Postherpetic Neuralgia: The Never-Ending Challenge

[Neurosurgical treatment of postherpetic neuralgia]

Postherpetic neuralgia is a chronic and debilitating condition that can occur following an episode of herpes zoster (shingles). It is characterized by severe, persistent pain in the area where the shingles rash occurred. While various treatment approaches exist, including medications and non-invasive therapies, some cases of postherpetic neuralgia may require neurosurgical intervention. Neurosurgical treatment options for postherpetic neuralgia aim to alleviate the pain by targeting the affected nerves or neural pathways. One common approach is spinal cord stimulation (SCS). In SCS, electrodes are implanted along the spinal cord, and electrical impulses are delivered to interfere with the transmission of pain signals. This technique can modulate pain perception and significantly reduce the intensity and frequency of postherpetic neuralgia symptoms. Neurosurgical treatment of postherpetic neuralgia is typically considered when conservative measures have failed to provide sufficient relief. However, it is crucial for patients to undergo a comprehensive evaluation and consultation with a neurosurgeon to determine the most appropriate treatment approach based on their specific condition and medical history. The risks, benefits, and potential outcomes of neurosurgical interventions should be carefully discussed between the patient and their healthcare provider to make an informed decision.

Analysis of the Risk Factors for Mechanical Allodynia in Herpetic Neuralgia: A Retrospective Cross-Sectional Study

Purpose

Mechanical allodynia is reportedly common during herpetic neuralgia. The purpose of this study was to establish a risk prediction model to predict the individual risk of allodynia in herpetic neuralgia.

Methods

Three hundred and eighty-six patients with trunk herpetic neuralgia were divided into two regions, T2-5 and T6-11. The causality between allodynia and other factors was analyzed by a binary logistic regression model.

Results

42.2% of subjects had allodynia, 137 suffered from dynamic allodynia, and 110 with dynamic allodynia experienced local sweating. The following 5 items as predictors determined this model: local sweating (Odd Ratio = 27.57, P<0.001), lesion location (Odd Ratio=2.46, P =0.017), pain intensity (Odd Ratio=1.38, P =0.020), pain duration (Odd Ratio=0.94, P =0.006), and local scars (Odd Ratio=0.07, P<0.001). The presence and development of allodynia are associated with local sweating. The positive proportion of the Iodine-starch test between the T2-5 (50.0%) with the T6-11 (23.7%) had a statistically significant difference (χ2=5.36, P=0.021). 29.5% of patients at the T2-6 had obvious sweating, which was different from only sticky feelings at the T6-11 (70.5%, χ2=10.88, P=0.001). 19.2% of patients with residual scars and allodynia was significantly lower than 48.5% of patients without allodynia (χ2=15.28, P<0.001).

Conclusion

This analysis suggests that local sweating is a concomitant symptom in dynamic allodynia, which imply the sympathetic nerves innervating the sweat glands of the skin were also involved during herpetic neuralgia. This may assist in the evaluation of dynamic allodynia and prove the role of sympathetic nerve intervention for herpetic neuralgia.

Comparison of the Severity of Zoster-Associated Pain and Incidence of Postherpetic Neuralgia in Patients with and without Pre-Existing Spinal Disorders at the Same Spinal Nerve Level: A Retrospective Multicenter Study

The incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN) are significantly influenced by age. As individuals age, the occurrence of spinal disorders increases, thereby raising the likelihood of HZ and PHN coexistence. Considering this, our study aimed to explore the potential impact of pre-existing spinal disorders at the nerve level where HZ developed, on the severity of zoster-associated pain (ZAP) and the incidence of PHN. For our investigation, we retrospectively analyzed a total of 237 patients who presented with HZ and ZAP at various sensory levels (cervical, thoracic, lumbar, and sacral) with or without pre-existing spinal disorders. The presence or absence of spinal disorders at the sensory level affected by HZ was determined using computed tomography or magnetic resonance imaging. Our study results revealed that the group with spinal disorders at the sensory level where HZ developed did not exhibit an increased incidence of PHN. However, 3-6 months after HZ onset, this same group showed significantly higher ZAP scores compared to the group without spinal disorders. It implies a need for heightened pain management, as the coexistence of these conditions can increase pain severity. This study furnishes an initial standpoint to delve into intricate interactions between two diseases.

