficacious and safe during 24 months for the treatment of CLBP and leg pain in PSPS-T1 patients ineligible for spine surgery. SIGNIFICANCE STATEMENT: This randomized controlled trial shows that Differential Target Multiplexed SCS (DTM SCS) is an effective and safe long-term treatment for PSPS type 1 patients suffering from axial low back pain with or without leg pain and who are ineligible for spinal surgery. Currently, CMM treatments are their only option and provide limited benefits. Besides superior pain relief, DTM SCS provides significant improvements in functional disability, quality of life, high levels of satisfaction and perceived impression of change.

Detoxification of Neuromodulation-Eligible Patients by a Standardized Protocol: A Retrospective Pilot Study.

OBJECTIVES: Patients eligible for spinal cord stimulation (SCS) generally experience excruciating pain, requiring more opioid consumption, which is usually an indication for SCS implantation. After final implantation, SCS has the ability to stabilize or decrease opioid usage in half of the patients. In this study, opioids were actively eliminated prior to implantation of any neuromodulation device with a standardized detoxification protocol. This pilot study aims to explore the feasibility, effectiveness, and safety of this opioid detoxification protocol prior to neuromodulation techniques. MATERIALS AND METHODS: In this retrospective pilot study, 70 patients who were taking opioids and who were eligible for neuromodulation techniques underwent the detoxification program. A combined in- and out-patient clinic protocol was applied, whereby clonidine was the main component of both parts of the program. A multidisciplinary team with pain physicians and psychologists was responsible for performing this detoxification program. Safety and feasibility were systematically recorded during the hospitalization. RESULTS: No serious safety issues were reported. At the start of the program, patients reported a mild sedative effect of clonidine. Additionally, most patients presented mild symptoms of opioid withdrawal, which were partially countered by the sedative effect of clonidine. Both patients and the medical staff found this protocol feasible in clinical practice. Concerning the effectiveness, a statistically significant decrease in median morphine milligram equivalents (MMEs) was found with an MME of 175 (Q1-Q3: 118.1-240) at baseline, and at the last available follow-up visit the MME was 0 (Q1-Q3: 0-16.88). CONCLUSIONS: This standardized detoxification program has proven its effectiveness, safety, and feasibility in this single-center experience pilot study in patients eligible for neuromodulation techniques.

Dorsal root ganglion stimulation for patients with refractory pain due to anterior cutaneous nerve entrapment syndrome: A case series.

BACKGROUND: Anterior cutaneous nerve entrapment syndrome (ACNES) is a painful condition that can be refractory in a small percentage of patients. Abdominal pain caused by thoracic nerve entrapment in the abdominal wall characterizes ACNES. In the small number of refractory patients to all standard treatments, medication overuse and abuse are serious problems. Dorsal root ganglion (DRG) stimulation might be a good treatment to improve pain scores and to lower medication use. METHODS: We describe the retrospective analysis of nine cases of patients who underwent DRG stimulation for refractory ACNES using a treatment algorithm. We focused on reported pain intensity scores, medication use, and adverse events. RESULTS: All nine patients experienced a decrease in pain intensity during the trial period and received a permanent pulse generator implantation. Three months after permanent implantation, eight of nine patients showed a pain reduction of more than 50%. Medication use was substantially lower. DISCUSSION AND CONCLUSION: This case series shows that DRG stimulation might be a very good treatment for refractory ACNES.

Trigeminal neuropathy: Two case reports of gasserian ganglion stimulation.

This report describes the successful treatment of two patients with trigeminal neuropathy by using gasserian ganglion stimulation. Case reports: The first case report deals with a 53-year-old woman suffering from right-sided facial pain after a gamma knife lesion for schwannoma of the right inner ear. For 9 years, several interventions with the aim of relieving the pain were unsuccessful; in fact, they had aggravated the symptoms. A trial with a neurostimulator at the level of the Gasser ganglion had an immediately positive effect on her score for facial pain, which decreased from 7.3 to 0 on a visual analog scale, assessed during a period of 2 months. Additionally, the patient had weaned off all her medication by the end of the period. The second case report describes a 64-year-old man suffering from trigeminal neuropathy, which mainly manifested itself as an itch. For a period of 15 years, neither medication nor several interventions were effective. A trial with an electrode at the level of the Gasser ganglion reduced his pain score from 7.0 to 1.5 on a visual analog scale, assessed during a period of three months. His medication could be limited to pregabalin 150 mg bidaily. In contrast, prior to the implantation, his oral medication consisted of pregabalin 75 mg up to five times a day. Conclusion: These case reports show that stimulation of the gasserian ganglion is a successful, minimally invasive, and non-destructive treatment in refractory trigeminal neuropathy and should be considered earlier in the treatment algorithm of trigeminal neuropathy.

