Repetitive transcranial magnetic stimulation (rTMS) versus transcranial direct current stimulation (tDCS) in the management of patients with fibromyalgia: A randomized controlled trial

ObjectivesThe aim of this study was to compare the effects of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on pain and quality of life in patients with fibromyalgia.MethodsThirty participants were randomized into two groups of 15 patients, to receive 3 sessions of either high-frequency (10 Hz) rTMS or 2 mA, 20 min anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex (DLPFC) over 1 week. Pain was assessed using a Visual Analog Scale (VAS) before treatment, immediately after treatment, 6 and 12 weeks later. Quality of life was evaluated using the Revised Fibromyalgia Impact Questionnaire (FIQR) and psychiatric symptoms were measured using the Depression Anxiety Stress Scale-21 Item (DASS-21) before treatment, and 6 and 12 weeks after treatment.ResultsFor the VAS there was a significant time-group interaction, showing that the behavior of two groups differed regarding changes of VAS in favor of the RTMS group (df = 1.73, F = 4.80, p = <0.016). Time-group interaction effect on DASS-21 and FIQR was not significant. 66.6% of patients in rTMS group and 26.6% of patients in tDCS group experienced at least a 30% reduction of VAS from baseline to last follow-up (p = 0.028).DiscussionWith the methodology used in this study, both rTMS and tDCS were safe modalities and three sessions of rTMS over DLPFC had greater and longer lasting analgesic effects compared to tDCS in patients with FM. However, considering the limitations of this study, further studies are needed to explore the most effective modality.     

1.2 kHz High-Frequency Stimulation as a Rescue Therapy in Patients With Chronic Pain Refractory to Conventional Spinal Cord Stimulation

ObjectivesWe aimed to investigate the efficacy of new subperception stimulation paradigms including 1.2 kHz-high-frequency stimulation (HFS) and advanced-HFS field-shaping algorithm (dorsal horn HFS [DHHFS]) in refractory cases which initially benefited from conventional spinal cord stimulation (SCS) and lost the effect throughout time.Materials and MethodsIn the context of a rescue-therapy, patients underwent externalization of the implanted SCS-leads and were tested with multiple combinations of new SCS paradigms. Pain intensity was analyzed using the numeric rating scale (NRS), and data were collected preoperatively and at multiple postoperative follow-ups.ResultsThirty-seven patients underwent externalization of the leads. Mean preoperative NRS-score was 8.1/10 points (SD ± 0.9) for the ON-stimulation period. Patients received a combination of either tonic, burst and 1.2 kHz-HFS, or burst and 1.2 kHz-HFS, DHHFS, or 1.2 kHz-HFS and DHHFS, or 1.2 kHz-HFS alone. The mean postoperative NRS-score after the testing-phase was 3.8/10 points (SD ± 2.5), showing a 48.0% mean reduction (p < 0.001). In total, 29 patients reported a significant reduction above 50% in NRS-scores and therefore were reimplanted with new generators that could deliver the new paradigms. Eight patients underwent full SCS-system explantation. The patients who continued with the new paradigms (n = 29) reported mean NRS-scores of 3.5/10 points (SD ± 1.7) 12 months postoperatively, still showing a significant reduction of 43.3% when compared to preoperative scores (p < 0.001).ConclusionRescue-therapy with combination of multiple waveforms, including tonic, burst, 1.2 kHz-HFS, and DHHFS, was associated with a significant pain relief in patients with failed conventional SCS. This approach is a safe and efficient and should be considered before explantation of the SCS-system.     

The Predictive Value of Transcutaneous Electrical Nerve Stimulation for Patient Selection in Peripheral Nerve Field Stimulation for Chronic Low Back Pain: A Prospective Study

ObjectivePeripheral nerve field stimulation (PNFS) is an effective alternative treatment for patients with chronic low back pain. Transcutaneous electrical nerve stimulation (TENS) is frequently used in pain therapy. Aim of this prospective study was to examine the predictive value of TENS for later PNFS treatment.Materials and MethodsBetween 2014 and 2019, a prospective cohort study of 41 patients with chronic lumbar pain was conducted. Pain intensity (NRS) was assessed before and after TENS use, preoperatively/postoperatively and in the follow-up after three and six months, SF12v2 questionnaires with physical (PCS) and mental component summary (MCS) scores, and Oswestry disability index (ODI) questionnaire at baseline as well as three and six months after PNFS implantation. Implantation of the PNFS-system with two percutaneous leads was performed after four to seven days of positive testing. Statistical analysis was performed using depending t-test, ANOVA, and Spearman correlation.ResultsThe cohort consisted of 41 patients (19 females, 22 males) with a median age of 60.5 years (IQR^25-75 52–67). Two patients were lost to follow-up. After positive PNFS testing a pulse generator (IPG) was implanted in 15 patients with positive TENS effect and 15 patients without TENS effect. Leads were explanted in nine patients after negative PNFS trial phase. TENS positive patients showed significant correlation to a positive effect in the PNFS trial phase in NRS reduction (p = 0.042) indicating that TENS responders will also respond to PNFS (94% patients). After three and six months follow-up median NRS and SF12v2 (PCS) improved significantly in both cohorts, SF12v2 (MCS) and ODI only in the TENS positive cohort, respectively.ConclusionTENS can be predictive for patient selection in PNFS, as TENS positive patients showed significant correlation with a positive PNFS trial period. Therefore, TENS positive patients might be justifiable to be directly implanted with leads and IPG. TENS positive patients further tend to show a better improvement in the follow-up.     