Pain Fluctuations of Women with Subacute Herpetic Neuralgia During Local Methylcobalamin in Combination with Lidocaine Treatment: A Single-Blinded Randomized Controlled Trial

Purpose

To evaluate the efficacy and pain fluctuations of methylcobalamin in combination with lidocaine local injection treatment for subacute herpetic neuralgia (SHN).

Methods

Seventy-nine women (60.4 ± 2.7 years) with thoracic SHN were enrolled and randomized to receive a combination of methylcobalamin and lidocaine local injection (MI, N=40), or a combination of lidocaine patch 5% and oral methylcobalamin (PO, N=39) for four weeks. Repeated-measures analyses of variance were used to evaluate the effect on pain levels. Generalized estimation equations were used to analyze the cause-effect relationship between pain fluctuations and influencing factors.

Results

At the treatment endpoint, the group, treatment time, and group interacted with treatment time effects of the pain scores and area were statistically significant (P<0.001), The pain scores were 2.9 ±0.9 (MI) and 4.3 ± 1.5 (PO). 80.00% (MI) or 28.21% (PO) of patients had pain scores ≤ 3, the odds ratio was 2.84 (95% CI: 1.68 to 4.79). The incidence of postherpetic neuralgia was 5.0% (2/40) at 3 months. Pain fluctuated repeatedly during treatment. The pain fluctuation increased from 8.75 log folds in the afternoon, to 79.85 log folds at night. With the ADLs level increasing from 1 to 3, the pain fluctuated from 4.28 to 17.70 log folds. Allodynia, itching, sleep quality, and ADLs were the significant influencing factors (P<0.05).

Conclusion

This study validated the efficacy of methylcobalamin combined with lidocaine for SHN, and confirmed that pain levels in patients with SHN had an obvious circadian rhythm. ADLs were an important cause of pain fluctuations.

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

Introduction

Postherpetic neuralgia (PHN) is a severe condition that remains a challenge to treat. Spinal cord stimulation (SCS) is used in cases of insufficient efficacy of conservative treatment. However, in contrast to many other neuropathic pain syndromes, there is a huge problem in reaching long-term stable pain relief in patients with PHN using conventional tonic SCS. The objective of this article was to present a review of the current management strategies of PHN, their efficacy, and safety.

Materials and Methods

We searched for articles containing the keywords "spinal cord stimulation AND postherpetic neuralgia," "high-frequency stimulation AND postherpetic neuralgia," "burst stimulation AND postherpetic neuralgia" and "dorsal root ganglion stimulation AND postherpetic neuralgia" in Pubmed, Web of Science, and Scopus databases. The search was limited to human studies published in the English language. There were no publication period limitations. Bibliographies and references of selected publications on neurostimulation for PHN were further manually screened. The full text of each article was studied once the abstract was analyzed by the searching reviewer and found appropriate. The initial search yielded 115 articles. Initial screening based on abstract and title allowed us to exclude 29 articles (letters, editorials, and conference abstracts). The full-text analysis allowed us to exclude another 74 articles (fundamental research articles, research utilizing animal subjects, and systemic and nonsystemic reviews) and results of PHN treatment presented with other conditions, leaving 12 articles for the final bibliography.

Results

12 articles reporting on the treatment of 134 patients with PHN were analyzed, with a disproportionally large amount of traditional SCS treatment than that to alternative SCS: DRGS (13 patients), burst SCS (1 patient), and high-frequency SCS (2 patients). Long-term pain relief was achieved in 91 patients (67.9%). The mean VAS score improvement was 61.4% with a mean follow-up time of 12.85 months. Although the number of patients in alternative SCS studies was very limited, almost all of them showed good responses to therapy with more than 50% VAS improvement and reduction of analgesic dosage. The article contains a review analysis of 12 articles concerning the current methods of treatment for postherpetic neuralgia including conservative treatment, spinal cord stimulation, and novel neuromodulation strategies. Available information on the pathophysiology of PHN and the effect or stimulation on its course, together with a number of technical nuances concerning various types of neurostimulation are also elucidated in this article. A number of alternative invasive treatments of PHN are also discussed.

