Long-Term Effects of Spinal Cord Stimulation on Pain in Postherpetic Neuralgia

INTRODUCTION

Postherpetic neuralgia (PHN) is a pain syndrome that develops within few months after the acute herpetic outbreak. The pain may be accompanied by specific cutaneous signs in the distribution of affected dermatomes and feel unbearable reaching up to 9-10/10 on visual analog scale (VAS). Despite the introduction of new medications, drug resistance develops in at least 50% of cases. Neuromodulation techniques such as spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are considered as ones of the last resorts for PHN treatment, especially in pharmacoresistant patients. Recently, several studies with limited number of cases have shown high efficiency of neuromodulation (regression of pain syndrome in more than 82% of cases) after SCS in PHN patients, but these findings require further confirmation and have not been supported by large RCTs.

METHODS

Initially, 32 patients diagnosed with chronic drug-resistant PHN underwent a trial of SCS. Based on the trial results, a decision was made whether to implant a permanent SCS system. The condition of all patients implanted with SCS system was assessed using the VAS, SF-36, Patient Global Impression of Change (PGIC), and Medicine Quantification Scale, version III (MQS) questionnaires before the surgery and in the long-term follow-up. We also conducted systematic follow-up of patients who did not pass the test stimulation stage, using them as a control group to track the levels of pain. The hypothesis of normal distribution for quantitative values was tested using Shapiro-Wilk tests.

RESULTS

During the trial period, tonic spinal stimulation was effective in 16 out of 32 (50%) patients with drug-resistant PHN. Among 14 patients with implanted stimulators, a significant pain reduction (more than 50% from the baseline) was observed in 10 patients (71.4%). The pain level in patients with a tonic SCS was statistically lower than in patients receiving conservative therapy. For the entire group of patients with implanted SCS, a significant improvement was also observed in results of SF-36, PGIC, and MQS.

CONCLUSION

Our clinical series demonstrates that tonic SCS was effective in 50% of patients with refractory PHN undergoing SCS trial. Significant improvement in pain control obtained during the long-term follow-up in patients treated with tonic SCS improves the quality of life and reduces the need for analgesic medications.

A Perspective on Electrical Stimulation and Sympathetic Regeneration in Peripheral Nerve Injuries

Peripheral nerve injuries (PNIs) are common and devastating. The current standard of care relies on the slow and inefficient process of nerve regeneration after surgical intervention. Electrical stimulation (ES) has been shown to both experimentally and clinically result in improved regeneration and functional recovery after PNI for motor and sensory neurons; however, its effects on sympathetic regeneration have never been studied. Sympathetic neurons are responsible for a myriad of homeostatic processes that include, but are not limited to, blood pressure, immune response, sweating, and the structural integrity of the neuromuscular junction. Almost one quarter of the axons in the sciatic nerve are from sympathetic neurons, and their importance in bodily homeostasis and the pathogenesis of neuropathic pain should not be underestimated. Therefore, as ES continues to make its way into patient care, it is not only important to understand its impact on all neuron subtypes, but also to ensure that potential adverse effects are minimized. This piece gives an overview of the effects of ES in animals models and in humans while offering a perspective on the potential effects of ES on sympathetic axon regeneration.

[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.

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

PURPOSE OF REVIEW

Postherpetic neuralgia is an annoying pain that mainly affects older people. In order to give patients more options, this review summarizes the pharmacological and interventional treatments for postherpetic neuralgia and updates the research on the efficacy, thereby providing doctors with more treatment options. The adverse effects and effective doses of its various treatments are also presented so that the therapy can be prescribed according to their concrete physical conditions. In a word, this review is dedicated to providing a comprehensive overview of the treatment options for postherpetic neuralgia and offering patients more choices.

RECENT FINDINGS

Combinational therapy is more excellent than monotherapy. The local anesthesia and gabapentin comprised outstanding compatibility. In addition, two therapeutic tools for PHN patients, especially for the intractable ones, electroacupuncture (EA), and osteopathic manipulative treatment (OMT), show their efficacy and become potential options to alleviate pain. In terms of treatment, guidelines recommend patients use tricyclic antidepressants (TCAs), gabapentin, pregabalin, and 5% lidocaine patches as the first-line medications, and gabapentin is investigated most, especially the gabapentin enacarbil (GEn). And drug efficacy can be limited by adverse effects and tolerated doses. Interventional treatments, with their invasiveness and operational difficulty, are usually considered for intractable patients. Combinational therapies may be used when a single therapy cannot achieve the desired effect. Therapies such as OMT and EA have also been proposed to palliate pain in some cases, and future directions of treatment may be investigated in Chinese medicine and acupuncture.

