The lidocaine patch 5% effectively treats all neuropathic pain qualities: results of a randomized, double-blind, vehicle-controlled, 3-week efficacy study with use of the neuropathic pain scale

An update on the treatment of postherpetic neuralgia

Like other types of neuropathic pain, postherpetic neuralgia (PHN) can be resistant to many types of pharmacologic and interventional therapies. Although many analgesic agents have been used for the treatment of other types of neuropathic pain, tricyclic antidepressants, antiepileptic drugs, opioids, and lidocaine patch appear to demonstrate relative analgesic efficacy for the treatment of pain from PHN. There are fewer studies on the use of interventional options for the treatment of pain from PHN. The majority of interventional therapies show equivocal analgesic efficacy although some data indicate that intrathecal methylprednisolone may be effective. Further randomized, controlled trials will be needed to confirm the analgesic efficacy of analgesic and interventional therapies to determine their role in the overall treatment of patients with PHN.

PERSPECTIVE

This article reviews the analgesic options for the treatment of PHN and suggests that tricyclic antidepressants, membrane stabilizers, opioids, and lidocaine patch may demonstrate analgesic efficacy in this group of patients. These data may potentially help clinicians who attempt to provide analgesia in patients with PHN.

Topical amitriptyline versus lidocaine in the treatment of neuropathic pain

OBJECTIVE

Oral amitriptyline, a tricyclic antidepressant, is effective for treating neuropathic pain. We conducted a double-blind, randomized, placebo-controlled crossover study to evaluate the efficacy of topical 5% amitriptyline and 5% lidocaine in treating patients with neuropathic pain.

METHODS

Thirty-five patients with postsurgical neuropathic pain, postherpetic neuralgia, or diabetic neuropathy with allodynia or hyperalgesia were assigned to receive 3 topical creams (5% amitriptyline, 5% lidocaine, or placebo) in random sequence. The primary outcome measure was change in pain intensity (baseline vs. posttreatment average pain) using a 0 to 100 mm Visual Analog Scale. Secondary outcome measures included the McGill Pain Questionnaire, requirement for rescue medication, and patient satisfaction. Primary statistical comparisons were made with paired t tests or signed-rank tests.

RESULTS

A reduction in pain intensity was observed with topical lidocaine (P<0.05). No significant change in pain intensity was found with topical amitriptyline or placebo. In pairwise comparison of treatments, topical lidocaine and placebo each reduced pain more than topical amitriptyline (P<0.05).

DISCUSSION

This randomized, placebo-controlled crossover study examining topical 5% amitriptyline and 5% lidocaine in the treatment of neuropathic pain showed that topical lidocaine reduced pain intensity but the clinical improvement is minimal and that topical 5% amitriptyline was not effective.

The management of pain in children with life-limiting illnesses

The management of pain in children with life-limiting illnesses is complex and unfortunately not often done effectively. Pain is a multidimensional symptom that can overshadow all other experiences of both the child and family. This article focuses on topics common to practitioners caring for children with lifelimiting illnesses, including a review of myths and obstacles to achieving adequate pain control, a review of the pathophysiology of pain, an overview of the use of opioids in children, an approach to the management of neuropathic pain, and a brief discussion of nonpharmacologic pain management strategies.

Validation and Reliability of the Neuropathic Pain Scale (NPS) in Multiple Sclerosis

OBJECTIVE

Central neuropathic pain occurs in around 28% of patients with multiple sclerosis (MS). The Neuropathic Pain Scale (NPS) has received preliminary validation in peripheral neuropathic pain conditions. The aim of this study was to validate its use in MS central pain syndromes.

METHODS

We administered the NPS to 141 patients with MS, together with the Short Form McGill Pain Questionnaire (SFMPQ), the Hospital Anxiety and Depression Scale (HADS), and Short Form 36 Health Survey (SF-36).

