Application of support vector machine in identifying neuromodulation states in patients with zoster-associated pain

Four-limb Neurostimulation with Neuroelectrodes Placed in the Lower Cervical Epidural Space

Postherpetic neuralgia (PHN) is a severe and distressing complication in elderly patients with herpes zoster and is associated with increased sympathetic nervous system activity. Spinal cord stimulation (SCS) implantation has been shown to effectively relieve PHN. In recent years, heart rate variability (HRV) analysis, as a reliable and objective indicator of autonomic nervous system (ANS) activity, has been widely used in the assessment of chronic pain. This study aims to investigate the clinical effects of SCS implantation on HRV in patients with PHN and its correlation with pain outcomes. A total of 28 patients who met the inclusion criteria and were treated in the Department of Pain Medicine, the Third Xiangya Hospital of Central South University between November 2023 and March 2024 were retrospectively included. All patients underwent SCS implantation. HRV parameters before and after SCS implantation were collected, including the standard deviation of all normal-to-normal intervals over 24 hours (SDNN), root mean square of successive differences (RMSSD), standard deviation of successive differences (SDSD), percentage of adjacent normal-to-normal intervals differing by more than 50 milliseconds (PNN50), low-frequency power (LF), high-frequency power (HF), the LF/HF ratio, and total power (TP) within 5 minutes across all frequency bands. Univariate linear regression analysis was performed to explore the correlations among HRV parameters before and after SCS treatment. After SCS implantation, the HRV time-domain indices SDNN, RMSSD, SDSD, and PNN50, as well as the frequency-domain indices LF, HF, and TP, were significantly increased (all P<0.05), while the change in LF/HF ratio was not statistically significant (P>0.05). SCS treatment also had positive effects on pain relief, improvement of negative emotions, and reduction of psychological stress (all P<0.05). Differences were observed among implantation segments. In patients receiving SCS implantation below the T8 thoracic segment, SDNN, LF, and HF decreased significantly (all P<0.05). Correlation analysis revealed that pain scores were significantly correlated with SDNN. Significant correlations were also observed among the HRV time-domain indices SDSD, RMSSD, and PNN50 (all P<0.05), whereas correlations among frequency-domain indices were relatively weak. The changes in time-domain and frequency-domain HRV indices showed a synergistic trend. Pain outcomes in patients with PHN are accompanied by synchronous changes in autonomic nervous system activity. SCS implantation can improve HRV stability in patients with PHN and contribute to better cardiac rhythm regulation. HRV measurement may serve as evidence reflecting ANS activity in patients with PHN.

Spinal cord stimulation (SCS) has shown effectiveness in relieving zoster-associated pain (ZAP), but some patients still experience moderate or severe pain after SCS treatment. This study aims to evaluate the impact of SCS combined with dorsal root ganglion (DRG) pulsed radiofrequency (PRF) as a dual neuromodulation strategy on the prognosis of ZAP. The clinical records of patients diagnosed with ZAP who underwent SCS (SCS group) or SCS combined with PRF (SCS + PRF group) at The Third Xiangya Hospital, Central South University, were retrospectively analyzed to compare the effectiveness of the two treatment approaches for ZAP. Outcome measures included changes in Visual Analog Scale (VAS) scores before and after neuromodulation treatment, response rates, and incidence of progression to postherpetic neuralgia (PHN).13 SCS patients and 15 SCS + PRF patients were analyzed. Admission VAS scores were similar (P = 0.934). Upon discharge, no significant differences in VAS or response rates were observed (P > 0.05). However, at 6-month follow-up, the SCS + PRF group had lower VAS scores (1.53 ± 1.06 vs. 3.23 ± 1.50, P < 0.001) and a lower proportion of residual moderate pain (P = 0.041). None in the SCS + PRF group progressed to PHN in the acute/subacute phases, differing significantly from the SCS group (P = 0.038).Therefore, SCS combined with DRG PRF is feasible and effective in the treatment of ZAP. This dual neuromodulation strategy may be a more appropriate regimen for the treatment of ZAP.

