Effect of low-frequency dorsal root ganglion stimulation in the treatment of chronic pain.

BACKGROUND: The role of stimulation parameters, especially stimulation frequency is not well understood in dorsal root ganglion stimulation. Previous studies documented higher effectiveness for frequencies as low as 20 Hz, but there is evidence that even lower values could lead to better outcomes. In this study, we investigate the influence of low-frequency DRG-S. METHOD: This is a randomized double-blind clinical trial with a crossover design. Patients with an already implanted DRG-S system were included and randomly tested with 4 Hz, 20 Hz, 60 Hz, and sham stimulation. Amplitude was adjusted to subthreshold values for each frequency. Each frequency was tested for 5 days, followed by a 2-day washout period. Patients were assessed using VAS, McGill Pain Questionnaire, EQ-5D-5L, and Beck Depression Inventory. RESULTS: Seventeen patients were in included. Time between inclusion in this study and primary implant was 32.8 months. Baseline stimulation frequency was 20 Hz in all patients. Mean baseline pain intensity was VAS 3.2 (SD 2.2). With 4-Hz stimulation, VAS was 3.8 (SD 1.9), with 20 Hz VAS 4.2 (SD 2.0) and with 60 Hz VAS 4.6 (SD 2.7). Worst pain control was seen with sham stimulation with a VAS of 5.3 (SD 3.0). Stimulation with 4 Hz achieved lower VAS scores, but this was only statistically significant when compared to sham (p = 0.001). A similar trend favoring 4-Hz stimulation was seen using the Beck Depression Inventory, but in this case no statistical significance was found. Outcomes of McGill Pain Questionnaire and EQ-5D-5L favored 20 Hz stimulation, but again without statistical significance. CONCLUSIONS: Low-frequency stimulation was not significantly better than classic 20-Hz stimulation in relieving pain intensity; the study might however be underpowered. Longer washout and observational periods might also be necessary to show clear differences in frequency response.

Spinal cord stimulation in non-reconstructable critical limb ischemia: a retrospective study of 71 cases.

BACKGROUND: Spinal cord stimulation (SCS) is a therapeutic option for patients with a peripheral arterial disease with critical limb ischemia (CLI) and consequent ischemic rest pain. Neuromodulation is chosen when vascular reconstruction is not possible or failed. Data about the effect of SCS over limb salvage rates are dissonant. METHOD: We report on a retrospective cohort of CLI patients who were implanted with SCS systems between July 2010 and December 2013 in a single center. Major amputation, postoperative complications, and death were recorded. RESULTS: Seventy-two CLI patients underwent SCS implantation, with 35 of them classified as non-reconstructable and 37 with previous but failed or only partially successful vascular procedures. A total of 21 subjects were at Fontaine's stage III (29.2%), and the remaining 51 were at stage IV (70.8%). In total, 26.4% of the patients had diabetes (n = 19), two of them at Fontaine's stage III. The mean follow-up was 17.1 ± 10.5 months. At the last follow-up, 59.2% of all patients (42/71), 85.7% of Fontaine's stage III (18/21), 48.0% of Fontaine's stage IV (24/50), and 52.6% of diabetic patients (10/19) were alive without major amputation. The probability of limb survival at 12 months was 72% for all patients, 94% for Fontaine's stage III, 62% for Fontaine's stage IV, and 61% for diabetic patients. The probability of survival at 12 months for patients who underwent major limb amputation (n = 25) was 86% with a mean survival time of 31.03 ± 4.63 months. CONCLUSIONS: Non-reconstructable CLI patients treated with SCS can achieve meaningful clinical outcomes with few procedure-related complications. The therapy may be more beneficial in patients classified as Fontaine's Stage III.

Cerebral perfusion changes in acute subdural hematoma.