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.

Utilizing pre-operative MR imaging and adapting optimal needle puncture approach to improve radiofrequency ablation fraction of thoracic dorsal root ganglia

This experimental study evaluates the location of thoracic dorsal root ganglions (DRGs) through magnetic resonance imaging (MRI) scans, and evaluates the radiofrequency ablation (RFA) fraction of different puncture approaches on distinct DRG locations. Eight normal adult corpse specimens were used as thoracic spine specimens. An MRI examination was performed on each specimen using the following MRI sequences: STIR T2WI, fs-FRFSE T2WI, and 3D FIESTA-c. Then thoracic spine specimens (n = 14) were divided into three groups for RFA: Group A, using a transforaminal approach irrespective of DRG location; Group B, using a transforaminal, trans-lateral-zygapophysial or translaminar approach according to the DRG location; and Group C using a combination of puncture approaches. The quality of visualization of thoracic DRGs on STIR T2WI, fs-FRFSE T2WI, and 3D FIESTA-c scans were 53.5% (77/144), 88.2% (127/144), and 93.1% (134/144), respectively. In group A, the RFA fractions of the extraforaminal DRGs (N = 29), intraforaminal DRGs (N = 12) and intraspinal DRGs (N = 7) via a transforaminal approach were 72.6 ± 18.9%, 54.2 ± 24.8% and 32.9 ± 28.1% respectively. In group B, RFA of extraforaminal DRGs via a transforaminal approach (N = 43) or a trans-lateral zygapophysial approach (N = 45) led to ablation fractions of 71.9 ± 15.2% and 72.0 ± 17.9%, respectively; RFA of intraforaminal DRGs via a transforaminal approach (N = 14) or a translaminar approach (N = 16) led to ablation fractions of 57.1 ± 18.0% and 52.5 ± 20.6%, respectively; RFA of intraspinal DRGs via a transforaminal approach (N = 12) or a translaminar approach (N = 14) led to ablation fractions of 34.8 ± 24.6% and 71.8 ± 16.0%, respectively. In group C, the combined approach led to an ablation fraction for extraforaminal DRGs (N = 69) of 82.5 ± 14.1%, for intraforaminal DRGs (N = 39) of 81.5 ± 11.8%, and for intraspinal DRGs (N = 36) of 80.8 ± 13.3%. MRI can accurately assess DRG location before RFA. Adopting different and combined puncturing approaches tailored to different DRG locations can significantly increase the DRG RFA fraction.

Pain Control in Dermatologic Conditions

PURPOSE OF REVIEW

Pain management in dermatologic conditions can be complicated by the primary disease burden and associated decreased quality of life, disability, and psychosocial issues. This review focuses on pain management strategies in some of the more painful dermatologic conditions.

RECENT FINDINGS

Pain management in painful dermatologic conditions such as pyoderma gangrenosum, postherpetic neuralgia, lower limb ulcers, and hidradenitis suppurativa revolves around treatment of the underlying disease process. Topical agents such as topical steroids and systemic immunosuppressants with over-the-counter analgesics usually suffice in mild to moderate pain. Severe pain may need neuropathic agents and referral to interventional pain physicians for consideration of advanced techniques such as epidural steroid injections and sympathetic nerve blocks. Part of the treatment process is for dermatologists to establish patient expectations and to treat pain within their scope of practice. More research is needed towards pain control in painful dermatologic conditions with elucidation of treatment algorithms unique to each condition.

Percutaneous Trigeminal Stimulation for Intractable Facial Pain: A Case Series

BACKGROUND

Facial pain syndromes can be refractory to medical management and often need neurosurgical interventions. Neuromodulation techniques, including percutaneous trigeminal ganglion (TG) stimulation, are reversible and have emerged as alternative treatment options for intractable facial pain.

OBJECTIVE

To report the complication rates and analgesic effects associated with TG stimulation and identify potential predictors for these outcomes.

METHODS

A retrospective chart review of 59 patients with refractory facial pain who underwent TG stimulation was conducted. Outcomes following trial period and permanent stimulation were analyzed. Patients with >50% pain relief during trial stimulation received permanent implantation of the stimulation system.

