Practice parameter: treatment of postherpetic neuralgia: an evidence-based report of the Quality Standards Subcommittee of the American Academy of Neurology

Lidocaine patch for treatment of acute localized pain in the emergency department: a systematic review and meta-analysis

OBJECTIVE

Lidocaine patches are commonly prescribed for acute localized pain. Most of the existing evidence is, however, derived from postoperative or chronic pain. The objective of this study is to assess the efficacy and safety of lidocaine patch compared to placebo patch or nonsteroidal anti-inflammatory drugs (NSAIDs) for acute localized pain.

METHODS

Systematic review and meta-analysis of trials randomizing patients with acute localized pain to lidocaine patch versus placebo patch or NSAIDs.

OUTCOMES

Change in pain score (any validated scale) from baseline to a specific time endpoint (primary efficacy); adverse events (primary harm), and time to exit the study due to reaching a pain relief target (secondary). We used Cochrane revised tool to assess the risk of bias and GRADE to rate the quality of evidence. The meta-analysis was performed using a random-effects model and Cochrane Q test for heterogeneity. Data were summarized as risk ratios and weighted mean differences with 95% confidence interval (CI).

RESULTS

We conducted a comprehensive search of MEDLINE, EMBASE, and other major databases, identifying 10 randomized controlled trials with a total of 523 patients. These trials collectively found that lidocaine patches were more effective in controlling both musculoskeletal and neuropathic pain compared to placebo patches. Due to heterogeneity among the studies, we did not pool the efficacy data. The risk of adverse events was similar between the groups (risk ratio: 0.90; 95% CI: 0.48-1.67; moderate-quality evidence). In the two trials comparing lidocaine patches with NSAIDs, there was no statistically significant difference in pain relief between the treatments.

CONCLUSION

Low to moderate-quality evidence from small trials supports the efficacy and safety of lidocaine patch for the treatment of acute localized pain.

Efficacy and safety of bloodletting puncture and cupping in postherpetic neuralgia: A systematic review and meta‑analysis

The present study aimed to evaluate the efficacy and safety of bloodletting puncture and cupping (BLP-C) in postherpetic neuralgia (PHN) and to provide guidance for clinical treatment. Randomized controlled trials (RCTs) of BLP-C therapy in PHN were systematically searched in eight databases from inception to September 2022. Literature screening, data extraction and quality assessment were performed by two independent researchers. Dichotomous and continuous variables were pooled using the risk ratio (RR) and weighted mean difference (WMD), respectively. A total of 13 studies involving 1,129 patients with PHN (571 in the experimental group and 558 in the control group) were included in the present meta-analysis. Overall efficacy (RR=1.21, 95% CI: 1.15 to 1.28, P<0.00001), VAS score (WMD=-1.10, 95% CI: -1.31 to -0.90, P<0.00001) and PSQI score (WMD=-2.42, 95% CI: -2.87 to -1.96, P<0.0001) were significantly different between the BLP-C group and Western medicine group. Furthermore, subgroup analysis demonstrated that BLP-C alone or combined with other traditional Chinese medicines was more effective than Western medicine in PHN. A total of four RCTs mentioned adverse reactions, most of which were in the Western medicine group and were relieved after treatment discontinuation. In conclusion, BLP-C is superior to Western medicine in relieving pain and improving the sleep quality of patients with PHN with a lower incidence of adverse effects.

Real-world safety and efficacy of amenamevir in patients with herpes zoster in Japan: A postmarketing observational study (REWARD)

The helicase-primase inhibitor amenamevir (AMNV) was approved for herpes zoster in Japan in 2017. The authors conducted a 1-month postmarketing observational study to evaluate the real-world safety and efficacy (cutaneous improvement and pain resolution) of AMNV in patients with herpes zoster. Of the 3453 patients registered between March 2018 and December 2020, 3110 were included in the safety analyses. The mean age (±standard deviation) was 63.7 ± 17.5 years, with 57.9% of patients aged ≥65 years. Most patients had mild (53.3%) or moderate (41.0%) cutaneous lesions. Regarding pain, 43.9%, 25.6%, and 12.5% of patients had pain at the levels of 1-3, 4-6, and 7-10 on the numerical rating scale. In total, 30.0%, 27.2%, and 16.1% of patients were concomitantly treated with analgesics: acetaminophen, nonsteroidal anti-inflammatory drugs, and Ca2+ channel α 2δ ligands, respectively, and 10.6% were treated with topical antiherpetic drugs. Adverse drug reactions occurred in 0.77% of patients, including four serious adverse drug reactions in four patients (hyponatremia, thrombocytopenia, rash, and rhabdomyolysis). Regarding important potential risks, renal disorder, cardiovascular events, and decreased platelets were observed in one, one, and two patients, respectively. Concerning efficacy, the cutaneous improvement rate (significantly improved or improved) was 95.5%, with significantly higher improvement rates in patients treated with AMNV for 7 days and in patients with less severe cutaneous lesions or less pain. Factors affecting the time to pain resolution were the severity of cutaneous lesions and pain at the start of AMNV treatment and older age. This study demonstrated that the AMNV is safe and effective in patients with herpes zoster in a real-world clinical setting.

Neuropathic Pain in the Emergency Setting: Diagnosis and Management

Neuropathic pain, traditionally considered a chronic condition, is increasingly encountered in the emergency department (ED), accounting for approximately 20% of patients presenting with pain. Understanding the physiology and key clinical presentations of neuropathic pain is crucial for ED physicians to provide optimal treatment. While diagnosing neuropathic pain can be challenging, emphasis should be placed on obtaining a comprehensive medical history and conducting a thorough clinical examination. Patients often describe neuropathic pain as a burning or shock-like sensation, leading them to seek care in the ED after ineffective relief from common analgesics such as paracetamol and NSAIDs. Collaboration between emergency medicine specialists, neurologists, and pain management experts can contribute to the development of evidence-based guidelines specifically tailored for the emergency department setting. This article provides a concise overview of the common clinical manifestations of neuropathic pain that may prompt patients to seek emergency care.

Comparison of Efficacy of Acupuncture-Related Therapy in the Treatment of Postherpetic Neuralgia: A Network Meta-Analysis of Randomized Controlled Trials

Background

Postherpetic neuralgia (PHN) is the most common sequela of herpes zoster, and the efficacy of the treatment regimens recommended in the guidelines is not entirely reliable. Acupuncture and moxibustion are widely used complementary alternative therapies that have a positive effect on the treatment of PHN. However, there are various forms of acupuncture and moxibustion, and there are differences in efficacy between the different forms.

Methods

The retrieval work of randomised controlled trials (RCTs) of acupuncture for PHN in English databases (including PubMed, Cochrane Library, Embase, Web of Science) and Chinese databases (including China National Knowledge Infrastructure (CNKI), WeiPu database, WanFang database, and China Biomedical Literature Database) were conducted from the time of database creation to June 2022. Literature screening, data extraction, and evaluation of risk of bias for the included studies were carried out independently by two researchers, and data analysis was performed using Stata 14.2 software.

Results

A total of 30 RCTs including 2138 patients with PHN were included. In terms of pain improvement, acupoint embedding + Western medicine group, bloodletting-cupping group, and bloodletting-cupping + Western medicine group ranked top. In terms of total efficiency, acupuncture + Western medicine group, bloodletting-cupping + Western medicine group, and acupoint embedding group ranked top. There were no statistically significant differences in the incidence of adverse events between treatment regimens.

Conclusions

In a comprehensive comparison of the outcome indicators of 14 different treatment regimens, we considered acupoint injection + Western medicine and bloodletting-cupping + Western medicine to be the best combinations for the treatment of PHN. Due to the limitations of the study, the above conclusions still need to be validated in further multi-centre, large-sample prospective randomised controlled clinical trials.