Conclusions

Spinal cord stimulation is an established treatment option for patients with pharmacologically resistant PHN. High-frequency stimulation, burst stimulation, and dorsal root ganglion stimulation are promising options in the management of PHN due to the absence of paresthesias which can be painful for patients with PHN. But more research is still required to recommend the widespread use of these new methods.

A comparative study between transcutaneous electrical nerve stimulation and pulsed electromagnetic field therapy in the management of post-herpetic neuralgia of the sciatic nerve

OBJECTIVES

To compare the efficacy of pulsed electromagnetic field therapy (PEMFT) versus transcutaneous electrical nerve stimulation (TENS) in the treatment of post-herpetic neuralgia of the sciatic nerve.

METHODS

A double-blinded randomized clinical study has included 56 patients (18 males and 38 females). Participants were randomly and equally assigned into 2 groups. Both groups received conventional physical therapy treatment. Moreover, group (A) has an additional TENS, and group (B) had PEMFT. Both modalities were applied once daily, 3 times a week for 20 minutes for 8 successive weeks. Visual analog scale (VAS) and carbamazepine intake (CMI) dose have been assessed before and after interventions.

RESULTS

There was a significant decrease in VAS and CMI post-treatment in group A and B compared with that pretreatment (P > .001). The percent decrease in VAS and CMI in group A were 72.44% and 69.47% respectively and that for group B was 68.95% and 67.94% respectively. The findings revealed a non-significant difference in VAS and CMI (P > .05) between groups. The Means of VAS and CMI were (2.4 ± 0.78, 204.5 ± 16.76 and 2.67 ± 0.9, 210.57 ± 16.5) in group A and group B respectively. The mean difference for VAS and CMI was (-0.27 and -6.07) between groups post-treatment respectively.

CONCLUSION

Both TENS and PEMFT were effective and nearly equivalent in improving the post-herpetic neuralgia of the sciatic nerve as measured by in VAS and CMI. Clinical recommendations should be highlighted to instigate the using of TENS and PEMFT in the management of post-herpetic neuralgia of the sciatic nerve.

A new susceptibility index to predict the risk of severe herpes zoster-associated pain: A Japanese regional population-based cohort study, the Shizuoka study

BACKGROUND

Approximately 7-20% of patients with herpes zoster (HZ) develop zoster-associated pain (ZAP). ZAP not only impairs quality of life and psychological well-being, but also can reduce work effectiveness, which has negative economic effects. Reports of ZAP risk factors are inconsistent.

OBJECTIVE

To confirm risk factors for the development of severe ZAP in HZ patients in Japan using a large-scale database, the Shizuoka Kokuho Database.

METHODS

A population-based cohort study using the Shizuoka Kokuho Database was conducted. Of 792,647 patients, 7491 (0.95%) experienced "severe ZAP" (as defined in this study). We developed a ZAP risk prediction scoring system by identifying risk factors using logistic regression analysis of several candidate risk factors for severe ZAP: age, sex, seasonality, and presence of comorbidities (using the Charlson comorbidity index), excluding HIV/AIDS.

RESULTS

We identified peripheral vascular disease and the onset from October to December as novel risk factors for severe ZAP, in addition to the previously reported risk factors of age and comorbidities (cerebral vascular disease, chronic pulmonary disease, rheumatic disease, peptic ulcer, liver disease, diabetes, and malignant neoplasms with/without metastasis). In contrast, dementia was found to reduce ZAP risk. We developed a susceptibility index to predict the risk of ZAP.

CONCLUSION

We newly demonstrated that peripheral vascular disease and the onset from October to December are ZAP risk factors. Our comorbidity findings support previous observations. The susceptibility index proposed here provides a new approach to the prevention of ZAP using early intervention for high-risk patients.

