Pregabalin and Transcutaneous Electrical Nerve Stimulation for Postherpetic Neuralgia Treatment

Non-pharmacological management of neuropathic pain in older adults: a systematic review

INTRODUCTION

Neuropathic pain encompasses multiple diagnoses with detrimental impacts on quality of life and overall health. In older adults, pharmacological management is limited by adverse effects and drug interactions, while surgical management involves perioperative risk. Prior reviews addressing non-pharmacological interventions for neuropathic pain have not focused on this demographic. Therefore, this systematic review synthesizes the evidence regarding the effectiveness of non-pharmacological interventions in reducing neuropathic pain severity in older adults.

METHODS

PubMed, CINAHL, Web of Science, and PsycInfo were searched using key terms, with inclusion criteria of age ≥ 65, neuropathic pain, non-pharmacological intervention, pain severity measurement, English language, peer-reviewed, and either randomized controlled trial (RCT) or quasi-experimental design. In total, 2759 records were identified, with an additional 28 records identified by review of reference lists. After removal of duplicates, 2288 records were screened by title and abstract, 404 full-text articles were assessed, and 19 articles were critically reviewed and synthesized.

RESULTS

Of the 14 RCTs and 5 quasi-experimental studies included in the review, the most common intervention was electric and/or magnetic therapy, followed by acupuncture, mindfulness meditation, exercise, and light therapy. Several studies revealed both statistical and clinical significance, but conclusions were limited by small sample sizes and methodological shortcomings. The interventions were generally safe and acceptable.

CONCLUSIONS

Results should be interpreted with consideration of clinical vs statistical significance, mediators of pain severity, and individual variations in effectiveness. Further research should address multimodal and novel interventions, newer models of care, and technology-based interventions.

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.

Analgesic Treatment Approach for Postherpetic Neuralgia: A Narrative Review

Post-herpetic neuralgia (PHN) is an entity derived from peripheral nerve damage that occurs during the reactivation of the Varicella Zoster Virus (VZV), which manifests itself through pain with neuropathic characteristics. This can prove to be very difficult to manage in the chronic stages of disease reappearance. There currently exists a multitude of treatment alternatives for PHN, however, prevention through the early initiation of antiviral regimens is vital. There are various pharmacological options available, but it is important to individualize each patient to maximize efficacy and minimize adverse effects. Interventional procedures have become a cornerstone in difficult-to-manage cases, and have shown promising outcomes when used in a multimodal approach by experienced specialists. It is necessary to make an objective diagnosis of PHN and start early treatment. Additionally there is current evidence that vouches for interventional therapies as well as individualization, with a clear establishment of therapeutic objectives according to the needs of each patient.

Physiotherapy interventions for pain relief in individuals with peripheral neuropathic pain: A systematic review and meta-analyses of randomized controlled trials

OBJECTIVE

To evaluate the effectiveness of physiotherapy interventions on peripheral neuropathic pain (pNeP) due to any underlying cause.

METHODS

Multiple databases were searched from database inception until Dec 2021. Studies on physiotherapy interventions for pain relief assessed using the visual analogue scale among individuals with pNeP of any underlying cause were included. Methodological quality was assessed using the PEDro scale and the quality of the evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool.

RESULTS

The searches yielded 1498 articles. Seventeen studies met the inclusion criteria and were included in the review. Meta-analysis revealed a significant benefit for laser therapy compared to sham laser on pNeP (weighted mean difference [WMD] -1.27; 95% CI: -2.29 to -0.25; p = 0.01) in people with carpal tunnel syndrome. The pooled analyses revealed a significant effect of spinal cord stimulation compared to control for failed back syndrome (standardised mean difference [SMD; Hedges'g] -0.73; 95% CI: -1.17 to -0.30; p = 0.001) and diabetic neuropathy (SMD -1.63; 95% CI -2.06--1.21; p < 0.001). The effect of acupuncture on chemotherapy-induced pain (SMD - 2.09; 95% CI: -4.27-0.09; p = 0.06) and electromagnetic stimulation on diabetic neuropathic pain (Hedges' g - 0.77; 95% CI: -1.82-0.27; p = 0.15) were insignificant.

CONCLUSION

Evidence supports the use of spinal cord stimulation for the treatment of pNeP secondary to failed back surgery syndrome and diabetic neuropathy. Laser therapy was more effective than sham laser for alleviating pain due to carpal tunnel syndrome. The efficacy of acupuncture and electromagnetic therapy for chemotherapy-induced pain and diabetic neuropathy, respectively remains inconclusive.

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.

Characterising the Features of 381 Clinical Studies Evaluating Transcutaneous Electrical Nerve Stimulation (TENS) for Pain Relief: A Secondary Analysis of the Meta-TENS Study to Improve Future Research