Comparing Prodrugs with Acyclovir for Treating Postherpetic Neuralgia among Herpes Zoster Patients: A Systematic Review and Meta-Analysis

Postherpetic neuralgia (PHN) is a common, painful, and long-term complication of herpes zoster (HZ). PHN increases the demand for healthcare services and, previous studies showed that patients who received antiviral agents were less likely to develop PHN. The objective of this study was to compare the efficacy of prodrugs and acyclovir in treating PHN among patients with HZ. The search included the PubMed, Medline, Embase, and Cochrane Center of Register of Controlled Trails databases through February 2022. Clinical trials and randomized controlled trials (RCTs) involving antiviral agent intervention for HZ patients diagnosed with PHN were eligible for inclusion. A meta-analysis was conducted to calculate pooled risk ratios (RRs) with 95% confidence intervals (CIs) with a fix-effect model. Five RCTs with 1147 HZ patients met our eligibility criteria. Our meta-analysis found that there was a significantly lower risk of PHN for members of the prodrugs group (famciclovir and valaciclovir) compared with those who received acyclovir (RR = 0.86, 95%, CI: 0.75 to 0.98, p = 0.03). The review of studies indicated that the efficacy of prodrugs was better than acyclovir for reliving PHN.

Efficacy and Safety of Botulinum Toxin A and Pulsed Radiofrequency on Postherpetic Neuralgia: A Randomized Clinical Trial

This study evaluated the effectiveness and safety of botulinum toxin type A (BoNT-A) and pulsed radiofrequency (RF) in the clinical treatment of postherpetic neuralgia (PHN). A total of 100 patients with PHN were randomly divided into two groups (n = 50 per group): RF group and BoNT-A group. Based on conventional drug treatment, patients were treated with either a single nerve root pulsed radiofrequency therapy or a single local subcutaneous injection of BoNT-A in the lesion area. All the patients were followed up for 24 weeks on pain scores, sleep quality, anxiety, and depression scores, etc. In the last follow-up at the end of 24 weeks postoperation, the pain scores of patients in both groups were significantly lower than those before the operation (P < 0.05), indicating that both treatments were effective against PHN; however, there was no significant difference between these two groups (P > 0.05). It is noteworthy that the subcutaneous injection of BoNT-A is relatively easy to administer and less expensive compared to RF. Therefore, we believe that the subcutaneous injection of BoNT-A is an effective and safe method for the treatment of PHN.

Acupuncture therapies for postherpetic neuralgia: a protocol for a systematic review and Bayesian network meta-analysis

INTRODUCTION

Postherpetic neuralgia (PHN) is the most common sequela of herpes zoster, and it is often refractory to guideline-recommended treatments. Acupuncture therapy, a wildly applied complementary-alternative treatment, may help in the management of PHN. Diverse types of acupuncture therapy for PHN have been proposed, however, their comparative efficacies remain unclear. This study protocol plans to compare the efficacy and safety of different acupuncture therapies for PHN.

METHODS AND ANALYSIS

Databases including MEDLINE, Embase, Cochrane Library, Web of Science, Chinese Biomedical Database, China National Knowledge Infrastructure, VIP Database, Wanfang Database, WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, Chinese Clinical Trial Register and OpenGrey will be searched from their inception to January 2022. Randomised controlled trials (RCTs) assessing the effectiveness of acupuncture therapy on the management of PHN will be selected. The primary outcome is pain intensity. Secondary outcomes include negative emotions, sleep condition, quality of life and adverse events. Reviewers will conduct study selection, data extraction and risk of bias assessment procedures. Then, standard pair-wised meta-analysis and Bayesian network meta-analysis will be performed (if applicable). The Confidence in Network Meta-Analysis application will be used to assess the confidence in the evidence for the primary outcome.

ETHICS AND DISSEMINATION

All data used for this study will be extracted from published RCTs, thus, no ethical approval will be required. The results of this systematic review will be disseminated through peer-reviewed journal and conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42020219576.

Acupuncture (superficial dry-needling) as a treatment for chronic postherpetic neuralgia - a randomized clinical trial

BACKGROUND

Postherpetic neuralgia is a painful condition where finding sufficient treatment poses a great challenge. Acupuncture is often used as an alternative treatment for these pains, yet no randomized trials, using a sham-placebo have been performed to confirm its effect. Our objective was to investigate the efficacy of acupuncture compared to sham-acupuncture when treating chronic postherpetic dermal pain.

METHODS

We performed a sham-controlled double-blinded randomized clinical trial (RCT) with two arms. The intervention group received superficial dry-needling, and the control group received sham acupuncture using blunted needles. Twenty-six patients received two treatments. They filled out questionnaires at baseline and 1 month after treatment: (1) average and maximum pain (Numeric Rating Scale), (2) neuropathic pain (Neuropathic Pain Scale Inventory) and (3) Quality of Life (QoL) (Short-form 36).

RESULTS

Thirteen patients were allocated to the intervention group and 15 to the control group. We did not detect any significant changes in levels of pain and neuropathic pain. One QoL parameter, regarding emotional problems, reached a level of statistical significance. The sham-blinding was successful. This is the first RCT on the effect of acupuncture (superficial dry-needling) on postherpetic neuralgia (PHN), using a sham procedure as control. We observed no significant changes or tendencies in the measured levels of pain. One QoL parameter had significant improvement in the intervention group compared to the control group.

CONCLUSION

In conclusion, acupuncture was not superior to treatment with sham acupuncture. Though individual patients may experience some pain relief from acupuncture, our results do not support the routine use of this type of acupuncture to treat PHN.

Association Between the Risk for Cardiovascular Events and Antiviral Treatment for Herpes Zoster

BACKGROUND

Cardiovascular risk increases following herpes zoster. We investigated whether treatment with antiviral agents, steroids, and common cardiovascular medications was associated with the risk of postherpetic cardiovascular events.

METHODS

This was a nationwide population-based, retrospective, cohort study using the National Health Insurance Service health claims data in Korea. We included patients with a first-ever diagnosis of herpes zoster in 2003-2014 and no prior cardiovascular event. The primary outcome was the occurrence of composites of myocardial infarction (International Statistical Classification of Diseases, Tenth Revision, code I21) and stroke (codes I60-I63) since the herpes zoster. We analyzed the exposure (intravenous or oral administration) to antiviral agents, steroids, antithrombotics, and statins within ±7 days from the index date of herpes zoster diagnosis. Follow-up was performed until occurrence of the primary outcome, death, or 31 December 2015, whichever came first.

RESULTS

Of 84 993 patients with herpes zoster, the proportions of patients who received the treatment with antiviral agents, steroids, antithrombotics, and statins were 90.5%, 48.0%, 9.1%, and 7.9%, respectively. During the mean (standard deviation) follow-up period of 5.4 (3.1) years, 1523 patients experienced the primary outcome. Multivariate Cox regression analysis demonstrated that treatment with antiviral agents (adjusted hazard ratio, 0.82; 95% confidence interval, .71-.95) and statins (0.71; .59-.85) were significantly associated with the lower risk of primary outcome. Use of antithrombotics and steroids were not associated with the risk.

CONCLUSIONS

After herpes zoster, treatment with antiviral agents was significantly associated with lower risk of cardiovascular events. We need more information on the cardiovascular protective role of herpes zoster treatments.