Modulation of mRNA expression of IL-6andmTORC1 and efficacy and feasibility of an integrated approach encompassing cognitive behavioral therapy along with Pregabalin for management of neuropathic pain in Postherpetic Neuralgia: A Pilot Study

OBJECTIVE

This study was designed to explore the efficacy and feasibility of cognitive behavioural therapy(CBT) along with pregabalin and compare it with pregabalin monotherapy for the management of neuropathic pain in post-herpetic neuralgia (PHN) patients and to explore the modulation of mRNA expression of interleukin (IL)-6 and mammalian target of rapamycin-1 (mTORC1) genes in these patients.

DESIGN

Randomized controlled pilot study.

METHODS

The patients aged >18 years of age with an established diagnosis of PHN with evident allodynia and hyperalgesia who had pain for at least 3 months after healing of rash with pain intensity ≥4/10 on NRS-Pain Scale were enrolled. The trial was registered with the Clinical Trials Registry-India (CTRI/2019/03/018014). A detailed baseline assessment regarding type and duration of pain and disability using pain-relevant self-report questionnaires was done. Two ml venous blood samples were collected for gene expression studies at base line and at end of 12 weeks of treatment. Patients were randomized into one of the two groups. Group PR received pregabalin and Group CP received CBT along with pregabalin. The pain intensity was measured using numeric rating scale (NRS)-Pain scale, neuropathic component of the pain by using Neuropathic Pain Symptom Inventory (NPSI) and Pain Detect Questionnaire (PDQ), sleep interference by NRS-Sleep, pain-related catastrophic thoughts by using Pain Catastrophizing Scale (PCS), depression and quality of life using Beck Depression Inventory-II (BDI-II) and Short Form-12 (SF-12), respectively. The research funding was supported by the intramural grant from the institution.

RESULTS

A total of 40 patients with 20 in each group were included. Following integrated approach encompassing CBT and Pregabalin, group CP had significant downregulation of mRNA expression of IL-6; however, no such correlation was observed with mTOR expression. A significant decline in the intensity of pain, NPSI scoring for burning, allodynia, and pain-related catastrophizing were observed; also a significant improvement in depressive symptoms and quality of life were observed with the use of CBT.

CONCLUSIONS

A significant downregulation of mRNA expression of IL-6 was observed; however, no significant correlation was observed between NRS pain score and ΔCt values of mRNA expression of both mTORC1 gene and IL-6 gene at baseline and at the end of 12th week. In addition, we note a significant decrease in pain intensity, depressive symptoms, and pain-related catastrophizing while improving QOL was observed with the use of CBT as a clinical adjunct along with pregabalin in PHN patients.

Local Administration of Methylcobalamin for Subacute Ophthalmic Herpetic Neuralgia: A Randomized, Phase III Clinical Trial

OBJECTIVES

The ophthalmic branch of the trigeminal nerve is one of the most frequently involved sites of postherpetic neuralgia. A single-center randomized controlled study was conducted to evaluate the efficacy of local methylcobalamin injection for subacute ophthalmic herpetic neuralgia (SOHN).

METHODS

One hundred and five patients with a pain score of 4 or greater were randomized to receive a combination of methylcobalamin and lidocaine via local injection (LM group, n = 35), intramuscular methylcobalamin and local lidocaine injection (IM group, n = 35), and oral methylcobalamin tablet and lidocaine local injection (OM group, n = 35) for 4 weeks. Multilevel mixed modeling was employed to examine treatment responses.

RESULTS

Pain scores were reduced in all groups, but this reduction was significantly greater in the LM group (6.7 at baseline vs. 2.8 at endpoint) when compared with systemic administration (IM group 6.8 vs. 4.9, OM group 6.7 vs. 5.1). Clinically relevant reduction of pain (>30%) was seen in 91% of patients in the LM group, a significantly greater proportion than in the systemic groups (66% IM group, 57% OM group). Analgesic use reduced significantly in the LM group (94% at baseline vs. 6% at endpoint) but not in systemic groups (IM group 97% vs. 86%, OM group 94% vs. 80%). Health-related quality of life was higher in the LM group than in the systemic groups. In mixed modelling, increased age was associated with a lower response to methylcobalamin.

