The Effectiveness of Various Types of Electrical Stimulation of the Spinal Cord for Chronic Pain in Patients with Postherpetic Neuralgia: A Literature Review

Clinical study of short-term spinal cord stimulation for herpes zoster-associated pain

BACKGROUND

Zoster-associated neuralgia refers to neuropathic pain from herpes zoster, which can persist as postherpetic neuralgia (PHN). Preventing the progression to chronic PHN is crucial, yet optimal interventions is still not clear.

OBJECTIVES

This study evaluates the efficacy of short-term spinal cord stimulation (tSCS) in patients with subacute and chronic PHN.

METHODS

A clinical study involved 135 patients with herpes zoster-associated pain (HZAP), divided into two groups: Experimental group which received short-term spinal cord stimulation therapy, and Control group which received conventional medical treatment and nerve block therapy. Pain intensity, sleep quality, anxiety and depression and quality of life were assessed at baseline and at 2 weeks, 1-, 3-, 6-, and 12-month post-treatment. Univariate and multivariate analyses identified factors associated with treatment efficacy.

RESULTS

At 1-month follow-up, the experimental group showed significantly higher efficacy in pain reduction (P < 0.01). Higher Pittsburgh Sleep Quality Index (β = 0.093, P = 0.004) and PHQ-9 scores (β = 0.065, P = 0.031) before treatment were associated with better outcomes. At 3 months, longer disease duration (β = 0.103, P = 0.008) and higher Pittsburgh Sleep Quality Index scores (β = 0.114, P = 0.002) correlated with better efficacy, while higher Patient Health Questionnaire-9 scores were negatively correlated (β = - 0.023, P = 0.036). Although as follow-up time increases, the significant superiority of efficacy gradually shrinks compared with nerve block therapy at 6-12 months, the tSCS group still had better effects in improving sleep quality, anxiety and depression symptoms, and quality of life.

CONCLUSIONS

Short-term spinal cord stimulation is a safe and effective short-term treatment for HZAP, offering faster and more effective pain relief and quality of life improvement compared to nerve block therapy. However, there are challenges in maintaining the long-term effects of tSCS. Further studies with larger samples are needed to confirm these findings.

Pathophysiology of Pain and Mechanisms of Neuromodulation: A Narrative Review (A Neuron Project)

Pain serves as a vital innate defense mechanism that can significantly impact an individual's quality of life. Understanding the physiological effects of pain well plays an important role in developing novel pain treatments. Nociceptor neurons play a key role in pain and inflammation. Interactions between nociceptors and the immune system occur both at the site of injury and within the central nervous system. Modulating chemical mediators and nociceptor activity offers promising new approaches to pain management. Essentially, the sensory nervous system is essential for modulating the body's protective response, making it critical to understand these interactions to discover new pain treatment strategies. New innovations in neuromodulation have led to alternatives to opioids individuals with chronic pain with consequent improvement in disease-based treatment and nerve targeting. New neural targets from cellular and structural perspectives have revolutionized the field of neuromodulation. This narrative review aims to elucidate the mechanisms of pain transmission and processing, examine the characteristics and properties of nociceptors, and explore how the immune system influences pain perception. It further provides an updated overview of the physiology of pain and neuromodulatory mechanisms essential for managing acute and chronic pain. We assess the current understanding of different pain types, focusing on key molecules involved in each type and their physiological effects. Additionally, we compare painful and painless neuropathies and discuss the neuroimmune interactions involved in pain manifestation.

Comparison of ultrasound- and computed tomography-guided pulsed radiofrequency in treating ophthalmic branch postherpetic neuralgia: a retrospective study

OBJECTIVE

The objective of this study was to compare the efficacy and safety between ultrasound- and computed tomography-guided pulsed radiofrequency in treating ophthalmic branch postherpetic neuralgia.

METHODS

A retrospective study was conducted on data of 84 patients with ophthalmic branch postherpetic neuralgia. According to the puncture guiding method, the patients were divided into the ultrasound- and computed tomography-guided groups, which received the ultrasound- and computed tomography-guided supraorbital nerve pulsed radiofrequency treatment, respectively. The puncture time, numeric rating scale pain score before pulsed radiofrequency and after pulsed radiofrequency, effective rate of treatment, and intraoperative and postoperative adverse events were observed.