Durability of the Therapeutic Effect of Restorative Neurostimulation for Refractory Chronic Low Back Pain.

OBJECTIVES: The purpose of the ongoing follow-up of ReActiv8-A clinical trial is to document the longitudinal benefits of episodic stimulation of the dorsal ramus medial branch and consequent contraction of the lumbar multifidus in patients with refractory mechanical chronic low back pain (CLBP). We report the four-year outcomes of this trial. MATERIALS AND METHODS: ReActiv8-A is a prospective, single-arm trial performed at nine sites in the United Kingdom, Belgium, and Australia. Eligible patients had disabling CLBP (low back pain Numeric Rating Scale [NRS] ≥6; Oswestry Disability Index [ODI] ≥25), no indications for spine surgery or spinal cord stimulation, and failed conventional management including at least physical therapy and medications for low back pain. Fourteen days postimplantation, stimulation parameters were programmed to elicit strong, smooth contractions of the multifidus, and participants were given instructions to activate the device for 30-min stimulation-sessions twice daily. Annual follow-up through four years included collection of NRS, ODI, and European Quality of Life Score on Five Dimensions (EQ-5D). Background on mechanisms, trial design, and one-year outcomes were previously described. RESULTS: At baseline (N = 53) (mean ± SD) age was 44 ± 10 years; duration of back pain was 14 ± 11 years, NRS was 6.8 ± 0.8, ODI 44.9 ± 10.1, and EQ-5D 0.434 ± 0.185. Mean improvements from baseline were statistically significant (p < 0.001) and clinically meaningful for all follow-ups. Patients completing year 4 follow-up, reported mean (±standard error of the mean) NRS: 3.2 ± 0.4, ODI: 23.0 ± 3.2, and EQ-5D: 0.721 ± 0.035. Moreover, 73% of participants had a clinically meaningful improvement of ≥2 points on NRS, 76% of ≥10 points on ODI, and 62.5% had a clinically meaningful improvement in both NRS and ODI and 97% were (very) satisfied with treatment. CONCLUSIONS: In participants with disabling intractable CLBP who receive long-term restorative neurostimulation, treatment satisfaction remains high and improvements in pain, disability, and quality-of-life are clinically meaningful and durable through four years.

Real-World Analysis: Long-Term Effect of Spinal Cord Stimulation With Different Waveforms for Patients With Failed Back Surgery Syndrome.

INTRODUCTION: Spinal cord stimulation (SCS) is effective for patients with failed back surgery syndrome (FBSS). SCS improves their pain, as well as their functionality and health-related quality of life. Different waveforms for SCS have emerged that show improvement in small prospective studies. Analysis of real-world data shows the clinical implementation and the effect of different waveforms in SCS. METHODS: A real-world analysis was performed of 208 patients with FBSS who were treated over 3 years. Stimulators with tonic, burst, high-density, and 10-kHz high-frequency (HF10) waveforms were implanted in patients with FBSS who had predominant pain in the back, legs, or both back and legs. Pain as measured by the VAS, functional disability as measured by the Oswestry Disability Index (ODI), and health-related quality of life as measured by the 3-level EuroQol 5-Dimension (EQ5D-3L) questionnaire were determined at baseline and for outcome assessment. RESULTS: SCS is effective for patients with FBSS. This analysis showed a change in baseline VAS score from 8.0 to 4.7 (P < 0.0001) at 24 months. The EQ5D-3L score improved from 0.29 to 0.49 (P < 0.0001) at 24 months. The ODI score improved from 54% to 42% (P < 0.0001) at 24 months. The unanticipated explantation rate was only 1.6%. CONCLUSION: This study of SCS showed significant long-term improvement in pain, disability, and quality of life in a large dataset of patients with FBSS. Strict selection procedures and a strong opioid policy contributed to the high success rate and low unanticipated explantation rate. There was no difference in pain reduction between tonic and HF10 stimulation. Further investigation is necessary to detect any difference between other waveforms of SCS.