Background and Objectives: Characterising the features of methodologies, clinical attributes and intervention protocols, of studies is valuable to advise directions for research and practice. This article reports the findings of a secondary analysis of the features from studies screened as part of a large systematic review of TENS (the meta-TENS study). Materials and Methods: A descriptive analysis was performed on information associated with methodology, sample populations and intervention protocols from 381 randomised controlled trials (24,532 participants) evaluating TENS delivered at a strong comfortable intensity at the painful site in adults with pain, irrespective of diagnosis. Results: Studies were conducted in 43 countries commonly using parallel group design (n = 334) and one comparator group (n = 231). Mean ± standard deviation (SD) study sample size (64.05 ± 58.29 participants) and TENS group size (27.67 ± 21.90 participants) were small, with only 13 of 381 studies having 100 participants or more in the TENS group. Most TENS interventions were ‘high frequency’ (>10 pps, n = 276) and using 100 Hz (109/353 reports that stated a pulse frequency value). Of 476 comparator groups, 54.2% were active treatments (i.e., analgesic medication(s), exercise, manual therapies and electrophysical agents). Of 202 placebo comparator groups, 155 used a TENS device that did not deliver currents. At least 216 of 383 study groups were able to access other treatments whilst receiving TENS. Only 136 out of 381 reports included a statement about adverse events. Conclusions: Clinical studies on TENS are dominated by small parallel group evaluations of high frequency TENS that are often contaminated by concurrent treatment(s). Study reports tended focus on physiological and clinical implications rather than the veracity of methodology and findings. Previously published criteria for designing and reporting TENS studies were neglected and this should be corrected in future research using insights gleaned from this analysis.

Pharmacological and non-pharmacological strategies for preventing postherpetic neuralgia: a systematic review and network meta-analysis

Background

Postherpetic neuralgia (PHN) is a refractory complication of herpes zoster (HZ). To prevent PHN, various strategies have been aggressively adopted. However, the efficacy of these strategies remains controversial. Therefore, we aimed to estimate the relative efficacy of various strategies used in clinical practice for preventing PHN using a network meta-analysis (NMA).

Methods

We performed a systematic and comprehensive search to identify all randomized controlled trials. The primary outcome was the incidence of PHN at 3 months after acute HZ. We performed both frequentist and Bayesian NMA and used the surface under the cumulative ranking curve (SUCRA) values to rank the interventions evaluated.

Results

In total, 39 studies were included in the systematic review and NMA. According to the SUCRA value, the incidence of PHN was lower in the order of continuous epidural block with local anesthetics and steroids (EPI-LSE), antiviral agents with subcutaneous injection of local anesthetics and steroids (AV + sLS), antiviral agents with intracutaenous injection of local anesthetics and steroids (AV + iLS) at 3 months after acute HZ. EPI-LSE, AV + sLS and AV + iLS were also effective in preventing PHN at 1 month after acute HZ. And paravertebral block combined with antiviral and antiepileptic agents was effective in preventing PHN at 1, 3, and 6 months.

Conclusions

The continuous epidural block with local anesthetics and steroid, antiviral agents with intracutaneous or subcutaneous injection of local anesthetics and a steroid, and paravertebral block combined with antiviral and antiepileptic agents are effective in preventing PHN.

Invasive and Non-Invasive Electrical Neuromodulation in Trigeminal Nerve Neuralgia: A Systematic Review and Meta-Analysis

BACKGROUND

Trigeminal neuralgia is a chronic disease characterized by intense facial pain that is caused by trigeminal nerve affectation. It usually affects adults from 50 years of age, and is more frequent in women. Additionally, it presents serious psychological effects that often lead to depression, which is why it is considered highly disabling. The therapeutic approach is based on the modification of nerve activity through electrical, surgical or chemical stimulation in specific regions of the nervous system.

OBJECTIVE

To perform a meta-analysis of the scientific literature related to invasive and non-invasive electrical neuromodulation of trigeminal neuralgia, in order to assess their effects over pain and adverse effects.

METHODS

A literature search was conducted in 4 databases, followed by a manual search of articles on invasive or non-invasive electrical neuromodulation to control the pain of trigeminal neuralgia, including the last 15 years.

RESULTS

Regarding non-invasive methods, clinical trials did not present enough results in order to perform a meta-analysis. Regarding invasive methods, clinical trials meta-analysis showed no statistical differences between different treatment methods. In all cases, improvements in patients' pain were reported, although results regarding adverse effects were variable.

CONCLUSION

In the treatment of trigeminal neuralgia, the continuous radiofrequency provides better short and medium-term results, but pulsed radiofrequency shows less adverse effects after treatment, and has better results in the long-term.

Combination of pregabalin and transcutaneous electrical nerve stimulation for neuropathic pain in a stroke patient after contralateral C7 nerve transfer: a case report

BACKGROUND

Contralateral C7 nerve transfer is a new surgical treatment for stroke patients with unilateral upper extremity paralysis, but neuropathic pain in the nonparalyzed side is the common complication after surgery. We report a stroke patient with neuropathic pain after C7 nerve transfer who received combination treatment of transcutaneous electrical nerve stimulation(TENS) and pregabalin.

CASE SUMMARY

A 53-year old, 6 months post-stroke patient with right hemiplegia after contralateral C7 nerve transfer was admitted in our department with a significant neuropathic pain in his left upper extremity. The treatment of pregabalin and TENS were used for patient. The visual analogue scale(VAS), medical outcomes study sleep scale(MOS-SS) and hospital anxiety and depression scale(HADS) were assessed after 1 months treatment. After treatment, the pain of his nonparalyzed upper extremity was relieved, the sleeping quality and the anxiety and depression were improved in patient.

CONCLUSION

This report suggests that the combination of pregabalin and TENS have prominent clinical effects on neuropathic pain of nonparalyzed side in stroke patients after contralateral C7 nerve transfer.

