Pain caused by herpes zoster infection

Genome-wide association study identifies candidate loci associated with chronic pain and postherpetic neuralgia

BACKGROUND

Human twin studies and other studies have indicated that chronic pain has heritability that ranges from 30% to 70%. We aimed to identify potential genetic variants that contribute to the susceptibility to chronic pain and efficacy of administered drugs. We conducted genome-wide association studies (GWASs) using whole-genome genotyping arrays with more than 700,000 markers in 191 chronic pain patients and a subgroup of 89 patients with postherpetic neuralgia (PHN) in addition to 282 healthy control subjects in several genetic models, followed by additional gene-based and gene-set analyses of the same phenotypes. We also performed a GWAS for the efficacy of drugs for the treatment of pain.

RESULTS

Although none of the single-nucleotide polymorphisms (SNPs) were found to be genome-wide significantly associated with chronic pain (p ≥ 1.858 × 10^-7), the GWAS of PHN patients revealed that the rs4773840 SNP within the ABCC4 gene region was significantly associated with PHN in the trend model (nominal p = 1.638 × 10^-7). In the additional gene-based analysis, one gene, PRKCQ, was significantly associated with chronic pain in the trend model (adjusted p = 0.03722). In the gene-set analysis, several gene sets were significantly associated with chronic pain and PHN. No SNPs were significantly associated with the efficacy of any of types of drugs in any of the genetic models.

CONCLUSIONS

These results suggest that the PRKCQ gene and rs4773840 SNP within the ABCC4 gene region may be related to the susceptibility to chronic pain conditions and PHN, respectively.

WITHDRAWN: Topical lidocaine for the treatment of postherpetic neuralgia

Background

This is an update of the original Cochrane review published in Issue 2, 2007. The cause of postherpetic neuralgia is damage to peripheral neurons, dorsal root ganglia, and the dorsal horn of the spinal cord, secondary to herpes zoster infection (shingles). In postherpetic neuralgia, peripheral neurons discharge spontaneously and have lowered activation thresholds, and exhibit an exaggerated response to stimuli. Topical lidocaine dampens peripheral nociceptor sensitisation and central nervous system hyperexcitability, and may benefit patients with postherpetic neuralgia.

Objectives

To examine efficacy and safety of topical lidocaine in the treatment of postherpetic neuralgia.

Search methods

We searched the Cochrane Pain, Palliative and Supportive Care Group Trials Register, CENTRAL, MEDLINE, EMBASE, LILACS, SIGLE, Citation Index, the reference lists of all eligible trials, key textbooks, and previous systematic reviews. Last search conducted April 2011.

Selection criteria

Randomised or quasi‐randomised trials comparing topical applications of lidocaine in patients of all ages with postherpetic neuralgia (pain persisting at the site of shingles at least one month after the onset of the acute rash).

Data collection and analysis

Two review authors extracted data, and a third checked them.

Main results

In the original review three studies involving 182 topical lidocaine treated participants and 132 control participants were included. Two studies gave data on pain relief, and the remaining study provided data on secondary outcome measures. The largest study published as an abstract compared topical lidocaine patch to a placebo patch and accounted for 150 of the 314 participants (48%).

A meta‐analysis combining two studies identified a significant difference between topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P = 0.003).

There was a statistical difference between the groups for the secondary outcome measure of mean VAS score reduction (P = 0.03), but this was only for a single small study. There were a similar number of adverse skin reactions in both treatment and placebo groups.

The highest recorded blood lidocaine concentration varied between 59 ng/ml and 431 ng/ml between studies. The latter figure is high and the authors of the study suggest that the sample had been contaminated during the assay procedure.

Authors' conclusions

Since the last version of this review in Issue 2, 2007 no new studies have been found and the results therefore remain the same. There is still insufficient evidence to recommend topical lidocaine as a first‐line agent in the treatment of postherpetic neuralgia with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (e.g. topical anaesthetic applications versus anti‐epileptic drugs).

Topical lidocaine may benefit some patients on an individual basis though there is stronger evidence for the use of other drugs. Postherpetic neuralgia is a long‐lasting pain disorder that causes pain from stimuli that are not normally painful. Local anaesthetics (such as lidocaine) can reduce the sensation of pain that is transmitted through nerves, and allow pain relief in patients with postherpetic neuralgia. This review found three small studies involving 182 topical lidocaine treated participants and 132 control participants using lidocaine for patients with postherpetic neuralgia. Two studies provided data on pain relief amongst patients with postherpetic neuralgia, and they showed some improvement in pain when topical lidocaine was compared to a placebo. No comparison was made with other medications that are in current use for the treatment of postherpetic neuralgia. The side effects of topical lidocaine are very minimal, but include skin problems (such as irritation and redness). We are unable to recommend the use of topical lidocaine as a first‐line treatment for postherpetic neuralgia at this stage. Further studies are needed to compare topical lidocaine to other medications in the treatment of postherpetic neuralgia.