INTRODUCTION: Acute subdural hematoma (aSDH) is one of the main causes of high mortality and morbidity in traumatic brain injury. Prognosis is poor due to the rapid volume shift and mass effect. Cerebral perfusion is likely affected in this condition. This study quantifies perfusion changes in aSDH using early ER polytrauma CT with perfusion imaging (CTP). METHODS: Data of 54 patients with traumatic aSDH were retrospectively collected. Glasgow Coma scale (GCS), perfusion parameters, therapeutic decisions and imaging data including hematoma thickness, midline shift, and hematoma localization were analyzed. The cortical perfusion parameters of each hemisphere, the area anterior to the hematoma (AAH), area below the hematoma (ABH), area posterior to the hematoma (PAH), and corresponding mirrored contralateral regions were determined. RESULTS: We found a significant difference in Tmax in affected and unaffected whole-hemisphere data (mean 4.0 s vs. 3.3 s, p < 0.05) and a significantly different mean for Tmax in ABH and for the corresponding mirrored area (mABH) (mean 3.8 s vs. 3.1 s, p < 0.05). No significant perfusion changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were found. CONCLUSION: There was a significant elevation of time to maximum (Tmax) values in the underlying cortical area of aSDH. Possible pathophysiological explanations, the influence on immediate surgical decision-making and further therapeutic consequences have to be evaluated.

Frequency dependency of therapeutic efficacy in dorsal root ganglion stimulation for neuropathic pain.

BACKGROUND: The influence of the stimulation frequency on the outcomes of dorsal root ganglion stimulation (DRG-S) to treat pain is not well understood. It is assumed that specific neural components dedicated to different tasks in the DRG can be preferably influenced at specific frequencies. The identification of frequencies designed for the type of pain and the ratio of neuropathic versus nociceptive pain might improve overall pain control and open new indications in DRG-S. METHOD: We report on a randomized double-blind clinical trial with a crossover design. Patients with a permanent DRG-S system underwent phases of stimulation with 20 Hz, 40 Hz, 60 Hz, 80 Hz, and sham in a randomized order. Each phase lasted for 4 days and was followed by a 2-day washout period. Pain intensity and quality of life were assessed with visual analog scale (VAS), McGill Pain Questionnaire (MPQ), EQ-5D, and Beck Depression Inventory (BDI). Analgesics intake was assessed. RESULTS: Overall 19 patients were included in the study. CRPS was the most frequent pain etiology (7). Five patients had a PainDetect score of 12 or lower at baseline. The mean VAS before the system was implanted was 8.6 and 3.9 at the baseline. Pain intensity was reduced to 3.7 by the stimulation with 20 Hz but increased with higher frequencies reaching 5.8 at 80 Hz. A significant difference among the groups was shown over all variables examined (VAS, MPQ, EQ-5D, BDI). The best results were seen at 20 Hz for all variables, including the smallest increase in pain medication consumption. CONCLUSIONS: The choice of the stimulation frequency shows a clear influence on pain reduction and quality of life. Lower stimulation frequencies seem to be most effective in neuropathic pain. Further studies are required to determine whether specific frequencies should be preferred based on the condition treated.

Combination of waveforms in modern spinal cord stimulation.

BACKGROUND: After the surge of burst stimulation, different waveforms were developed to optimize results in spinal cord stimulation. Studies have shown higher responder rates for multiwave therapy, but since the launch of such multiwave systems, little is known about the patients' preference regarding waveforms in the long-term follow-up. No study connected particular waveforms to specific pain etiologies or required stimulation parameters so far. METHOD: Thirty-four patients with refractory chronic neuropathic pain were treated with spinal cord stimulation systems providing multiwave therapy between September 2018 and October 2019. Patients with a follow-up of at least 6 months were selected; 10 subjects were excluded due to revision surgery, infection, and loss to follow-up. Data regarding pain intensity and preferred waveform for the trial, the implantation, 3-month and 6-month follow-up were recorded. RESULTS: During the trial phase, 10 patients (43.5%) achieved significant pain relief using tonic stimulation, 5 using burst (21.7%), 3 using microburst (13.0%), and 4 using a combination of tonic and microburst (17.4%). One single patient preferred Contour stimulation during the trial. After 3 months, 6 patients preferred microburst (25%), 6 preferred tonic (25%), 5 used a combination of tonic and microburst (20.8%), and 5 patients used burst (20.8%). After 6 months, similar results were obtained. Contour and Whisper were used in complex cases failing to other waveforms. CONCLUSIONS: Tonic stimulation, isolated or in combination, remains an important component in spinal cord stimulation, being used by almost half of the patients. Over time, the usage of microburst increased considerably. Whisper and Contour, although battery-consuming, are good salvage options in complex cases.