RESULTS

Cronbach's alpha was 0.78 (95% CI 0.69; 0.83), implying a high degree of internal consistency. Three factors, "Familiar," "Superficial," and "Alien Perception," were extracted, accounting for 64% of the variance. The NPS 10-item total correlates with: the SFMPQ 15-item total score, rho=0.63 (95% CI 0.49; 0.74), its Visual Analog Scale, rho=0.49 (95% CI 0.33; 0.64), the transformed Pain domain of the SF-36 rho=-0.49 (95% CI -0.63; -0.32), but not with its remaining seven health domains, or with either the HADS anxiety or the depression scores. Limits of agreement for short-term test or re-test reliability of the 100 point NPS total (median 2 days, range 1 to 7) were -12 to 14 and when administered to 78 patients who rated their neuropathic pain the "Same" [median interval 33 days (range 19 to 126), the long-term test or re-test correlation coefficient was 0.71 (95% CI 0.6; 0.79)].

DISCUSSION

The NPS appears a useful tool in the assessment of neuropathic pain in MS patients and possibly in measuring outcomes of therapeutic interventions.

Cost-Effectiveness of a Lidocaine 5% Medicated Plaster Relative to Gabapentin for Postherpetic Neuralgia in the United Kingdom

BACKGROUND

Approximately 50% of elderly patients develop postherpetic neuralgia (PHN) after herpes zoster infection (shingles). A lidocaine 5% medicated plaster marketed in the United Kingdom in January 2007 has been shown to be an effective topical treatment for PHN with minimal risk of systemic adverse effects.

OBJECTIVE

This paper assessed the cost-effectiveness of using a lidocaine plaster in place of gabapentin in English primary care practice to treat those PHN patients who had insufficient pain relief with standard analgesics and could not tolerate or had contraindications to tricyclic antidepressants (TCAs). The analysis took the perspective of the National Health Service (NHS).

METHODS

The costs and benefits of gabapentin and the lidocaine plaster were calculated over a 6-month time horizon using a Markov model. The model structure allowed for differences in costs, utilities, and transition probabilities between the initial 30-day run-in period and maintenance therapy and also accounted for add-in medications and drugs received by patients who discontinued therapy. Most transition probabilities were based on non-head-to-head clinical trials identified through a systematic review. Data on resource utilization, discontinuation rates, and add-in or switch medications were obtained from a Delphi panel; cost data were from official price tariffs. Published utilities were adjusted for age and were supplemented and validated by the Delphi panel.

RESULTS

Six months of therapy with the lidocaine plaster cost pound 549 per patient, compared with pound 718 for gabapentin, and generated 0.05 more quality-adjusted life-years (QALYs). The lidocaine plaster therefore dominated gabapentin (95% CI, dominant- pound 2163/QALY gained). Probabilistic sensitivity analysis showed that there was a 90.15% chance that the lidocaine plaster was both less costly and more effective than gabapentin and a 99.99% chance that it cost < pound 20,000/QALY relative to gabapentin. Extensive deterministic sensitivity analyses confirmed the robustness of the conclusions.

CONCLUSION

This study found that the lidocaine 5% medicated plaster was a cost-effective alternative to gabapentin for PHN patients who were intolerant to TCAs and in whom analgesics were ineffective, from the perspective of the NHS.

Gene therapy applications for the treatment of neuropathic pain

Neuropathic pain is notoriously difficult to treat; currently available pharmaceutical drugs result in moderate analgesia in approximately a third of patients. As our understanding of the biological processes involved in the establishment and maintenance of neuropathic pain increases, so does the development of novel treatment options. Significant advancements have been made in the past few years in gene transfer, a very powerful potential therapy that can be used to directly target affected areas of the neuraxis or body tissues involved in neuropathic pain. Candidate gene products include directly analgesic proteins as well as proteins that interfere with pain-associated biochemical changes in nerve or other tissues underlying the disease process.