Postherpetic Neuralgia: Current Evidence on the Topical Film-Forming Spray with Bupivacaine Hydrochloride and a Review of Available Treatment Strategies

PURPOSE OF REVIEW

This is a comprehensive review of the literature about the use of bupivacaine hydrochloride for the treatment of post-herpetic neuralgia (PHN). It briefly reviews the background, biology, diagnosis and conventional treatment for PHN, and then introduces and compares the recent evidence for the use of topical bupivacaine.

RECENT FINDINGS

PHN is defined by pain lasting 90 days or more after the initial presentation of herpes zoster ("Shingles", HZ) rash and is the most common complication of this disease. A product of re-activation of the Varicella-Zoster virus (VZV), HZ is diagnosed more than 1 million times annually in the United States. Approximately 20% of patients with HZ will experience PHN and will continue to suffer intermittent neuropathic symptoms, including itching and pain, that is sharp, stabbing, throbbing or burning, with the pain localized to the site of their original rash. This long-lasting pain compares with the severity of long-standing rheumatics and osteo-arthritis and is accompanied by severe allodynia causing significant suffering, and a financial burden that is manifested in both healthcare costs and loss of quality-adjusted life years. Prevention of PHN may be achieved with the Zoster vaccine, although there is still a large segment of unvaccinated population. Moreover, the Zoster vaccine is not always effective for prevention. Current treatment includes medical (systemic tricyclic antidepressants, anticonvulsants and opioids, topical lidocaine and capsaicin) and interventional (subcutaneous Botox injections, nerve blocks and nerve stimulation) therapies. These therapies are not always effective, and each carries their own profile of side effects and risks. Moreover, up to 50% of patients with PHN are refractory to management. Recent evidence is emerging to support the use of topical local anesthetics for the treatment of PHN. Two small studies recently found topical lidocaine spray to be effective in treating paroxysmal pain attacks associated with PHN. Bupivacaine is a longer-lasting local anesthetic, and a film-forming formulation allows easy and durable application to the affected skin. Recent studies show that topical film-forming bupivacaine is safe and as effective as lidocaine for the treatment of PHN. PHN is an important though common complication of HZ and can cause long-lasting pain and disability. Current treatment for PNH is limited by efficacy and safety profiles of individual therapies. Recent evidence points to topical local anesthetics as an effective and safe alternative to conventional therapy. Film-forming bupivacaine may offer a durable and safe option for this otherwise difficult to treat syndrome.

Pharmacological and non-pharmacological treatments for neuropathic pain: Systematic review and French recommendations

Neuropathic pain remains a significant unmet medical need. Several recommendations have recently been proposed concerning pharmacotherapy, neurostimulation techniques and interventional management, but no comprehensive guideline encompassing all these treatments has yet been issued. We performed a systematic review of pharmacotherapy, neurostimulation, surgery, psychotherapies and other types of therapy for peripheral or central neuropathic pain, based on studies published in peer-reviewed journals before January 2018. The main inclusion criteria were chronic neuropathic pain for at least three months, a randomized controlled methodology, at least three weeks of follow-up, at least 10 patients per group, and a double-blind design for drug therapy. Based on the GRADE system, we provide weak-to-strong recommendations for use and proposal as a first-line treatment for SNRIs (duloxetine and venlafaxine), gabapentin and tricyclic antidepressants and, for topical lidocaine and transcutaneous electrical nerve stimulation specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a second-line treatment for pregabalin, tramadol, combination therapy (antidepressant combined with gabapentinoids), and for high-concentration capsaicin patches and botulinum toxin A specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a third-line treatment for high-frequency rTMS of the motor cortex, spinal cord stimulation (failed back surgery syndrome and painful diabetic polyneuropathy) and strong opioids (in the absence of an alternative). Psychotherapy (cognitive behavioral therapy and mindfulness) is recommended as a second-line therapy, as an add-on to other therapies. An algorithm encompassing all the recommended treatments is proposed.

Transcutaneous electrical nerve stimulation (TENS): a review of applications in dermatology

Background: A transcutaneous electrical nerve stimulation (TENS) unit is an inexpensive, accessible therapeutic device with multiple dermatology-related uses.Objective: This review aims to describe the dermatological applications of TENS.Methods: PubMed was searched for literature related to TENS in dermatology. Articles describing this association were reviewed for evidence.Results: TENS offered pain relief during photodynamic therapy for the treatment of actinic keratoses, with a reduction in visual analog scale (VAS) scores for patients using TENS during photodynamic therapy compared to those using no intervention. In the treatment of refractory postherpetic neuralgia pain, patients received greater pain relief when given pregabalin along with TENS therapy compared to pregabalin and no TENS therapy. TENS was the most effective therapy in reducing the incidence of PHN when compared to antiviral agents or combination therapy. The administration of TENS three times per week for four weeks improved VAS scores for pruritus associated with atopic dermatitis and lichen simplex chronicus. This benefit extended into the treatment of other conditions, resulting in improvement of pruritus measured by VAS and Dermatology Life Quality Index scores for macular amyloidosis and lichen planus.Conclusions: TENS is beneficial in the field of dermatology, particularly involving the relief of chronic pruritus.

The beneficial use of ultramicronized palmitoylethanolamide as add-on therapy to Tapentadol in the treatment of low back pain: a pilot study comparing prospective and retrospective observational arms

Background

This pilot study was designed to compare the efficacy of ultramicronized palmitoylethanolamide (um-PEA) as add-on therapy to tapentadol (TP) with TP therapy only in patients suffering from chronic low back pain (LBP).