Spinal Cord Stimulation Improves the Microvascular Perfusion Insufficiency Caused by Critical Limb Ischemia

Cortical Mapping in Conventional and High Dose Spinal Cord Stimulation: An Exploratory Power Spectrum and Functional Connectivity Analysis With Electroencephalography

We read with great interest the article entitled “Effect of spinal cord stimulation on quality of life and opioid consumption in patients with failed back surgery syndrome” by Elkholy et al.1 Through a prospective observational study, the authors analyzed the outcome of patients with diagnosis of “Failed Back Surgery Syndrome” (FBSS) who underwent neuromodulation procedures using reliable outcome measurement scores in a 1-year follow-up period. Significant results in patients' pain reduction and improvement in quality of life (QoL) were reported, and Spinal Cord Stimulation (SCS) was considered an effective modality treatment for cases of FBSS. The persistence or recurrence of low back and/or leg pain after successful decompression and spinal procedures, also known as FBSS, may impact on patients' QoL and psychological behavior even more than before the first treatment.2 The incidence of FBSS among population is variable and other non-structural factors may play a role in its development. Despite growing interest in scientific literature, no clear consensus has been reached concerning its management.3 According to the authors' findings, we report our retrospective analysis of forty-four patients with diagnosis of FBSS treated at our Institution. We used: the Visual Analogue Scale (VAS) to assess patients' painful symptoms, that is similar to the Numerical Rating Scale (NRS) used by the authors1; the Oswestry Disability Index (ODI) score to correlate the motor activity of these patients with their disability grade; the EQ-5D-3L questionnaire to explore potential changes in QoL. Despite the use of different scales and questionnaires, our findings are consistent with those presented by Elkholy et al.1 A significant improvement was observed in all the tested domains (ODI, DN4, VAS and HQ-5D-3L) by comparing their values before and after successful SCS placement, respectively. There was a dramatic reduction in pain self-perception assessed with the VAS score (8 vs. 3.3) (p < 0.001) and in neuropathic pain assessed with the DN4 score (4.9 vs. 2.2) (p < 0.001). There was a two-fold reduction in back pain investigated through the ODI index after permanent SCS implantation (49.0 vs. 25.0). Finally, SCS implantation provided a considerable improvement in patients' QoL evaluated through the EQ-5D-3 L questionnaire (0.36 vs. 0.79) (p < 0.001). Figure 1 shows an iconographic case example. Moreover, we investigated the variation in opioid consumption at 1-year follow-up, and 65,7% of patients completely stopped the opioid-intake, in contrast to what reported by the authors.1 Inclusion and exclusion criteria are crucial for the most appropriate selection of patients for SCS treatment; patients with history of previous opioid use for alternative pain management were excluded from our analysis. Investigating less evident but specific elements of the history of patients with FBSS could enhance a 360-degree evaluation of the pain condition, and improve our understanding of both clinical and QoL improvement after SCS implantation.4, 5 In this tangled setting, we aim to draw the readers' focus towards critical matters that warrant additional exploration and future research to facilitate a comprehensive, evidence-based assessment over the long-term outcomes after SCS implantation. The authors declare no conflict of interest. Research data are not shared.

The purpose of this case report is to describe an occurrence of a rare complication of lead extrusion, which was observed 10months after spinal cord stimulator (SCS) implantation. A patient with low back pain and failed back surgery syndrome underwent implantation of a SCS without complications. Ten months after implantation, one SCS lead extruded from her lower back leading to surgical removal of the leads. After identifying the complication of a SCS lead extruding from the patient's back, a surgical revision was performed to remove the SCS leads but retain the implantable pulse generator (IPG) in the gluteal region. During the surgery, it was noted that the anchors were in the appropriate position, sutured and fibrosed to a deep fascial layer. There were no complications from the surgical revision and no infectious process was observed. We report the occurrence and management of a rare complication of SCS lead extrusion after SCS implantation for failed back surgery syndrome. After recognition, removal of the leads with retention of the IPG was able to effectively resolve the complication. The revising procedure was well tolerated but resulted in the recurrence of the patient's previous low back pain. We believe that knowledge of this case and its management will aid future physicians in the recognition and management of this rare complication of SCS implantation. Furthermore, as there is a paucity of literature discussing the management of lead extrusion after SCS implantation, we hope that this case report will spur additional research on the management of this complication.