Pharmacological management of chronic neuropathic pain - consensus statement and guidelines from the Canadian Pain Society

Neuropathic pain (NeP), generated by disorders of the peripheral and central nervous system, can be particularly severe and disabling. Prevalence estimates indicate that 2% to 3% of the population in the developed world suffer from NeP, which suggests that up to one million Canadians have this disabling condition. Evidence-based guidelines for the pharmacological management of NeP are therefore urgently needed. Randomized, controlled trials, systematic reviews and existing guidelines focusing on the pharmacological management of NeP were evaluated at a consensus meeting. Medications are recommended in the guidelines if their analgesic efficacy was supported by at least one methodologically sound, randomized, controlled trial showing significant benefit relative to placebo or another relevant control group. Recommendations for treatment are based on degree of evidence of analgesic efficacy, safety, ease of use and cost-effectiveness. Analgesic agents recommended for first-line treatments are certain antidepressants (tricyclics) and anticonvulsants (gabapentin and pregabalin). Second-line treatments recommended are serotonin noradrenaline reuptake inhibitors and topical lidocaine. Tramadol and controlled-release opioid analgesics are recommended as third-line treatments for moderate to severe pain. Recommended fourth-line treatments include cannabinoids, methadone and anticonvulsants with lesser evidence of efficacy, such as lamotrigine, topiramate and valproic acid. Treatment must be individualized for each patient based on efficacy, side-effect profile and drug accessibility, including cost. Further studies are required to examine head-to-head comparisons among analgesics, combinations of analgesics, long-term outcomes, and treatment of pediatric and central NeP.

Topical lidocaine for the treatment of postherpetic neuralgia

BACKGROUND

The cause of postherpetic neuralgia is damage to peripheral neurons, dorsal root ganglia, and the dorsal horn of the spinal cord, secondary to herpes zoster infection (shingles). In postherpetic neuralgia, peripheral neurons discharge spontaneously and have lowered activation thresholds, and exhibit an exaggerated response to stimuli. Topical lidocaine dampens peripheral nociceptor sensitisation and central nervous system hyperexcitability, and may benefit patients with postherpetic neuralgia.

OBJECTIVES

To examine the efficacy and safety of topical lidocaine in the treatment of postherpetic neuralgia.

SEARCH STRATEGY

We searched the Cochrane Pain, Palliative and Supportive Care Group Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and LILACS, SIGLE for conference proceedings, Citation Index, the reference lists of all eligible trials, key textbooks, and previous systematic reviews. We also wrote to authors of all identified trials.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing all topical applications of lidocaine, including gels and patches in patients of all ages with postherpetic neuralgia (pain persisting at the site of shingles at least one month after the onset of the acute rash).

DATA COLLECTION AND ANALYSIS

Two review authors extracted data, and a third checked them. We obtained some missing data from the US Food and Drugs Administration.

MAIN RESULTS

Three trials involving 182 topical lidocaine treated participants and 132 control participants were included. Two trials gave data on pain relief, and the remaining study provided data on secondary outcome measures. The largest trial published as an abstract compared topical lidocaine patch to a placebo patch and accounted for 150 of the 314 patients (48%).A meta-analysis combining two of the three studies identified a significant difference between the topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P = 0.003). There was a statistical difference between the groups for the secondary outcome measure of mean VAS score reduction (P = 0.03), but this was only for a single small trial. There were a similar number of adverse skin reactions in both treatment and placebo groups. The highest recorded blood lidocaine concentration varied between 59 ng/ml and 431 ng/ml between trials. The latter figure is high and the authors of the study suggest that the sample had been contaminated during the assay procedure.

AUTHORS' CONCLUSIONS

There is insufficient evidence to recommend topical lidocaine as a first-line agent in the treatment of postherpetic neuralgia with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (e.g. topical anaesthetics versus anti-epileptics).

