An update on the treatment of postherpetic neuralgia

Environmental factors and their impact on chronic pain development and maintenance

It is more than recognized and accepted that the environment affects the physiological responses of all living things, from bacteria to superior vertebrates, constituting an important factor in the evolution of all species. Environmental influences range from natural processes such as sunlight, seasons of the year, and rest to complex processes like stress and other mood disorders, infections, and air pollution, being all of them influenced by how each creature deals with them. In this chapter, it will be discussed how some of the environmental elements affect directly or indirectly neuropathic pain, a type of chronic pain caused by a lesion or disease of the somatosensory nervous system. For that, it was considered the edge of knowledge in translational research, thus including data from human and experimental animals as well as the applicability of such findings.

Cerebrospinal Fluid Proteomic Profiles in Patients with Postherpetic Neuralgia

The intrinsic mechanism of postherpetic neuralgia (PHN) remains unclear. Herein, we aimed to seek the hub proteins in the cerebrospinal fluid (CSF), which display significant changes between the PHN and nonpainful patients (Control). First, the proteomic results showed that compared with the Control-CSF, there were 100 upregulated and 50 downregulated differentially expressed proteins (DEPs) in the PHN-CSF. Besides, functional analyses including gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) revealed that biological processes and pathways including complement activation, infection, coagulation, and lipid metabolism were activated, while synaptic organization was suppressed. Next, the protein-protein interaction (PPI) analysis indicated that increased PLG, F2, APOA1, APOA2, SERPINC1, and KNG1 and reduced APOE, which were all enriched in the top pathways according to the KEGG analysis, were defined as hub proteins. Finally, three of the hub proteins, such as PLG, APOA1, and APOE, were reconfirmed in a larger cohort using both enzyme-linked immunosorbent assay (ELISA) and Western blotting methods. Above all, the results indicated that PLG, APOA1, and APOE and their involved processes such as infection, inflammation, cholesterol metabolism, and coagulation shall be potential therapeutic approaches. (The raw mass spectrometry proteome data and search results have been deposited to the iProx-integrated Proteome Resources (http://www.iprox.cn) with the data set identifier IPX0007372000.).

Analysis of Efficacy and Factors Associated with Reccurence After Radiofrequency Thermocoagulation in Patients with Postherpetic Neuralgia: a Long-Term Retrospective and Clinical Follow-Up Study

INTRODUCTION

Postherpetic neuralgia (PHN) is a painful condition that persists for 1 month or more after herpes zoster rash has healed. Radiofrequency thermocoagulation (RF-TC) provides analgesia by destroying the dorsal root ganglion and blocking the pain upload pathway; nonetheless, the concomitant neurological-related side effects and recurrence remain a concern.

METHODS

In this study, 228 patients with PHN in the thoracic segment treated with RF-TC of the dorsal root ganglion of the spinal nerve were included, and were followed up regularly after surgery. The numerical rating scale (NRS) scores, time to recurrence, and intraoperative and postoperative adverse events were recorded and analyzed. The Kaplan-Meier method was used to plot survival curves and calculate the cumulative effective rate and recurrence rate. Cox regression analyses were performed to identify factors associated with postoperative recurrence. Predictive models were built to assess the value of applications.

RESULTS

The NRS scores decreased in all postoperative periods compared with preoperative ones. At 10-year-follow-up, recurrence was observed in 34.6% (79/228) of patients that underwent PHN. The main postoperative complications were numbness and reduced abdominal muscle strength, which gradually decreased with time, while the abdominal muscle strength gradually recovered. No other adverse events occurred. Interval-censored multivariable Cox regression analysis demonstrated that disease course, complications, pain grade, and type of RF electrode were associated with a significantly higher risk of relapse. The main intraoperative adverse effect was a transient increase in pain during RF-TC.

CONCLUSION

CT-guided RF-TC of the dorsal root ganglion of the spinal nerve for PHN is a relatively safe and effective surgical option. Disease course, type of RF electrode, complications, and pain grade are risk factors for postoperative recurrence and can assist in clinical decision-making before the RF-CT procedure.

Persistence of a T Cell Infiltrate in Human Ganglia Years After Herpes Zoster and During Post-herpetic Neuralgia

Varicella-zoster virus (VZV) is a human herpesvirus which causes varicella (chicken pox) during primary infection, establishes latency in sensory ganglia, and can reactivate from this site to cause herpes zoster (HZ) (shingles). A major complication of HZ is a severe and often debilitating pain called post-herpetic neuralgia (PHN) which persists long after the resolution of the HZ-associated rash. The underlying cause of PHN is not known, although it has been postulated that it may be a consequence of immune cell mediated damage. However, the nature of virus-immune cell interactions within ganglia during PHN is unknown. We obtained rare formalin fixed paraffin embedded sections cut from surgically excised ganglia from a PHN-affected patient years following HZ rash resolution. VZV DNA was readily detected by qPCR and regions of immune infiltration were detected by hematoxylin and eosin staining. Immunostaining using a range of antibodies against immune cell subsets revealed an immune cell response comprising of CD4⁺ and CD8⁺ T cells and CD20⁺ B cells. This study explores the immune cell repertoire present in ganglia during PHN and provides evidence for an ongoing immune cell inflammation years after HZ.