Predicting the Response of High Frequency Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome: A Retrospective Study with Machine Learning Techniques.

Despite the proven clinical value of spinal cord stimulation (SCS) for patients with failed back surgery syndrome (FBSS), factors related to a successful SCS outcome are not yet clearly understood. This study aimed to predict responders for high frequency SCS at 10 kHz (HF-10). Data before implantation and the last available data was extracted for 119 FBSS patients treated with HF-10 SCS. Correlations, logistic regression, linear discriminant analysis, classification and regression trees, random forest, bagging, and boosting were applied. Based on feature selection, trial pain relief, predominant pain location, and the number of previous surgeries were relevant factors for predicting pain relief. To predict responders with 50% pain relief, 58.33% accuracy was obtained with boosting, random forest and bagging. For predicting responders with 30% pain relief, 70.83% accuracy was obtained using logistic regression, linear discriminant analysis, boosting, and classification trees. For predicting pain medication decrease, accuracies above 80% were obtained using logistic regression and linear discriminant analysis. Several machine learning techniques were able to predict responders to HF-10 SCS with an acceptable accuracy. However, none of the techniques revealed a high accuracy. The inconsistent results regarding predictive factors in literature, combined with acceptable accuracy of the currently obtained models, might suggest that routinely collected baseline parameters from clinical practice are not sufficient to consistently predict the SCS response with a high accuracy in the long-term.

High-Frequency Supraorbital Nerve Stimulation With a Novel Wireless Minimally Invasive Device for Post-Traumatic Neuralgia: A Case Report.

BACKGROUND: Post-traumatic neuropathic pain in the head and face is a condition that is often refractory to medical management. Peripheral nerve stimulation (PNS) can be an effective treatment. Successful implantation of a novel minimally invasive wireless device is reported here. OBJECTIVE: To assess analgesic effects of a minimally invasive wireless PNS device in the treatment of post-traumatic supraorbital neuralgia (SON). CASE SUMMARY: The patient presented with SON following multiple post-traumatic cranioplasty surgeries, which were complicated by infections. Medical and interventional management failed, and the patient reported a numeric rating scale (NRS) pain score of 8 out of 10. Two octopolar implantable neural stimulators (INSs) (StimRelieve LLC, Pompano Beach, FL, U.S.A.) were implanted with a minimally invasive, percutaneous technique to stimulate the supraorbital nerves. Stimulation parameters were set at a frequency of 10 kHz and a pulse width of 30 microseconds. RESULTS: At 12- and 24-month follow-up evaluations, the patient's NRS score was only 2 out of 10, and the patient occasionally required 1 g of paracetamol to control the pain. Stimulation was reported to be paresthesia free. There were no adverse events related to the procedure or the treatment until today. CONCLUSIONS: High-frequency stimulation with an external pulse generator and minimally invasive, percutaneous, and bilateral placement of 2 passive INSs on the supraorbital nerves resulted in a significant pain relief in this patient with post-traumatic SON. The device was safe and effective, and the cosmesis was satisfactory.

Is the Self-Reporting of Failed Back Surgery Syndrome Patients Treated With Spinal Cord Stimulation in Line With Objective Measurements?

OBJECTIVES: To understand the subjective pain experience of patients, healthcare providers rely heavily on self-reporting. However, to quantify this unique pain experience, objective parameters are not yet available in daily clinical practice. With regard to patients with failed back surgery syndrome (FBSS) treated with spinal cord stimulation (SCS), pain therapists may recover the individual functional information about the patient's posture from the implantable pulse generator (IPG) of the stimulator. The aim of this study is to investigate whether subjective self-reporting is in correlation with the functional capacities of a patient. MATERIALS AND METHODS: Thirty-nine patients with FBSS, treated with SCS were included. The accelerometer in the IPG detects positional changes and provides an objective output of seven functional positions (lying back, lying prone, lying left, lying right, transition, upright, and upright + mobile). The Oswestry Disability Index (ODI), VAS-diary, and the Pittsburgh Sleep Quality Index (PSQI) were assessed to evaluate physical functioning, pain intensities, and subjective sleep quality. Additionally, 21 patients wore a wearable actigraph device to objectify sleep quality. The agreement and Spearman correlations between objective and subjective parameters were assessed. RESULTS: Spearman rank correlations revealed no significant correlations between the ODI (subscales walking, sitting, standing, and sleeping) and the output of the IPG (percentage upright + mobile, transition, upright, and lying, respectively). Sleep parameters measured with the Actiwatch and the PSQI were not in agreement. CONCLUSIONS: This study demonstrated that self-reporting questionnaires do not correlate with the findings of objective measurements. Therefore, we recommend using both subjective and objective parameters when determining treatment options for FBSS patients.

