Therapeutic Strategies for Postherpetic Neuralgia: Mechanisms, Treatments, and Perspectives

Comparative long-term efficacy of short-term spinal cord stimulation versus bipolar pulsed radiofrequency for refractory postherpetic neuralgia: a 24 month prospective study

BACKGROUND

Postherpetic neuralgia (PHN) is a debilitating neuropathic pain condition that persists after herpes zoster infection, often resistant to conventional medications. This study compares the long-term efficacy and safety of short-term spinal cord stimulation (stSCS) versus bipolar pulsed radiofrequency (bPRF) in managing refractory PHN.

METHODS

In this prospective, controlled observational study, 140 PHN patients (aged ≥ 18 years; PHN duration ≥ 3 months) with inadequate pain relief from standard therapies were enrolled and randomized equally into two groups (n = 70 each). The stSCS group received percutaneous implantation of an 8-contact electrode for temporary neuromodulation, while the bPRF group underwent application of controlled high-frequency pulses to the dorsal root ganglion. Outcome measures included pain intensity (VAS, NRS), neuropathic pain characteristics (DN4), quality of life (SF-36, EQ-5D), sleep quality (PSQI), and psychological status (SAS, SDS), assessed at baseline and at follow-up intervals over 24 months.

RESULTS

Both stSCS and bPRF achieved significant short-term pain relief. However, from 6 to 24 months post-treatment, the stSCS group demonstrated significantly lower VAS scores and superior pain control compared to the bPRF group. In addition, improvements in sleep quality and emotional well-being were more pronounced in the stSCS group at 12, 18, and 24 months. Both treatments exhibited favorable safety profiles with only minor, transient adverse events reported.

CONCLUSIONS

While both stSCS and bPRF effectively alleviate pain in patients with refractory PHN, stSCS offers superior long-term benefits in pain reduction, sleep quality, and psychological outcomes. These findings suggest that stSCS may be the preferred neuromodulation strategy for patients with chronic PHN requiring sustained symptom management.

Analysis of the effects of combined electrical spinal cord stimulation and pregabalin therapy in patients with herpes zoster trigeminal neuralgia

OBJECTIVE

To analyze the clinical effects of combined electrical spinal cord stimulation (SCS) and pregabalin treatment in patients with herpes zoster (HZ) trigeminal neuralgia.

METHODS

This retrospective study analyzed clinical data from 121 patients diagnosed with HZ trigeminal neuralgia. Data were collected using the hospital's HIT system and categorized into two groups based on treatment: the pregabalin group (n = 59, treated with pregabalin) and the pregabalin + SCS group (n = 62, treated with pregabalin plus electrical SCS). The pregabalin + SCS group was further divided into the Gasserian ganglion subgroup (n = 26) and the trigeminal nerve branch subgroup (n = 36) based on the therapeutic target.

RESULTS

The overall efficacy rate was higher in the pregabalin + SCS group (95.16 %) than in the pregabalin group (83.05 %). At 1, 4, and 12 weeks of treatment, the pregabalin + SCS group showed significantly lower scores on the NRS, BPI, HADS-A, and HADS-D compared to the pregabalin group. Additionally, at 4 and 12 weeks of treatment, the pregabalin + SCS group exhibited lower PSQI scores, and the Gasserian ganglion subgroup demonstrated lower NRS and BPI scores compared to the trigeminal nerve branch subgroup. Binary logistic regression analysis identified disease duration and treatment method as independent factors influencing treatment efficacy in HZ trigeminal neuralgia.

CONCLUSION

The addition of electrical SCS to standard pharmacological treatment significantly improves the efficacy of HZ trigeminal neuralgia management.