Neuropathic pain in soft tissue complaints

Many soft tissue complaints are associated with the development of neuropathic pain. This pain is produced by pathophysiological processes that are different to the processes involved in the generation of the inflammatory or nociceptive pain more commonly encountered in soft tissue disorders. One of the consequences of this is that neuropathic pain can often be less responsive to standard analgesic therapies. The use of alternative analgesic strategies may be necessary if we are to treat neuropathic pain successfully. This chapter aims to outline some of the clinical features associated with neuropathic pain, the aetiological factors leading to its development and the evidence base (or lack) behind current treatment strategies. It will try to provide a rational approach to the management of neuropathic pain in patients with soft tissue disorders, particularly focusing on pharmacological management. Neuropathic pain is the focus of much current research activity, particularly pharmacological research, and this chapter will attempt to identify gaps in our clinical knowledge and highlight opportunities for further research.

Post-herpetic neuralgia in older adults: evidence-based approaches to clinical management

Many individuals across the globe have been exposed to the varicella-zoster virus (VZV) that causes chickenpox. After chickenpox has resolved, the virus remains latent in the dorsal root ganglia where it can re-emerge later in life as herpes zoster, otherwise known as shingles. Herpes zoster is a transient disease characterised by a dermatomal rash that is usually associated with significant pain. Post-herpetic neuralgia (PHN) is the term used for the condition that exists if the pain persists after the rash has resolved. Advanced age and compromised cell-mediated immunity are significant risk factors for reactivation of herpes zoster and the subsequent development of PHN. Though the pathophysiology of PHN is unclear, studies suggest peripheral and central demyelination as well as neuronal destruction are involved. Both the vaccine against VZV (Varivax) and the newly released vaccine against herpes zoster (Zostavax) may lead to substantial reductions in morbidity from herpes zoster and PHN. In addition, current evidence suggests that multiple medications are effective in reducing the pain associated with PHN. These include tricyclic antidepressants, antiepileptics, opioids, NMDA receptor antagonists as well as topical lidocaine (lignocaine) and capsaicin. Reasonable evidence supports the use of intrathecal corticosteroids, but the potential for neurological sequelae should prompt caution with their application. Epidural corticosteroids have not been shown to provide effective analgesia for PHN. Sympathetic blockade may assist in treating the pain of herpes zoster or PHN. For intractable PHN pain, practitioners have performed delicate surgeries and attempted novel therapies. Although such therapies may help reduce pain, they have been associated with disappointing results, with up to 50% of patients failing to receive acceptable pain relief. Hence, it is likely that the most effective future treatment for this disease will focus on prevention of VZV infection and immunisation against herpes zoster infection with a novel vaccine.

Multimodal approaches to the management of neuropathic pain: the role of topical analgesia

Because of their localized activity and low systemic absorption, topical analgesics have a favorable safety profile and a low risk for drug-drug interactions. There is a growing body of evidence on the efficacy and safety of these agents in a variety of pain disorders, including the most prevalent neuropathic pain conditions. The molecular basis for the usage of peripheral analgesics in neuropathic pain and the available clinical trial evidence for a wide variety of topical agents are reviewed.

Recent Advances in Understanding Pain Mechanisms Provide Future Directions for Pain Management

PURPOSE/OBJECTIVES

To review current knowledge of neurobiologic mechanisms that generate and maintain chronic pain and to explain how they might be applied in targeting treatment of chronic, inflammatory, and neuropathic pain syndromes.

DATA SOURCES

Published research, literature review articles, and abstracts as well as national statistics.

DATA SYNTHESIS

Treatment for chronic pain associated with cancer and other syndromes remains suboptimal and falls significantly short of clinical needs. Data highlight the role that multiple neurobiologic mechanisms play in modulating and maintaining pain at various levels of the central and peripheral nervous systems. Novel agents have been developed that use a more targeted approach to treating chronic pain.

CONCLUSIONS

A growing body of evidence highlights the critical role that neurobiologic mechanisms play in the initiation and maintenance of chronic pain. A thorough understanding of these mechanisms ultimately may result in targeted treatment approaches that focus on the central and peripheral mechanisms involved in mediation of chronic, inflammatory, and neuropathic pain syndromes.

IMPLICATIONS FOR NURSING

A majority of patients undergoing active treatment for cancer experiences unrelieved pain. By gaining a better understanding of the mechanisms that generate and maintain chronic pain, oncology nurses can promote targeted pain management strategies that incorporate novel therapeutic agents.