"For your eyes only": ophthalmic complications following lung transplantation

Ophthalmic complications in the lung transplant population are a little-known entity. It includes a spectrum of diseases ranging from infections such as cytomegalovirus (CMV) retinitis, herpetic keratitis, Pseudallescheria boydii to non-infectious complications such as posterior subcapsular cataracts (PSCs), cyclosporine retinopathy, and post-transplant lymphoproliferative disorder (PTLD). These diseases can be attributed to high levels of immunosuppression, advanced age, and drug-specific side effects. Underlying comorbidities such as diabetes mellitus may also play a role in the pathogenesis. Patients can present with varied symptoms such as blurry vision, floaters or eye pain. Prompt diagnosis often requires a high index of suspicion. With increasing numbers of transplants being performed worldwide, it is imperative for the pulmonologist and transplant physician to recognize these often subtle symptoms. Any visual symptom should trigger an ophthalmological evaluation in order to manage these complications; some of which pose the risk of systemic dissemination and significant morbidity. The following article provides an in-depth review of the common presenting symptoms, treatments and recent advances related to common ophthalmic complications following lung transplantation. While this article focuses on the lung transplant sub-population, the authors would like to point out that some of these complications are shared by other solid-organ transplants as well, by virtue of their shared immunosuppressive therapies.

The Uncommon Localization of Herpes Zoster

Introduction:

Herpes zoster is an acute, cutaneous viral infection caused by the reactivation of varicella-zoster virus (VZV) that is the cause of varicella. It is an acute neurological disease which can often lead to serious postherpetic neuralgia (PHN). Different nerves can be included with the skin rash in the area of its enervation especially cranial nerves (CV) and intercostal nerves.

Case report:

In this report we present a patient with herpes zoster which involved ulnar nerve with skin rash in the region of ulnar innervations in women with no disease previously diagnosed. The failure of her immune system may be explained by great emotional stress and overwork she had been exposed to with neglecting proper nutrition in that period.

Conclusion:

Herpes zoster may involve any nerve with characteristic skin rash in the area of its innervations, and failure in immune system which leads reactivation of VZV may be caused by other factors besides the underlying illness.

Streptomycin-lidocaine injections for the treatment of postherpetic neuralgia: Report of three cases with literature review

The sudden, stabbing, paroxysmal pain of neuralgia is the fiercest agony that a patient may experience in his life. Many varied medical treatments and surgical procedures have been suggested in the literature for neuralgic pain. Most of the patients fail to respond to medical treatments or succumb to complications of total anesthesia owing to surgical procedures. Herein, we tried a new treatment modality in patients suffering from postherpetic neuralgia with appreciable success in all the three cases that are presented in this paper. Streptomycin sulfate dissolved in 2% lidocaine solution was deposited at the peripheral branches on the involved nerves targeting the trigger zones, given weekly once for a maximum of 6 week period and continued once in 2 weeks if symptoms persisted. All patients were followed-up for 1 year and there was a marked improvement on follow-up.

Efficacy and safety of carisbamate in patients with diabetic neuropathy or postherpetic neuralgia: results from 3 randomized, double-blind placebo-controlled trials

The results of 3 proof-of-concept studies to evaluate carisbamate's efficacy and safety in treating neuropathic pain are presented. In studies 1 (postherpetic neuralgia, n = 91) and 2 (diabetic neuropathy, n = 137), patients received carisbamate 400 mg/day or placebo for 4 weeks and then crossed over to the other treatment for 4 weeks. In study 3 (diabetic neuropathy, higher carisbamate doses), patients (n = 386) were randomized (1:1:1:1) to receive either carisbamate 800 mg/day, 1200 mg/day, pregabalin 300 mg/day or placebo for 15 weeks. Primary efficacy end point was the mean of the last 7 average daily pain scores obtained on days the study drug was taken, for all 3 studies. Least square mean (95% CI) differences between carisbamate and placebo groups on the primary end point were as follows: study 1: -0.512 (-1.32, 0.29) carisbamate 400 mg/day; study 2: -0.307 (-0.94, 0.33) carisbamate 400 mg/day; and study 3: -0.51 (-1.10, 0.08), carisbamate 800 mg/day; -0.55 (-1.13, 0.04), carisbamate 1200 mg/day; and -0.43 (-1.01, 0.15), pregabalin 300 mg/day. Neither carisbamate (all 3 studies) nor pregabalin (study 3) significantly differed from placebo, although multiple secondary end points showed significant improvement in efficacy with carisbamate in studies 1 and 2. Dizziness was the only treatment-emergent adverse event occurring at ≥10% difference in carisbamate groups versus placebo (study 1: 12% vs. 1%; study 3: 14% vs. 4%; study 2: 1% vs. 2%). Carisbamate, although well tolerated, did not demonstrate efficacy in neuropathic pain across these studies, nor did the active comparator pregabalin (study 3).