Methods

This pilot observational study consists in two arms: the prospective arm and the retrospective one. In the prospective arm patients consecutively selected received um-PEA as add-on therapy to TP for 6 months; in the retrospective arm patients were treated with TP only for 6 months. Pain intensity and neuropathic component were evaluated at baseline, during and after 6 months. The degree of disability and TP dosage assumption were evaluated at baseline and after 6 months.

Results

Statistical analysis performed with generalized linear mixed model on 55 patients (30 in the prospective group and 25 in the retrospective group) demonstrated that um-PEA as add-on treatment to TP in patients with chronic LBP, in comparison to TP alone, led to a significantly higher reduction in pain intensity, in the neuropathic component, the degree of disability and TP dosage assumption. No serious side effects were observed.

Conclusion

Overall, the present findings suggest that um-PEA may be an innovative therapeutic intervention as add-on therapy to TP for the management of chronic LBP with a neuropathic component, as well as to improve patient quality of life. Additionally, this combination treatment allowed a reduction in TP dose over time and did not show any serious side effects.

Transcutaneous electrical nerve stimulation (TENS) for neuropathic pain in adults

BACKGROUND

Neuropathic pain, which is due to nerve disease or damage, represents a significant burden on people and society. It can be particularly unpleasant and achieving adequate symptom control can be difficult. Non-pharmacological methods of treatment are often employed by people with neuropathic pain and may include transcutaneous electrical nerve stimulation (TENS). This review supersedes one Cochrane Review 'Transcutaneous electrical nerve stimulation (TENS) for chronic pain' (Nnoaham 2014) and one withdrawn protocol 'Transcutaneous electrical nerve stimulation (TENS) for neuropathic pain in adults' (Claydon 2014). This review replaces the original protocol for neuropathic pain that was withdrawn.

OBJECTIVES

To determine the analgesic effectiveness of TENS versus placebo (sham) TENS, TENS versus usual care, TENS versus no treatment and TENS in addition to usual care versus usual care alone in the management of neuropathic pain in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PsycINFO, AMED, CINAHL, Web of Science, PEDro, LILACS (up to September 2016) and various clinical trials registries. We also searched bibliographies of included studies for further relevant studies.

SELECTION CRITERIA

We included randomised controlled trials where TENS was evaluated in the treatment of central or peripheral neuropathic pain. We included studies if they investigated the following: TENS versus placebo (sham) TENS, TENS versus usual care, TENS versus no treatment and TENS in addition to usual care versus usual care alone in the management of neuropathic pain in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all database search results and identified papers requiring full-text assessment. Subsequently, two review authors independently applied inclusion/exclusion criteria to these studies. The same review authors then independently extracted data, assessed for risk of bias using the Cochrane standard tool and rated the quality of evidence using GRADE.

MAIN RESULTS

We included 15 studies with 724 participants. We found a range of treatment protocols in terms of duration of care, TENS application times and intensity of application. Briefly, duration of care ranged from four days through to three months. Similarly, we found variation of TENS application times; from 15 minutes up to hourly sessions applied four times daily. We typically found intensity of TENS set to comfortable perceptible tingling with very few studies titrating the dose to maintain this perception. Of the comparisons, we had planned to explore, we were only able to undertake a quantitative synthesis for TENS versus sham TENS. Insufficient data and large diversity in the control conditions prevented us from undertaking a quantitative synthesis for the remaining comparisons.For TENS compared to sham TENS, five studies were suitable for pooled analysis. We described the remainder of the studies in narrative form. Overall, we judged 11 studies at high risk of bias, and four at unclear risk. Due to the small number of eligible studies, the high levels of risk of bias across the studies and small sample sizes, we rated the quality of the evidence as very low for the pooled analysis and very low individual GRADE rating of outcomes from single studies. For the individual studies discussed in narrative form, the methodological limitations, quality of reporting and heterogeneous nature of interventions compared did not allow for reliable overall estimates of the effect of TENS.Five studies (across various neuropathic conditions) were suitable for pooled analysis of TENS versus sham TENS investigating change in pain intensity using a visual analogue scale. We found a mean postintervention difference in effect size favouring TENS of -1.58 (95% confidence interval (CI) -2.08 to -1.09, P < 0.00001, n = 207, six comparisons from five studies) (very low quality evidence). There was no significant heterogeneity in this analysis. While this exceeded our prespecified minimally important difference for pain outcomes, we assessed the quality of evidence as very low meaning we have very little confidence in this effect estimate and the true effect is likely to be substantially different from that reported in this review. Only one study of these five investigated health related quality of life as an outcome meaning we were unable to report on this outcome in this comparison. Similarly, we were unable to report on global impression of change or changes in analgesic use in this pooled analysis.Ten small studies compared TENS to some form of usual care. However, there was great diversity in what constituted usual care, precluding pooling of data. Most of these studies found either no difference in pain outcomes between TENS versus other active treatments or favoured the comparator intervention (very low quality evidence). We were unable to report on other primary and secondary outcomes in these single trials (health-related quality of life, global impression of change and changes in analgesic use).Of the 15 included studies, three reported adverse events which were minor and limited to 'skin irritation' at or around the site of electrode placement (very low quality evidence). Three studies reported no adverse events while the remainder did not report any detail with regard adverse events.

