Dynamic of the somatosensory system in postherpetic 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.

Subgrouping patients with zoster-associated pain according to sensory symptom profiles: A cluster analysis

Background and goal of study

Patients with zoster-associated pain exhibit a variety of sensory symptoms and forms of pain and complain of different pain patterns. The purpose of this study is to subgroup patients with zoster-associated pain who visited a hospital using painDETECT sensory symptom scores, analyze their respective characteristics and pain-related data, and compare similarities and differences among the groups.

Materials and methods

The characteristics of 1,050 patients complaining of zoster-associated pain and pain-related data were reviewed retrospectively. To identify subgroups of patients with zoster-associated pain according to sensory symptom profiles, a hierarchical cluster analysis was performed based on the responses to a painDETECT questionnaire. Demographics and pain-related data were compared among all subgroups.

Results and discussion

Patients with zoster-associated pain were classified into 5 subgroups according to the distribution of sensory profiles, with each subgroup exhibiting distinct differences in the expression of sensory symptoms. Patients in cluster 1 complained of burning sensations, allodynia, and thermal sensitivity, but felt numbness less strongly. Cluster 2 and 3 patients complained of burning sensations and electric shock-like pain, respectively. Cluster 4 patients complained of most sensory symptoms at similar intensities and reported relatively strong prickling pain. Cluster 5 patients suffered from both burning and shock-like pains. Patient ages and the prevalence of cardiovascular disease were significantly lower in cluster 1. Patients in clusters 1 and 4 reported longer pain duration compared with those in clusters 2 and 3. However, no significant differences were found with respect to sex, body mass index, diabetes mellitus, mental health problems, and sleep disturbance. Pain scores, distribution of dermatomes and gabapentinoid use were also similar among the groups.

Conclusions

Five different subgroups of patients with zoster-associated pain were identified on the basis of sensory symptoms. A subgroup of younger patients with longer pain duration showed specific and distinct symptoms, such as burning sensations and allodynia. Unlike patients with acute or subacute pain, patients with chronic pain were associated with diverse sensory symptom profiles.

Safety and Efficacy of CT-Guided Pulsed Radiofrequency Combined with Steroid and Ozone Injection-Treated Cervical 3-8 Herpes Zoster Neuralgia Using a Posterior and Upper Quarter of the Cervical Foramina Puncture Approach

Background

Herpes zoster neuralgia has a considerable impact on people’s quality of life, especially after the development of postherpetic neuralgia. There are many clinical reports on the treatment of herpes zoster neuralgia, but there have been no special reports on the treatment of herpes zoster involving the neck. Our research focuses on a posterior and upper quarter of the cervical foramina puncture approach for herpes zoster involving the cervical 3–8 (C3-8) nerve region and to consider the safety and efficacy of pulsed radiofrequency combined with steroid injection and ozone injection in this puncture path under CT guidance.

Materials and Methods

A total of 104 patients with herpes zoster neuralgia involved in the cervical 3–8 nerve region use a posterior and upper quarter of the cervical foramina puncture approach received pulsed radiofrequency combined with steroid and ozone injection to the dorsal root ganglion. The total number of injection procedures, complications, NRS collection (preprocedure, postprocedure at once, two, four and 12 weeks) and drug dose decreases were documented.

Results

During a total of 257 procedures, 254 procedures successfully completed PRF (3 cases failed to reach the C8 aim points), and the rate of puncture failure was 1.17%. Drug injection was successfully performed in 252 procedures (the injection success rate was 99.21%); the NRSs (preprocedure, postprocedure at once, two, four and twelve weeks) were 5.75 ± 0.682, 2.6 ± 1.023, 2.21 ± 0.925, 1.89 ± 1.162, and 1.43 ± 1.369, and the difference among them was statistically significant. Drug dosages decreased before and after operation and showed statistically significant differences.

Conclusion

Pulsed radiofrequency combined with steroid and ozone injection for herpes zoster neuralgia involving the C3-8 nerves under CT guidance through a posterior superior quarter approach showed safety and efficacy and had a high success rate, and the NRS decreased significantly.

C-tactile touch perception in patients with chronic pain disorders

Supplemental Digital Content is Available in the Text. C-tactile stimulation in patients with chronic pain results in reduced pleasantness perception. Results suggest impaired C-tactile function with functional loss of pleasant touch perception in patients with postherpetic neuralgia.

Introduction:

Slow brushing over the skin activates C-tactile nerve fibers that transmit pleasant tactile experiences in healthy subjects, leading to an inverted U-shaped velocity dependence of ratings: C-tactile optimal stroking stimulations are rated as more pleasant than slower or faster stimulations. Chronic pain diseases such as postherpetic neuralgia (PHN) and complex regional pain syndrome show altered C-fiber innervation density, sensory loss, and pain sensitization.