New Therapy for Refractory Chronic Mechanical Low Back Pain-Restorative Neurostimulation to Activate the Lumbar Multifidus: One Year Results of a Prospective Multicenter Clinical Trial.

OBJECTIVES: The purpose of the international multicenter prospective single arm clinical trial was to evaluate restorative neurostimulation eliciting episodic contraction of the lumbar multifidus for treatment of chronic mechanical low back pain (CMLBP) in patients who have failed conventional therapy and are not candidates for surgery or spinal cord stimulation (SCS). MATERIALS AND METHODS: Fifty-three subjects were implanted with a neurostimulator (ReActiv8, Mainstay Medical Limited, Dublin, Ireland). Leads were positioned bilaterally with electrodes close to the medial branch of the L2 dorsal ramus nerve. The primary outcome measure was low back pain evaluated on a 10-Point Numerical Rating Scale (NRS). Responders were defined as subjects with an improvement of at least the Minimal Clinically Important Difference (MCID) of ≥2-point in low back pain NRS without a clinically meaningful increase in LBP medications at 90 days. Secondary outcome measures included Oswestry Disability Index (ODI) and Quality of Life (QoL; EQ-5D). RESULTS: For 53 subjects with an average duration of CLBP of 14 years and average NRS of 7 and for whom no other therapies had provided satisfactory pain relief, the responder rate was 58%. The percentage of subjects at 90 days, six months, and one year with ≥MCID improvement in single day NRS was 63%, 61%, and 57%, respectively. Percentage of subjects with ≥MCID improvement in ODI was 52%, 57%, and 60% while those with ≥MCID improvement in EQ-5D was 88%, 82%, and 81%. There were no unanticipated adverse events (AEs) or serious AEs related to the device, procedure, or therapy. The initial surgical approach led to a risk of lead fracture, which was mitigated by a modification to the surgical approach. CONCLUSIONS: Electrical stimulation to elicit episodic lumbar multifidus contraction is a new treatment option for CMLBP. Results demonstrate clinically important, statistically significant, and lasting improvement in pain, disability, and QoL.

Therapy-Related Explants After Spinal Cord Stimulation: Results of an International Retrospective Chart Review Study.

OBJECTIVES: Clinical trials of spinal cord stimulation (SCS) have largely focused on conversion from trial to permanent SCS and the first years after implant. This study evaluates the association of type of SCS and patient characteristics with longer-term therapy-related explants. MATERIALS AND METHODS: Implanting centers in three European countries conducted a retrospective chart review of SCS systems implanted from 2010 to 2013. Ethics approval or waiver was obtained, and informed consent was not required. The chart review recorded implants, follow-up visits, and date and reasons for any explants through mid-2016. Results are presented using Cox regression to determine factors associated with explant for inadequate pain relief. RESULTS: Four implanting centers in three countries evaluated 955 implants, with 8720 visits over 2259 years of follow-up. Median age was 53 years; 558 (58%) were female. Explant rate was 7.9% per year. Over half (94 of 180) of explants were for inadequate pain relief, including 32/462 (6.9%) of implants with conventional nonrechargeable SCS, 37/329 (11.2%) with conventional rechargeable and 22/155 (14.2%) with high-frequency (10 kHz) rechargeable SCS. A higher explant rate was found in univariate regression for conventional rechargeable (HR 1.98, p = 0.005) and high-frequency stimulation (HR 1.79, p = 0.035) than nonrechargeable SCS. After covariate adjustment, the elevated explant rate persisted for conventional rechargeable SCS (HR 1.95, p = 0.011), but was not significant for high-frequency stimulation (HR 1.71, p = 0.069). CONCLUSIONS: This international, real-world study found higher explant rates for conventional rechargeable and high-frequency SCS than nonrechargeable systems. The increased rate for conventional rechargeable stimulation persisted after covariate adjustment.