SP61 Cost effectiveness of spinal cord stimulation in chronic low back pain

001 Cost effectiveness of spinal cord stimulation in chronic low back pain

Spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are used to treat refractory pain, but even well-selected patients can fail to have analgesic benefit following implantation. The analgesia afforded by SCS/PNS may be enhanced or attenuated by the ongoing use of analgesic medications that are often consumed by patients who receive SCS and PNS implants. We undertook a scoping review to scan and summarize the evidence for impact of adjuvant pharmacotherapy on SCS and PNS therapy in animal and human settings. A comprehensive medical literature review was performed on major medical databases including MEDLINE, EMBASE, CINAHL, CENTRAL, and Google Scholar from inception until July 31, 2024, for both human and animal studies. Data on the effect of pharmacotherapy on SCS analgesic efficacy and adverse effects were extracted and summarized using the Arksey and O'Malley population, concept, context model for scoping reviews. Twenty-seven studies, 9 on animals and 18 on humans were identified. In human studies, SCS non-responders with neuropathic pain had analgesia restored by addition of intrathecal baclofen and clonidine. Patients who eliminated opioid use, or who were opioid naive, had superior clinical outcomes with SCS compared to those continuing opioids. Cannabinoids were associated with enhanced SCS analgesia. Patients on benzodiazepines had higher likelihood of SCS explantation. Animal studies showed intrathecal ketamine restored SCS analgesic benefits, while baclofen, clonidine, cannabinoid receptor agonists, tricyclic antidepressants, serotonin, and norepinephrine reuptake inhibitors, augmented SCS responses while benzodiazepines were found to inhibit analgesic effects of PNS. This review indicates that adjunctive analgesic therapy may play a significant role in either enhancing or attenuating analgesic benefits from SCS and PNS. By optimizing the use of analgesic medications, it may be possible to restore or enhance pain relief from both SCS and PNS.

ObjectivesThe understanding of the cortical effects of spinal cord stimulation (SCS) remains limited. Multiple studies have investigated the effects of SCS in resting-state electroencephalography. However, owing to the large variation in reported outcomes, we aimed to describe the differential cortical responses between two types of SCS and between responders and nonresponders using magnetoencephalography (MEG). Materials and MethodsWe conducted 5-minute resting-state MEG recordings in 25 patients with chronic pain with active SCS in three sessions, each after a one-week exposure to tonic, burst, or sham SCS. We extracted six spectral features from the measured neurophysiological signals: the alpha peak frequency; alpha power ratio (power 7–9 Hz/power 9–11 Hz); and average power in the theta (4–7.5 Hz), alpha (8–12.5 Hz), beta (13–30 Hz), and low-gamma (30.5–60 Hz) frequency bands. We compared these features (using nonparametric permutation t-tests) for MEG sensor and cortical map effects across stimulation paradigms, between participants who reported low (< 5, responders) vs high (≥ 5, nonresponders) pain scores, and in three representative participants. ResultsWe found statistically significant (p < 0.05, false discovery rate corrected) increased MEG sensor signal power below 3 Hz in response to burst SCS compared with tonic and sham SCS. We did not find statistically significant differences (all p > 0.05) between the power spectra of responders and nonresponders. Our data did not show statistically significant differences in the spectral features of interest among the three stimulation paradigms or between responders and nonresponders. These results were confirmed by the MEG cortical maps. However, we did identify certain trends in the MEG source maps for all comparisons and several features, with substantial variation across participants. ConclusionsThe considerable variation in cortical responses to the various SCS treatment options necessitates studies with sample sizes larger than commonly reported in the field and more personalized treatment plans. Studies with a finer stratification between responders and nonresponders are required to advance the knowledge on SCS treatment effects.