RESULTS

The puncture time in the ultrasound-guided group was significantly shorter than that in the computed tomography-guided group (p<0.05). At 1, 4, and 12 weeks after pulsed radiofrequency, in two groups, the numeric rating scale pain score was significantly lower than that before pulsed radiofrequency, respectively (p<0.05). At each time, the numeric rating scale pain score showed no significant difference between the two groups (p>0.05). At 12 weeks after pulsed radiofrequency, there was no significant difference in the effective rate of treatment between the two groups (p>0.05). During the intraoperative and postoperative periods, the incidences of adverse event hematoma and oculocardiac reflex in the ultrasound-guided group were significantly lower than those in the computed tomography-guided group, respectively (p<0.05).

CONCLUSIONS

Both ultrasound- and computed tomography-guided supraorbital nerve pulsed radiofrequencys have good efficacy in treating the ophthalmic branch postherpetic neuralgia. Compared with the computed tomography-guided pulsed radiofrequency, the ultrasound-guided pulsed radiofrequency has faster puncture operation and is safer. It is more worthy of clinical applications.

A central and peripheral dual neuromodulation strategy in pain management of zoster-associated pain

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.

Risk factors for poor prognosis in patients with zoster-associated neuralgia who underwent interventional pain management

Background

Zoster-associated neuralgia (ZAN) is recognized as a challenging neuralgia that often leads to poor prognosis in patients receiving interventional pain management. Identifying risk factors early can enable clinicians to develop personalized treatment plans; however, research in this area is limited.

Methods

We retrospectively screened all patients with ZAN who received interventional therapy in the Pain Department of Soochow University First Affiliated Hospital from January 1, 2022 to August 31, 2023. Data on patient demographics, medical history, neutrophil-to-lymphocyte ratio (NLR), clinical scoring, and treatment methods were collected. Interventional therapy included short-term nerve electrical stimulation (st-NES), pulsed radiofrequency (PRF) and radiofrequency thermocoagulation (RF-TC). Patients were categorized into poor prognosis and control groups based on outcomes 3 months post-discharge. Multivariate logistic regression was used to identify risk factors for poor prognosis.

Results

The final analysis included 282 patients. The rate of poor prognosis was 32.6% (92/282). Multivariate logistic regression analysis revealed that age ≥ 65 years (odds ratio, 2.985; 95% confidence interval, 1.449-6.148; p = 0.003), disease duration >3 months (odds ratio, 3.135; 95% confidence interval, 1.685-5.832; p < 0.001), head and face pain (odds ratio, 3.140; 95% confidence interval, 1.557-6.330; p = 0.001), use of immunosuppressants (odds ratio, 2.737; 95% confidence interval, 1.168-6.416; p = 0.021), higher NLR (odds ratio, 1.454; 95% confidence interval, 1.233-1.715; p < 0.001), PRF (st-NES as reference) (odds ratio, 2.324; 95% confidence interval, 1.116-4.844; p = 0.024) and RF-TC (st-NES as reference) (odds ratio, 5.028; 95% confidence interval, 2.139-11.820; p < 0.001) were found to be independent risk factors for poor prognosis in patients with ZAN who underwent interventional pain management.

Conclusion

Age ≥ 65 years (odds ratio, 2.985; 95% confidence interval, 1.449-6.148; p = 0.003), disease duration >3 months (odds ratio, 3.135; 95% confidence interval, 1.685-5.832; p < 0.001), head and face pain (odds ratio, 3.140; 95% confidence interval, 1.557-6.330; p = 0.001), immunosuppressants use (odds ratio, 2.737; 95% confidence interval, 1.168-6.416; p = 0.021), higher NLR (odds ratio, 1.454; 95% confidence interval, 1.233-1.715; p < 0.001), PRF (odds ratio, 2.324; 95% confidence interval, 1.116-4.844; p = 0.024) and RF-TC (odds ratio, 5.028; 95% confidence interval, 2.139-11.820; p < 0.001) were identified as independent risk factors for poor prognosis in patients with ZAN who underwent interventional pain management.

Repetitive transcranial magnetic stimulation in central post-stroke pain: a meta-analysis and systematic review of randomized controlled trials

Background

The rehabilitation of central post-stroke pain (CPSP) is a complex clinical challenge, and repetitive transcranial magnetic stimulation (rTMS) has been widely applied in the research of neurofunctional recovery following stroke. However, there is currently no reliable evidence-based medicine supporting the efficacy of rTMS in central post-stroke pain. This review aims to evaluate the effects of rTMS on central post-stroke pain.

Methods

Following the PRISMA guidelines, we conducted searches on PubMed, Cochrane Library, Embase, Web of Science, CNKI, and Wan Fang Data Knowledge Service Platform. We searched for randomized controlled trials (RCTs) investigating the use of rTMS in treating central post-stroke pain, and conducted screening based on inclusion and exclusion criteria. Characteristics of the included RCTs were extracted. The heterogeneity of the trials was assessed using the I2 statistic. Meta-analysis was performed using Stata 17 software. Bias risk and methodological quality were evaluated using the Cochrane RoB 2 tool and the Pedro scale.