Implantable Peripheral Nerve Stimulation for Trigeminal Neuropathic Pain: A Systematic Review and Meta-Analysis

ObjectivesImplantable peripheral nerve stimulation has been increasingly used to treat neuropathic pain. This neuromodulation strategy may be an alternative option for intractable trigeminal neuropathic pain; however, evidence for this treatment approach remains limited. A systematic review was conducted to identify studies of patients that underwent peripheral nerve stimulation implantation for trigeminal neuropathic pain.Materials and MethodsDatabases including, PubMed, EMBASE, and Cochrane Library were searched up to October 5, 2020. The primary outcomes were changes in pain scores and response rates of neuromodulation therapy. A random effects model was used for meta-analysis. Subgroup analysis was performed to examine the source of heterogeneity.ResultsThirteen studies including 221 participants were evaluated. The estimated response rate of neuromodulation treatment was 61.3% (95% CI: 44.4–75.9%, I² = 70.733%, p < 0.0001) at the last follow-up. The overall reduction in pain scores was 2.363 (95% CI: 1.408–3.319, I² = 85.723%, p < 0.0001). Subgroup analysis further confirmed that stimulation target (peripheral branch vs. trigeminal ganglion vs. trigeminal nerve root) contributed the heterogeneity across enrolled studies. Better clinical outcome was associated with stimulation of the trigeminal peripheral branch (p < 0.0001).ConclusionPeripheral nerve stimulation may be a promising approach in the management of trigeminal neuropathic pain, especially for patients intractable to conventional therapy.     

Effect of Patient Characteristics on Clinical Outcomes More Than 12 Months Following Dorsal Root Ganglion Stimulation Implantation: A Retrospective Review

IntroductionDorsal root ganglion (DRG) stimulation is an effective treatment option for lower extremity complex regional pain syndrome and other focal pain conditions. However, the patient characteristics that may predict long-term outcomes have not been defined.Materials and MethodsThis was a retrospective observational study that included 93 patients who were implanted with a DRG stimulator at a single private practice institution. A variety of demographic data was collected. Follow-up results were reviewed from multiple time points more than 12 months. Patients were classified as either “responder” or “nonresponder” status using two different thresholds, “greater than or equal to 50% pain relief” and “greater than or equal to 80% pain relief.”Results: A history of prior chronic opioid use was associated with significantly lower rates of responder status based on both a 50% pain relief threshold and 80% pain relief threshold at the one week to one month, three months, and 12-months visits.ConclusionsThis single-center retrospective study found patients prescribed chronic opioids at the time of DRG stimulator implantation had a higher likelihood of less than 50% pain relief and 80% pain relief at one month, three months, and 12 months follow-up visits.     

Spinal Cord Stimulation Attenuates Below‐Level Mechanical Hypersensitivity in Rats After Thoracic Spinal Cord Injury

ObjectivesThe burden of pain after spinal cord injury (SCI), which may occur above, at, or below injury level, is high worldwide. Spinal cord stimulation (SCS) is an important neuromodulation pain therapy, but its efficacy in SCI pain remains unclear. In SCI rats, we tested whether conventional SCS (50 Hz, 80% motor threshold [MoT]) and 1200 Hz, low-intensity SCS (40% MoT) inhibit hind paw mechanical hypersensitivity, and whether conventional SCS attenuates evoked responses of wide-dynamic range (WDR) neurons in lumbar spinal cord.Materials and MethodsMale rats underwent a moderate contusive injury at the T9 vertebral level. Six to eight weeks later, SCS or sham stimulation (120 min, n = 10) was delivered through epidural miniature electrodes placed at upper-lumbar spinal cord, with using a crossover design. Mechanical hypersensitivity was examined in awake rats by measuring paw withdrawal threshold (PWT) to stimulation with von Frey filaments. WDR neurons were recorded with in vivo electrophysiologic methods in a separate study of anesthetized rats.ResultsBoth conventional SCS and 1200 Hz SCS increased PWTs from prestimulation level in SCI rats, but the effects were modest and short-lived. Sham SCS was not effective. Conventional SCS (10 min) at an intensity that evokes the peak Aα/β waveform of sciatic compound action potential did not inhibit WDR neuronal responses (n = 19) to graded or repeated electrical stimulation that induces windup.ConclusionsConventional SCS and 1200 Hz, low-intensity SCS modestly attenuated below-level mechanical hypersensitivity after SCI. Inhibition of WDR neurons was not associated with pain inhibition from conventional SCS.     

Transgrade Dorsal Root Ganglion Stimulation as a Salvage Technique for Three Different Anatomical Barriers: A Case Series

BackgroundDorsal root ganglion stimulation (DRGS) is an effective treatment for complex regional pain syndrome (CRPS) and post-surgical neuropathic pain. However, some patients have surgical and anatomical conditions that are contraindications to traditional DRGS technique. A novel transgrade approach to DRGS placement has been described and demonstrated effective for post spine surgery patients. We present three patients, each with a different reason in which DRGS would not be accessible via the traditional anterograde approach, who all had successful DRGS transgrade placement.Materials and MethodsThe case series includes three patients with either CRPS or post-surgical neuropathic pain who had an anatomical or post-surgical condition that historically would have rendered DRGS contraindicated. Two patients had previously failed dorsal column stimulation. All three patients had successful placement with the transgrade approach—entry into the contralateral epidural space at the level of the targeted foramen from a cephalad angle. Each patient gave their verbal and written consent to be included in the case series.ResultsFollowing treatment with a transgrade approach, all three patients had significant pain relief and improvement in function without complication.ConclusionBarriers to anterograde foraminal access including previous implantation, previous instrumentation, and epidural adhesions may prevent DRGS placement in certain indicated patients. This can be especially challenging in patients who have failed other neuromodulation options like dorsal column stimulation. Our case series demonstrated that the transgrade technique can be successfully used in these cases to increase access to DRGS.