AUTHORS' CONCLUSIONS

In this review, we reported on the comparison between TENS and sham TENS. The quality of the evidence was very low meaning we were unable to confidently state whether TENS is effective for pain control in people with neuropathic pain. The very low quality of evidence means we have very limited confidence in the effect estimate reported; the true effect is likely to be substantially different. We make recommendations with respect to future TENS study designs which may meaningfully reduce the uncertainty relating to the effectiveness of this treatment modality.

Targeting Neuronal Networks with Combined Drug and Stimulation Paradigms Guided by Neuroimaging to Treat Brain Disorders

Improved therapy of brain disorders can be achieved by focusing on neuronal networks, utilizing combined pharmacological and stimulation paradigms guided by neuroimaging. Neuronal networks that mediate normal brain functions, such as hearing, interact with other networks, which is important but commonly neglected. Network interaction changes often underlie brain disorders, including epilepsy. "Conditional multireceptive" (CMR) brain areas (e.g., brainstem reticular formation and amygdala) are critical in mediating neuroplastic changes that facilitate network interactions. CMR neurons receive multiple inputs but exhibit extensive response variability due to milieu and behavioral state changes and are exquisitely sensitive to agents that increase or inhibit GABA-mediated inhibition. Enhanced CMR neuronal responsiveness leads to expression of emergent properties--nonlinear events--resulting from network self-organization. Determining brain disorder mechanisms requires animals that model behaviors and neuroanatomical substrates of human disorders identified by neuroimaging. However, not all sites activated during network operation are requisite for that operation. Other active sites are ancillary, because their blockade does not alter network function. Requisite network sites exhibit emergent properties that are critical targets for pharmacological and stimulation therapies. Improved treatment of brain disorders should involve combined pharmacological and stimulation therapies, guided by neuroimaging, to correct network malfunctions by targeting specific network neurons.

Transcutaneous electrical nerve stimulation for acute pain

BACKGROUND

This is a second update of a Cochrane Review originally published in Issue 2, 2009. Transcutaneous Electrical Nerve Stimulation (TENS) is a non-pharmacological agent, based on delivering low voltage electrical currents to the skin. TENS is used by people to treat a variety of pain conditions.

OBJECTIVES

To assess the analgesic effectiveness of TENS, as a sole treatment, for acute pain in adults.

SEARCH METHODS

We searched the following databases up to 3 December 2014: the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library; MEDLINE; EMBASE; CINAHL; and AMED. We also checked the reference lists of included trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of adults with acute pain (< 12 weeks) if they examined TENS given as a sole treatment and assessed pain with subjective pain scales. Trials were eligible if they compared TENS to placebo TENS, no treatment controls, pharmacological interventions or non-pharmacological interventions. We excluded trials on experimental pain, case reports, clinical observations, letters, abstracts or reviews. Also we excluded trials investigating the effect of TENS on pain during childbirth (labour), primary dysmenorrhoea or dental procedures. Studies where TENS was given with another treatment as part of the formal trial design were excluded. We did not restrict any articles based on language of publication.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and carried out study selection, data extraction, 'Risk of bias' assessment and analyses of data. We extracted data on the following: types of participants and pain condition, trial design and methods, treatment parameters, adverse effects, and outcome measures. We contacted trial authors for additional information if necessary.

MAIN RESULTS

We included 12 trials in the original review (2009) and included no further trials in the first update (2011). An additional seven new trials met the inclusion criteria in this second update. In total, we included 19 RCTs involving 1346 participants at entry, with 11 trials awaiting classification either because the full text was unavailable or information in the full text failed to clarify eligibility. We excluded most trials because TENS was given in combination with another treatment as part of the formal study design or TENS was not delivered using appropriate TENS technique. The types of acute pain included in this Cochrane Review were procedural pain, e.g. cervical laser treatment, venepuncture, screening flexible sigmoidoscopy and non-procedural pain, e.g. postpartum uterine contractions and rib fractures. We pooled data for pain intensity for six trials (seven comparisons) comparing TENS with placebo but the I(2) statistic suggested substantial heterogeneity. Mean difference (MD) with 95% confidence intervals (CIs) on a visual analogue scale (VAS, 100 mm) was -24.62 mm (95% CI -31.79 to -17.46) in favour of TENS. Data for the proportion of participants achieving ≥ 50% reduction in pain was pooled for four trials (seven comparisons) and relative risk was 3.91 (95% CI 2.42 to 6.32) in favour of TENS over placebo. We pooled data for pain intensity from five trials (seven comparisons) but the I(2) statistic suggested considerable heterogeneity. MD was -19.05 mm (95% CI -27.30 to -10.79) in favour of TENS using a random-effects model. It was not possible to pool other data. There was a high risk of bias associated with inadequate sample sizes in treatment arms and unsuccessful blinding of treatment interventions. Seven trials reported minor adverse effects, such as mild erythema and itching underneath the electrodes and participants disliking TENS sensation.

AUTHORS' CONCLUSIONS

This Cochrane Review update includes seven new trials, in addition to the 12 trials reviewed in the first update in 2011. The analysis provides tentative evidence that TENS reduces pain intensity over and above that seen with placebo (no current) TENS when administered as a stand-alone treatment for acute pain in adults. The high risk of bias associated with inadequate sample sizes in treatment arms and unsuccessful blinding of treatment interventions makes definitive conclusions impossible. There was incomplete reporting of treatment in many reports making replication of trials impossible.