Results

A total of six randomized controlled trials involving 288 patients met our inclusion criteria. In our analysis, rTMS was more effective in treating patients with CPSP compared to the placebo group (SMD=-1.15, 95% CI: -1.69, -0.61, P < 0.001). Furthermore, results from subgroup analysis indicated no statistically significant difference in the improvement of pain for durations exceeding 6 months when comparing rTMS to conventional treatment (SMD=-0.80, 95% CI: -1.63, 0.03, P = 0.059).

Conclusion

TMS can alleviate pain in CPSP patients and improve their motor function, but its effects on depression, anxiety, and MEP-latency are not significant.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, CRD42024497530.

Strategies and safety simulations for ultrasonic cervical spinal cord neuromodulation

Objective. Focused ultrasound spinal cord neuromodulation has been demonstrated in small animals. However, most of the tested neuromodulatory exposures are similar in intensity and exposure duration to the reported small animal threshold for possible spinal cord damage. All efforts must be made to minimize the risk and assure the safety of potential human studies, while maximizing potential treatment efficacy. This requires an understanding of ultrasound propagation and heat deposition within the human spine.Approach. Combined acoustic and thermal modelling was used to assess the pressure and heat distributions produced by a 500 kHz source focused to the C5/C6 level via two approaches (a) the posterior acoustic window between vertebral posterior arches, and (b) the lateral intervertebral foramen from which the C6 spinal nerve exits. Pulse trains of fifty 0.1 s pulses (pulse repetition frequency: 0.33 Hz, free-field spatial peak pulse-averaged intensity: 10 W cm-2) were simulated for four subjects and for ±10 mm translational and ±10∘rotational source positioning errors.Main results.Target pressures ranged between 20%-70% of free-field spatial peak pressures with the posterior approach, and 20%-100% with the lateral approach. When the posterior source was optimally positioned, peak spine heating values were below 1 ∘C, but source mispositioning resulted in bone heating up to 4 ∘C. Heating with the lateral approach did not exceed 2 ∘C within the mispositioning range. There were substantial inter-subject differences in target pressures and peak heating values. Target pressure varied three to four-fold between subjects, depending on approach, while peak heating varied approximately two-fold between subjects. This results in a nearly ten-fold range between subjects in the target pressure achieved per degree of maximum heating.Significance. This study highlights the utility of trans-spine ultrasound simulation software and need for precise source-anatomy positioning to assure the subject-specific safety and efficacy of focused ultrasound spinal cord therapies.

The deep and the deeper: Spinal cord and deep brain stimulation for neuropathic pain

Neuropathic pain occurs in people experiencing lesion or disease affecting the somatosensorial system. It is present in 7 % of the general population and may not fully respond to first- and second-line treatments in up to 40 % of cases. Neuromodulation approaches are often proposed for those not tolerating or not responding to usual pharmacological management. These approaches can be delivered surgically (invasively) or non-invasively. Invasive neuromodulation techniques were the first to be employed in neuropathic pain. Among them is spinal cord stimulation (SCS), which consists of the implantation of epidural electrodes over the spinal cord. It is recommended in some guidelines for peripheral neuropathic pain. While recent studies have called into question its efficacy, others have provided promising data, driven by advances in techniques, battery capabilities, programming algorithms and software developments. Deep brain stimulation (DBS) is another well-stablished neuromodulation therapy routinely used for movement disorders; however, its role in pain management remains limited to specific research centers. This is not only due to variable results in the literature contesting its efficacy, but also because several different brain targets have been explored in small trials, compromising comparisons between these studies. Structures such as the periaqueductal grey, posterior thalamus, anterior cingulate cortex, ventral striatum/anterior limb of the internal capsule and the insula are the main targets described to date in literature. SCS and DBS present diverse rationales for use, mechanistic backgrounds, and varying levels of support from experimental studies. The present review aims to present their methodological details, main mechanisms of action for analgesia and their place in the current body of evidence in the management of patients with neuropathic pain, as well their particularities, effectiveness, safety and limitations.