Objectives:

We aimed to investigate whether C-tactile function is affected in painful conditions.

Methods:

We assessed psychophysically C-tactile function and sensory perception thresholds in 16 patients with PHN, 19 patients with complex regional pain syndrome, and 22 healthy controls.

Results:

Assessment of C-tactile function showed a significantly altered perceived pleasantness of CT stimulation between healthy controls and patients with chronic pain. In specific, tactile stimulation was perceived less pleasant on the affected and contralateral side when compared with controls. In patients with PHN, velocity-dependent pleasantness ratings could not be obtained, suggesting highly impaired C-tactile function with functional loss of pleasant touch perception.

Conclusions:

In conclusion, this is the first report of impaired C-tactile function in patients with PHN. Reduced pleasantness resulting from gentle touch can reflect defective C-fiber function or result from central nervous system effects in a chronic pain state.

Contralateral Sensory and Pain Perception Changes in Patients With Unilateral Neuropathy

OBJECTIVE

To test whether contralateral sensory abnormalities in the clinically unaffected area of patients with unilateral neuropathic pain are due to the neuropathy or pain mechanisms.

METHODS

We analyzed the contralateral clinically unaffected side of patients with unilateral painful or painless neuropathy (peripheral nerve injury [PNI], postherpetic neuropathy [PHN], radiculopathy) by standardized quantitative sensory testing following a validated protocol. Primary outcome was the independent contribution of the following variables on the contralateral sensory function using generalized linear regression models: pain intensity, disease duration, etiology, body area, and sensory patterns in the most painful area.

RESULTS

Among 424 patients (PNI n = 256, PHN n = 78, radiculopathy n = 90), contralateral sensory abnormalities were frequent in both painful (n = 383) and painless (n = 41) unilateral neuropathy, demonstrating sensory loss for thermal and mechanical nonpainful stimuli and both sensory loss and gain for painful test stimuli. Analysis by etiology revealed contralateral pinprick hyperalgesia in PHN and PNI. Analysis by ipsilateral sensory phenotype demonstrated mirror-image pinprick hyperalgesia in both mechanical and thermal hyperalgesia phenotypes. Pain intensity, etiology, and affected body region predicted changes in only single contralateral somatosensory parameters. Disease duration had no impact on the contralateral sensory function.

CONCLUSION

Mechanisms of sensory loss seem to spread to the contralateral side in both painful and painless neuropathies. Contralateral spread of pinprick hyperalgesia was restricted to the 2 ipsilateral phenotypes that suggest sensitization; this suggest a contribution of descending net facilitation from supraspinal areas, which was reported in rodent models of neuropathic pain but not yet in human patients.

Application and Therapeutic Effect of Puncturing of the Costal Transverse Process for Pulsed Radiofrequency Treated T1-T3 Herpes Zoster Neuralgia

Purpose

In CT-guided dorsal root ganglion puncture, especially T1–T3, it is often difficult to reach the target due to obstruction of the lamina, transverse process, and ribs. Therefore, a safe and effective puncture method with high success rate is urgently needed to guide us in our clinical work.

Patients and Methods

A total of 44 patients with dorsal root ganglion underwent pulsed radiofrequency therapy for pain T1–T3 herpes zoster neuralgia at the pain department of Affiliated Hospital of Jiaxing University from January 2019 to February 2020 were retrospectively reviewed. Each patient underwent the same surgical method. The patient’s operation time, CT filming times, nerve electrophysiological tests, the NRS scores before and after operation at one, four, eight, and 12 weeks, Pittsburgh Sleep Disorder Index (PSQI), dosage of gabapentin capsules and tramadol hydrochloride sustained-release tablets, surgical complications and incidence of postherpetic neuralgia (PHN) were recorded.

Results

The success rate of 44 patients who underwent puncturing of the costal transverse process to T1 target was 88.46%, to T2 target was 90.68%, and to T3 target was 90.68%, respectively. The NRS score of patients before surgery was 5.48±0.59, and those at one, four, eight, and 12 weeks after surgery were 3 (3,3), 1 (1,2), 0 (0, 1), and 0 (0, 0). The difference of NRS score between preoperation and postoperation is statistically significant. No intraoperative and postoperative complications occurred. Two patients developed PHN after standard treatment, and the incidence of it was 4.55%.

Conclusion

CT-guided puncturing of the costal transverse process in the dorsal root ganglion of patients who underwent pulsed radiofrequency treatment of T1–T3 herpes zoster neuralgia showed a high success rate and is considered to be safe and effective.

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.