Post-herpetic neuralgia

Background

In spite of the large body of evidence available in the literature, definition and treatment of Post-Herpetic Neuralgia (PHN) are still lacking a consistent and universally recognized standardization. Furthermore, many issues concerning diagnosis, prediction and prevention of PHN need to be clarified in view of recent contributions.

Objectives

To assess whether PHN may be better defined, predicted, treated and prevented in light of recent data, and whether available alternative or adjunctive therapies may improve pain relief in treatment recalcitrant PHN.

Methods

Systematic reviews, meta-analyses, randomized controlled trials, cohort studies and protocols were searched; the search sources included PubMed, Cochrane Library, NICE, and DARE. More than 130 papers were selected and evaluated.

Results

Diagnosis of PHN is essentially clinical, but it can be improved by resorting to the many tools available, including some practical and accessible questionnaires. Prediction of PHN can be now much more accurate, taking into consideration a few well validated clinical and anamnestic variables. Treatment of PHN is presently based on a well characterized array of drugs and drug associations, including, among others, tricyclic antidepressants, gabapentinoids, opioids and many topical formulations. It is still unsatisfactory, however, in a substantial proportion of patients, especially those with many comorbidities and intense pain at herpes zoster (HZ) presentation, so that this frequent complication of HZ still strongly impacts on the quality of life of affected patients.

Conclusion

Further efforts are needed to improve the management of PHN. Potentially relevant interventions may include early antiviral therapy of acute HZ, prevention of HZ by adult vaccination, as well as new therapeutic approaches for patients experiencing PHN.

A randomized, prospective study of efficacy and safety of oral tramadol in the management of post-herpetic neuralgia in patients from north India

OBJECTIVE

To evaluate the safety and efficacy of oral tramadol therapy (50 to 200 mg/day) in the treatment for post-herpetic neuralgia (PHN).

METHODS

The study was a prospective, single-blind, non-responder vs. responder, randomized trial conducted in 100 outpatients of PHN after oral administration of tramadol for 4 weeks. Those patients who had achieved 50% or greater pain relief after 14 days of oral tramadol treatment were categorized as responders and those reporting < 50% pain relief were categorized as non-responders. Rescue analgesia was provided by the topical application of a cream consisting of the combination of 3.33% doxepin and 0.05% capsaicin to the affected areas of PHN patients of both groups for at least 14 days, along with tramadol therapy. The rescue analgesia was extended to 4 weeks in patients of the non-responder group. The primary endpoints were measured using a numerical rating scale (NRS) at rest and with movement. Secondary endpoints included additional pain ratings such as global perceived effect (GPE), Neuropathic Pain Symptom Inventory scores (NPSI), daily sleep interference score (DSIS), quality of life (QOL) as per WHO QOL-BREF Questionnaire scores, patient and clinician ratings of global improvement. The 2 groups were compared on the basis of pain intensity scores, encompassing primary as well as secondary endpoints, and QOL after 28 days of the treatment regimen.

RESULTS

Pain intensity scores measured by NRS (at resting and with movement), NPSI, and DSIS were consistently reduced (P < 0.001) over 28 days at varying intervals in both the groups, but the magnitude of reduction was higher in responders than non-responders. A concomitant improvement (P < 0.001) was observed in GPE on days 3, 14, and 28 as compared to the respective baseline scores in both the groups. Although the WHO QOL-BREF scores showed significant (P < 0.001) improvement in QOL of PHN patients at days 14 and 28 in both the groups, the magnitude of improvement was higher in responders as compared to non-responders. Significant improvement in pain intensity scores and QOL in non-responders is mainly attributed to the use of rescue analgesia for 28 days rather than recommended tramadol therapy.

CONCLUSIONS

Treatment with tramadol 50 to 200 mg per day was associated with significant pain reduction in terms of enhanced pain relief, reduced sleep interference, greater global improvement, diminished side-effect profile, and improved QOL in PHN patients from North India. Further categorization of PHN patients may be helpful so that additional or alternative therapy may be prescribed to non-responders.

Trigeminal postherpetic neuralgia responsive to treatment with capsaicin 8 % topical patch: a case report

Postherpetic neuralgia has been variably defined but is generally understood to be pain that persists for longer than a few months after an attack of herpes zoster. Pain persists for years in approximately 10 % of those afflicted with acute herpes zoster. The likelihood of postherpetic neuralgia increases with older age, severity of the zoster, trigeminal location, and other factors. Postherpetic neuralgia is a neuropathic pain and treatment usually involves sequential trials of topical and systemic drugs; a variety of other therapies may be considered in refractory cases. A new topical capsaicin 8 % patch has been approved for this indication based on the positive studies in patients with non-trigeminal postherpetic neuralgia. Experience with the use of the capsaicin 8 % patch for trigeminal distribution neuralgia is lacking. We report a case of trigeminal postherpetic neuralgia which was safely and effectively treated with capsaicin 8 % patch.