Sequential medication strategies for postherpetic neuralgia: a cost-effectiveness analysis

Several medications are recommended for relief of postherpetic neuralgia (PHN). A sequential treatment algorithm has been suggested, but its cost-effectiveness is unclear. We developed a decision model to estimate the cost-effectiveness of this algorithm compared with other sequential medication strategies in 70-year-olds with PHN, using literature data to model medication-related PHN relief while also accounting for severe medication side effects. Hypothetical patients with and without coronary artery disease (CAD) were considered separately, with and without localized pain. Sequential medication switches occurred as the result of inadequate relief or intolerable side effects. Probabilistic sensitivity analyses were performed to estimate the favorability of each medication early in treatment sequences. In patients without CAD, tricyclic and gabapentin were equally favored as initial therapy if mortality with tricyclic use was not increased, but gabapentin was strongly favored if it was. In patients with CAD, gabapentin was overwhelmingly favored. In either patient group, opioids, pregabalin, and tramadol were not favored as initial therapy but were sensible choices later in treatment sequences. The lidocaine patch was a reasonable first choice in patients with localized PHN. Our analysis supports the suggested treatment algorithm, with cost-effectiveness ratios within acceptable ranges for medications given sequentially, based on literature-based estimates of effectiveness and tolerability.

PERSPECTIVE

This article examines the cost-effectiveness of recommended sequential treatment strategies for postherpetic neuralgia. This decision analysis-based synthesis of effectiveness and cost data found that recommended treatment algorithms are also economically reasonable.

Pain after spinal cord injury: an evidence-based review for clinical practice and research. Report of the National Institute on Disability and Rehabilitation Research Spinal Cord Injury Measures meeting

BACKGROUND/OBJECTIVES

To examine the reliability, validity, sensitivity, and practicality of various outcome measures for pain after spinal cord injury (SCI), and to provide recommendations for specific measures for use in clinical trials.

DATA SOURCES

Relevant articles were obtained through a search of MEDLINE, EMBASE, CINAHL, and PubMed databases from inception through 2006.

STUDY SELECTION

The authors performed literature searches to find articles containing data relevant to the reliability and validity of each pain outcome measure in SCI and selected non-SCI populations.

DATA EXTRACTION

After reviewing the articles, an investigator extracted information utilizing a standard template. A second investigator reviewed the chosen articles and the extracted pertinent information to confirm the findings of the first investigator.

DATA SYNTHESIS

Taking into consideration both the quantity and quality of the studies analyzed, judgments on reliability and validity of the measures were made by the two investigators. Based upon these judgments, recommendations were formulated for use of specific measures in future clinical trials. In addition, for a subset of measures a voting process by a larger group of SCI experts allowed formulation of recommendations including determining which measures should be incorporated into a minimal dataset of measures for clinical trials and which ones need revision and further validity and reliability testing before use.

CONCLUSIONS

A 0-10 Point Numerical Rating Scale (NRS) is recommended as the outcome measure for pain intensity after SCI, while the 7-Point Guy/Farrar Patient Global Impression of Change (PGIC) scale is recommended as the outcome measure for global improvement in pain. The SF-36 single pain interference question and the Multidimensional Pain Inventory (MPI) or Brief Pain Inventory (BPI) pain interference items are recommended as the outcome measures for pain interference after SCI. Brush or cotton wool and at least one high-threshold von Frey filament are recommended to test mechanical allodynia/hyperalgesia while a Peltier-type thermotester is recommended to test thermal allodynia/hyperalgesia. The International Association for the Study of Pain (IASP) or Bryce-Ragnarsson pain taxonomies are recommended for classification of pain after SCI, while the Neuropathic Pain Scale (NPS) is recommended for measuring change in neuropathic pain and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) for quantitating neuropathic and nociceptive pain discrimination.