Stimulation of the Gasserian ganglion in the treatment of refractory trigeminal neuropathy.

OBJECTIVES: We evaluated the effectiveness of a custom-made neurostimulator with which to treat patients for refractory trigeminal neuropathic pain (TNP) at the level of the Gasserian ganglion. MATERIALS AND METHODS: A retrospective analysis of 22 patients referred to our pain clinic, AZ Sint-Nikolaas, between 2010 and 2015, was conducted using the McGill Pain and EuroQoL questionnaire before, two weeks after, and at the final follow-up after neurostimulator treatment. RESULTS: Successful test stimulations were achieved for 77.3% of patients, with satisfactory long-term pain relief reported by 44% at 24 months. The predictive value of the trial stimulation was 80%, with 82.4% of patients reporting one or more complication, the most common being neck discomfort due to fibrosis. A small cohort size (22) limited our statistical analyses. However younger patients presented with a higher incidence of negative results after 24 months or physical complications. Cut-off ages were set at the age of 62 and 58 years respectively. CONCLUSION: Stimulation of the Gasserian ganglion is a promising technique for the treatment of refractory TNP and should be considered ahead of more invasive techniques such as motor cortex or deep brain stimulation. The referral of refractory TNP patients should also be accomplished as early as possible to improve outcome.

Chronic Low Back Pain: Restoration of Dynamic Stability.

OBJECTIVES: Electrical stimulation for multifidus muscle contraction is a novel approach for treating chronic low back pain (CLBP). A multicenter, open-label feasibility study investigated this modality in patients with continuing CLBP despite medical management and no prior back surgery and no known pathological cause of CLBP. METHODS: Twenty-six patients with continuing CLBP despite physical therapy and medication were implanted with commercially-available implantable pulse generators and leads positioned adjacent to the medial branch of the dorsal ramus as it crosses the L3 transverse process such that electrical stimulation resulted in contraction of the lumbar multifidus (LM) muscle. Patients self-administered stimulation twice daily for 20 min. Low back pain (VAS), Oswestry Disability Index (ODI) and Quality of Life (EQ-5D) scores were collected at three and five months and compared to baseline. Stimulation was withdrawn between months 4 and 5 to test durability of effect. RESULTS: At three months, 74% of patients met or exceeded the minimally important change (MIC) in VAS and 63% for disability. QoL improved in 84% of patients (N = 19) and none got worse. Five of the 11 patients on disability for CLBP (45%) resumed work by three months. Half the patients reported ≥50% VAS reduction by month 5. Twenty-one lead migration events occurred in 13 patients, of which 7 patients are included in the efficacy cohort. CONCLUSIONS: Episodic stimulation to induce LM contraction can reduce CLBP and disability, improve quality of life and enable return to work. A dedicated lead design to reduce risk of migration is required.

One-year outcomes of spinal cord stimulation of the dorsal root ganglion in the treatment of chronic neuropathic pain.

OBJECTIVES: Spinal cord stimulation of the dorsal root ganglion (DRG-SCS) is a new therapy for treating chronic neuropathic pain. Previous work has demonstrated the effectiveness of DRG-SCS for pain associated with failed back surgery syndrome, complex regional pain syndrome, chronic postsurgical pain, and other etiologies through 6 months of treatment; this report describes the maintenance of pain relief, improvement in mood, and quality of life through 12 months. MATERIALS AND METHODS: Subjects with intractable pain in the back and/or lower limbs were implanted with an active neurostimulator device. Up to four percutaneous leads were placed epidurally near DRGs. Subjects were tracked prospectively for 12 months. RESULTS: Overall, pain was reduced by 56% at 12 months post-implantation, and 60% of subjects reported greater than 50% improvement in their pain. Pain localized to the back, legs, and feet was reduced by 42%, 62%, and 80%, respectively. Measures of quality of life and mood were also improved over the course of the study, and subjects reported high levels of satisfaction. Importantly, excellent pain-paresthesia overlap was reported, remaining stable through 12 months. DISCUSSION: Despite methodological differences in the literature, DRG-SCS appears to be comparable to traditional SCS in terms of pain relief and associated benefits in mood and quality of life. Its benefits may include the ability to achieve precise pain-paresthesia concordance, including in regions that are typically difficult to target with SCS, and to consistently maintain that coverage over time.