RESULTS

Successful trial stimulation was endorsed by 71.2% of patients. During the trial period, 1 TG lead erosion was identified. History of trauma (facial/head trauma and oral surgery) was the only predictor of a failed trial compared to pain of idiopathic etiology (odds ratio: 0.15; 95% CI: 0.03-0.66). Following permanent implantation, approximately 29.6% and 26.5% of patients were diagnosed with lead erosion and infection of the hardware, respectively. TG lead migrations occurred in 11.7% of the patients. The numeric rating scale score showed a statistically significant reduction of 2.49 (95% CI: 1.37-3.61; P = .0001) at an average of 10.8 mo following permanent implantation.

CONCLUSION

TG stimulation is a feasible neuromodulatory approach for the treatment of intractable facial pain. Facial/head trauma and oral surgery may predict a nonsuccessful trial stimulation. Future development of specifically designed electrodes for stimulation of the TG, and solutions to reduce lead contamination are needed to mitigate the relatively high complication rate.

Efficacy of Pulsed Radiofrequency to Cervical Nerve Root for Postherpetic Neuralgia in Upper Extremity

Background

Postherpetic neuralgia (PHN) seriously affects a patient’s quality of life, and it is urgent to find a method that can effectively alleviate the PHN of the upper extremity.

Objective

To observe the Efficacy of pulsed radiofrequency (PRF) to cervical nerve root for PHN in upper extremity under CT guidance.

Study Design

Retrospective comparative study.

Setting

Shengjing Hospital of China Medical University.

Methods

Fifty patients with PHN in upper extremity were enrolled in Pain Management. Patients were randomized into two groups: cervical nerve root block (A group, n = 25) and cervical nerve root PRF (B group, n = 25). At each observation time, the general characteristics, visual analog scale (VAS), quality of life scores assessment (SF-36), the total efficacy rate, dosage of antiepileptic and narcotic analgesics, and the incidence of complications were followed up.

Results

Compared with the preoperative, the postoperative VAS decreased, the physical component summary (PCS) and the mental component summary (MCS) increased in both groups (P < 0.05). The differences between group B and group A were statistically significant after 1 month, which could be maintained for 1 year (P < 0.05). The total efficacy rate of group A and group B was 52.0% and 80.0% at 1 Year, respectively. The total efficacy rate of group B was higher than that of group A (P < 0.05). The dosage of antiepileptic and narcotic analgesics in group B decreased significantly, and the decline was significant compared with group A (P < 0.05). The incidence of complications between the two groups were similar (P > 0.05).

Conclusion

CT-guided PRF to cervical nerve root for the treatment of PHN in the upper extremity is safe and effective. PRF can replicate the location of pain, precise positioning, reduce trauma, and increased pain relief rate.

C1-C3 unilateral dorsal root entry zone rhizotomy for the treatment of persistent postherpetic occipital neuralgia

Background:

Postherpetic occipital neuralgia (PHON) is a neuropathic pain condition that usually presents as paroxysmal pain that is stabbing in nature.[5,7] It involves the occiput and posterior scalp in the distribution of the greater and/or lesser occipital nerves. It usually develops after an episode of shingles.[5,7] Treatment usually first consists of medical therapy and then progresses to invasive treatment (e.g., peripheral nerve stimulation, spinal cord epidural stimulation, C2-C3 ganglionectomy, or dorsal root entry zone [DREZ] rhizotomy).[1-4,6] Here, we present a case of persistent PHON that was treated with C1-C3 DREZ.

Case Description:

A 37-year-old female had a history of several episodes of shingles involving the left neck and occiput; they resolved after treatment with valacyclovir. Subsequently, however, she developed severe lancinating pain of the neck and the occiput and was diagnosed with PHON. Initially, she was treated with oxcarbazepine but was stopped due to cognitive side effects. She then had a cervical spinal cord stimulator implanted which produced relief for several years; it was later removed due to breakage of the electrodes. She then underwent a left- sided C1-C2 hemilaminectomy with a C1-C3 DREZ procedure.[1] Postoperatively, she had immediate resolution of her pain, but developed a new left hemiparesis (4+/5), accompanied by imbalance, decreased sensation to light touch, and loss of proprioception. On 6 weeks follow up, the pain was still relieved, and she exhibited significant improvement in her left-sided hemiparesis and hemisensory deficit to which returned to baseline. Similar outcome was maintained at four months follow up.

Conclusion:

Although high cervical DREZ lesions may effectively treat post herpetic/occipital neuralgia that fails other measures, there may be associated major neurological morbidity that makes this procedure acceptable as a salvage option, and after clearly explaining the risks to the patient.