CYP2D6*4 polymorphism, tramadol treatment and its clinical impact in patients with postherpetic neuralgia

Aim: The aim of this study was to investigate the associations between the CYP2D6*4 polymorphism, interindividual differences in CYP2D6 activity and adverse drug effects in postherpetic neuralgia (PHN) patients receiving tramadol. Patients & methods: The study comprised 158 patients (including 78 nonresponders and 80 responders) with PHN who were undergoing analgesic treatment at the Pain Clinic in the Out Patient Department of the University College of Medical Sciences, Guru Teg Bahadur Hospital (New Delhi, India). The numerical rating scale scores were measured at the resting and movement stages; Neuropathic Pain Symptom Inventory scores were evaluated by the treating physician. WHO-brief questionnaire scores for quality of life and adverse drug effects during the time of study were recorded. All samples were analyzed for the CYP2D6*4 polymorphism using the PCR-restriction fragmentation length polymorphism method. Results: The genotype distribution did not vary significantly among different age groups in nonresponders and responders. The CYP2D6*4 polymorphism was significantly associated with lower Neuropathic Pain Symptom Inventory (burning, squeezing stabbing and pressure) scores. The quality-of-life (sociological, psychological and environmental domains) scores correlated with CYP2D6*4 and showed significant results (p < 0.05) using a generalized linear model. No association was found between the physiological domain compared with the CYP2D6*4 allele (p > 0.05). In addition, the homozygous mutated CYP2D6*4 allele was not related to adverse effects of analgesic therapy. Conclusion: The CYP2D6*4 polymorphism may not be a predictor for treatment outcome of patients with PHN receiving tramadol. However, further investigation is required to confirm these findings in a larger sample size.

Assessment of the quality of postherpetic neuralgia treatment information on the Internet

The objective of this study was to assess the quality of websites presenting treatment information for postherpetic neuralgia. The term "postherpetic neuralgia treatment" was searched using the Google and Yahoo search engines. Fifty websites from each were evaluated using the Journal of the American Medical Association (JAMA) benchmarks, the Health on the Net (HON) seal, and the DISCERN instrument. The treatments suggested on each website were compared with 3 recognized first-line treatment options (antidepressants, anticonvulsants, and topical lidocaine). Less than half of the included websites fulfilled all JAMA benchmark requirements. Less than one-third of the websites displayed the HON seal. The DISCERN instrument evaluation revealed that most websites were of moderate quality. Commercial websites tended to be inferior in comparison to noncommercial websites. Most websites recommended at least 2 of the 3 recommended treatments as well as several second- and third-line treatments. One-third to one-half of websites recommended a nonbeneficial treatment. In conclusion, many different postherpetic neuralgia treatments are found on the Internet and patients may be left separating recommended treatments from nonrecommended treatments without help from their healthcare providers.

PERSPECTIVE

This study examined the quality of websites related to postherpetic neuralgia treatment. The results demonstrated that most websites offering advice on postherpetic neuralgia treatment are of only moderate quality and often offer treatment suggestions that are nonbeneficial. Patients and providers must use caution when taking advice from these sites.

Pharmacokinetics and safety of FV-100, a novel oral anti-herpes zoster nucleoside analogue, administered in single and multiple doses to healthy young adult and elderly adult volunteers

FV-100 is the prodrug of the highly potent anti-varicella zoster virus bicyclic nucleoside analogue CF-1743. To characterize the pharmacokinetics and safety of oral FV-100, 3 randomized, double-blind, placebo-controlled clinical trials were conducted: (i) a single-ascending-dose study in 32 healthy subjects aged 18 to 55 years (100-, 200-, 400-, and 800-mg doses) with an evaluation of the food effect in the 400-mg group; (ii) a multiple-ascending-dose study in 48 subjects aged 18 to 55 years (100 mg once daily [QD], 200 mg QD, 400 mg QD, 400 mg twice a day, and 800 mg QD for 7 days); and (iii) a 2-part study in subjects aged 65 years and older with a single 400-mg dose in 15 subjects and a 400-mg QD dosing regimen for 7 days in 12 subjects. FV-100 was rapidly and extensively converted to CF-1743, the concentration of which remained above that required to reduce viral activity by 50% for the 24-hour dosing period. Renal excretion of CF-1743 was very low. A high-fat meal reduced exposure to CF-1743; a low-fat meal did not. Pharmacokinetic parameters for the elderly subjects were comparable to those for the younger subjects. FV-100 was well tolerated by all subjects. The pharmacokinetic and safety profiles of FV-100 support its continued investigation for the treatment of herpes zoster and prevention of postherpetic neuralgia with once-daily dosing and without dose modifications for elderly or renally impaired patients.