A phase 2a, randomized, crossover trial of gabapentin enacarbil for the treatment of postherpetic neuralgia in gabapentin inadequate responders

OBJECTIVE

To compare the efficacy of high-dose (3,600 mg/day) vs low-dose (1,200 mg/day) oral gabapentin enacarbil (GEn) on pain intensity in adults with postherpetic neuralgia (PHN) and a history of inadequate response to ≥1,800 mg/day gabapentin.

DESIGN

Multicenter, randomized, double-blind, crossover study (NCT00617461).

SETTING

Thirty-five outpatient centers in Germany and the United States.

SUBJECTS

Subjects aged ≥18 years with a diagnosis of PHN.

METHODS

During a 2-week baseline period, subjects received open-label treatment with 1,800 mg/day gabapentin. Subjects who had a mean 24-hour average pain intensity score ≥4 during the last 7 days of the baseline period were randomized to receive GEn (1,200 or 3,600 mg/day) for treatment period 1 (28 days), followed by GEn 2,400 mg/day (4 days), and the alternate GEn dose for treatment period 2 (28 days).

RESULTS

There was a modest but significant improvement in pain intensity scores with GEn 3,600 mg vs 1,200 mg (adjusted mean [90% confidence interval] treatment difference, -0.29 [-0.48 to -0.10]; P = 0.013). The difference in efficacy between doses was observed primarily in subjects who received the higher dose during treatment period 2; certain aspects of the study design may have contributed to this outcome. Plasma steady-state gabapentin exposure during GEn treatment was as expected and consistent between treatment periods. No new safety signals or adverse event trends relating to GEn exposure were identified.

CONCLUSIONS

While the overall results demonstrated efficacy in a PHN population, the differences between treatment periods confound the interpretation. These findings could provide insight into future trial designs.

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.

Neuroimaging the genomics of pain processing--a perspective

The significant inter-individual variability in pain behavior and its contributing factors remains a pervasive clinical challenge and has generated intense scientific investigations in this field. Recent studies indicate that our genes considerably influence nociceptive information processes, how our nociceptive system copes with peripheral injury, and the individual response to analgesic treatments. Neuroimaging studies of pain are beginning to link such genetic influences with physiological processes in the human brain. This review presents the pioneering endeavors of the hybrid approach of neuroimaging pain genes in humans and identifies potential future directions.

Progress in genetic studies of pain and analgesia

Interindividual variability in pain sensitivity and the response to analgesic manipulations remains a considerable clinical challenge as well as an area of intense scientific investigation. Techniques in this field have matured rapidly so that much relevant data have emerged only in the past few years. Our increasing understanding of the genetic mediation of these biological phenomena have nonetheless revealed their surprising complexity. This review provides a comprehensive picture and critical analysis of the field and its prospects.

Topical lidocaine for the treatment of postherpetic neuralgia

BACKGROUND

The cause of postherpetic neuralgia is damage to peripheral neurons, dorsal root ganglia, and the dorsal horn of the spinal cord, secondary to herpes zoster infection (shingles). In postherpetic neuralgia, peripheral neurons discharge spontaneously and have lowered activation thresholds, and exhibit an exaggerated response to stimuli. Topical lidocaine dampens peripheral nociceptor sensitisation and central nervous system hyperexcitability, and may benefit patients with postherpetic neuralgia.

OBJECTIVES

To examine the efficacy and safety of topical lidocaine in the treatment of postherpetic neuralgia.

SEARCH STRATEGY

We searched the Cochrane Pain, Palliative and Supportive Care Group Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and LILACS, SIGLE for conference proceedings, Citation Index, the reference lists of all eligible trials, key textbooks, and previous systematic reviews. We also wrote to authors of all identified trials.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing all topical applications of lidocaine, including gels and patches in patients of all ages with postherpetic neuralgia (pain persisting at the site of shingles at least one month after the onset of the acute rash).

DATA COLLECTION AND ANALYSIS

Two review authors extracted data, and a third checked them. We obtained some missing data from the US Food and Drugs Administration.

MAIN RESULTS

Three trials involving 182 topical lidocaine treated participants and 132 control participants were included. Two trials gave data on pain relief, and the remaining study provided data on secondary outcome measures. The largest trial published as an abstract compared topical lidocaine patch to a placebo patch and accounted for 150 of the 314 patients (48%).A meta-analysis combining two of the three studies identified a significant difference between the topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P = 0.003). There was a statistical difference between the groups for the secondary outcome measure of mean VAS score reduction (P = 0.03), but this was only for a single small trial. There were a similar number of adverse skin reactions in both treatment and placebo groups. The highest recorded blood lidocaine concentration varied between 59 ng/ml and 431 ng/ml between trials. The latter figure is high and the authors of the study suggest that the sample had been contaminated during the assay procedure.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend topical lidocaine as a first-line agent in the treatment of postherpetic neuralgia with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (e.g. topical anaesthetics versus anti-epileptics).