Lack of body positional effects on paresthesias when stimulating the dorsal root ganglion (DRG) in the treatment of chronic pain.

OBJECTIVES: One prominent side effect from neurostimulation techniques, and in particular spinal cord stimulation (SCS), is the change in intensity of stimulation when moving from an upright (vertical) to a recumbent or supine (horizontal) position and vice versa. It is well understood that the effects of gravity combined with highly conductive cerebrospinal fluid provide the mechanism by which changes in body position can alter the intensity of stimulation-induced paresthesias. While these effects are well established for leads that are placed within the more medial aspects of the spinal canal, little is known about these potential effects in leads placed in the lateral epidural space and in particular within the neural foramina near the dorsal root ganglion (DRG). MATERIALS AND METHODS: We prospectively validated a newly developed paresthesia intensity rating scale and compared perceived paresthesia intensities when subjects assumed upright vs. supine bodily positions during neuromodulation of the DRG. RESULTS: On average, the correlation coefficient between stimulation intensity (pulse amplitude) and perceived paresthesia intensity was 0.83, demonstrating a strong linear relationship. No significant differences in paresthesia intensities were reported within subjects when moving from an upright (4.5 ± 0.14) to supine position 4.5 (± 0.12) (p > 0.05). This effect persisted through 12 months following implant. CONCLUSIONS: Neuromodulation of the DRG produces paresthesias that remain consistent across body positions, suggesting that this paradigm may be less susceptible to positional effects than dorsal column stimulation.

Stimulation of dorsal root ganglia for the management of complex regional pain syndrome: a prospective case series.

BACKGROUND: Complex regional pain syndrome (CRPS) is a chronic and progressive pain condition usually involving the extremities and characterized by sensorimotor, vascular, and trophic changes. Spinal cord stimulation (SCS) is an effective intervention for this condition, but is hampered by the technical challenges associated with precisely directing stimulation to distal extremities. Dorsal root ganglia (DRG) may be more effective as a physiological target for electrical modulation due to recruitment of the primary sensory neurons that innervate the painful distal anatomical regions. METHODS: Eleven subjects diagnosed with uni- or bilateral lower-extremity CRPS were recruited as part of a larger study involving chronic pain of heterogeneous etiologies. Quadripolar epidural leads of a newly developed neurostimulation system were placed near lumbar DRGs using conventional percutaneous techniques. The neurostimulators were trialed; 8 were successful and permanently implanted and programed to achieve optimal pain-paresthesia overlap. RESULTS: All 8 subjects experienced some degree of pain relief and subjective improvement in function, as measured by multiple metrics. One month after implantation of the neurostimulator, there was significant reduction in average self-reported pain to 62% relative to baseline values. Pain relief persisted through 12 months in most subjects. In some subjects, edema and trophic skin changes associated with CRPS were also mitigated and function improved. Neuromodulation of the DRG was able to provide excellent pain-paresthesia concordance in locations that are typically hard to target with traditional SCS, and the stimulation reduced the area of pain distributions. CONCLUSIONS: Neuromodulation of the DRG appears to be a promising option for relieving chronic pain and other symptoms associated with CRPS. The capture of discrete painful areas such as the feet, combined with stable paresthesia intensities independent of body position, suggests this stimulation modality may allow more selective and consistent targeting of painful areas than traditional SCS.

Sustained effectiveness of 10 kHz high-frequency spinal cord stimulation for patients with chronic, low back pain: 24-month results of a prospective multicenter study.