Retrospective Analysis of 170 Patients Followed up with Herpes Zoster and Postherpetic Neuralgia in Nothern Cyprus

Herpes zoster is viral infection that occurs with reactivation of the varicella-zoster virus (VZV). It is usually a painful but self-limited dermatomal rash with  cutaneous distribution. Although it's usually a painful, self-limiting rash, it can be much more serious; In addition, acute cases often lead to postherpetic neuralgia (PHN) and seriously impair quality of life. It is important to recognize those at risk of developing postherpetic neuralgia, early treatment and prevent complications. Objectives :Our aim is to determine the clinical features of our herpes zoster diseases and to review the treatments in patients with postherpetic neuralgia. Methods: A search for HZ and PHN was conducted in a general practice research database, comprising 2 general practices( dermatologist and physatrist) and representing 5600 people. We analyzed a retrospective 170 case series of pediatirc and adults addmited  to the dermatology and physical therapy and rehabilitation outpatient clinic between October 2018 and October 2020. Results: A total of 170 new cases had been diagnosed with HZ in the dermatology and physical therapy and rehabilitation clinics over 2 years . Female to male ratio was 2:1 and the age ranged from 5 years to 88 years. The thoracic dermatomes were the most commonly involved. The risk of developing PHN 1 month after the start of the zoster rash was 21 %. Independent risk indicators for the occurrence of PHN were age [55–74] years. Conclusion : The risk of developing PHN increases with age and with commorbitity. Preventive strategies such as vaccination should focus on patients with herpes zoster aged >55 years.

The effect of subcutaneous injection of methylprednisolone acetate and lidocaine for refractory postherpetic neuralgia: a prospective, observational study

BACKGROUND

Postherpetic neuralgia (PHN) is the most common and bearable complication of herpes zoster (HZ). This pain may have negative impact on the patient's all aspects of daily life and health-related quality of life (HRQOL). Despite numerous advances in treatment, many patients remain resistant to the current therapy options. It is the first time subcutaneous injection of methylprednisolone acetate and lidocaine has been used to treat refractory PHN. We report the results of this treatment evaluating pain relief and HRQOL improvement in this disorder.

METHODS

A total of 43 patients with refractory PHN was enrolled in the observational study. All patients received daily subcutaneous injection of methylprednisolone acetate and lidocaine for 10 consecutive days. The severity of pain was assessed by using Visual Analog Scale (VAS), and 36-Item Short Form Survey (SF-36) was applied to evaluate HRQOL. Assessment of the pain and HRQOL was carried out at baseline and posttreatment at 4 weeks as well as 6 and 12 months.

RESULTS

At baseline, all patients experienced severe PHN with average VAS scores of 8.44 ± 0.85 (minimum 7; maximum 10). At 4 weeks, 6 months, and 12 months after treatment, the pain had significantly decreased (P < .001), and all subjects showed significant improvement in all eight domains of HRQOL. No major adverse events associated with the subcutaneous injection were observed.

CONCLUSIONS

Our results indicate that subcutaneous injection of methylprednisolone acetate and lidocaine can be an effective and safe treatment for PHN.

Effectiveness of acupuncture therapy for postherpetic neuralgia: an umbrella review protocol

INTRODUCTION

Several systematic reviews and meta-analysis indicate that acupuncture and related therapies may be a valuable adjunctive technique to pharmacological interventions for pain management of postherpetic neuralgia (PHN). However, the robustness of the results of these studies has not been evaluated. The aim of this proposed umbrella review is to provide more reliable evidence of the effectiveness of acupuncture therapy for PHN based on medical references for healthcare decision makers.

METHODS AND ANALYSIS

PubMed, EMBASE, The Cochrane Library, Web of Science, Chinese BioMedical Literature Database, VIP Database for Chinese Technical Periodicals, China National Knowledge Infrastructure and Wan fang Database will be used to retrieve reviews. The time of publication will be limited from inception to March 2021. Two reviewers will screen all retrieved articles independently to identify their eligibility and extract the data. The quality will be assessed independently by two trained reviewers using Assessment of Multiple Systematic Reviews-2 for methodological quality, Risk of Bias in Systematic Review for level of bias, Preferred Reporting Items for Systematic Reviews and Meta-Analysis for reporting quality and Grading of Recommendations Assessment, Development and Evaluation for the quality of evidence. Any disagreements will be settled by discussion or the involvement of a third reviewer.

ETHICS AND DISSEMINATION

The protocol of this review does not require ethical approval because the research will be based on publicly available data. The findings will be disseminated through publication in peer-reviewed international journals or presentation in academic conference.

PROSPERO REGISTRATION NUMBER

CRD42020173341.

REPORTING CHECKLIST

PRISMA-P, 2015.

Oral Medicine Considerations for Older Patients

With the projected increase to 1.3 billion people aged 65 years or older by 2040, healthcare professionals are faced with significant challenges in managing this population of patients. In the oral cavity, oral mucosal disease is a significant problem found in older populations. Several facial pain conditions are more likely to be seen in this cohort of patients. Although management of this group of patients may not always be appropriate in general practice, an awareness of the range of oral medicine conditions that may be encountered in older patients is essential to allow prompt referral and treatment.

Comparing Gene Expression in the Parabrachial and Amygdala of Diestrus and Proestrus Female Rats after Orofacial Varicella Zoster Injection

The orofacial pain pathway projects to the parabrachial and amygdala, and sex steroids have been shown to affect neuronal activity in these regions. GABA positive cells in the amygdala are influenced by sex steroid metabolites to affect pain, and sex steroids have been shown to alter the expression of genes in the parabrachial, changing neuronal excitability. Mechanisms by which sex steroids affect amygdala and parabrachial signaling are unclear. The expression of genes in the parabrachial and amygdala in diestrus (low estradiol) and proestrus (high estradiol) female rats were evaluated in this study. First, varicella zoster virus was injected into the whisker pad of female rats to induce a pain response. Second, gene expression was quantitated using RNA-seq one week after injection. Genes that had the greatest change in expression and known to function in pain signaling were selected for the quantitation of protein content. Protein expression of four genes in the parabrachial and seven genes in the amygdala were quantitated by ELISA. In the parabrachial, neurexin 3 (Nrnx3) was elevated at proestrus. Nrnx3 has a role in AMPA receptor and GABA signaling. Neuronatin (Nnat) and protein phosphatase, Mg²⁺/Mn²⁺ dependent 1E (Ppm1e) were elevated in the parabrachial of diestrus animals both genes having a role in pain signaling. Epoxide hydroxylase (Ephx2) was elevated in the parabrachial at proestrus and the vitamin D receptor (Vdr) was elevated in the amygdala. Ephx2 antagonists and vitamin D have been used to treat neuropathic pain. In conclusion, sex steroids regulate genes in the parabrachial and amygdala that might result in the greater pain response observed during diestrus.

Viral infections of oral cavity

Viral infections of the oral cavity usually manifest as either ulceration or blistering presentation of oral tissues. Oral viral infections are encountered in dental practice but received less clinical interest due to the lesser frequency of patients and diagnostic challenges. The clinical presentation, pathogenic mechanism, investigations, and management of oral viral infections are integrated into the article which will enable general dentists to develop critical thinking processes on differential diagnosis and management through a multidisciplinary approach with specialist dentists.

Efficacy of intermittent epidural dexamethasone bolus for zoster-associated pain beyond the acute phase

Herpes zoster develops when latent varicella zoster virus is reactivated in the trigeminal or dorsal root ganglions. Zoster-associated pain (ZAP) is neuropathic pain caused by the herpes zoster virus. Histological studies of postherpetic neuralgia patients suggest that inflammation is involved in ZAP. The effectiveness of local anesthetic and steroid epidural injections in ZAP patients has been reported. However, most studies included patients with acute herpes zoster, and the safety and therapeutic effects of different doses of epidural steroids in ZAP patients remain elusive. In this study, we randomly assigned 42 patients with severe ZAP beyond the acute phase, as determined by a numeric rating scale (NRS) score ≥7, to receive continuous epidural infusion of local anesthetics with either a one-time 5-mg dose or intermittent repeated doses (15 mg total) of dexamethasone. We found that intermittent repeated epidural dexamethasone bolus resulted in reduced NRS scores and an increased likelihood of complete remission in ZAP patients without any adverse effects. Thus, our results suggest that intermittent repeated epidural dexamethasone administration is safe and effective for treatment of ZAP beyond the acute phase.