The role of periradicular infiltration in dorsal root ganglion stimulation for chronic neuropathic pain.

BACKGROUND: Targeting the correct spinal level is essential in dorsal root ganglion (DRG) stimulation. Anatomical selection of the DRG alone is not ideal since the pain area is not necessarily confined to the borders of the dermatomes. This study aims to establish the role of periradicular infiltration therapy (PRT) in the preoperative assessment of the correct level for DRG stimulation performed under general anesthesia. METHOD: We report a prospective study of 20 patients selected for DRG stimulation and submitted to a PRT for identification of the spinal level. Lead implantation for the stimulation trial occurred under general anesthesia: 19 patients experienced positive results and underwent implantation of the pulse generator. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. PRT levels were compared with the levels targeted with DRG leads. Patients were followed for up to 12 months; pain intensity and coverage of the painful area were assessed. RESULTS: In 12 patients, the trial leads were placed on the same level as previously tested positive by PRT. In 6 patients, leads were placed in the PRT target and additionally in adjacent spinal levels. In one case, the selected target for the trial diverged from the PRT target because of intense fibrosis in the chosen level. Coverage of the target area of at least 50% was achieved by two-thirds of the patients. For the six subjects with additional implanted leads as a consequence of the PRT results, 80% achieved a coverage of at least 50%. A total of 47.4% of the patients achieved sustained significant pain relief in the last follow-up. None of the patients needed a repeated surgery for implantation of additional leads. CONCLUSIONS: PRT is a helpful tool to confirm the stimulation targets. A PRT preceding the stimulation trial is an additional opportunity to optimize the coverage of the target area with stimulation-induced paresthesia for patients operated under general anesthesia.

Synergetic efficacy of simultaneous DRG- and traditional spinal cord stimulation.

BACKGROUND: Dorsal root ganglion stimulation has established its role in chronic pain states and is commonly used as an alternative treatment to traditional spinal cord stimulation. Due to its approach, DRG stimulation is preferably used in pain conditions affecting a small area or a distinct nerve root. In selected patients, a combination of both techniques might be useful. METHODS: We report a series of five patients with chronic pain treated with DRG stimulation and traditional spinal cord stimulation from 2011 to 2018. Pain was reported on the VAS scale at the baseline, before and 12 months after the second procedure. RESULTS: All patients suffered from back and lower limb pain, four with a FBSS syndrome, one with CRPS. In all but one patient, SCS was implanted first and complemented with a DRG in the course (4-90 months between procedures). An additional stimulation system was implanted because the previous stimulation failed to reach the pain area or because the patient had an altered perception of other pain component after stimulation. All but one patient had a consistent and satisfying therapeutic effect with both systems activated. CONCLUSION: The combination of dorsal root ganglion and traditional spinal cord stimulation is surgically and technically feasible. In selected patients, the combination of both methods offers an option to alleviate pain states not sufficiently or not efficiently treated with one method alone. The introduction of IPGs combining SCS and DRG stimulation paradigms might be useful to increase acceptance of this option.

Using assistive robots to promote inclusive education.