Temporary Spinal Cord Stimulation for Herpes Zoster With Myelitis: A Case Series

Introduction: Preventing the development of postherpetic neuralgia (PHN), the most prevalent and severe complication of herpes zoster (HZ), is vital. Recently, it has been suggested that using temporary spinal cord stimulation (tSCS) for 10-14 days can improve HZ-associated pain (ZAP) and prevent PHN. However, myelitis complicates HZ. Permanent SCS has been successful in treating neuropathic pain induced by postoperative transverse myelitis of the spine that has not responded to traditional multidisciplinary treatment. However, it is unknown whether tSCS can reduce ZAP complicated with myelitis. Methodology: Between January 2020 and April 2022, all patients with HZ who visited our pain clinic with spinal cord edema and who underwent tSCS were enrolled in this study; their medical records were retrospectively examined. Pain intensity was assessed at baseline (before initiating interventional procedures), just before tSCS, after tSCS removal, and one and three months after tSCS. Results: Twelve patients were enrolled. The mean Numerical Rating Scale (NRS) was 7.9 ± 1.6 at baseline (before interventional procedures), 6.8 ± 2.2 before tSCS (after interventional procedures), and 3.5 ± 2.4 after tSCS. Compared with before tSCS, the mean NRS decreased to 3.3 ± 2.3 after tSCS (P = 0.0004). The mean NRS changes with interventional procedures before and after tSCS were -1.2 ± 2.2 (P = 0.0945) and 3.3 ± 2.3 (P = 0.0004), respectively; the change after tSCS was significantly higher (between-group difference: -2.1 ± 3.7; P = 0.0324). Conclusions: Temporary SCS alleviated pain in cases of shingles with myelitis refractory to interventional therapy. Even in cases with myelitis, tSCS for ZAP remains an effective way to prevent PHN.

Comprehensive Bibliometric Analysis of Research Articles on Post-Herpetic Neuralgia and Varicella-Zoster Virus: A 20-Year Review(2003-2022)

Objective

Post-herpetic neuralgia (PHN) is a debilitating condition that has garnered considerable attention from pain physicians due to its association with the or Varicella-Zoster Virus (VZV). In this study, we aimed to conduct a bibliometric analysis to quantitatively assess the research outcomes related to PHN and VZV over the past two decades (2003-2022).

Methods

We conducted a bibliometric analysis by querying the Web of Science database for articles related to PHN published from 2003 to 2022. In this analysis, we collected relevant information from the database including the number of publications, publication year, source, country, institution, and citation data.

Results

A total of 1073 publications were extracted from the database, with 387 articles (36.1%) being authored by individuals from the United States, making it the leading country in terms of article publications. The top ten institutions that made significant contributions to research on PHN and VZV were primarily concentrated within the United States. Notably, the New England Journal of Medicine and Pain claimed the two highest positions in terms of citation count, with 2482 and 1591 citations, respectively. The topics covered in these articles mainly revolved around "Postherpetic Neuralgia", "Herpes Zoster", "Epidemiology", "Vaccine", and "Quality-of-life".

Conclusion

Over the past two decades, there has been a gradual increase in publications on PHN and VZV, demonstrating significant advancements in academic achievements. Vaccines have proven effective in reducing PHN incidence among the elderly, but there is a lack of research on interventional treatments and underlying mechanisms. To elevate evidence-based medicine, researchers should conduct more controlled clinical trials. Additionally, leveraging pathogenesis research findings can lead to the development of better pain relief medications.

A bibliometric and visualization analysis of global research on postherpetic neuralgia from 2000 to 2022: A review

Postherpetic neuralgia (PHN) represents a notable clinical challenge as it is the most prevalent and severe complication of herpes zoster (HZ). The primary objective was to investigate the current research status and hotspots of PHN research during the period from 2000 to 2022. The literature pertaining to PHN was gathered through the utilization of the Web of Science Core Collection, spanning from January 2000 to December 2022. The software, CiteSpace version 6.2.R2, was employed to produce visual depictions of publications related to PHN across various dimensions such as year, country/region, institution, journal, author, keyword, and reference. This study involved a total of 3505 papers. The USA held a dominant position in the production of scholarly articles. Argentina exhibited the highest frequency of participation in international collaboration. Out of all the institutions, Pfizer exhibited the highest degree of productivity. Harvard University exhibited the highest frequency of participation in international collaboration. The Pain exhibited the most noteworthy productivity rate and citation count among all other journals. Ralf Baron was identified as the most productive author, whereas DWORKIN RH attained the highest citation count. Contemporary scholarly investigations are predominantly centered on identifying risk factors, devising preventative measures, and exploring novel and secure methods of pain management. The current investigation has revealed the focal areas and patterns of studies pertaining to PHN. Presently, the research in this field is focused on identifying the risk factors and preventive measures for PHN, alongside exploring novel and secure pain management strategies.