The Use of Tricyclic Antidepressants for Postherpetic Neuralgia - A Case Series

Postherpetic neuralgia (PHN) is one of the most debilitating forms of neuropathic pain that can occur after a herpes zoster infection. PHN can significantly impair patients' quality of life due to persistent neuropathic pain. Current first-line treatments for PHN include anticonvulsants like gabapentin and pregabalin, topical agents such as lidocaine patches, and opioids in severe cases. However, many patients fail to achieve adequate pain control with these medications. Tricyclic antidepressants (TCAs) such as amitriptyline and nortriptyline may be considered as a second-line option, providing relief for patients with refractory pain. TCAs act by modulating neurotransmitters involved in pain pathways, offering analgesia in neuropathic conditions like PHN. This case series reviews four patients with PHN who found significant pain relief with the addition of TCAs after failing multiple other treatments. The patients, aged between 66 and 71, presented with severe PHN and had tried various treatments, including acetaminophen (APAP), nonsteroidal anti-inflammatory drugs (NSAIDs), lidocaine patches, gabapentinoids, and opioids, without achieving adequate pain relief. Each patient was prescribed a TCA, either amitriptyline or nortriptyline, alongside other pain medications. All four patients experienced notable reductions in pain intensity on the Numeric Rating Scale (NRS), resulting in improved daily function and better pain tolerance. Side effects were minimal, with only one patient reporting mild sedation and another reporting transient dry mouth, both of which were manageable. This case series underscores the potential of TCAs in managing PHN, particularly when other medications fail. While the results are promising, further research is needed to confirm the long-term efficacy and safety of TCAs in this patient population.

Genetically predicted amino acids related to neural regulation mediate the association between diabetes mellitus and postherpetic neuralgia: a Mendelian randomization study

BACKGROUND

Postherpetic neuralgia (PHN) and diabetes mellitus frequently coexist in clinical settings; however, the causal relationship between them remains unclear. Moreover, the potential mediating role of amino acids related to neural regulation in this association has not been fully explored yet.

METHODS

Univariable Mendelian randomized (UVMR) was utilized to examine the causal relationship between various subtypes of diabetes mellitus and PHN, with the inverse variance weighted method as the main approach. Multivariable MR (MVMR) was conducted to assess the direct effect of diabetes mellitus, accounting for waist circumference, diabetic neuropathy/ulcers, and depression. Moreover, a two-step MR analysis was employed to investigate the mediating role of neurotransmitter-related amino acids in the association between diabetes mellitus and PHN.

RESULTS

A significant statistical correlation was found between type 2 diabetes mellitus (T2DM) and PHN (odds ratio, OR: 1.23, 95% confidence interval, CI: 1.01-1.49, P = 0.036), while in type 1 diabetes mellitus or pregnancy diabetes mellitus, no evidence of the association with PHN was observed. MVMR analyses demonstrated that the effect of T2DM on PHN remained significant after adjusting for waist circumference, diabetic neuropathy/ulcers, and depression. Further mediation analysis revealed that phenylalanine accounted for 49.2% (95% CI: 22.7- 75.6%) of the total effect of T2DM on PHN.

CONCLUSION

The current study suggested that T2DM was associated with an increased risk of PHN, with phenylalanine playing a mediating role. These findings provided valuable insights for the screening and prevention of PHN in clinical practice.

An update on botulinum toxin treatment of painful diabetic neuropathy, post-traumatic painful neuropathy/neuralgia, post-herpetic neuralgia and occipital neuralgia

The literature in botulinum toxin treatment for painful diabetic neuropathy (PDN), post traumatic neuralgia (PTN), postherpetic neuralgia (PHN) and occipital neuralgia (ON) was reviewed up to Oct 1st, 2024. Using the efficacy criteria set forth by the Assessment and Guideline subcommittee of the American Academy of Neurology, the current levels of efficacy for these conditions could be designated as followings: PDN: B (probably effective, two class II study), PTN: A (effective, two class I studies); PHN: A (effective, two class I studies), ON: (undetermined due to lack of blinded investigations). Due to the small number of patients in these studies, proof of efficacy requires conduction of controlled and blinded studies in large cohorts of patients with longer follow ups. Future prospects of botulinum therapy for these pain disorders were discussed along with the advantages of this mode of treatment over the current modes of treatment.