Transdermal treatment options for neurological disorders: impact on the elderly

As people grow old, their need for medications increases dramatically because of the higher incidence of chronic pain, diabetes mellitus, cardiovascular and neurological diseases in the elderly population. Furthermore, the elderly require special consideration with respect to drug delivery, drug interactions and adherence. In particular, patients with chronic neurological diseases often require multiple administration of drugs during the day to maintain constant plasma medication levels, which in turn increases the likelihood of poor adherence. Consequently, several attempts have been made to develop pharmacological preparations that can achieve a constant rate of drug delivery. For example, transdermal lisuride and apomorphine have been shown to reduce motor fluctuations and duration of 'off' periods in advanced Parkinson's disease, while rotigotine allows significant down-titration of levodopa without severe adverse effects. Thus, parkinsonian patients with long-term levodopa syndrome or motor disorders during sleep could benefit from use of transdermal lisuride and apomorphine. Moreover, transdermal dopaminergic drugs, particularly rotigotine, seem the ideal treatment for patients experiencing restless legs syndrome or periodic limb movement disorder during sleep, disorders that are quite common in elderly people or in association with neurodegenerative diseases. Unlike dopaminergic drugs, transdermal treatments for the management of cognitive and behavioural dysfunction in patients with Parkinson's disease and Alzheimer's disease have inconsistent effects and no clearly established role. Nevertheless, because of their favourable pharmacological profile and bioavailability, the cholinesterase inhibitors tacrine and rivastigmine are expected to show at least the same benefits as oral formulations of these drugs, but with fewer severe adverse effects. Transdermal delivery systems play an important role in the management of neuropathic pain. The transdermal lidocaine (lignocaine) patch is recommended as first-line therapy for the treatment of postherpetic neuralgia. Furthermore, in patients with severe persistent pain, transdermal delivery systems using the opioids fentanyl and buprenorphine are able to achieve satisfactory analgesia with good tolerability, comparable to the benefits seen with oral formulations. Transdermal administration is the ideal therapeutic approach for chronic neurological disorders in elderly people because it provides sustained therapeutic plasma levels of drugs, is simple to use, and may reduce systemic adverse effects. Several transdermal delivery systems are currently under investigation for the treatment of Parkinson's disease, Alzheimer's disease and neuropathic pain. Although most transdermal delivery systems treatments cannot be considered as first-line therapy at present, some of them provide clear advantages compared with other routes of administration and may become the preferred treatment in selected patients. In general, however, most transdermal treatments still require long-term evaluation in large patient groups in order to optimise dosages and evaluate the actual incidence of local and systemic adverse effects.

EFNS guidelines on pharmacological treatment of neuropathic pain

Neuropathic pain treatment remains unsatisfactory despite a substantial increase in the number of trials. This EFNS Task Force aimed at evaluating the existing evidence about the pharmacological treatment of neuropathic pain. Studies were identified using first the Cochrane Database then Medline. Trials were classified according to the aetiological condition. All class I and II controlled trials (according to EFNS classification of evidence) were assessed, but lower-class studies were considered in conditions that had no top level studies. Only treatments feasible in an outpatient setting were evaluated. Effects on pain symptoms/signs, quality of life and comorbidities were particularly searched for. Most of the randomized controlled trials included patients with postherpetic neuralgia (PHN) and painful polyneuropathies (PPN) mainly caused by diabetes. These trials provide level A evidence for the efficacy of tricyclic antidepressants, gabapentin, pregabalin and opioids, with a large number of class I trials, followed by topical lidocaine (in PHN) and the newer antidepressants venlafaxine and duloxetine (in PPN). A small number of controlled trials were performed in central pain, trigeminal neuralgia, other peripheral neuropathic pain states and multiple-aetiology neuropathic pains. The main peripheral pain conditions respond similarly well to tricyclic antidepressants, gabapentin, and pregabalin, but some conditions, such as HIV-associated polyneuropathy, are more refractory. There are too few studies on central pain, combination therapy, and head-to-head comparison. For future trials, we recommend to assess quality of life and pain symptoms or signs with standardized tools.