Treatment Patterns and Medication Use in Patients with Postherpetic Neuralgia

BACKGROUND

Postherpetic neuralgia (PHN) is a chronic, painful condition characterized by persistent pain following resolution of a herpes zoster (HZ) infection. Epidemiologic data demonstrate that the risks for HZ infections and the development of PHN increase with age.

OBJECTIVE

To characterize prescribing patterns, health care utilization, and treatment costs for adults with PHN based on real-world data.

METHODS

This study analyzed medical and pharmacy claims from 2010 to 2014 in the MarketScan Commercial and Medicare Supplemental databases. PHN patients were identified based on criteria from a published algorithm. PHN treatment patterns were analyzed by age and reported descriptively for patients aged < 65 or ≥ 65 years. Excess incremental health care costs were calculated for PHN patients by comparing expenditures for a cohort of PHN patients to expenditures of a propensity score-matched control group of patients with HZ alone.

RESULTS

Approximately 0.4% of patients aged < 65 years were diagnosed with HZ versus 1.3% of patients aged ≥ 65 years; approximately 15.3% of HZ patients aged < 65 years and 26.4% of patients aged ≥ 65 years were diagnosed with PHN. Overall, opioids remained the most frequently prescribed initial treatment. Approximately 21.6% of PHN patients received an opioid as an initial treatment for PHN, 15.1% received gabapentin; 8.9% received a prescription nonsteroidal anti-inflammatory drug (NSAID); 8.3% received a lidocaine patch; 3.3% received pregabalin; 2.5% received a tricyclic antidepressants (TCAs); 0.8% received other topical lidocaine; and < 1% received capsaicin. Observed first-line use of the lidocaine patch and gabapentin was higher in patients aged ≥ 65 years relative to patients aged < 65 years. When separated by age group, only 24.6% of patients aged < 65 years and 38.5% of patients aged ≥ 65 years were prescribed a recommended first-line treatment for initial PHN therapy (gabapentin, lidocaine patch, pregabalin, and TCAs). Comparisons of treatment costs of PHN patients to matched HZ patients without PHN indicated that PHN patients initiated on opioids had the highest mean additional health care expenditure compared with PHN patients initiated on other medications. On average, PHN patients initiated on opioids had $7,601 additional health care expenditure compared with HZ patients with no PHN; additional expenditures were $6,428 for pregabalin, $4,213 for lidocaine patches, $3,478 for gabapentin, $3,304 for NSAIDs, and $2,797 for TCAs, respectively.

CONCLUSIONS

Management of PHN is associated with substantial utilization of opioid-based therapies across all ages. Medications supported by evidence either as first-line therapies or as part of a multimodal regimen for the management of PHN are underused relative to opioid-based PHN therapies. Improving adherence to evidence-based PHN treatment regimens offers the potential to reduce opioid prescribing first line and reduce overall treatment costs. Given the emphasis to reduce opioid prescribing to minimize the risk of dependence, abuse, and diversion, multimodal analgesic treatments that can avoid or reduce opioid use should be considered.

DISCLOSURES

Research funding was provided by SCILEX Pharmaceuticals. The sponsor reviewed and approved the research plan and provided support for manuscript preparation through Patel's role as a coauthor of this manuscript. The sponsor's product (lidocaine patch) was not used in this study. Patel is a paid employee of SCILEX Pharmaceuticals. Goss is an employee and minority owner of Boston Healthcare Associates, which received a research grant from SCILEX Pharmaceuticals to conduct this study. Gudin reports advisory board fees from AcelRx Pharmaceuticals and BioDelivery Sciences International and consulting fees from Averitas, Daiichi, Hisumitsu, Nektar, Purdue, Quest Diagnostics, SCILEX Pharmaceuticals, and US WorldMeds, unrelated to this study. Fudin reports advisory board fees from AcelRx Pharmaceuticals, Human Half-Cell, Quest Diagnostics, GlaxoSmithKline, SCILEX Pharmaceuticals, BioDelivery Sciences, Daiichi Sankyo, and Salix Pharmaceuticals; speaker fees from Daiichi Sankyo, Salix Pharmaceuticals, Abbott Laboratories, Acutis Diagnostics, and AstraZeneca; and consulting fees from Firstox Laboratories, unrelated to this study. The other authors have nothing to disclose. Parts of this research were presented at the AMCP Managed Care & Specialty Pharmacy Annual Meeting; April 22, 2016; San Francisco, CA, and at the 35th Annual Scientific Meeting of the American Pain Society; May 11-14, 2016; Austin, TX.

Viral, bacterial, and fungal infections of the oral mucosa: Types, incidence, predisposing factors, diagnostic algorithms, and management

For millions of years, microbiota residing within us, including those in the oral cavity, coexisted in a harmonious symbiotic fashion that provided a quintessential foundation for human health. It is now clear that disruption of such a healthy relationship leading to microbial dysbiosis causes a wide array of infections, ranging from localized, mild, superficial infections to deep, disseminated life-threatening diseases. With recent advances in research, diagnostics, and improved surveillance we are witnessing an array of emerging and re-emerging oral infections and orofacial manifestations of systemic infections. Orofacial infections may cause significant discomfort to the patients and unnecessary economic burden. Thus, the early recognition of such infections is paramount for holistic patient management, and oral clinicians have a critical role in recognizing, diagnosing, managing, and preventing either new or old orofacial infections. This paper aims to provide an update on current understanding of well-established and emerging viral, bacterial, and fungal infections manifesting in the human oral cavity.

Novel insights on the management of pain: highlights from the ‘Science of Relief’ meeting

The ‘Science of Relief’ event, held in Milan on 10–11 May 2019, was aimed at promoting dialog between different stakeholders among scientific associations, pharma industry, healthcare services and related institutions. The goal was to renew interest and attention on the management of pain, sharing new solutions in order to bring the patients and their quality of life to the center of attention. An international group of scientists and clinicians presented and discussed new and known evidence in the field of chronic pain, from physiopathology and diagnosis to the choice of appropriate and timely pharmacological treatments. This paper reports the highlights of those presentations.

Patient and economic burdens of postherpetic neuralgia in China

Background

Little is known about the patient-reported and economic burdens of postherpetic neuralgia (PHN) among China’s urban population.

Methods

This noninterventional study was conducted among adults ≥40 years with PHN who were seeking medical care at eight urban hospitals in China. At one study site, patients completed a questionnaire evaluating the patient-reported disease burden (N=185). The questionnaire consisted of validated patient-reported outcomes including the Brief Pain Inventory (BPI), 5-dimension, 3-level EuroQol (EQ-5D-3L), Medical Outcomes Study Sleep Scale, and Work Productivity and Activity Impairment Questionnaire for Specific Health Problems. Questions on non-pharmacologic therapy and out-of-pocket (OOP) expenses were also included. At all study sites, physicians (N=100) completed a structured review of patient charts (N=828), which was used to derive health care resource utilization and associated costs from the societal perspective. Annual costs in Chinese Yuan Renminbi (RMB) for the year 2016 were converted to US dollars (US$).

Results

Patients (N=185, mean age 63.0 years, 53.5% female) reported pain of moderate severity (mean BPI score 4.6); poor sleep quantity (average of 5.3 hrs per night) and quality; and poorer health status on the EQ-5D-3L relative to the general Chinese population. Respondents also reported average annual OOP costs of RMB 16,873 (US$2541) per patient, mainly for prescription PHN medications (RMB 8990 [US$1354]). Substantial work impairment among employed individuals resulted in annual indirect costs of RMB 28,025 (US$4221). In the chart review, physicians reported that patients (N=828) had substantial health resource utilization, especially office visits; 98% had all-cause and 95% had PHN-related office visits. Total annual direct medical costs were RMB 10,002 (US$1507), mostly driven by hospitalizations (RMB 8781 [US$1323]).

Conclusion

In urban China, PHN is associated with a patient-reported burden, affecting sleep, quality-of-life, and daily activities including work impairment, and an economic burden resulting from direct medical costs and indirect costs due to lost productivity. These burdens suggest the need for appropriate prevention and management of PHN.