[Postherpetic neuralgia]

Postherpetic neuralgia is considered to be a neuropathic pain syndrome. Typically, patients experience pain in the dermatomes of skin lesions persisting for more than 3 months after skin restitution. About 10% of patients with herpes zoster develop postherpetic neuralgia. Its prevalence increases with age. Common clinical symptoms include continuous burning pain, sharp pain attacks, and allodynia. Additionally, sensory hyperactivation or loss in the affected skin area is present. Pathophysiology includes mechanisms of peripheral and central sensitization, based on damaged nerve fibers as the main mechanisms for pain generation and its maintenance. Clinical studies did show pain relief in postherpetic neuralgia after administration of antidepressants, antiepileptic drugs, opioids, and topical capsaicin and lidocaine. Nevertheless, about one third of patients do not respond to conventional treatment. Given the fact that postherpetic neuralgia is considered to be a chronic pain disease, a multidisciplinary treatment approach is necessary.

[Postherpetic neuralgia]

Postherpetic neuralgia is considered to be a neuropathic pain syndrome. Typically, patients experience pain in the dermatomes of skin lesions persisting for more than 3 months after skin restitution. About 10% of patients with herpes zoster develop postherpetic neuralgia. Its prevalence increases with age. Common clinical symptoms include continuous burning pain, sharp pain attacks, and allodynia. Additionally, sensory hyperactivation or loss in the affected skin area is present. Pathophysiology includes mechanisms of peripheral and central sensitization, based on damaged nerve fibers as the main mechanisms for pain generation and its maintenance. Clinical studies did show pain relief in postherpetic neuralgia after administration of antidepressants, antiepileptic drugs, opioids, and topical capsaicin and lidocaine. Nevertheless, about one third of patients do not respond to conventional treatment. Given the fact that postherpetic neuralgia is considered to be a chronic pain disease, a multidisciplinary treatment approach is necessary.

Prevention of post-herpetic neuralgia using transcutaneous electrical nerve stimulation

BACKGROUND

Post-herpetic neuralgia (PHN) is the most common complication of herpes zoster (HZ) and is difficult to treat. The role of antiviral agents and nonpharmacologic procedures in preventing PHN is not entirely clear. Recent retrospective study showed that transcutaneous electrical nerve stimulation (TENS) may completely prevent PHN. The aim of our study was to identify predictors for PHN and evaluate the treatment with antiviral agents and TENS.

METHODS

We conducted a multicenter prospective, randomized intervention study in patients with a new onset of HZ. Immunocompromised patients were excluded. Patients were randomly assigned to four groups (TENS, Antiviral agents, TENS and Antiviral agents, and Control Group). At the inclusion, the following criteria were recorded: age, gender, duration of pain before the onset of the rash, the number of efflorescence, the intensity of pain, and the analgesic prescribed. During the follow-up, we recorded a spontaneous pain sensation, pain intensity, and presence of allodynia, hyperalgesia, or paraesthesia.

RESULTS

With each additional year of age, the odds for the presence of PHN with unchanged values of other predictors increase (odds ratio (OR) = 1.03 [1.01; 1.05], p = 0.001). The same is true for the initial intensity of the pain (OR = 1.25 [1.09; 1.43], p = 0.002). The odds for acute and subacute herpetic neuralgia are greater than for PHN. The odds for subacute herpetic neuralgia are the lowest in the group treated with TENS (OR = 0.15 [0.05; 0.47], p = 0.001).

CONCLUSIONS

PHN cannot be completely prevented. TENS as a single therapy was found the most successful among the tested treatments in reducing the incidence of subacute herpetic neuralgia.

Factors predicting adverse events associated with pregabalin administered for neuropathic pain relief

BACKGROUND

Pregabalin administration is occasionally abandoned due to adverse events such as somnolence, dizziness, unsteadiness, weight gain and edema. However, the exact causes of these differences in adverse events associated with pregabalin have not been elucidated.

OBJECTIVE

To identify factors predicting adverse events associated with pregabalin administered for neuropathic pain.

METHODS

The present study was a retrospective analysis involving 208&nbsp;patients with neuropathic pain who had been treated with pregabalin in the pain clinic at the authors' hospital between July 2010 and September 2011. Variables were extracted from the clinical records for regression analysis of factors related to the occurrence of adverse events associated with pregabalin administration. Multivariate logistic regression analysis was used to examine the relationship between various predictive factors and the adverse events.

RESULTS

Predictive factors were: duration of therapy (OR 1.684&nbsp;[95%&nbsp;CI 1.179 to 2.406]; P=0.0042) for somnolence; nonsteroidal anti-inflammatory drugs (OR 0.132 [95% CI 0.030 to 0.578]; P=0.0072), age (OR 3.137 [95% CI 1.220 to 8.066]; P=0.0177) and maintenance dose (OR 0.437 [95% CI 0.217 to 0.880]; P=0.0205) for unsteadiness; serum creatinine (OR 6.439&nbsp;[95% CI 1.541 to 26.902]; P=0.0107) for body weight gain; and neurotropin (OR 8.538 [95% CI 1.159 to 62.901]; P=0.0353) and serum creatinine (OR 6.912 [95% CI 1.118 to 42.726]; P=0.0375) for edema.