PURPOSE: This paper describes the development and test of physical and virtual integrated augmentative manipulation and communication assistive technologies (IAMCATs) that enable children with motor and speech impairments to manipulate educational items by controlling a robot with a gripper, while communicating through a speech generating device. METHOD: Nine children with disabilities, nine regular and nine special education teachers participated in the study. Teachers adapted academic activities so they could also be performed by the children with disabilities using the IAMCAT. An inductive content analysis of the teachers' interviews before and after the intervention was performed. RESULTS: Teachers considered the IAMCAT to be a useful resource that can be integrated into the regular class dynamics respecting their curricular planning. It had a positive impact on children with disabilities and on the educational community. However, teachers pointed out the difficulties in managing the class, even with another adult present, due to the extra time required by children with disabilities to complete the activities. CONCLUSIONS: The developed assistive technologies enable children with disabilities to participate in academic activities but full inclusion would require another adult in class and strategies to deal with the additional time required by children to complete the activities. Implications for Rehabilitation Integrated augmentative manipulation and communication assistive technologies are useful resources to promote the participation of children with motor and speech impairments in classroom activities. Virtual tools, running on a computer screen, may be easier to use but further research is needed in order to evaluate its effectiveness when compared to physical tools. Full participation of children with motor and speech impairments in academic activities using these technologies requires another adult in class and adequate strategies to manage the extra time the child with disabilities may require to complete the activities.

Coeficientes alométricos das partes e dos órgãos de codornas de corte mantidas em diferentes ambientes térmicos / Allometric coefficients of the cuts and organs of meat quail kept in different thermal environments

Objetivou-se comparar os coeficientes alométricos (b) que descrevem o crescimento das partes e dos órgãos de codornas de corte mantidas em diferentes ambientes térmicos. Foram utilizadas 300 codornas distribuídas em delineamento inteiramente ao acaso, com dois tratamentos (ambiente climatizado, AC) com temperatura de 26ºC e ambiente sem climatização (ASC, 32oC) e seis repetições de 25 aves. Ajustaram-se equações alométricas em função do peso em jejum (PJ) para as variáveis: peso do peito (PPEI), coxa (PCX), sobrecoxa (PSCX), asa (PASA), coração (PCOR), fígado (PFÍG), moela (PMOE) e intestino (PINT). Para comparar os "b" das partes e dos órgãos das aves mantidas nos diferentes ambientes, realizaram-se testes de paralelismo. Não houve diferença entre os "b" em nenhuma das partes e dos órgãos das codornas mantidos no ambiente AC ou no ASC. Observou-se que os PPEI e os PSCX apresentaram crescimento heterogônico positivo (b>1), os PCX crescimento isogônico (b=1), os PASA e os órgãos crescimento heterogônico negativo (b<1) em relação ao PJ. Os "b" que descrevem o crescimento das partes e dos órgãos de codornas de corte mantidas nos diferentes ambientes não são influenciados. O peso do peito e o da sobrecoxa apresentaram crescimento tardio, a asa e os órgãos (coração, fígado, moela e intestino) crescimento precoce, e o peso da coxa apresentou crescimento proporcional em relação ao peso em jejum.(AU)

This study was carried out to compare the allometric coefficients (b) that describe the cuts and organs' growth of quails kept in different thermal environments. Three hundred meat quails were distributed in a completely randomized design with two treatments (climatized environment (CE) with 26°C of ambient temperature and environment without climatization (EWC, 32°C)) and six replicates of 25 birds. Allometric equations based on weekly fasting weight (WF) for the breast weight (BW), thigh (TW), drumstick (DW), wing (WW), heart (HW), liver (LW) gizzard (GW) and intestine (IW) were performed. To compare the "b" of the cuts and organs parallelism tests were carried out. There was no difference between the "b" in any cuts and organs of quails kept in CE or EWC environments. We observed that the BW and DW showed positive heterogonic growth (b>1), TW isogonic growth (b=1), and WW and organs negative heterogonic growth (b<1) in relation PJ. The "b" that describes the growth of cuts and organs of quails kept in CE or EWC environments are not affected. The breast and drumstick presented late growth, the wing and the organs early growth, and the thigh showed a proportional increase with the fasting weight.(AU)