CONCLUSIONS

This study indicates that local injection of methylcobalamin produces significant pain relief from SOHN and is superior to systemic administration.

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.

Analysis of the Risk Factors for Postherpetic Neuralgia

Background: Postherpetic neuralgia is the most common complication of herpes zoster, affecting 30% of patients. It seriously affects the quality of life of patients and the curative effect of treatment is limited. So far, researchers do not fully understand the risk factors for postherpetic neuralgia and more research is needed. Objective: The aim of this paper was to investigate the risk factors for postherpetic neuralgia and provide reference for clinical diagnosis and treatment. Methods: A total of 202 inpatients with herpes zoster in the General Hospital of Tianjin Medical University were recruited as study subjects. According to the occurrence of postherpetic neuralgia, the patients were divided into the postherpetic neuralgia group and the nonpostherpetic neuralgia group. Data on age, gender, initial symptoms, clinical classification, involved nerves, pain grading, antiviral therapy, glucocorticoid use, and other clinical data of patients in the two groups were collected and statistically analyzed. Univariate and multivariate analysis methods were used to analyze the differences between the two groups and determine the influencing factors of postherpetic neuralgia. Results: The univariate statistical analysis of the factors influencing postherpetic neuralgia showed that the contribution of gender, initial symptoms, general clinical classification, use of glucocorticoid, and the interval from onset to antiviral therapy were not statistically significant, while the differences in age, specific clinical classification, involved nerves, severity of pain during the acute stage, and body side of skin lesion distribution were statistically significant. Multivariate logistic regression analysis showed that gender, use of glucocorticoid, interval from onset to antiviral therapy, involved nerves, and specific clinical classification showed no statistical significance. However, there were significant differences in age, body side of skin lesion distribution, general clinical classification, and degree of pain during the acute stage of the disease. Conclusion: Pain during the acute stage of herpes zoster, age greater than 70 years, and serious type of skin lesion are risk factors for postherpetic neuralgia (p < 0.05, OR >1).

Postherpetic foot drop in an elderly case: undiagnosed diabetes mellitus?

Postherpetic neuralgia is the most commonly seen complication of herpes zoster, primarily in elderly and immunocompromised patients. However, motor involvement due to herpes zoster is very rare. A 65-year-old male patient presented with left leg pain, numbness and difficulty walking. He was diagnosed with having herpes zoster and treated with valacyclovir. Despite anti-convulsant and physical therapy, the patient developed foot drop and had an unexplained weight loss. Clinical and laboratory findings suggested previously undiagnosed diabetes mellitus. Three weeks after initiation of insulin treatment, he became normoglycemic, his pain was reduced, and foot drop disappeared almost completely. Postherpetic motor involvement as an unusual complication may signal an underlying systemic disease, particularly in elderly.

Plerixafor may treat intractable post-herpetic neuralgia

Varicella-zoster virus (VZV) causes varicella (chicken pox) and establishes latency in ganglia. A reactivation of latent VZV leads to herpes zoster (shingles). Herpes zoster often causes herpetic pain that can last for months or years after the rash has healed. Prolonged herpetic pain is defined as post-herpetic neuralgia (PHN). There is an unmet need to explore novel therapeutic approaches for intractable PHN. Postmortem studies have shown that VZV induces neuro-inflammation and damage to the ganglia and spinal cord. These pathological changes may be critical factors resulting in PHN. Accumulated evidence suggests that stem cells may alleviate neuropathic pain in animal models through immunomodulatory actions and neuronal repair. Unfortunately, exogenous stem cell transplantation has limited clinical use due to safety concerns, immune rejection, and complications. Pharmacological mobilization of endogenous bone marrow stem cells may overcome these obstacles. Plerixafor is a SDF-1/CXCR4 axis blocker which can stimulate the release of stem cells from the bone marrow into blood circulation. We propose a hypothesis that endogenous stem cells mobilized by plerixafor may relieve the symptoms of PHN. If so, it may represent a novel approach for the treatment of intractable PHN.