The combination of morphine and minocycline may be a good treatment for intractable post-herpetic neuralgia

Post-herpetic neuralgia (PHN) is a devastating complication of shingles. The treatment of PHN with traditional pharmaceutical agents has various side effects. Therefore, the treatment of intractable PHN is often very time consuming, mainly because the available treatments often lead to intolerable side effects before the efficient dose can be reached. Opioids such as morphine and oxycodone are the most widely used drugs for the alleviation for severe chronic pain. A number of high quality studies demonstrated that opioids are effective in relieving neuropathic pain including PHN. Yet concerns of misuse, abuse and tolerance of opioids have, however, severely influenced their contribution to neuropathic pain, especially the tolerance that resulted in a loss of drug effect or the necessity for escalating doses to produce pain relief. The glia cells, particularly microglia and astrocytes are thought to play an important role in central sensitization. It is known that activated microglia cells produce NO, cytokines, and cyclooxygenase. All of these chemicals regulate synaptic transmissions in the central nervous system. Additionally, glia modulations showed antiallodynic and antihyperalgesic properties in various experimental pain models. Minocycline, a semisynthetic, second-generation tetracycline can potently inhibit microglial activation and proliferation. Also, the growing body of recent evidence indicates that minocycline attenuates morphine tolerance in neuropathic mice with a mechanism related to microglia. The combination of morphine and minocycline has synergetic effect. This can prevent the development of intractable PHN and attenuate morphine antinociceptive tolerance and further improve the efficacy of morphine and therefore reducing its dosage and side effects. We thereby hypothesize that the combination of morphine and minocycline may produce a duel effect of morphine antinociceptive and minocycline selectively inhibiting the activation of microglia.

Characterization of the host immune response in human Ganglia after herpes zoster

Varicella-zoster virus (VZV) causes varicella (chicken pox) and establishes latency in ganglia, from where it reactivates to cause herpes zoster (shingles), which is often followed by postherpetic neuralgia (PHN), causing severe neuropathic pain that can last for years after the rash. Despite the major impact of herpes zoster and PHN on quality of life, the nature and kinetics of the virus-immune cell interactions that result in ganglion damage have not been defined. We obtained rare material consisting of seven sensory ganglia from three donors who had suffered from herpes zoster between 1 and 4.5 months before death but who had not died from herpes zoster. We performed immunostaining to investigate the site of VZV infection and to phenotype immune cells in these ganglia. VZV antigen was localized almost exclusively to neurons, and in at least one case it persisted long after resolution of the rash. The large immune infiltrate consisted of noncytolytic CD8(+) T cells, with lesser numbers of CD4(+) T cells, B cells, NK cells, and macrophages and no dendritic cells. VZV antigen-positive neurons did not express detectable major histocompatibility complex (MHC) class I, nor did CD8(+) T cells surround infected neurons, suggesting that mechanisms of immune control may not be dependent on direct contact. This is the first report defining the nature of the immune response in ganglia following herpes zoster and provides evidence for persistence of non-latency-associated viral antigen and inflammation beyond rash resolution.

Herpes zoster and postherpetic neuralgia

Herpes zoster (HZ; shingles) results from reactivation of varicella-zoster virus that has been dormant in the spinal and cranial sensory ganglia following primary infection with varicella (chickenpox), usually during childhood. In developed countries more than 95% of the adult population are seropositive for varicella-zoster virus and are therefore at risk of developing HZ. Reactivation can occur at any age, but it is associated with an age-related decline in cell-mediated immunity and therefore occurs more frequently in older adults. Thus, HZ affects up to 25% of individuals during their lifetime, but approximately 50% of those aged 80 years or more. Whilst the disease is rarely life-threatening, it is associated with a number of acute symptoms such as a vesicular rash and pain. Longer-term complications include visual disturbances and postherpetic neuralgia (PHN), which is potentially the most troubling problem of all, and is associated with severe itching and allodynia. These can combine to negatively impact the day-to-day functioning and quality of life of the patient. Hospitalization associated with HZ and PHN is frequent in older individuals and a significant cost to healthcare providers. Current management of HZ with antiviral drugs and analgesics produces reasonable results in younger patients, in whom the disease is usually milder, and is effective against acute pain and skin rash. However, it is much less effective against PHN, which occurs more commonly and more severely in older patients. Once PHN has developed, current treatments offer only limited benefit and adverse effects are common. Management is challenging and often unsatisfactory (<50% of patients gain 50% relief of pain). With the older adult population steadily growing in size, the number of patients presenting with HZ is also likely to increase and this will place a greater burden on healthcare systems. Prevention strategies, such as vaccinating those at greatest risk, may offer the best option for the future.

Postherpetic neuralgia: from preclinical models to the clinic

Postherpetic neuralgia (PHN), a common complication of herpes zoster, which results from reactivation of varicella zoster virus, is a challenging neuropathic pain syndrome. The incidence and severity of herpes zoster and PHN increases with immune impairment or age and may become a greater burden both in terms of health economics and individual suffering. A clearer understanding of the underlying mechanisms of this disease and translation of preclinical outcomes to the clinic may lead to more efficacious treatment options. Here we give an overview of recent findings from preclinical models and clinical research on PHN.

Postherpetic neuralgia in the elderly

Postherpetic neuralgia (PHN) is the most common complication of herpes zoster (HZ) or 'shingles' and affects a significant proportion of HZ patients with the disease, with the elderly being most frequently and seriously affected. Characterised by various types of pain (constant, intermittent and stimulus evoked) that persist between 3 months and many years after the resolution of the HZ rash, PHN can have a severe impact on the patient's quality of life and functional ability. PHN remains highly resistant to current treatments. In this review, we discuss the epidemiology, clinical features and management of PHN in the elderly and the potential of vaccination against varicella zoster virus as a means to prevent HZ, and thus decrease the incidence and severity of PHN.