Efficacy and tolerability of a fixed dose combination of cortex phospholipid liposomes and cyanocobalamin for intramuscular use in peripheral neuropathies

Peripheral neuropathies are frequently encountered in clinical practice and are associated with a major impairment in quality of life. However, their management remains poor, and current therapies are often burdened with major side effects and can present poor efficacy on pain and functionality. Therefore, it has been suggested that the combination of two or more different drugs may improve analgesic efficacy and reduce side effects. Tricortin® 1000 is formulated with 12 mg of Brain cortex phospholipid liposomes + 1000 µg of Cyanocobalamin injectable solution (PL+CNCbl) for intramuscular use and is indicated in the treatment of poly-algo-neuropathic syndromes. This combination exerts a marked neurotrophic action by promoting the synthesis of endogenous phospholipids; moreover, the peculiar formulation optimizes the delivery of CNCbl which has analgesic and neurotrophic action. This paper discusses the pharmacotherapy of peripheral neuropathies, including low-back pain, neck pain, postherpetic neuropathy (PHN) and focuses on the fixed dose combination PL+CNCbl clinical efficacy in association with other treatments or in monotherapy.

Is acupuncture an effective postherpetic neuralgia treatment? A systematic review and meta-analysis

Background

Postherpetic neuralgia (PHN) refers to pain which remains after the healing of rashes from herpes zoster. Previous literatures have shown that acupuncture has potential benefits for PHN, but evidence remains lacking. Thus, we have performed a systematic review and meta-analysis to identify the effectiveness of acupuncture in the treatment of PHN.

Methods

Six databases were searched for randomized controlled trials (RCTs) to assess the effects of acupuncture on PHN. After selecting the studies, extracting the data, and assessing study quality, meta-analysis was performed on several of the studies with RevMan 5.3. The GRADE (Grading of Recommendations Assessment Development and Evaluation) system was used to assess the overall quality of the evidence.

Results

Acupuncture helps relieve pain intensity (standardized mean difference [SMD]: -1.78, 95% confidence interval [CI]: -2.36 to -1.21). For other intervention types, electroacupuncture (SMD: -1.28, 95% CI: -2.51 to -0.05), fire needle (SMD: -2.23, 95% CI: -2.62 to -1.84), bloodletting and cupping (SMD: -2.46, 95% CI: -2.95 to -1.97) have better effects on pain intensity relief. To date, no study has reported on the onset of pain relief time. The Hamilton Anxiety Scale score (SMD: -18.94, 95% CI: -37.37 to -0.52) was lower for the acupuncture group than for the control group. It was also found that acupuncture can improve quality of life (QOL) (SMD: 3.78, 95% CI: 2.50 to 5.06). The quality of evidence for acupuncture for PHN pain intensity was moderate according to the GRADE system.

Conclusion

Acupuncture may reduce pain intensity, relieve anxiety and improve quality of life in patients with PHN. Further randomized trials with larger sample sizes and of higher methodological quality are needed to confirm these results.

Neuromodulation in Postherpetic Neuralgia: Case Reports and Review of the Literature

Objective

Postherpetic neuralgia (PHN) is common in the United States. Current treatment options for PHN are fairly limited. Spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are considered mostly experimental and still rarely performed in patients with PHN.

Design

Two case reports and a review of the literature.

Setting

Tertiary academic medical center.

Methods

1) Pubmed, Ovid, and EBMR databases were searched for all reports that had the following key words: postherpetic neuralgia, spinal cord stimulation, and peripheral nerve stimulation. 2) A retrospective chart review was performed for all the patients that underwent PNS for PHN at Mayo Clinic Florida (MCF).

Results

There were 20 original reports that described 309 patients with PHN who were treated with SCS. Sixteen reports had a permanent implantation of SCS, with a total of 255 patients, out of which 120 had long-term pain relief. There were six reports of subcutaneous PNS for PHN (in a thoracic area). Four reports provided data on success rates where all five patients received complete pain relief. In our practice, two patients underwent subcutaneous PNS for PHN (in the thoracic area) with good pain relief for 10 months and 2.5 years, respectively.

Conclusions

Based on our review of the literature and the two cases at MCF, subcutaneous PNS seems to be a promising intervention in the treatment of PHN.

Parameters associated with efficacy of epidural steroid injections in the management of postherpetic neuralgia: the Mayo Clinic experience

Purpose: Thirty percent of patients with postherpetic neuralgia (PHN) receiving conservative treatment report unsatisfactory pain relief. Epidural steroid injections (ESIs) are commonly used as a therapeutic intervention in these patients. In this study, we aimed to determine if there are variables that predict the efficacy of ESI in patients with PHN.

Patients and methods: We retrospectively identified patients seen at Mayo Clinic who had PHN and received ESI. From their medical records, we abstracted the demographic variables, concurrent medication use, anatomic approach and medication for ESI, and degree of pain relief at 2 and 12 weeks' postintervention.

Results: None of the studied variables were significantly associated with efficacy of ESI in patients with PHN. PHN that began <11 months before treatment was predictive of a response to ESI at 12 weeks postintervention (positive predictive value, 55%). Patients who reported poor ESI efficacy 2 weeks after the intervention had a 94% chance of still having pain at 12 weeks.

Conclusion: For this cohort of patients with PHN being treated with ESI, no demographic characteristics, concurrently used medications, or type of ESI were associated with ESI treatment efficacy at 2 or 12 weeks after the intervention.

Cost-Effectiveness of Treatment Options for Neuropathic Pain: a Systematic Review

BACKGROUND

Neuropathic pain significantly reduces an individual's quality of life and places a significant economic burden on society. As such, many cost-effectiveness analyses (CEAs) have been published for treatments available for neuropathic pain.

OBJECTIVES

The primary objective of this systematic review was to provide a detailed summary of the estimates of cost-effectiveness from published CEAs comparing available treatments for neuropathic pain. The secondary objectives were to identify the key drivers of cost-effectiveness and to assess the quality of published CEAs in neuropathic pain.

METHODS

We searched Embase, MEDLINE, Cochrane CENTRAL and seven other databases to identify CEAs reporting the costs, health benefits (e.g., quality-adjusted life-years or disability-adjusted life-years) and summary statistics, such as incremental cost-effectiveness ratios, of treatments for neuropathic pain. We excluded studies reporting diseases other than neuropathic pain, those for which the full text was not available (e.g., conference abstracts), studies not written in English or not published in peer-reviewed journals, and narrative reviews, editorials and opinion papers. Titles and abstract reviews, full-text reviews, and data extraction were all performed by two independent reviewers, with disagreement resolved by a third reviewer. Mean costs, health benefits, and summary statistics were reported and qualitatively compared across studies, stratified by time horizon. Drivers of cost-effectiveness were assessed using reported one-way sensitivity analyses. The quality of all included studies was evaluated using the Tufts CEA Registry Quality Score and study reporting using the CHEERS (Consolidated Health Economic Evaluation Reporting Standards) checklist.

RESULTS

A total of 22 studies were identified and included in this systematic review. Included studies were heterogeneous in the treatments compared, methodology and design, perspectives, and time horizons considered, making cross-study comparisons difficult. No single treatment was consistently the most cost-effective across all studies, but tricyclic antidepressants were the preferred treatment at a willingness-to-pay threshold of $US50,000 per quality-adjusted life-year in several studies with a short time horizon and a US payer perspective. Among the 14 studies reporting one-way sensitivity analyses, drivers of cost-effectiveness included utility values for health states and the likelihood of pain relief with treatment. The quality of the identified CEAs was moderate to high, and overall reporting largely met CHEERS recommendations.

LIMITATIONS

To assess drivers of cost-effectiveness and quality, we only included studies with the full text available and thus excluded some CEAs that reported cost-effectiveness results. The heterogeneity of the included studies meant that the study results could not be synthesized and comparison across studies was limited.