Thiamine, cobalamin, locally injected alone or combination for herpetic itching: a single-center randomized controlled trial

OBJECTIVES

The present study was designed to explore the efficacy of locally injected thiamine or cobalamin in relieving itch or pain and improving the daily living activities among patients with herpetic itching.

METHODS

Eighty eligible patients with herpetic itching with a worst itching score of ≥ 4 were randomized to receive locally injected thiamine (B1 group), cobalamin (B12 group), lidocaine (LD group), or combination of thiamine and cobalamin (COB group) for 4 weeks. The treatment efficacy was assessed based on the patients' pruritus and pain severity, global impression of change, and activities of daily living and quality of life.

RESULTS

After 7 days, thiamine yielded a significant itch relief, cobalamin yielded a significant pain relief, and their combination significantly relieved both pain and itch; which all continued till the endpoint (all Ps<0.001). However, lidocaine did not provide significant itch or pain relief than the other groups. Sixteen patients in the thiamine group achieved ≥ 30% itch reduction; 18 patients in the cobalamin group obtained ≥ 30% pain reduction; and 18 patients achieved ≥ 30% itch reduction and 19 patients obtained ≥ 30% pain reduction in the combination group. The activities of daily living and quality of life data at the endpoint were consistent with a significant benefit in the thiamine (P<0.05), cobalamin, and combination groups (both Ps<0.001).

DISCUSSION

Locally injected thiamine had a significant antipruritic effect, cobalamin had an analgesic effect, and their combination had the dual effect with no obvious synergies. This intervention was efficacious, tolerable, and safe for herpetic itching.

Peripheral nerve adjustment for postherpetic neuralgia: a randomized, controlled clinical study

OBJECTIVE

To observe the therapeutic effect of peripheral nerve adjustment for the treatment of postherpetic neuralgia (PHN).

METHODS

One hundred and two patients with PHN were randomly assigned to three groups; the control group (A), the experimental group (B), which was subjected to peripheral nerve adjustment, and patients who received a sham peripheral nerve adjustment, thus serving as a positive control group (C). The patients' Visual Analogue Scale (VAS) and total oral rescue dosage for pain management were recorded at days 1, 3, 7, 14, and 28 following treatment. Quality of life (QOL), 36-Item Short-Form Health Survey (SF-36), and side effects were recorded following treatment.

RESULTS

We observed that the average VAS score was significantly lower in the treatment group (B) than in the control groups A and C following treatment (P < 0.05). In addition, the QOL and SF-36 scores for group B improved substantially following treatment compared to groups A and C, and this effect was maintained up to 180 days after treatment (P < 0.05). The average dosage of pain medication was also lower in group B, compared to groups A and C, following treatment (P < 0.05).

CONCLUSIONS

We conclude that peripheral nerve adjustment can relieve PHN pain and improve patients' quality of life. The possible mechanisms involved may include the reduction of both peripheral and central sensitization, the modulation of nerve plasticity, and an increase in endogenous analgesic molecules.

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.

The use of narrow band ultraviolet light B in the prevention and treatment of postherpetic neuralgia (a pilot study)

Background:

Postherpetic neuralgia (PHN) is a common complication of herpes zoster that is frequently unresponsive to most of the available treatment modalities. Broad band ultraviolet B radiation (UVB) has a well-known anti-inflammatory effect. Moreover, it decreases neural damage and cutaneous nerve density. It was found that broad band UVB might have a role in the prevention and treatment of PHN.

Aim:

This study was carried out to evaluate the effect ofnarrow band UVB (nbUVB) in the treatment PHN.

Patients and Methods:

The study included 17 patients with distressing post herpetic neuralgia. Patients were evaluated using the Verbal Rating Scale (VRS). The patients received nbUVB sessions, three times a week, for a total of 15 sessions or until the pain disappeared. Patients were followed up for a period of 3 months after the end of therapy.