Quantification of crisugabalin (HSK16149) in biological matrix by LC-MS/MS method: An application to rat pharmacokinetic and tissue distribution studies

Crisugabalin (HSK16149), a novel VGCC α2δ ligand, has been approved for the treatment of adult diabetic peripheral neuropathic pain (DPNP) and postherpetic neuralgia (PHN). In this study, an LC-MS/MS method was developed for the determination of crisugabalin in rat plasma and tissues homogenate. Samples were extracted by protein precipitation and separated on a Hypersil GOLD aQ column with methanol and 2 mM ammonium acetate in water containing 0.1 % formic acid as mobile phase. Crisugabalin and its internal standard HSK7891 were ionized by electrospray ionization source and detected by multiple reaction monitoring with transitions of m/z 210.9 → 134.4 and m/z 246.0 → 129.3. Over the range of 0.0100-10.0 μg/mL, the selectivity, linearity, precision and accuracy, matrix effect, stability, recovery and dilution integrity of crisugabalin were validated in rat plasma. Validation was also performed in rat liver homogenate at concentrations ranging from 0.0200-20.0 μg/g. The method was then successfully applied to determine the pharmacokinetics and tissue distribution of crisugabalin. In rats, orally administered crisugabalin was completely and rapidly absorbed with a peak time of about 0.57 h, and was mainly distributed to kidney, bladder and liver tissues. Crisugabalin exhibited linear pharmacokinetics over the oral dose range of 3-30 mg/kg.

Effectiveness and Safety of Gabapentin versus Pregabalin in the Treatment of Postherpetic Neuralgia: A Retrospective Cohort Study

Aims/Background Postherpetic neuralgia (PHN) is a common chronic pain disease that persists after the rash (clusters of clear blisters on the surface of the skin) has healed, adversely affecting the quality of life of affected patients. Gabapentin (GPT) and pregabalin (PGB) are two commonly used drugs for the treatment of PHN, but there have been broad concerns regarding their efficacy and safety. Thus, this retrospective cohort study was conducted to investigate the effectiveness and safety of GPT versus PGB in the treatment of PHN. Methods A total of 150 patients with PHN receiving routine antiviral and neurotrophic therapies, admitted between January 2022 and November 2023, were selected. 71 patients who were treated with GPT were included in the control group, while the remaining 79 patients who were given PGB were categorized in the observation group. Information on clinical effectiveness, safety (xerostomia, drowsiness, blurred vision, ataxia, and dizziness), analgesic effect (Visual Analogue Scale [VAS] and time to pain relief), sleep quality (Sleep Quality Scale [SQS] and Pittsburgh Sleep Quality Index [PSQI]), and adverse emotions (Self-rating Anxiety/Depression Scale [SAS/SDS]) was collected for analysis. Results Compared to the control group, the observation group exhibited significantly higher clinical effectiveness of PGB in the treatment of PHN (p < 0.05). In other aspects, the overall incidence of adverse events such as xerostomia, drowsiness, blurred vision, ataxia, and dizziness (p > 0.05) was equivalent in these two groups. In addition, significantly lower VAS, SQS, PSQI, SAS, and SDS scores were observed in the observation group after treatment, compared with the control group (p < 0.05). The observation group showed evidently shorter time to pain relief than the other group (p < 0.05). Conclusion PGB is an effective and safe medication for the treatment of PHN, by improving the analgesic effect and sleep quality, and alleviating negative emotions.