CONCLUSIONS

Though many pulished studies have evaluated the cost-effectiveness of treatments for neuropathic pain, significant heterogeneity between CEAs prevented synthesis of the results. Standardized methodology and improved reporting would allow for more reliable comparisons across studies.

Premedication With Gabapentin Significantly Reduces the Risk of Postherpetic Neuralgia in Patients With Neuropathy

Postherpetic neuralgia (PHN) is the most common complication of varicella zoster virus (VZV) reactivation and a cause of considerable physical and psychosocial morbidity. No known treatment effectively prevents the development of PHN in patients with VZV reactivation. In this study, our objective was to evaluate the efficacy of premedication with gabapentin for reducing the risk of PHN in patients with diabetic and nondiabetic neuropathy. We retrospectively searched the electronic health records of patients with diabetic and nondiabetic neuropathy treated with gabapentin at Mayo Clinic before diagnosis of VZV reactivation. In total, PHN developed in 7 patients with diabetic neuropathy receiving gabapentin (n=62 [11.3%]) compared with 26 not receiving premedication with gabapentin (n=50 [52.0%]) (odds ratio, 0.12; 95% CI, 0.05-0.31; P<.001); PHN developed in 11 patients with nondiabetic neuropathy receiving gabapentin (n=109 [10.1%]) compared with 108 not receiving premedication with gabapentin (n=217 [49.8%]) (odds ratio, 0.11; 95% CI, 0.06-0.22; P<.001). In this cohort of patients with neuropathy, gabapentin administration before the onset of VZV reactivation significantly reduced the risk of PHN.

[Pharmacological profiles and clinical effects of amenamevir tablet as treatments for herpes zoster]

Herpes zoster is a viral infectious disease caused by reactivation of varicella zoster virus (VZV) in a latently infected ganglion, and is characterized by blistering and pain developing in a zonal region innervated from the ganglion. Amenamevir is an antiherpes agent that does not have a nucleic acid-like structure, and exerts antiviral action by inhibiting the enzymatic activity of a virus-derived helicase-primase complex, which is considered essential for viral DNA replication. Amenamevir is mainly metabolized by CYP3A, and excreted into feces. In in vitro antiviral testing, amenamevir demonstrated higher antiviral activity against ZV than aciclovir, and its antiviral activity did not diminish even against acyclovir-resistant VZV. In a phase III clinical study in patients with herpes zoster in Japan, cessation of new rash formation by the 4th day of administration, the primary endpoint of the study, was observed in 81.1% of the patients given oral administration of amenamevir 400 mg once daily after meal, verifying its non-inferiority to valaciclovir hydrochloride (P<0.0001 by non-inferiority test using Farrington-Manning test extended to Mantel-Haenszel type adjustment). Adverse reactions were observed in 10.0% (25/249 patients), and were mainly abnormal clinical laboratory tests results. Based on the above results, the efficacy and safety of amenamevir tablet 400 mg once daily administration in herpes zoster treatment have been confirmed, and amenamevir can be a novel treatment option in Japan.

Neuropathic Pain

PURPOSE OF REVIEW

Neuropathic pain is a frequently encountered condition that is often resistant to treatment and is associated with poor patient satisfaction of their treatment. Several medications have been shown to be effective in treating neuropathic pain associated with diabetic neuropathy and postherpetic neuralgia, and these medications are often used to treat neuropathic pain associated with other conditions as well. This article summarizes the diagnosis and assessment of patients with neuropathic pain as well as available pharmacologic and interventional treatment options.

RECENT FINDINGS

Evidence-based recommendations for the treatment of neuropathic pain have been published, and first-line medications include antidepressants, anticonvulsants, topical agents, as well as opioid analgesics. Interventional options include anesthetic and steroid injections, nerve blocks, and spinal cord stimulation. Essential to the treatment algorithm of neuropathic pain is the assessment and treatment of psychosocial comorbidities and the utilization of a multidisciplinary team approach, including cognitive-behavioral and rehabilitative therapies. Questions remain about the comparative effectiveness of various medications and combination therapies. Increasing interest also exists in the optimization and personalization of pharmacotherapy based upon the underlying mechanism(s) of neuropathic pain according to the quality of the patient's symptoms.

SUMMARY

The management of chronic neuropathic pain is challenging and is best achieved with the use of a multidisciplinary team. Pain is a subjective experience, and it is important to validate a patient's pain, address psychosocial comorbidities, and set realistic treatment goals. Evidence-based guidelines are available to guide treatment, but frequently, high-quality evidence-based recommendations are lacking.

Efficacy of iontophoresis-assisted epithelium-on corneal cross-linking for keratoconus

Corneal cross-linking (CXL) is a noninvasive therapeutic procedure for keratoconus that is aimed at improving corneal biomechanical properties by induction of covalent cross-links between stromal proteins. It is accomplished by ultraviolet A (UVA) radiation of the cornea, which is first saturated with photosensitizing riboflavin. It has been shown that standard epithelium-off CXL (S-CXL) is efficacious, and it has been recommended as the standard of care procedure for keratoconus. However, epithelial removal leads to pain, transient vision loss, and a higher risk of corneal infection. To avoid these disadvantages, transepithelial CXL was developed. Recently, iontophoresis has been adopted to increase riboflavin penetration through the epithelium. Several clinical observations have demonstrated the safety and efficacy of iontophoresis-assisted epithelium-on CXL (I-CXL) for keratoconus. This review aimed to provide a comprehensive summary of the published studies regarding I-CXL and a comparison between I-CXL and S-CXL. All articles used in this review were mainly retrieved from the PubMed database. Original articles and reviews were selected if they were related to the I-CXL technique or related to the comparison between I-CXL and S-CXL.

Current perspectives on corneal collagen crosslinking (CXL)

Corneal collagen crosslinking has revolutionized the treatment of keratoconus and post-refractive corneal ectasia in the past decade. Corneal crosslinking with riboflavin and ultraviolet A is proposed to halt the progression of keratectasia. In the original "Conventional Dresden Protocol" (C-CXL), the epithelium is removed prior to the crosslinking process to facilitate better absorption of riboflavin into the corneal stroma. Studies analyzing its short- and long-term outcomes revealed that although there are inconsistencies as to the effectiveness of this technique, the advantages prevail over the disadvantages. Therefore, corneal crosslinking (CXL) is widely used in current practice to treat keratoconus. In an attempt to improve the visual and topographical outcomes of C-CXL and to minimize time-related discomfort and endothelial-related side effects, various modifications such as accelerated crosslinking and transepithelial crosslinking methods have been introduced. The comparison of outcomes of these modified techniques with C-CXL has also returned contradictory results. Hence, it is difficult to clearly identify an optimal procedure that can overcome issues associated with the CXL. This review provides an up-to-date analysis on clinical and laboratory findings of these popular crosslinking protocols used in the treatment of keratoconus. It is evident from this review that in general, these modified techniques have succeeded in minimizing the immediate complications of the C-CXL technique. However, there were contradictory viewpoints regarding their effectiveness when compared with the conventional technique. Therefore, these modified techniques need to be further investigated to arrive at an optimal treatment option for keratoconus.

Efficacy and Safety of Once-Daily Controlled-Release Pregabalin for the Treatment of Patients With Postherpetic Neuralgia: A Double-Blind, Enriched Enrollment Randomized Withdrawal, Placebo-Controlled Trial

OBJECTIVES

To assess efficacy and safety of once-daily controlled-release (CR) formulation of pregabalin in patients with postherpetic neuralgia.

METHODS

An enriched enrollment, randomized withdrawal trial, with 6-week single-blind pregabalin treatment phase and 13-week double-blind phase, where patients with ≥50% decrease in mean pain score at single-blind end point from baseline were randomized (1:1) to pregabalin CR (82.5 to 660 mg/d) or placebo. Primary efficacy outcome was time to loss of therapeutic response (LTR) (<30% decrease in weekly mean pain score from single-blind baseline or discontinuation due to adverse event or lack of efficacy). Secondary efficacy outcomes included change in weekly mean pain score (1-wk recall period) at double-blind end point.