Post herpetic neuralgia, schwann cell activation and vitamin D

While the underlying pathophysiology of herpes zoster infection has been well characterised, many of the mechanisms relating to the subsequent development of post herpetic neuralgia (PHN) remain uncertain. The dorsal horn atrophy and reduction in skin innervation seen in PHN patients does not adequately explain many clinical features or the efficacy of a number of topical treatments. In the central nervous system the glia, their receptors and their secreted signalling factors are now known to have a major influence on neural function. In the peripheral nervous system, schwann cell activation in response to infection and trauma releases a number of neuroexcitatory substances. Activation of the nervi nervorum in the peripheral nervous system also leads to the release of calcitonin gene related peptide, substance P and nitric oxide. Schwann cell and/or nervi nervorum activation could be an additional mechanism of pain generation in PHN. Such a paradigm shift would mean that drugs useful in the treatment of glial cell activation such as naloxone, naltrexone, minocycline, pentoxifyllline, propentofylline, AV411 (ibudilast) and interleukin 10 could be useful in PHN. These drugs could be used systemically or even topically. High dose topical vitamin D would appear to offer particular promise because vitamin D has the ability to both reduce glial inflammation and reduce nitric oxide production.

Herpes zoster and postherpetic neuralgia: past, present and future

OBJECTIVES

The history behind the current understanding of the varicella-zoster virus and its relationship to the pain conditions caused by shingles and postherpetic neuralgia are reviewed. The framework for the current conceptualization is Hope-Simpson's latency hypothesis. Data from recent work in virology, neuroanatomy and epidemiology are reviewed, as is work using varicella-zoster virus-infected animals. The recent data largely confirm Hope-Simpson's hypothesis and extend it significantly.

5% lidocaine medicated plaster versus pregabalin in post-herpetic neuralgia and diabetic polyneuropathy: an open-label, non-inferiority two-stage RCT study

OBJECTIVE

To compare efficacy and safety of 5% lidocaine medicated plaster with pregabalin in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

STUDY DESIGN AND METHODS

This was a two-stage adaptive, randomized, open-label, multicentre, non-inferiority study. Data are reported from the initial 4-week comparative phase, in which adults with PHN or painful DPN received either topical 5% lidocaine medicated plaster applied to the most painful skin area or twice-daily pregabalin capsules titrated to effect according to the Summary of Product Characteristics. The primary endpoint was response rate at 4 weeks, defined as reduction averaged over the last three days from baseline of > or = 2 points or an absolute value of < or = 4 points on the 11-point Numerical Rating Scale (NRS-3). Secondary endpoints included 30% and 50% reductions in NRS-3 scores; change in allodynia severity rating; quality of life (QoL) parameters EQ-5D, CGIC, and PGIC; patient satisfaction with treatment; and evaluation of safety (laboratory parameters, vital signs, physical examinations, adverse events [AEs], drug-related AEs [DRAEs], and withdrawal due to AEs).

RESULTS

Ninety-six patients with PHN and 204 with painful DPN were analysed (full analysis set, FAS). Overall, 66.4% of patients treated with the 5% lidocaine medicated plaster and 61.5% receiving pregabalin were considered responders (corresponding numbers for the per protocol set, PPS: 65.3% vs. 62.0%). In PHN more patients responded to 5% lidocaine medicated plaster treatment than to pregabalin (PPS: 62.2% vs. 46.5%), while response was comparable for patients with painful DPN (PPS: 66.7% vs 69.1%). 30% and 50% reductions in NRS-3 scores were greater with 5% lidocaine medicated plaster than with pregabalin. Both treatments reduced allodynia severity. 5% lidocaine medicated plaster showed greater improvements in QoL based on EQ-5D in both PHN and DPN. PGIC and CGIC scores indicated greater improvement for 5% lidocaine medicated plaster treated patients with PHN. Improvements were comparable between treatments in painful DPN. Fewer patients administering 5% lidocaine medicated plaster experienced AEs (safety set, SAF: 18.7% vs. 46.4%), DRAEs (5.8% vs. 41.2%) and related discontinuations compared to patients taking pregabalin.

CONCLUSION

5% lidocaine medicated plaster showed better efficacy compared with pregabalin in patients with PHN. Within DPN, efficacy was comparable for both treatments. 5% lidocaine medicated plaster showed a favourable efficacy/safety profile with greater improvements in patient satisfaction and QoL compared with pregabalin for both indications, supporting its first line position in the treatment of localized neuropathic pain.

Efficacy and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin in post-herpetic neuralgia and diabetic polyneuropathy

OBJECTIVE

Neuropathic pain is often difficult to treat due to a complex pathophysiology. This study evaluated the efficacy, tolerability and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin for neuropathic pain in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

METHODS

Patients completing 4-week monotherapy with 5% lidocaine medicated plaster or pregabalin were enrolled in an 8-week combination phase. Patients with adequate response to monotherapy (recalled average pain intensity of 4 or less on 11-point numeric rating scale in the previous 3 days [NRS-3 score]) continued their previous therapy, whereas those with insufficient response received combination therapy. Efficacy endpoints included change in NRS-3 from combination phase baseline, Patient and Clinical Global Impression of Change (PGIC/CGIC), and patient's satisfaction with treatment. Safety evaluation included adverse events (AEs), drug-related AEs (DRAEs), and withdrawal due to AEs.