Role of bacterial superinfections in the pathogenesis of postzosteric neuralgia

Varicella-zoster virus (VZV) is an alpha-herpes virus that causes varicella (chickenpox), establishes latency in dorsal root ganglia and may reactivate to cause herpes zoster (shingles). Postherpetic neuralgia is the most common debilitating complication of herpes zoster. It is currently supposed that scarring of the dorsal root ganglia and atrophy of the dorsal horn as a result of intense inflammation may play a central role in the pathogenesis of this condition. The exact pathogenesis of the inflammatory reaction leading to persistent ganglion damage is still poorly understood. However, immune suppression is a recognized risk factor for the development of postzosteric neuralgia in zoster patients (increased risk, e.g., in aged patients over 80 years or diabetes mellitus patients). There is some evidence that remote streptococcal and staphylococcal infections may induce immunologic disease mechanisms consequently affecting the central nervous system. Since streptococcal and/or staphylococcal superinfection of skin lesions is common in herpes zoster, we present a hypothesis of immunopathogenesis of postzosteric neuralgia, i.e., as the result of augmentation of local ganglion inflammation due to bacteria-driven clonal expansion of VZV-specific T-cell subsets in the affected skin. Based on the aforementioned hypothesis it is interesting: (1) to study the impact of concomitant systemic antibiotic treatment to the standard antiviral regimen on the rate and severity of both bacterial superinfection of zoster skin lesions and postzosteric neuralgia and (2) to quantify the VZV-specific T-cell response as a function of the degree of bacterial superinfection of zoster skin lesions. Challenging of the present hypothesis should provide an effective means of preventing postherpetic neuralgia by preventing and consequently treating the bacterial superinfection of zoster skin lesions.

The human histocompatibility leukocyte antigen (HLA) haplotype is associated with the onset of postherpetic neuralgia after herpes zoster

In some herpes zoster patients, pain persists for more than 3 months or more after healing of vesicular eruptions; this condition is termed postherpetic neuralgia (PHN). We have recently reported the association of the human histocompatibility leukocyte antigens (HLA) haplotype, HLA-A*3303-B*4403-DRB1*1302 with PHN patients; however, it has not been determined whether the haplotype is also associated with herpes zoster that did not develop subsequent PHN. To distinguish whether the haplotype is associated with herpes zoster or the development of PHN, we examined if herpes zoster patients without subsequently PHN are also associated with the HLA haplotype or not. Herpes zoster patients were followed up for more than 6 months, and HLA alleles and haplotypes were compared among the PHN patients (n = 52) the herpes zoster patients who did not develop PHN (n = 42) and healthy controls (n = 125). The frequencies of the risk haplotype in the PHN patients, in the healthy controls and in the herpes zoster patients without subsequent PHN were 16.3, 5.2 and 4.8%, respectively. While the frequency of the risk haplotype was significantly higher in the PHN patients than in the healthy controls (P = 0.0006) no difference was observed between the herpes zoster patients without subsequent PHN and the healthy controls. No significant association was found between the duration of symptoms or the site of herpes zoster and the HLA alleles and the haplotype. These results suggest that the HLA-A*3303-B*4403-DRB1*1302 haplotype plays an important role in the development of PHN after herpes zoster, but not in the onset of herpes zoster.

Hiccups, eructation, and other uncommon prodromal manifestations of herpes zoster

Although the most frequent presentation of herpes zoster involves sensory neurons, motor and autonomic symptomatology is also known to occur in this disease. An unusual symptom of hiccups is described here. Other infrequent manifestations of this common illness, including the Ramsay Hunt syndrome, herpes zoster ophthalmicus, urinary and fecal retention, sexual dysfunction, and zoster sine herpete, are reviewed. Greater awareness of unusual presentations of herpes zoster is necessary for proper diagnosis and timely management of complications that may otherwise lead to disability and serious long-term sequelae.

Nonopioid and adjuvant analgesics in chronic pain management: strategies for effective use

Nonopioid and adjuvant analgesics encompass a huge range of heterogenous drugs that differ chemically and mechanistically. These drugs generally are prescribed for mild-to-moderate pain, as coanalgesics for severe pain, or to target specific pain-generating mechanisms. This article provides an overview of some of the more commonly used nonopioid and adjuvant analgesics used to treat chronic pain, including salicylates, acetaminophen, nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, anticonvulsants, N-Methyl-D-Aspartate receptor antagonists, lidocaine, skeletal muscle relaxants, and topical analgesics.