Comprehensive nursing care improves symptoms and quality of life in elderly patients with postherpetic neuralgia

This study evaluates the clinical impact of comprehensive nursing care on senior patients suffering from postherpetic neuralgia (PHN), a chronic neuropathic pain condition resulting from the reactivation of the varicella-zoster virus. A total of 102 elderly patients diagnosed with PHN and treated at our hospital were divided into two groups: the control group, which received conventional nursing care, and the intervention group, which received comprehensive nursing care. Comparative analyses were conducted on pain levels, sleep quality, symptoms of depression and anxiety before and after the intervention. After a two-month period of nursing care, both groups exhibited a significant reduction in pain levels (p < 0.05), with the intervention group demonstrating a more substantial decrease (p < 0.001). Sleep quality improved in both groups (p < 0.05), with the intervention group showing a significantly greater improvement (p < 0.05). Additionally, the intervention group experienced a notable reduction in anxiety and depression ratings compared to the control group. Comprehensive nursing care interventions may effectively alleviate clinical symptoms, and diminish levels of depression and anxiety, while improving sleep quality in elderly patients with PHN. These findings underscore the potential benefits of employing a comprehensive approach to managing PHN in the elderly population.

Transcutaneous Electrical Nerve Stimulation for Prevention and Treatment of Post-Herpetic Neuralgia: A Narrative Review

The present investigation evaluated transcutaneous electrical nerve stimulation (TENS) for the non-pharmacological treatment of post-herpetic neuralgia (PHN). PHN is the most common complication of the Herpes Zoster virus, affecting one in every five patients with shingles, and presents as intense neuropathic pain that can persist for 90 days or longer after the initial onset of symptoms. Current pharmacological treatment options are mainly limited to symptom management, including oral medications such as tricyclic antidepressants and gabapentinoid preparations, as well as topical options such as lidocaine or capsaicin. TENS is a minimally invasive, non-pharmacological electrical nerve stimulation device currently approved for the treatment of neuropathic pain in adults, providing patients with an alternative or adjunct treatment option to medication with a reduced potential for unwanted side effects, drug-drug interactions or potentially life-threatening toxicity. Current indications for the use of TENS in the treatment of PHN are recommended only after therapeutic goals are attempted and unsuccessfully met by current mainstay medications. More research into the efficacy and safety of TENS for treating PHN should be conducted to clarify further its role as a mainstay treatment for this condition.

Effect of Preoperative Level of Glycemic Control with Pulsed Radiofrequency on the Incidence of Postherpetic Neuralgia in Patients with Herpes Zoster Combined with Type 2 Diabetes Mellitus: A Cohort Study

Purpose

To investigate the correlation between the level of glycosylated hemoglobin (HbA1c) and postherpetic neuralgia (PHN).

Patients and Methods

This cohort study included 100 patients with herpes zoster (HZ) undergoing treatment with pulsed radiofrequency (PRF). Patients with comorbid type 2 diabetes mellitus (T2DM) were divided into three groups based on their glycemic control levels: good [HbA1c < 7% (53.01 mmol/mol), group D1], fair [7% (53.01 mmol/mol) ≤ HbA1c < 9% (74.86 mmol/mol), group D2], and poor [9% (74.86 mmol/mol) ≤ HbA1c, group D3]. The control group (group N) consisted of patients without T2DM. The main outcome measured was the occurrence of PHN in the four groups.

Results

A total of 90 patients were included in the cohort. The occurrence of PHN was found to be higher in groups D2 and D3 when compared to group N (N vs D2, P = 0.007; N vs D3, P < 0.001). Furthermore, the occurrence of PHN was higher in groups D2 and D3 in comparison to group D1 (D1 vs D2, P = 0.022; D1 vs D3, P < 0.001), with the incidence of PHN in group D3 being greater than in group D2 (P < 0.001).

Conclusion

Preoperative HbA1c predicts the incidence of PHN after PRF in T2DM patients.