CLINICAL TRIAL REGISTRATION

EudraCT No. 2006-003132-29.

RESULTS

Of 229 patients in the per-protocol set (PPS: 68 PHN and 161 DPN), 71 received 5% lidocaine medicated plaster monotherapy, 57 had pregabalin added to 5% lidocaine medicated plaster, 57 pregabalin monotherapy and 44 received 5% lidocaine medicated plaster in addition to continued pregabalin treatment. There were no meaningful differences in demographic data between the treatment groups. Patients continuing on monotherapy demonstrated additional decreases in NRS-3 scores. Patients receiving combination therapy achieved clinically relevant reduction in NRS-3 values in addition to improvement achieved during the 4 weeks of monotherapy. Improvement was similar between the two combination therapy groups. Considerable improvements in patients' treatment satisfaction were reported. Incidences of AEs were in line with previous reports for the two treatments and combination therapy was generally well tolerated.

CONCLUSIONS

In patients with PHN and painful DPN failing to respond to monotherapy, combination therapy with 5% lidocaine medicated plaster and pregabalin provides additional clinically relevant pain relief and is safe and well-tolerated.

Efficacy and tolerability of a 5% lidocaine medicated plaster for the topical treatment of post-herpetic neuralgia: results of a long-term study

OBJECTIVE

Evaluation of long-term efficacy and safety of the 5% lidocaine medicated plaster for neuropathic pain symptoms in patients with post-herpetic neuralgia (PHN).

MATERIALS AND METHODS

Design - a 12-month, open-label, phase III study with an open-label extension conducted at 34 outpatient clinics in 12 European countries. Patients - aged >or=50 years, newly recruited (average pain intensity >or=4) or pre-treated with the 5% lidocaine medicated plaster in a previous study. Interventions - application of up to three 5% lidocaine medicated plasters dependent upon size of the painful area for up to 12 hours per day. Outcome measures - efficacy measures included patients' recall of pain relief and pain intensity in the previous week. Adverse events (AEs) were also reported.

RESULTS

249 patients participated in the 12-month study, 247 were analysed (full analysis set, FAS). Newly recruited patients had a mean average pain intensity (11-point numerical rating scale [NRS]) of 5.9 +/- 1.4 at baseline, which decreased to 3.9 +/- 1.6 at week 12 and remained stable at 3.9 +/- 2.3 until the end of the 12-month study. In pre-treated patients, pain intensity decreased further from baseline (3.9 +/- 1.9) to study end (3.4 +/- 2.0). Pain relief values were consistent with pain intensity reductions and were sustained in patients continuing treatment in the extension phase (mainly >or=24 months treatment in total). The most common AEs tended to be infections such as bronchitis and nasopharyngitis. Forty-eight drug-related adverse events (DRAEs), mainly mild to moderate localised skin reactions, occurred in 31 (12.4%) patients in the first 12 months. The profile of DRAEs was similar in the extension phase.

CONCLUSIONS

This study suggests that long-term treatment with the 5% lidocaine medicated plaster may provide substantial and maintained reductions in pain intensity, and that it is continuously well tolerated in patients suffering from peripheral neuropathic pain associated with previous herpes zoster infection. These findings support the use of the 5% lidocaine medicated plaster as one of the first-line therapies in this population.

Herpes zoster (shingles) and postherpetic neuralgia

Herpes zoster (HZ), commonly called shingles, is a distinctive syndrome caused by reactivation of varicella zoster virus (VZV). This reactivation occurs when immunity to VZV declines because of aging or immunosuppression. Herpes zoster can occur at any age but most commonly affects the elderly population. Postherpetic neuralgia (PHN), defined as pain persisting more than 3 months after the rash has healed, is a debilitating and difficult to manage consequence of HZ. The diagnosis of HZ is usually made clinically on the basis of the characteristic appearance of the rash. Early recognition and treatment can reduce acute symptoms and may also reduce PHN. A live, attenuated vaccine aimed at boosting immunity to VZV and reducing the risk of HZ is now available and is recommended for adults older than 60 years. The vaccine has been shown to reduce significantly the incidence of both HZ and PHN. The vaccine is well tolerated, with minor local injection site reactions being the most common adverse event. This review focuses on the clinical manifestations and treatment of HZ and PHN, as well as the appropriate use of the HZ vaccine.