Results:

Using intention to treat analysis, more than 50% improvement was achieved in 6 (35.29%) and 8 (47.06%) patients, at the end of therapy and after 3 months follow up, respectively. An improvement less that 50% was achieved in 11 (64.71%) and 9 (52.94%) patients, at the end of therapy and after 3 months follow up, respectively. The pain severity assessed by the VRS significantly improved both at the end of sessions (P = 0.005) and after 3 months follow up (P = 0.005).

Conclusion:

nbUVB may be of beneficial use in the treatment of PHN.

Limitation:

Small number of patients and limited follow-up period.

Acupuncture for the treatment of severe acute pain in herpes zoster: results of a nested, open-label, randomized trial in the VZV Pain Study

BACKGROUND

Data on the potential efficacy of acupuncture (AC) in controlling intense or very intense pain in patients with Herpes Zoster (HZ) has not been so far adequately assessed in comparison with standard pharmacological treatment (ST) by a controlled trial design.

METHODS

Within the VZV Pescara study, pain was assessed in HZ patients on a Visual Analogue Scale (VAS) and by the McGill Pain Questionnaire (MPQ) both at the beginning and at the end of treatment. Response rates, mean changes in pain intensity, differences in total pain burden with an area-under-the-curve (AUC) method over a 1-year follow-up and differences in the incidence of Post-Herpetic Neuralgia (PHN) were evaluated.

RESULTS

One hundred and two patients were randomized to receive either AC (n = 52) or ST (n = 50) for 4 weeks. Groups were comparable regarding age, sex, pain intensity at presentation and missed antiviral prescription. Both interventions were largely effective. No significant differences were observed in response rates (81.6% vs 89.2%, p = 0.8), mean reduction of VAS (4.1 +/- 2.3 vs 4.9 +/- 1.9, p = 0.12) and MPQ scores (1.3 +/- 0.9 vs 1.3 +/- 0.9, p = 0.9), incidence of PHN after 3 months (48.4% vs 46.8%, p = 0.5), and mean AUC during follow-up (199 +/- 136 vs 173 +/- 141, p = 0.4). No serious treatment-related adverse event was observed in both groups.

CONCLUSIONS

This controlled and randomized trial provides the first evidence of a potential role of AC for the treatment of acute herpetic pain.

TRIAL REGISTRATION

ChiCTR-TRC-10001146.

Predictors of pain intensity and persistence in a prospective Italian cohort of patients with herpes zoster: relevance of smoking, trauma and antiviral therapy

BACKGROUND

Herpes zoster (HZ) is a common disease, characterized by rash-associated localized pain. Its main complication, post-herpetic neuralgia (PHN), is difficult to treat and may last for months to years in the wake of rash resolution. Uncertainties remain as to the knowledge of predictors of HZ-related pain, including the role of antiviral therapy in preventing PHN in ordinary clinical practice. This prospective cohort study was aimed at investigating pain intensity at HZ presentation and its correlates, as well as the incidence of PHN and its predictors.

METHODS

Patients diagnosed with HZ were consecutively enrolled by a network of Italian General Practitioners and Hospital Units in the health district of Pescara, Italy, over two years. Uncertain cases were referred for microbiological investigation. Data were collected through electronic case report form (e-CRFs) at enrollment and at 1, 3, 6 and 12 months after enrollment. Pain intensity was coded on a five-degree semi-quantitative scale at each time point. PHN was defined as pain of any intensity during follow-up and quantified using an area-under-the-curve (AUC) method.

RESULTS

Four hundred and forty-one patients composed the final sample. Mean age was 58.1 years (SD = 20.4 years); 43.5% of patients were males; 7.9% did not receive prescription of antivirals. Intense/very intense pain at presentation was reported by 25.2% of patients and was significantly associated with female gender, older age, cigarette smoking, trauma and/or surgery at HZ site (logistic regression). PHN was diagnosed in 51.2% of patients at one month and in 30.0% of patients at three months. PHN was significantly associated with pain intensity at presentation, age, smoking, trauma and missed antiviral prescription (generalized estimating equations model). The same factors were also independent predictors of the overall pain burden as described by the AUC method (linear regression).