The Pain Quality Assessment Scale: Assessment of Pain Quality in Carpal Tunnel Syndrome

The Neuropathic Pain Scale (NPS) is a valid measure of the pain qualities and perceived depth of neuropathic pain. However, it does not include a number of pain qualities commonly seen in some neuropathic and non-neuropathic pain conditions. To address this limitation, additional items were added to the NPS to create a 20-item measure (Pain Quality Assessment Scale, PQAS) that would be even more useful for assessing neuropathic pain and also would be used to assess pain qualities associated with non-neuropathic pain. To evaluate the responsivity of the PQAS items to pain treatment, secondary analyses were conducted on data from a trial that compared the efficacy of lidocaine patch 5% versus a single steroid injection in 40 patients with carpal tunnel syndrome. Statistically significant (P < .0025) decreases in 10 of the 20 PQAS pain descriptor ratings occurred with both treatments, and 8 ratings showed nonsignificant trends (.0025 < P < .05) for decreasing before treatment to after treatment. No significant differences were found between the 2 treatment conditions on any of the items. The results support the validity of the PQAS items for assessing the effects of pain treatment on pain qualities of carpal tunnel syndrome.

PERSPECTIVE

Clinical trials that include measures of pain qualities can be used to identify the effects of treatments on distinct pain qualities. Measures such as the PQAS can potentially be used to help clinicians target analgesics more efficiently.

Diabetic neuropathies: diagnosis and treatment

Diabetic neuropathy can affect every organ system of the body. Diagnosis of diabetic neuropathy is usually one of exclusion. Clinical guidelines and the introduction of new medications for pain relief in peripheral neuropathy are improving medical and nursing management. Simpler diagnostic tests for cardiac autonomic neuropathy, which can be performed in an office setting, may mean earlier recognition and treatment with less mortality. Oral medications for the treatment of erectile dysfunction make it easier for the patient to seek treatment for a condition that impact quality of life.

Brain activity for spontaneous pain of postherpetic neuralgia and its modulation by lidocaine patch therapy

Postherpetic neuralgia (PHN) is a debilitating chronic pain condition, yet there is a lack of knowledge regarding underlying brain activity. Here we identify brain regions involved in spontaneous pain of PHN (n=11) and determine its modulation with Lidoderm therapy (patches of 5% lidocaine applied to the PHN affected body part). Continuous ratings of fluctuations of spontaneous pain during fMRI were contrasted to ratings of fluctuations of a bar observed during scanning, at three sessions: (1) pre-treatment baseline, (2) after 6h of Lidoderm treatment, and (3) after 2 weeks of Lidoderm use. Overall brain activity for spontaneous pain of PHN involved affective and sensory-discriminative areas: thalamus, primary and secondary somatosensory, insula and anterior cingulate cortices, as well as areas involved in emotion, hedonics, reward, and punishment: ventral striatum, amygdala, orbital frontal cortex, and ventral tegmental area. Generally, these activations decreased at sessions 2 and 3, except right anterior insular activity which increased with treatment. The sensory and affective activations only responded to the short-term treatment (6h of Lidoderm); while the ventral striatum and amygdala (reward-related regions) decreased mainly with longer-term treatment (2 weeks of Lidoderm). Pain properties: average magnitude of spontaneous pain, and responses on Neuropathic Pain Scale (NPS), decreased with treatment. The ventral striatal and amygdala activity best reflected changes in NPS, which was modulated only with longer-term treatment. The results show a specific brain activity pattern for PHN spontaneous pain, and implicate areas involved in emotions and reward as best reflecting changes in pain with treatment.

Metastatic bone cancer pain: Etiology and treatment options

Painful metastatic bone disease remains a challenge for physicians. The treatment choices available are wide and varied, with each having its appropriate place in the management of painful bone metastases. Radiotherapy remains the mainstay of treatment with or without surgery. Advances in understanding the intricate pathway responsible for pain generation and the addition of agents such as bisphosphonates to the physician's armamentarium further assist in the management of painful bone metastases.