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

Spinal cord stimulation (SCS) has shown effectiveness in relieving zoster-associated pain (ZAP), but some patients still experience moderate or severe pain after SCS treatment. This study aims to evaluate the impact of SCS combined with dorsal root ganglion (DRG) pulsed radiofrequency (PRF) as a dual neuromodulation strategy on the prognosis of ZAP. The clinical records of patients diagnosed with ZAP who underwent SCS (SCS group) or SCS combined with PRF (SCS + PRF group) at The Third Xiangya Hospital, Central South University, were retrospectively analyzed to compare the effectiveness of the two treatment approaches for ZAP. Outcome measures included changes in Visual Analog Scale (VAS) scores before and after neuromodulation treatment, response rates, and incidence of progression to postherpetic neuralgia (PHN).13 SCS patients and 15 SCS + PRF patients were analyzed. Admission VAS scores were similar (P = 0.934). Upon discharge, no significant differences in VAS or response rates were observed (P > 0.05). However, at 6-month follow-up, the SCS + PRF group had lower VAS scores (1.53 ± 1.06 vs. 3.23 ± 1.50, P < 0.001) and a lower proportion of residual moderate pain (P = 0.041). None in the SCS + PRF group progressed to PHN in the acute/subacute phases, differing significantly from the SCS group (P = 0.038).Therefore, SCS combined with DRG PRF is feasible and effective in the treatment of ZAP. This dual neuromodulation strategy may be a more appropriate regimen for the treatment of ZAP.

Case report: safety and efficacy of lidocaine infusion for the treatment of intractable zoster-associated neuralgia in solid organ transplant recipients

Introduction

Solid organ transplant recipients are at high risk for developing severe zoster-associated neuralgia, and the pharmaceutic therapies of pain management for these patients with limited organ function are challenging. Intravenous lidocaine infusion showed positive analgesic effects and is used for the management of neuropathic pain. This case series reports the safety and effectiveness of intravenous lidocaine infusion in the treatment of intractable zoster-associated neuralgia in solid organ transplant recipients.

Case series presentation

Five solid organ transplant recipients suffering from refractory zoster-associated neuralgia (numeric rating scale 8-10, despite using high doses of antiepileptic drugs or combined with opioids) were enrolled. Intravenous lidocaine (5 mg/kg ideal bodyweight) was administered over 1.5 h with the monitoring of vital signs. Pain intensity, patient satisfaction, adverse events, typical liver, and kidney function were evaluated. All subjects reported high satisfaction with their treatment and effective pain relief at the 6-month follow-up. One patient experienced short and mild numbness in the mouth and dizziness after the therapy, but no major adverse reactions were reported.

Conclusion

This case series provides evidence that intravenous lidocaine infusion provided effective pain relief as an analgesic treatment option for transplant patients with intractable zoster-associated neuralgia.

Clinical insights into traumatic injury of the inferior alveolar and lingual nerves: a comprehensive approach from diagnosis to therapeutic interventions

OBJECTIVES

This scoping review explores the risk and management of traumatic injuries to the inferior alveolar and lingual nerves during mandibular dental procedures. Emphasizing the significance of diagnostic tools, the review amalgamates existing knowledge to offer a comprehensive overview.

MATERIALS AND METHODS

A literature search across PubMed, Embase, and Cochrane Library informed the analysis.

RESULTS

Traumatic injuries often lead to hypo-/anesthesia and neuropathic pain, impacting individuals psychologically and socially. Diagnosis involves thorough anamnesis, clinical-neurological evaluations, and radiographic imaging. Severity varies, allowing for conservative or surgical interventions. Immediate action is recommended for reversible causes, while surgical therapies like decompression, readaptation, or reconstruction yield favorable outcomes. Conservative management, utilizing topical anesthesia, capsaicin, and systemic medications (tricyclic antidepressants, antipsychotics, and serotonin-norepinephrine-reuptake-inhibitors), proves effective for neuropathic pain.

CONCLUSIONS

Traumatic nerve injuries, though common in dental surgery, often go unrecorded. Despite lacking a definitive diagnostic gold standard, a meticulous examination of the injury and subsequent impairments is crucial.

CLINICAL RELEVANCE

Tailoring treatment to each case's characteristics is essential, recognizing the absence of a universal solution. This approach aims to optimize outcomes, restore functionality, and improve the quality of life for affected individuals.