Herpes zoster (shingles) and postherpetic neuralgia

Herpes zoster (HZ), commonly called shingles, is a distinctive syndrome caused by reactivation of varicella zoster virus (VZV). This reactivation occurs when immunity to VZV declines because of aging or immunosuppression. Herpes zoster can occur at any age but most commonly affects the elderly population. Postherpetic neuralgia (PHN), defined as pain persisting more than 3 months after the rash has healed, is a debilitating and difficult to manage consequence of HZ. The diagnosis of HZ is usually made clinically on the basis of the characteristic appearance of the rash. Early recognition and treatment can reduce acute symptoms and may also reduce PHN. A live, attenuated vaccine aimed at boosting immunity to VZV and reducing the risk of HZ is now available and is recommended for adults older than 60 years. The vaccine has been shown to reduce significantly the incidence of both HZ and PHN. The vaccine is well tolerated, with minor local injection site reactions being the most common adverse event. This review focuses on the clinical manifestations and treatment of HZ and PHN, as well as the appropriate use of the HZ vaccine.

Herpes zoster and postherpetic neuralgia: optimizing management in the elderly patient

Herpes zoster (HZ) results from reactivation of varicella-zoster virus (VZV) that has been persistent and clinically dormant in spinal ganglia or cranial sensory nerves since primary infection with VZV. The most common reason for reactivation is a decline in zoster-specific cell mediated immunity as a result of aging (immunosenescence). More than two-thirds of HZ cases occur in people >or=60 years of age. HZ incidence is higher in persons who are immunocompromised as a result of disease (e.g. malignancies such as lymphoma, HIV/AIDS, diabetes mellitus) or treatments such as chemotherapy and radiotherapy. HZ incidence is also increased by therapeutic immune suppression following organ transplantation and in patients taking high-dose corticosteroids. However, HZ may occur in otherwise healthy young people. Although serious and life-threatening complications sometimes occur, the most common complication is postherpetic neuralgia (PHN), which may persist for months or years and is significantly resistant to treatment despite substantial advances in the understanding of its pathological mechanisms. The medical and social costs of HZ and PHN are high, particularly in older patients. Prevention of PHN in patients with HZ is unsatisfactory although antiviral drugs reduce the duration of pain after HZ. A live attenuated vaccine has been shown to reduce the incidence of HZ and PHN as well as the burden of illness in subjects aged >or=60 years. In view of the increasing numbers of elderly persons in the population and the poor outcomes of PHN treatment, vaccination against HZ at approximately 60 years of age appears to be an appropriate strategy.

Antidepressant use in nonmajor depression: secondary analysis of a program to encourage active, rewarding lives for seniors (PEARLS), a randomized controlled trial in older adults from 2000 to 2003

BACKGROUND

It is estimated that major depressive disorder affects 0.9% of community-dwelling older adults in the United States. However, as many as 18% of older US adults reportedly suffer from depressive symptoms that do not necessarily fit the criteria for major depressive disorder (eg, dysthmia, minor depression).

OBJECTIVES

The goals of this study were to describe patterns of antidepressant medication use in older adults with dysthymia or minor depression and to examine factors associated with the use of antidepressants at baseline.

METHODS

This was a secondary analysis using cross-sectional data collected during a randomized controlled trial conducted from 2000 through 2003. It involved community senior service agencies and in-home visits in Seattle, Washington. Adults aged >or=60 years who had minor depression or dysthymia and were receiving services through community senior service agencies or living in senior public housing were included. Study participants were classified as users or nonusers of antidepressants. Prescription medication use in the past 2 weeks was assessed at baseline and 6 and 12 months. Medication name, dose, and directions were recorded from the medication label. Logistic regression was used to examine variables associated with baseline antidepressant use.

RESULTS

A total of 138 patients (mean age, 73.00 years) were included; the majority of study participants were female (779.00%). Overall, 42.33% were nonwhite (34.3% black, 4.4% Asian, 1.5% American Indian/Alaskan Native, 0.7% Hispanic, and 1.5% other). At baseline, 36.2% of study participants (n = 50) were using antidepressants. Selective serotonin reuptake inhibitors were the most common class of antidepressants, used by 62.00%, 70.22%, and 71.11% of antidepressant users at baseline, 6, and 12 months, respectively. However, nortriptyline was the most common antidepressant at baseline, taken by 20.00% of antidepressant users. Use of other prescription medications was associated with antidepressant use at baseline.

CONCLUSIONS

We found antidepressant use to be low in these relatively poor, community-dwelling, ethnically diverse older adults with dysthymia and minor depression in 2000 through 2003, with 36.22% of participants using antidepressants at baseline. Antidepressant users were more likely to be taking other prescription medications than nonusers.

Diagnosis and assessment of pain associated with herpes zoster and postherpetic neuralgia

Accurate evaluation of pain plays a critical role in identifying new interventions for the treatment and prevention of herpes zoster and postherpetic neuralgia (PHN). Different types of pain and other sensory symptoms are found in patients with herpes zoster, and these vary greatly with respect to their presence, location, duration, intensity, and quality. The results of recent studies of herpes zoster and PHN and the development of new methods for assessing neuropathic pain provide a foundation for diagnosing and assessing the pain associated with herpes zoster. We review the results of recent research to identify the essential components that must be considered in developing an evidence-based description of pain associated with herpes zoster and PHN.

PERSPECTIVE

Comprehensive assessments of pain are necessary for clinical research on the epidemiology, natural history, pathophysiologic mechanisms, treatment, and prevention of pain in herpes zoster and PHN.