RESULTS

In total, 801 patients were randomized and treated in the single-blind phase, and 413 in the double-blind phase (208, pregabalin CR; 205, placebo). Pregabalin CR significantly increased time to LTR versus placebo (Kaplan-Meier analysis) with significantly fewer LTR events with pregabalin CR than with placebo (29 [13.9%] vs. 63 [30.7%]; P<0.0001). Median time to LTR was not estimable. Pregabalin CR significantly improved weekly mean pain score versus placebo: LS mean difference (95% CI) of -1.11 (-1.47, -0.75) and -1.00 (-1.34, -0.65) (P<0.0001) from single-blind baseline and double-blind baseline, respectively. Most commonly reported adverse events in the single-blind phase were dizziness, somnolence, and peripheral edema. Pregabalin CR was well tolerated.

DISCUSSION

Time to LTR was significantly longer with pregabalin CR than with placebo. Safety profile of pregabalin CR was comparable to that reported for the immediate-release formulation in patients with postherpetic neuralgia.

Effects of photobiostimulation in the treatment of post-herpetic neuralgia: a case report

Abstract Objectives: to describe the effect of photobiomodulation therapy in the treatment of post-herpetic neuralgia in the elderly. Case report: a female patient, 61 years old, 56 kg, 1.67cm tall, sought treatment at the Laser Therapy Center of the Universidade do Vale do Paraíba, in the city of São José dos Campos, São Paulo, Brazil, on October 27, 2015. She had been diagnosed with herpes zoster on September 4, 2015 with complaints of intermittent neuralgia in the long thoracic nerve path and spikes of intense pain (level 10, according to the analogue pain scale). Photobiomodulation was performed with low intensity laser spot irradiations at 20 points around the herpesvirus nerve, with a distance of 2cm between each point. Irradiation was performed at each point after 20 seconds, with 3J/cm2 per point and total energy of 60 J. At the end of the treatment the pain level was 0 and the patient exhibited a normal sleep pattern (8 hours of sleep). Conclusions: Photobiomodulation treated painful discomfort, improved the quality of life of the patient and proved to be an effective, safe and promising treatment, with significant potential to become the therapy of choice in such cases.

Herpes Zoster in the Older Adult

Herpes zoster (HZ) is the result of reactivation of latent varicella zoster virus (VZV) and occurs most frequently in older adults. Classically, HZ presents as a unilateral, selflimited, dermatomal rash. Postherpetic neuralgia (PHN) is a common sequela, presenting as severe pain that persists after the rash has resolved. In the elderly, PHN can be debilitating and requires a prompt diagnosis, treatment with antivirals, and adequate pain control. A longer-term pain management strategy is required if PHN occurs. A modestly effective vaccine exists and is recommended for older individuals.

Neuropathic pain responds better to increased doses of pregabalin: an in-depth analysis of flexible-dose clinical trials

Background

Pregabalin is an effective treatment option for many patients with neuropathic pain. Higher doses of pregabalin have been shown to be more effective in improving pain outcomes but, in practice, failing to appropriately increase the dose can leave patients under-treated.

Methods

This was a pooled analysis of 6 flexible-dose clinical trials of pregabalin in patients with neuropathic pain (diabetic peripheral neuropathy, peripheral herpetic neuralgia, posttraumatic pain, or postsurgical pain). Patients were divided into “dose pathway” groups based on their weekly pregabalin dose from the start of their trial to the first week of their maintenance phase. These were: 150 mg/day only; 150 to 300 mg/day; 150 to 300 to 450 mg/day; 150 to 300 to 450 to 600 mg/day; 150 to 300 to 600 mg/day; 300 to 600 mg/day. Pain outcomes assessed for each group at each new dose were proportion of 30% and 50% responders (≥30% or ≥50% reduction in mean pain score from baseline) and mean change in pain score. Percent change in mean pain score from baseline was assessed using a marginal structural model.

Results

Seven hundred and sixty-one patients treated with flexible-dose pregabalin were included in the analysis. For each dose pathway group, there was a notably greater proportion of 30% and 50% responders and change in pain score, at each escalating dose. As assessed by the marginal structural model, higher doses of pregabalin were estimated to result in a significantly greater change in mean pain score at each week. This dose response with flexible-dose pregabalin was consistent with that previously observed with fixed-dose pregabalin.

Conclusion

Many patients who do not respond to lower doses of pregabalin will respond with notable improvements in pain outcomes when the dose is escalated. These data should encourage physicians treating patients with neuropathic pain to escalate pregabalin to the dose that delivers optimal analgesia and tolerable side effects.

Adverse Effects of Antidepressants for Chronic Pain: A Systematic Review and Meta-analysis

Background

Antidepressants are widely used in the treatment of chronic pain. Applied doses are lower than those needed to unfold an antidepressive effect. While efficacy of antidepressants for chronic pain has been reported in large randomized-controlled trials (RCT), there is inconsistent data on adverse effects and tolerability. We aimed at synthesizing data from RCT to explore adverse effect profiles and tolerability of antidepressants for treatment of chronic pain.

Methods

Systematic literature research and meta-analyses were performed regarding side effects and safety of different antidepressants in the treatment of chronic pain according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The National Center for Biotechnology Information library and MEDLINE were searched. Randomized placebo-controlled trials were included in quantitative data synthesis.

Results

Out of 1,975 screened articles, 33 papers published between 1995 and 2015 were included in our review and 23 studies were included in the meta-analyses. A higher risk for adverse effects compared to placebo was observed in all antidepressants included in our analyses, except nortriptyline. The most prevalent adverse effects were dry mouth, dizziness, nausea, headache, and constipation. Amitriptyline, mirtazapine, desipramine, venlafaxine, fluoxetine, and nortriptyline showed the highest placebo effect-adjusted risk of adverse effects. Risk for withdrawal due to adverse effects was highest in desipramine (risk ratio: 4.09, 95%-confidence interval [1.31; 12.82]) followed by milnacipran, venlafaxine, and duloxetine. The most common adverse effects under treatment with antidepressants were dry mouth, dizziness, nausea, headache, and constipation followed by palpitations, sweating, and drowsiness. However, overall tolerability was high. Each antidepressant showed distinct risk profiles of adverse effects.

Conclusion

Our synthesized data analysis confirmed overall tolerability of low-dose antidepressants for the treatment of chronic pain and revealed drug specific risk profiles. This encompassing characterization of adverse effect profiles might be useful in defining multimodal treatment regimens for chronic pain which also consider patients’ comorbidities and co-medication.

Lateral thalamic control of nociceptive response after whisker pad injection of varicella zoster virus

Pain is a common complication of herpes zoster (HZ) infection which results from reactivation of a latent varicella zoster virus (VZV). A third of HZ patients' progress to a chronic pain state known as post herpetic neuralgia (PHN), and about a quarter of these patients' have orofacial pain. The mechanisms controlling the pain responses are not understood. Studies suggest central pathways involving the thalamus could control pain related to HZ, and studies in our lab suggest (VGAT) in the lateral thalamus influences orofacial pain. We hypothesized that thalamic VGAT functions, in part, to reduce pain, particularly orofacial pain, associated with VZV. To address this hypothesis VZV was injected into the whisker pad. Affective and motivational aspects of pain were measured using the Place Escape/Avoidance Paradigm. Thalamic neuronal activity was modulated after injecting an adeno-associated virus (AAV) expressing an engineered acetylcholine Gi-protein-coupled receptor. This receptor inhibits neuronal firing when bound by clozapine-n-oxide (CNO). VGAT expression was attenuated in the thalamus by injecting an AAV construct that expressed a VGAT silencing shRNA. VZV-induced nociception was significantly decreased after administering CNO in male rats. Nociception significantly increased concomitant with increased thalamic c-fos expression after attenuating thalamic VGAT expression. These data establish that the lateral thalamus (posterior, ventral posteromedial, ventral posterolateral and/or reticular thalamic nucleus) controls VZV-induced nociception in the orofacial region, and that GABA in this region appears to reduce the response to VZV-induced nociception possibly by gating facial pain input.