CONCLUSIONS

The results of the present study indicate that care is warranted regarding long durations of therapy for somnolence, advanced age rather than dose-dependent adverse events for unsteadiness, elevated serum creatinine level for weight gain, and elevated serum creatinine level and combination use of neurotropin for edema. The safety of the combined use of pregabalin and nonsteroidal anti-inflammatory drugs were also suggested.

Pregabalin: latest safety evidence and clinical implications for the management of neuropathic pain

Used mainly for the management of neuropathic pain, pregabalin is a gabapentinoid or anticonvulsant that was initially developed as an antiepileptic agent. After more than a decade of experience with pregabalin, experience and studies have shown that the adverse effect profile of pregabalin is well tolerated for the management of neuropathic pain and other conditions. Its use is associated with benign central nervous system and systemic adverse effects, and there are very limited metabolic, idiosyncratic or known teratogenic adverse effects. Along with its efficacy in particular neuropathic pain conditions, pregabalin's safety led it to be one of the first pharmacotherapies considered for the management of neuropathic pain. This review discusses the use of pregabalin as well as its potential adverse effects, including the most commonly noted features of sedation, dizziness, peripheral edema and dry mouth. Although other adverse effects may occur, these appear to be uncommon. The review also discusses the clinical implications of pregabalin's use for the clinician.

Evidence-based guidance for the management of postherpetic neuralgia in primary care

This article aims to help primary care physicians negotiate gaps in current guidelines for postherpetic neuralgia (PHN). The objectives of this article are to: 1) briefly review the available guidelines and identify their strengths and weaknesses; 2) review the gaps in the guidelines; 3) review new data that were not included in the most recent guidelines; 4) provide expert opinion on how the new data and current guidelines can be used to make treatment decisions; and 5) review several important dimensions of care (eg, tolerability, dosing) and provide guidance. In general, all guidelines recognize the α2δ ligands, tricyclic antidepressants (TCAs), opioids, and tramadol as efficacious systemic options, with topical lidocaine serving as an efficacious nonsystemic approach for localized PHN treatment. The first-line treatment options typically recommended in the guidelines are α2δ ligands and TCAs, while opioids and tramadol are often recommended as second- or third-line options. Since the latest guidelines were published, newer agents (eg, topical capsaicin [8%] patch and gastroretentive gabapentin) have met the standard as first-line therapy with the publication of ≥ 1 randomized controlled trial. However, gabapentin enacarbil has not met this standard due to a lack of a published randomized controlled trial in PHN.

Treatment of Postherpetic Pain With Scrambler Therapy, a Patient-Specific Neurocutaneous Electrical Stimulation Device

OBJECTIVES

Postherpetic neuropathy (PHN) is common, severe, and often refractory to treatment. We treated 10 patients with refractory PHN using Scrambler therapy, a neurocutaneous stimulation device that delivers "nonpain" information with surface electrodes.

METHODS

Scrambler therapy was given as 30-minute sessions daily for 10 days. Pain was recorded before and after treatment. Two centers.

RESULT

The average pain score rapidly diminished from 7.64 ± 1.46 at baseline to 0.42 ± 0.89 at 1 month, a 95% reduction, with continued relief at 2 and 3 months. Patients achieved maximum pain relief with less than 5 treatments.

DISCUSSION

Scrambler therapy appears to have a promising effect on PHN, with prompt and continued relief and no side effects. Further research is warranted.

Combination pharmacotherapy for the treatment of neuropathic pain in adults

BACKGROUND

Pharmacotherapy remains an important modality for the treatment of neuropathic pain. However, as monotherapy current drugs are associated with limited efficacy and dose-related side effects. Combining two or more different drugs may improve analgesic efficacy and, in some situations, reduce overall side effects (e.g. if synergistic interactions allow for dose reductions of combined drugs).

OBJECTIVES

This review evaluated the efficacy, tolerability and safety of various drug combinations for the treatment of neuropathic pain.

SEARCH METHODS

We identified randomised controlled trials (RCTs) of various drug combinations for neuropathic pain from CENTRAL, MEDLINE, EMBASE and handsearches of other reviews and trial registries. The most recent search was performed on 9 April 2012.

SELECTION CRITERIA

Double-blind, randomised studies comparing combinations of two or more drugs (systemic or topical) to placebo and/or at least one other comparator for the treatment of neuropathic pain.

DATA COLLECTION AND ANALYSIS

Data extracted from each study included: proportion of participants a) reporting ≥ 30% pain reduction from baseline OR ≥ moderate pain relief OR ≥ moderate global improvement; b) dropping out of the trial due to treatment-emergent adverse effects; c) reporting each specific adverse effect (e.g. sedation, dizziness) of ≥ moderate severity. The primary comparison of interest was between study drug(s) and one or both single-agent comparators. We combined studies if they evaluated the same drug class combination at roughly similar doses and durations of treatment. We used RevMan 5 to analyse data for binary outcomes.

