Neuromodulation for chronic pain.

Neuromodulation is an expanding area of pain medicine that incorporates an array of non-invasive, minimally invasive, and surgical electrical therapies. In this Series paper, we focus on spinal cord stimulation (SCS) therapies discussed within the framework of other invasive, minimally invasive, and non-invasive neuromodulation therapies. These therapies include deep brain and motor cortex stimulation, peripheral nerve stimulation, and the non-invasive treatments of repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and transcutaneous electrical nerve stimulation. SCS methods with electrical variables that differ from traditional SCS have been approved. Although methods devoid of paraesthesias (eg, high frequency) should theoretically allow for placebo-controlled trials, few have been done. There is low-to-moderate quality evidence that SCS is superior to reoperation or conventional medical management for failed back surgery syndrome, and conflicting evidence as to the superiority of traditional SCS over sham stimulation or between different SCS modalities. Peripheral nerve stimulation technologies have also undergone rapid development and become less invasive, including many that are placed percutaneously. There is low-to-moderate quality evidence that peripheral nerve stimulation is effective for neuropathic pain in an extremity, low quality evidence that it is effective for back pain with or without leg pain, and conflicting evidence that it can prevent migraines. In the USA and many areas in Europe, deep brain and motor cortex stimulation are not approved for chronic pain, but are used off-label for refractory cases. Overall, there is mixed evidence supporting brain stimulation, with most sham-controlled trials yielding negative findings. Regarding non-invasive modalities, there is moderate quality evidence that repetitive transcranial magnetic stimulation does not provide meaningful benefit for chronic pain in general, but conflicting evidence regarding pain relief for neuropathic pain and headaches. For transcranial direct current stimulation, there is low-quality evidence supporting its benefit for chronic pain, but conflicting evidence regarding a small treatment effect for neuropathic pain and headaches. For transcutaneous electrical nerve stimulation, there is low-quality evidence that it is superior to sham or no treatment for neuropathic pain, but conflicting evidence for non-neuropathic pain. Future research should focus on better evaluating the short-term and long-term effectiveness of all neuromodulation modalities and whether they decrease health-care use, and on refining selection criteria and treatment variables.

Subcutaneous Stimulation as an Additional Therapy to Spinal Cord Stimulation for the Treatment of Low Back Pain and Leg Pain in Failed Back Surgery Syndrome: Four-Year Follow-Up.

OBJECTIVE: The objective of this study is to investigate the efficacy of long-term follow-up of subcutaneous stimulation (SubQ) as an additional therapy for patients with failed back surgery syndrome (FBSS) with chronic refractory pain, for whom spinal cord stimulation (SCS) alone was unsuccessful in treating low back pain. STUDY DESIGN: Prospective case series. MATERIALS AND METHODS: FBSS patients with leg and/or low back pain whose conventional therapies had failed, received a combination of SCS (8-contact Octad lead, 3877-45 cm, Medtronic, Minneapolis, MN, USA) and/or SubQ (4-contact Quad Plus lead (s), 2888-28 cm, Medtronic). Initially, an Octad lead was placed in the epidural space for SCS for a trial stimulation to assess the suppression of leg and/or low back pain. Where SCS alone was insufficient in treating low back pain, lead(s) were placed superficially in the subcutaneous tissue of the lower back, exactly in the middle of the pain area. A pulse generator (Prime Advanced, 37702, Medtronic) was implanted if the patient reported more than 50% pain relief during the trial period. We investigated the long-term effect of neuromodulation on pain with the visual analog scale (VAS), and disability using the Quebec Pain Disability Scale. The results after 46 months are presented. RESULTS: Eleven patients, five men and six women (age 51 ± 8 years, mean ± SD) were included in the pilot study. In nine cases, SCS was used in combination with SubQ leads. Two patients received only SubQ leads. In one patient, the SCS + SubQ system was removed after nine months and these results were not taken into account for the analysis. Baseline scores for leg (N = 8) and low back pain (N = 10) were VASbl: 59 ± 15 and VASbl: 63 ± 14, respectively. The long-term follow-up period was 46 ± 4 months. SCS significantly reduced leg pain after 12 months (VAS12: 20 ± 11, p12 = 0.001) and 46 months (VAS46: 37 ± 17, p46 = 0.027). Similarly, SubQ significantly reduced back pain after 12 months(VAS12: 33 ± 16, p12 = 0.001) and 46 months (VAS46: 40 ± 21, p46 = 0.013). At 12 months, the Quebec Pain Disability Scale (QPDS) was 49 ± 12 and after 46 months, 53 ± 15. Both at 12 and 46 months, the QPDS values were statistically significantly better (p12 = 0.001, p46 = 0.04) compared with baseline values (QPDSbl: 61 ± 15). In one patient, the pain suppressive effect of SCS/SubQ had disappeared completely over time and the pain scores returned to prestimulation values. In four, patients back pain scores increased over time due to new issues (SI-joint problems, degenerative spine problems, disc problems, and hip pain) unrelated to FBSS and for which SCS/SubQ was not targeted or a reason for implantation at the start of the pilot study. DISCUSSION: This is the first prospective report on the combined use of SCS and SubQ with a follow-up period of four years. These data show that SCS and/or SubQ provide persistent long-term pain relief for leg and back pain in patients with FBSS. One should also take into account that new back/leg pain problems may evolve over time and increase the pain score which impact overall pain treatment. CONCLUSION: SCS combined with SubQ can be considered an effective long term treatment for low back pain in patients with FBSS for whom SCS alone is insufficient in alleviating their pain symptoms.