OBJECTIVE: The aim of this study was to investigate the long-term efficacy and safety of paresthesia-free high-frequency spinal cord stimulation (HF10 SCS) for the treatment of chronic, intractable pain of the low back and legs. DESIGN: Prospective, multicenter, observational study. METHOD: Patients with significant chronic low back pain underwent implantation of a spinal cord stimulator capable of HF10 SCS. Patients' pain ratings, disability, sleep disturbances, opioid use, satisfaction, and adverse events were assessed for 24 months. RESULTS: After a trial period, 88% (72 of 82) of patients reported a significant improvement in pain scores and underwent the permanent implantation of the system. Ninety percent (65 of 72) of patients attended a 24-month follow-up visit. Mean back pain was reduced from 8.4 ± 0.1 at baseline to 3.3 ± 0.3 at 24 months (P < 0.001), and mean leg pain from 5.4 ± 0.4 to 2.3 ± 0.3 (P < 0.001). Concomitantly to the pain relief, there were significant decreases in opioid use, Oswestry Disability Index score, and sleep disturbances. Patients' satisfaction and recommendation ratings were high. Adverse Events were similar in type and frequency to those observed with traditional SCS systems. CONCLUSIONS: In patients with chronic low back pain, HF10 SCS resulted in clinically significant and sustained back and leg pain relief, functional and sleep improvements, opioid use reduction, and high patient satisfaction. These results support the long-term safety and sustained efficacy of HF10 SCS.

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).

High-frequency spinal cord stimulation for the treatment of chronic back pain patients: results of a prospective multicenter European clinical study.

OBJECTIVE: The objective of this prospective, open-label, multicenter European clinical trial was to quantify the efficacy and safety of a spinal cord stimulation (SCS) system that utilizes high-frequency (up to 10 kHz) waveforms, which do not produce paresthesia, for the treatment of chronic, intractable pain of the back and/or limbs. MATERIAL AND METHODS: Eighty-three patients, with significant back pain, were recruited for a trial of high-frequency stimulation through two percutaneous eight-contact epidural leads. Patients' pain ratings, disability, sleep disturbances, and satisfaction, as well as complication rates, were assessed for up to six months. RESULTS: After a trial period, 88% (72 out of 82) of patients reported a significant improvement in visual analog scale (VAS) scores and underwent permanent implantation of the high-frequency SCS system. Mean back pain VAS of 8.4 was reduced to 2.7 at six months (p< 0.001). Mean leg pain VAS of 5.4 was reduced to 1.4 at six months (p< 0.001). Seventy-four percent of patients had greater than 50% back pain relief at six months. There were significant improvements in Oswestry disability score and sleep, and reductions in pain medication use. Adverse events observed were those seen with conventional SCS therapy--lead migration, wound infection, and pain around implant site. CONCLUSIONS: In a cohort of patients with difficult-to-treat chronic back pain, high-frequency SCS provided significant and sustained low back pain and leg pain relief to more than 70% of treated subjects. Notably, this was achieved without paresthesia. Patients also experienced significant improvement in disability and sleep. Overall, the results confirm a favorable safety and efficacy profile of the high-frequency SCS system.

Electromagnetic navigation technology for more precise electrode placement in the foramen ovale: a technical report.

Introduction. Interventional pain management techniques require precise positioning of needles or electrodes, therefore fluoroscopic control is mandatory. This imaging technique does however not visualize soft tissues such as blood vessels. Moreover, patient and physician are exposed to a considerable dose of radiation. Computed tomography (CT)-scans give a better view of soft tissues, but there use requires presence of a radiologist and has proven to be laborious and time consuming. Objectives. This study is to develop a technique using electromagnetic (EM) navigation as a guidance technique for interventional pain management, using CT and/or magnetic resonance (MRI) images uploaded on the navigation station. Methods. One of the best documented interventional procedures for the management of trigeminal neuralgia is percutaneous radiofrequency treatment of the Gasserian ganglion. EM navigation software for intracranial applications already exists. We developed a technique using a stylet with two magnetic coils suitable for EM navigation. The procedure is followed in real time on a computer screen where the patient's multislice CT-scan images and three-dimensional reconstruction of his face are uploaded. Virtual landmarks on the screen are matched with those on the patient's face, calculating the precision of the needle placement. Discussion. The experience with EM navigation acquired with the radiofrequency technique can be transferred to other interventional pain management techniques, for instance, for the placement of a neuromodulation electrode close to the Gasserian ganglion. Currently, research is ongoing to extend the software of the navigation station for spinal application, and to adapt neurostimulation hardware to the EM navigation technology. This technology will allow neuromodulation techniques to be performed without x-ray exposure for the patient and the physician, and this with the precision of CT/MR imaging guidance.