Sex differences underlying orofacial varicella zoster associated pain in rats

BACKGROUND

Most people are initially infected with varicella zoster virus (VZV) at a young age and this infection results in chickenpox. VZV then becomes latent and reactivates later in life resulting in herpes zoster (HZ) or "shingles". Often VZV infects neurons of the trigeminal ganglia to cause ocular problems, orofacial disease and occasionally a chronic pain condition termed post-herpetic neuralgia (PHN). To date, no model has been developed to study orofacial pain related to varicella zoster. Importantly, the incidence of zoster associated pain and PHN is known to be higher in women, although reasons for this sex difference remain unclear. Prior to this work, no animal model was available to study these sex-differences. Our goal was to develop an orofacial animal model for zoster associated pain which could be utilized to study the mechanisms contributing to this sex difference.

METHODS

To develop this model VZV was injected into the whisker pad of rats resulting in IE62 protein expression in the trigeminal ganglia; IE62 is an immediate early gene in the VZV replication program.

RESULTS

Similar to PHN patients, rats showed retraction of neurites after VZV infection. Treatment of rats with gabapentin, an agent often used to combat PHN, ameliorated the pain response after whisker pad injection. Aversive behavior was significantly greater for up to 7 weeks in VZV injected rats over control inoculated rats. Sex differences were also seen such that ovariectomized and intact female rats given the lower dose of VZV showed a longer affective response than male rats. The phase of the estrous cycle also affected the aversive response suggesting a role for sex steroids in modulating VZV pain.

CONCLUSIONS

These results suggest that this rat model can be utilized to study the mechanisms of 1) orofacial zoster associated pain and 2) the sex differences underlying zoster associated pain.

The 5% Lidocaine-Medicated Plaster: Its Inclusion in International Treatment Guidelines for Treating Localized Neuropathic Pain, and Clinical Evidence Supporting its Use

When peripheral neuropathic pain affects a specific, clearly demarcated area of the body, it may be described as localized neuropathic pain (LNP). Examples include postherpetic neuralgia and painful diabetic neuropathy, as well as post-surgical and post-traumatic pain. These conditions may respond to topical treatment, i.e., pharmaceutical agents acting locally on the peripheral nervous system, and the topical route offers advantages over systemic administration. Notably, only a small fraction of the dose reaches the systemic circulation, thereby reducing the risk of systemic adverse effects, drug–drug interactions and overdose. From the patient’s perspective, the analgesic agent is easily applied to the most painful area(s). The 5% lidocaine-medicated plaster has been used for several years to treat LNP and is registered in approximately 50 countries. Many clinical guidelines recommend this treatment modality as a first-line option for treating LNP, particularly in frail and/or elderly patients and those receiving multiple medications, because the benefit-to-risk ratios are far better than those of systemic analgesics. However, some guidelines make only a weak recommendation for its use. This paper considers the positioning of the 5% lidocaine-medicated plaster in international treatment guidelines and how they may be influenced by the specific criteria used in developing them, such as the methodology employed by randomized, placebo-controlled trials. It then examines the body of evidence supporting use of the plaster in some prevalent LNP conditions. Common themes that emerge from clinical studies are: (1) the excellent tolerability and safety of the plaster, which can increase patients’ adherence to treatment, (2) continued efficacy over long-term treatment, and (3) significant reduction in the size of the painful area. On this basis, it is felt that the 5% lidocaine-medicated plaster should be more strongly recommended for treating LNP, either as one component of a multimodal approach or as monotherapy.

Postherpetic neuralgia: epidemiology, pathophysiology, and pain management pharmacology

Herpes zoster, also known as shingles, is a distinctive clinical condition caused by the reactivation of latent varicella zoster (chickenpox) virus following an initial infection. Approximately 1 million cases of herpes zoster occur annually in the US, and one in every three people develops herpes zoster during their lifetime. Postherpetic neuralgia is a neuropathic pain syndrome characterized by pain that persists for months to years after resolution of the herpes zoster rash. It stems from damage to peripheral and central neurons that may be a byproduct of the immune/inflammatory response accompanying varicella zoster virus reactivation. Patients with postherpetic neuralgia report decreased quality of life and interference with activities of daily living. Approaches to management of postherpetic neuralgia include preventing herpes zoster through vaccination and/or antiviral treatment, and administering specific medications to treat pain. Current guidelines recommend treatment of postherpetic neuralgia in a hierarchical manner, with calcium channel α2-δ ligands (gabapentin and pregabalin), tricyclic antidepressants (amitriptyline, nortriptyline, or desipramine), or topical lidocaine patches as first-line drugs. The safety and tolerability of pharmacologic therapies for pain are important issues to consider as postherpetic neuralgia affects primarily an older population. Patients should be educated on appropriate dosing, titration if applicable, the importance of adherence to treatment for optimal effectiveness, and possible side effects. Health-care professionals play a key role in helping to ameliorate the pain caused by postherpetic neuralgia through early recognition and diligent assessment of the problem; recommending evidence-based treatments; and monitoring treatment adherence, adverse events, responses, and expectations. Nurse practitioners are especially crucial in establishing communication with patients and encouraging the initiation of appropriate pain-relieving treatments.

Issues in the Treatment of Neurological Conditions Caused by Reactivation of Varicella Zoster Virus (VZV)

Varicella zoster virus (VZV) is a ubiquitous neurotropic human herpesvirus. Primary infection usually causes varicella (chicken pox), after which virus becomes latent in ganglia along the entire neuraxis. Decades later, virus reactivates to produce herpes zoster (shingles), a painful dermatomally distributed vesicular eruption. Zoster may be further complicated by postherpetic neuralgia, VZV vasculopathy, myelitis, and segmental motor weakness. VZV reactivation has also been associated with giant cell arteritis. This overview discusses treatment of various conditions that often require both corticosteroids and antiviral drugs. Treatment for VZV-associated disease is often based on case reports and small studies rather than large-scale clinical trials. Issues that require resolution include the optimal duration of such combined therapy, more effective treatment for postherpetic neuralgia, whether some treatments should be given orally or intravenously, the widening spectrum of zoster sine herpete, and the role of antiviral therapy in giant cell arteritis.

The topical 5% lidocaine medicated plaster in localized neuropathic pain: a reappraisal of the clinical evidence

Topical 5% lidocaine medicated plasters represent a well-established first-line option for the treatment of peripheral localized neuropathic pain (LNP). This review provides an updated overview of the clinical evidence (randomized, controlled, and open-label clinical studies, real-life daily clinical practice, and case series). The 5% lidocaine medicated plaster effectively provides pain relief in postherpetic neuralgia, and data from a large open-label controlled study indicate that the 5% lidocaine medicated plaster is as effective as systemic pregabalin in postherpetic neuralgia and painful diabetic polyneuropathy but with an improved tolerability profile. Additionally, improved analgesia and fewer side effects were experienced by patients treated synchronously with the 5% lidocaine medicated plaster, further demonstrating the value of multimodal analgesia in LNP. The 5% lidocaine medicated plaster provides continued benefit after long-term (≤7 years) use and is also effective in various other LNP conditions. Minor application-site reactions are the most common adverse events associated with the 5% lidocaine medicated plaster; there is minimal risk of systemic adverse events and drug–drug interactions. Although further well-controlled studies are warranted, the 5% lidocaine medicated plaster is efficacious and safe in LNP and may have particular clinical benefit in elderly and/or medically compromised patients because of the low incidence of adverse events.