MAIN RESULTS

We identified 21 eligible studies: four (578 participants) evaluated the combination of an opioid with gabapentin or pregabalin; two (77 participants) evaluated an opioid with a tricyclic antidepressant; one (56 participants) of gabapentin and nortriptyline; one (120 participants) of gabapentin and alpha-lipoic acid, three (90 participants) of fluphenazine with a tricyclic antidepressant; three (90 participants) of an N-methyl-D-aspartate (NMDA) blocker with an agent from a different drug class; five (604 participants) of various topical medications; one (313 participants) of tramadol with acetaminophen; and another one (44 participants) of a cholecystokinin blocker (L-365,260) with morphine. The majority of combinations evaluated to date involve drugs, each of which share some element of central nervous system (CNS) depression (e.g. sedation, cognitive dysfunction). This aspect of side effect overlap between the combined agents was often reflected in similar or higher dropout rates for the combination and may thus substantially limit the utility of such drug combinations. Meta-analysis was possible for only one comparison of only one combination, i.e. gabapentin + opioid versus gabapentin alone. This meta-analysis involving 386 participants from two studies demonstrated modest, yet statistically significant, superiority of a gabapentin + opioid combination over gabapentin alone. However, this combination also produced significantly more frequent side effect-related trial dropouts compared to gabapentin alone.

AUTHORS' CONCLUSIONS

Multiple, good-quality studies demonstrate superior efficacy of two-drug combinations. However, the number of available studies for any one specific combination, as well as other study factors (e.g. limited trial size and duration), preclude the recommendation of any one specific drug combination for neuropathic pain. Demonstration of combination benefits by several studies together with reports of widespread clinical polypharmacy for neuropathic pain surely provide a rationale for additional future rigorous evaluations. In order to properly identify specific drug combinations which provide superior efficacy and/or safety, we recommend that future neuropathic pain studies of two-drug combinations include comparisons with placebo and both single-agent components. Given the apparent adverse impact of combining agents with similar adverse effect profiles (e.g. CNS depression), the anticipated development and availability of non-sedating neuropathic pain agents could lead to the identification of more favourable analgesic drug combinations in which side effects are not compounded.

Translational investigation and treatment of neuropathic pain

Neuropathic pain develops from a lesion or disease affecting the somatosensory system. Translational investigations of neuropathic pain by using different animal models reveal that peripheral sensitization, spinal and cortical plasticity may play critical roles in neuropathic pain. Furthermore, descending facilitatory or excitatory modulation may also act to enhance chronic pain. Current clinical therapy for neuropathic pain includes the use of pharmacological and nonpharmacological (psychological, physical, and surgical treatment) methods. However, there is substantial need to better medicine for treating neuropathic pain. Future translational researchers and clinicians will greatly facilitate the development of novel drugs for treating chronic pain including neuropathic pain.

Transcutaneous electrical nerve stimulation for the management of painful conditions: focus on neuropathic pain

The management of neuropathic pain is challenging, with medication being the first-line treatment. Transcutaneous electrical nerve stimulation (TENS) is an inexpensive, noninvasive, self-administered technique that is used as an adjunct to medication. Clinical experience suggests that TENS is beneficial providing it is administered at a sufficiently strong intensity, close to the site of pain. At present, there are too few randomized controlled trials on TENS for neuropathic pain to judge effectiveness. The findings of systematic reviews of TENS for other pain syndromes are inconclusive because trials have a low fidelity associated with inadequate TENS technique and infrequent treatments of insufficient duration. The use of electrode arrays to spatially target stimulation more precisely may improve the efficacy of TENS in the future.

Transcutaneous electrical nerve stimulation for acute pain

BACKGROUND

Transcutaneous Electrical Nerve Stimulation (TENS) is a non-pharmacological agent, based on delivering low voltage electrical currents to the skin. TENS is used for the treatment of a variety of pain conditions.

OBJECTIVES

To assess the analgesic effectiveness of TENS for acute pain in adults to see if it had any clear analgesic effect in its own right.

SEARCH STRATEGY

The following databases were searched: Cochrane Pain, Palliative and Supportive Care Group Specialised Register; the Cochrane Central Register of Controlled Trials, CENTRAL (in The Cochrane Library); MEDLINE; EMBASE; CINAHL; AMED; PEDro; OTseeker; OpenSIGLE; and, reference lists of included studies. The most recent search was undertaken in August 2008.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of adults with acute pain (less than 12 weeks) were included if they examined TENS given as a sole treatment and assessed pain with subjective pain scales. Studies were eligible if they compared TENS to placebo TENS, no treatment controls, pharmacological interventions or non-pharmacological interventions. Studies on experimental pain, case reports, clinical observations, letters, abstracts or reviews were excluded. Studies on TENS and labour pain, pain due to dental procedures and primary dysmenorrhoea were excluded. Studies where TENS was given with another treatment as part of the formal study design were also excluded. No restrictions were made regarding language.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility and extracted data. Data were extracted on the following: types of participants and pain condition, study design and methods, treatment parameters, adverse effects, and outcome measures. Study authors were contacted for additional information if necessary.

MAIN RESULTS

Of 1479 studies identified in the search, 132 were identified as relevant. Of these, 116 were excluded; the vast majority of these were excluded due to TENS being given with another treatment. Four studies were categorised as awaiting classification as the information provided in the full text failed to clarify their eligibility. Twelve RCTs involving 919 participants at entry were included. The types of acute pain conditions included procedural pain, e.g. cervical laser treatment, venipuncture, screening flexible sigmoidoscopy and non-procedural pain, e.g. postpartum uterine contractions, rib fractures. It was not possible to perform a meta-analysis due to insufficient data.

AUTHORS' CONCLUSIONS

Due to insufficient extractable data in the studies included in this review, we are unable to make any definitive conclusions about the effectiveness of TENS as an isolated treatment for acute pain in adults.