CONCLUSIONS

Smoking, traumas and surgery at the HZ site emerged as new predictors of both HZ-related pain intensity and persistence, opening new perspectives in the prevention of HZ-related pain. An independent line of evidence was provided for the efficacy of antiviral therapy in preventing PHN and reducing total pain burden.

Transcutaneous electroporation mediated delivery of doxepin-HPCD complex: a sustained release approach for treatment of postherpetic neuralgia

The electroporation mediated transdermal delivery (Protocol - 120 V, 10 ms, 30 pulses at 1 Hz with post pulse waiting period of 20 min) of doxepin using pure drug solution (PDS) and doxepin-hydroxypropyl-beta-cyclodextrin (HPCD) complex solution (CDS) was studied using porcine epidermis model. The stoichiometry of drug-HPCD inclusion complex was determined by differential scanning calorimetry (DSC). The amount of doxepin retained in the epidermis following electroporation did not differ significantly between PDS and CDS. When the drug loaded epidermis was subjected to "Release studies", doxepin release attained a plateau within approximately 2.5 days in case of PDS, whereas in case of CDS, doxepin release was prolonged up to 5 days. Mechanistic studies across the nonbiological barriers demonstrated that the slow dissociation of complex was responsible for sustained release of drug from the epidermis. Pharmacodynamic studies were carried out by electroporation mediated delivery of CDS and PDS in hairless rats. The analgesic effect of doxepin was prolonged in case of CDS as compared to PDS.

Pregabalin for postherpetic neuralgia: placebo-controlled trial of fixed and flexible dosing regimens on allodynia and time to onset of pain relief

Time to onset of pain relief and improvement in allodynia in 269 patients with postherpetic neuralgia was examined in a 4-week randomized trial comparing flexibly dosed pregabalin (150-600 mg/d), fixed-dose pregabalin (300 mg/d), and placebo. For each patient with clinically meaningful pain reduction (>or=30%) at end point, onset of pain relief was defined as the first study day on which a patient reported >or=1-point reduction in pain relative to baseline. Average dose achieved was 396 mg/d in the flexible-dose group compared with 295 mg/d in the fixed-dose group. Median pain relief onset times were 3.5 days (flexible-dose), 1.5 days (fixed-dose), and >4 weeks (placebo). Compared with placebo, significantly more patients in both pregabalin treatment groups achieved >or=30% and >or=50% pain reduction at end point. Almost 95% of patients had brush-evoked allodynia, with 68% having moderate to severe allodynia (>or=40/100 mm). At baseline, pain and allodynia were highly correlated. Independent of treatment assignment, improvement in pain and improvement in allodynia were significantly correlated. Allodynia could serve as a useful surrogate outcome measure in future studies. Pregabalin was significantly better than placebo in alleviating allodynia (flexible-dose reduction, 26 mm; fixed-dose, 21 mm; placebo, 12 mm). Discontinuation rates due to adverse events were more frequent in the fixed-dose group.

PERSPECTIVE

A flexible-dose regimen reduces discontinuations, facilitates higher final doses, and results in a slightly greater pain relief. Allodynia (touch-evoked pain) can be of disabling severity and is present in nearly all patients with postherpetic neuralgia. Allodynia severity is correlated with pain severity and improvement in allodynia is correlated with clinical response.

Managing pain after shingles: a nursing perspective

Post-herpetic neuralgia (PHN) is the neuropathic pain syndrome that may develop following an attack of shingles. While for many the symptoms subside, there can be long-term pain problems for up to 40% of those affected with PHN, and for 3% of these, symptoms can be severe (Dworkin and Portenoy, 1996). Knowledge and understanding of the symptoms and various treatments and approaches available is important to enable nurses and patients to work together in partnership to achieve the best outcomes. Realizing that more than one approach may be needed can allow for treatments which are complementary and for optimization of both biomedical and self-care approaches.