Management of Painful Conditions in the Elderly

Persistent pain conditions in the elderly are most often due to degenerative disorders of the spine, osteoarthritis of the joints, malignant cancer, and vascular disorders. The consequences of persistent pain include depression, anxiety, de-creased socialization, sleep disturbance, impaired ambulation, and increased healthcare utilization. Proper pain assessment is the key to selecting appropriate treatment. Barriers to pain assessment are associated with the patient's perception of pain and the caregiver's attitude towards providing effective treatment. All elderly patients have age-related physiologic changes that affect absorption, distribution, metabolism, and clearance of medications used for pharmacologic treatment. Medications used in pain management include opioids, nonsteroidal anti-inflammatory drugs, gabapentin, nortriptylline, desipramine, and lidocaine 5%patch. Pharmacists have an important role in the monitoring of medications in elderly. As the utilization of prescription medication continues to increase in the elderly, pharmacists are becoming the frontline of healthcare care for this population.

Association of HLA-A*3303-B*4403-DRB1*1302 haplotype, but not of TNFA promoter and NKp30 polymorphism, with postherpetic neuralgia (PHN) in the Japanese population

Herpes zoster is a common disease caused by reactivation of the varicella zoster virus (VZV). In a small number of herpes zoster patients, pain persists beyond 4 weeks or more after healing of vesicular eruptions; this condition is termed postherpetic neuralgia (PHN). Positive associations of human histocompatibility leukocyte antigens (HLA) class I antigens, A33 and B44, with PHN in the Japanese population have been reported. Our hypothesis is that susceptibility genes to PHN might exist in the HLA region and the study objective is to further examine possible associations of genes in HLA class I, II and III regions, HLA-A, -B, -DRB1, tumor necrosis factor alpha (TNFA) promoter, and a natural killer cell activating receptor, NKp30 polymorphisms with PHN. Although TNFA or NKp30 in the class III region had been considered as a candidate locus, we found no associations of TNFA promoter or NKp30 polymorphisms with PHN in this study. We demonstrated that HLA-A*3303, -B*4403 and -DRB1*1302 alleles were significantly associated with PHN (P = 0.0007 for A*3303, P = 0.001 for B*4403 and P = 0.001 for DRB1*1302). The frequency of the HLA-A*3303-B*4403-DRB1*1302 haplotype was also significantly higher in the PHN patients than in the healthy controls (P = 0.0039). Our results suggest that this haplotype might be related to the pathogenesis of PHN.

Current management of postherpetic neuralgia

BACKGROUND

The herpes zoster rash occurs when a dormant varicella zoster virus reactivates in dorsal root and cranial nerve ganglia. Pain that persists in the region where this rash occurred after the cutaneous lesions have healed is termed postherpetic neuralgia (PHN). A wide variety of therapies has been used with varying degrees of success to prevent the occurrence of PHN and to reduce pain with established PHN.

REVIEW SUMMARY

In this review, we discuss the clinical presentation of PHN, current strategies for the prevention and management of this disease, and observations that have increased our understanding of the neural mechanisms involved in PHN.

CONCLUSIONS

Several classes of drugs are effective in attenuating the pain and hyperalgesia caused by PHN, but no single drug leads to the complete relief of symptoms. Additional research is needed to improve treatment strategies and define the role of invasive pain management techniques in cases where PHN is associated with intractable pain.

[Clinical characteristics and prognostic significance of preherpetic neuralgia]

INTRODUCTION

Herpes zoster is a world-wide disease of older age commonly presenting with preherpetic pain. The aim of the study was to determine clinical characteristics of preherpetic neuralgia and its influence on occurrence of postherpetic neuralgia.

MATERIAL AND METHODS

A prospective, controlled trial included 88 patients with preherpetic neuralgia. 44 herpes zoster patients without preherpetic neuralgia were included in the control group. All of them were clinically followed-up for three months after complete healing of skin lesions.

RESULTS

Older age (> 60 years) was significantly predominant (59.1%) compared with other age groups (p < 0.01) as well as female sex (59.9%) compared with the male sex (p < 0.01). There was no significant predominance of any type of preherpetic neuralgia (stabbing, burning, itching, dull pain). More intense preherpetic pain (reported as "severe" and "moderate") was established more often than mild pain. The mean duration of preherpetic pain was 4.4 days (ranged between 1-20 days). Postherpetic neuralgia developed in 36/88 patients with preherpetic neuralgia (affecting predominantly older than 50 years of age--31/36), but there was no significant difference in proportion of postherpetic neuralgia (PHN) according to those without preherpetic neuralgia.

DISCUSSION AND CONCLUSION

People older than 60 years are the most common age group among herpes zoster patients suffering from preherpetic neuralgia. Sex distribution of patients with preherpetic pain reveals highly significant predominance of female sex. Opposite to some other authors' reports, preherpetic neuralgia and its severity have not been proven as risk factors for postherpetic neuralgia in patients involved in our trial.