The results of spinal cord stimulation were prospectively evaluated using both subjective patient self-report measures and objective physical functional testing. The purpose of this study was to evaluate prospectively the effects of spinal cord stimulation implantation, performed with the patient awake and providing feedback, in patients with primary reports of intractable leg pain. Spinal cord stimulation has been used for treating chronic pain of many types. However, even among those with intractable lower extremity pain, the outcome results have shown great variability. The surgical procedure was performed with the patient awake and providing feedback to ensure optimal pain relief from the lead placement. The study group comprised 40 patients, ranging in age from 28 to 86 years. The average symptom duration was 65.4 months, and the average number of prior lumbar spine surgeries was 2.3 (range, 1 to 8). The primary data collection periods were preoperative, 6 weeks after, and 12 and 24 months after surgery. Statistically significant improvement in isometric lower extremity function was demonstrated 6 weeks after the spinal cord stimulation implantation. In the more painful leg, the performance increased from 457.5 ft-lb-sec to 629.8 ft-lb-sec (P < 0.01). The performance remained significantly improved at the 12- and 24-month follow-ups. Significant improvement was demonstrated on the physical scale of the Sickness Impact Profile at 6 weeks. At 24 months, all three scales (physical, psychological, and other) as well as the total score were significantly improved. Statistically significant decreases in pain, assessed by changes in visual analog scale scores, were noted in the legs, when walking, and in overall lifestyle. The use of narcotic medication decreased at all follow-up periods. At least 66% of the patients who were taking narcotics before spinal cord stimulation were taking reduced amounts or no narcotics 2 years later. At the time of the 24-month follow-up, at least 70% of patients reported that the procedure helped them, and would recommend it to someone with similar symptoms. Spinal cord stimulation implantation can result in improved physical function and decreased pain in patients who are carefully screened and in whom the implantation is performed with the patient awake to help ensure optimal pain-relieving lead placement.

Drivers and Risk Factors of Unplanned 30-Day Readmission Following Spinal Cord Stimulator Implantation

AimThe aim of the study was to compare the efficacy of single or double lead in percutaneous spinal cord stimulation (SCS).MethodFollow-up data of 41 patients (20 patients with double lead, 21 patients with single lead) who underwent percutaneous SCS were analysed. Demographic and clinical examination findings (gender, age, pain characteristic, neurological examination, medications used) and visual analogue scale (VAS) scores were recorded. VAS pain scores, clinical and neurological examination and complication findings were recorded at 1st and 12th months at post-procedure follow-up.ResultsTwenty patients had double lead and 21 patients had single lead. Five patients had root avulsion, 1 patient had complex regional pain syndrome, 1 patient had postherpetic neuralgia, 2 patients had phantom pain, 3 patients had ischaemic pain and 29 patients had postlaminectomy syndrome. In 10 patients, leads were placed in the cervical region and in 31 patients in the thoracic region. There was at least 50% reduction in VAS scores in 71.4% (15 patients) with single lead implantation and 65% (13 patients) with double lead implantation (p = 0.7). Infection was significantly higher in patients with double lead than in patients with single lead implantation (p < 0.05). In 1 patient, generator exchange was performed because the generator was exposed due to skin necrosis. No major complication was recorded.ConclusionSCS with single and double lead is an effective method in chronic pain syndromes. SCS with single lead can be preferred in terms of time, cost and labour saving.

Complex regional pain syndrome (CRPS) is a debilitating pain condition often resistant to standard treatment modalities. In these cases, spinal cord stimulation (SCS) can be an option, but the effect on CRPS remains disputed. We aimed to assess the long-term effect of SCS on CRPS. We retrospectively analysed 51 CRPS patients implanted with an SCS system at the University Hospitals in Aarhus or Odense, Denmark, with a median follow-up time of 4.4years. Primary outcomes were pain intensity on a numeric rating scale (NRS) and the Patients' Global Impression of Change (PGIC). Secondary outcomes were patient satisfaction, work status, consumption of pain medication, the Major Depression Inventory (MDI), Pain Catastrophizing Scale (PCS) and quality of life (QoL) measured using the Short-Form Health Survey (SF-36). For each outcome measure, baseline data were compared to the latest collected data point. A significant pain relief was found with a mean reduction in NRS score of 2.4 (95% CI: 1.7-3.0, p<0.0001). 68.8% reported 'much improved' or 'very much improved' on the PGIC scale. 87.5% would choose SCS again for the same outcome. A significant beneficial impact was found on MDI score, PCS, SF-36 summary scores and consumption of tricyclic antidepressants, antiepileptic drugs and opioids. No statistical effect was found on work status. Pain intensity, depression, pain catastrophizing, pain medication use and QoL were significantly improved after SCS implantation, with high patient satisfaction rates in CRPS patients. This study supports the continued use of SCS in the treatment of severe CRPS. This study presents detailed data from a large, well-characterized cohort of Danish CRPS patients treated with SCS, analyzing several outcome measures. The results serve to document SCS as an effective treatment for severe CRPS and expands the cumulative level of evidence in favor of its use. Additionally, analysis of preoperative patient characteristics suggests that SCS treatment should not be withheld in patients with a high degree of psychological distress or high consumption of analgesics.