Ozonoterapia y síndrome de cirugía fallida de espalda / No disponible

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Prospective, two-part study of the interaction between spinal cord stimulation and peripheral nerve field stimulation in patients with low back pain: development of a new spinal-peripheral neurostimulation method.

OBJECTIVE: The goal of the study was to assess the efficacy of interaction between spinal cord stimulation (SCS) and peripheral nerve field stimulation (PNFS) and to evaluate a new spinal-peripheral neuromodulation method for low back pain. MATERIALS AND METHODS: The prospective two-part study included patients with low back pain due to failed back surgery syndrome and/or spinal stenosis. In the first part 20 patients were implanted with SCS and PNFS. They selected the best program out of three: SCS alone, PNFS alone, or both together. In the second part another 20 patients with the same implanted leads were selecting between three programs: SCS and PNFS separately, SCS as anode and PNFS as cathode, or in reverse. RESULTS: In the first part 79% of the patients selected simultaneous use of SCS and PNFS. The overall success of the trials was 85%. In the second part communication between SCS and PNFS provided wider coverage of axial pain. The overall success of the trials was 90%. CONCLUSION: Simultaneous use of SCS and PNFS increase efficacy of both methods for axial back pain. The new SPN method showed great potential in providing coverage for back pain.

Costs and cost-effectiveness of spinal cord stimulation (SCS) for failed back surgery syndrome: an observational study in a workers' compensation population.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: We estimated the cost-effectiveness of spinal cord stimulation (SCS) among workers' compensation recipients with failed back surgery syndrome (FBSS). SUMMARY OF BACKGROUND DATA: Randomized controlled trial (RCT) evidence suggests that SCS is more effective at 6 months than medical management for patients with FBSS. However, procedure costs are high and workers' compensation claimants often have worse outcomes than other patients. METHODS: We enrolled 158 FBSS patients receiving workers' compensation into three treatment groups: trial SCS with or without permanent device implant (n = 51), pain clinic (PC) evaluation with or without treatment (n = 39), and usual care (UC; n = 68). The primary outcome was a composite measure of pain, disability and opioid medication use. As reported previously, 5% of SCS patients, 3% of PC patients and 10% of UC patients achieved the primary outcome at 24 months. Using cost data from administrative databases, we calculated the cost-effectiveness of SCS, adjusting for baseline covariates. RESULTS: Mean medical cost per SCS patient over 24 months was $52,091. This was $17,291 (95% confidence intervals [CI], $4100-30,490) higher than in the PC group and $28,128 ($17,620-38,630) higher than in the UC group. Adjusting for baseline covariates, the mean total medical and productivity loss costs per patient of the SCS group were $20,074 ($3840-35,990) higher than those of the PC group and $29,358 ($16,070-43,790) higher than those of the UC group. SCS was very unlikely (<5% probability) to be the most cost-effective intervention. CONCLUSION: In this sample of workers' compensation recipients, the high procedure cost of SCS was not counterbalanced by lower costs of subsequent care, and SCS was not cost-effective. The benefits and potential cost savings reported in RCTs may not be replicated in workers' compensation patients treated in community settings.