Development and validity testing of the neuropathy total symptom score-6: questionnaire for the study of sensory symptoms of diabetic peripheral neuropathy

OBJECTIVE

The aim of this study was to develop and validate a neuropathy sensory symptom scale, the Neuropathy Total Symptom Score-6 (NTSS-6), which evaluates individual neuropathy sensory symptoms in patients with diabetes mellitus (DM) and diabetic peripheral neuropathy (DPN) in clinical trials, with the intent of distinguishing a response to therapy.

METHODS

The NTSS-6 questionnaire was developed to evaluate the frequency and intensity of individual neuropathy sensory symptoms identified frequently by patients with DPN (ie, numbness and/or insensitivity; prickling and/or tingling sensation; burning sensation; aching pain and/or tightness; sharp, shooting, lancinating pain; and allodynia and/or hyperalgesia). The NTSS-6 was administered 8 times over a 1-year period to DPN patients. The NTSS-6's reliability (determined by internal consistency and test-retest reproducibility), construct validity, convergent validity, and minimally clinically important differences (MCIDs) were determined.

RESULTS

The NTSS-6 was administered to a total of 205 patients at 10 centers in the United States, Canada, Belgium, Germany, Hungary, Croatia, Slovenia, and the United Kingdom. Internal consistency was demonstrated at all 8 visits (Cronbach's alpha > 0.7). Test-retest reproducibility (intraclass correlation coefficient >0.9) was observed during the baseline period and at end point. Construct validity was demonstrated by statistically significant correlations between the NTSS-6 total score and the Neuropathy Symptoms and Change (NSC) score (r = 0.773-0.885, P < 0.001). Convergent validity was demonstrated by statistically significant correlations between the change in NTSS-6 total scores and the following: change in NSC scores (r = 0.519-0.708, P < 0.001); change in Neuropathy Impairment Score of the Lower Limbs and composite nerve function scores (r = 0.188-0.202, P < 0.007), and categories of the Clinical Global Impressions (r = 0.402, P < 0.001). The within- and between-groups MCIDs for the total NTSS-6 total scores were -1.26 and 0.97 points, respectively. The mean (SD) within-group MCID for all patients who improved on the Clinical Global Impression was -2.29 (3.4) points.

CONCLUSIONS

The NTSS-6 provided a valid assessment of neuropathy sensory symptoms in this sample of patients with DM and DPN, which suggests that it may be useful for symptom evaluation in clinical trials and practice. The NTSS-6 showed internal consistency, test-retest reliability, and construct validity. There was also convergent validity of the scores, indicating that the NTSS-6 may be a suitable questionnaire for clinical trials that evaluate symptoms of DPN in this well-defined patient population.

The epidemiology of chronic pain of predominantly neuropathic origin. Results from a general population survey

Progress in the understanding of chronic pain with neuropathic features has been hindered by a lack of epidemiologic research in the general population. The Leeds Assessment of Neuropathic Symptoms and Signs score (S-LANSS) was recently validated for use in postal surveys, making the identification of pain of predominantly neuropathic origin possible. Six family practices in 3 UK cities (Aberdeen, Leeds, and London) generated a total random sample of 6,000 adults. The mailed questionnaire included demographic items, chronic pain identification, and intensity questions, the S-LANSS, the Level of Expressed Needs questionnaire, and the Neuropathic Pain Scale. With a corrected response rate of 52%, the prevalence of any chronic pain was 48% and the prevalence of pain of predominantly neuropathic origin was 8%. Respondents with this chronic neuropathic pain were significantly more likely to be female, slightly older, no longer married, living in council rented accommodation, unable to work, have no educational qualifications, and be smokers than all other respondents. Multiple logistic regression modeling found that pain of predominantly neuropathic origin was independently associated with older age, gender, employment (being unable to work), and lower educational attainment. Respondents with this pain type also reported significantly greater pain intensity, higher scores on the NPS, higher levels of expressed need, and longer duration of pain. This is the first estimate of the prevalence and distribution of pain of predominantly neuropathic origin in the general population, using a previously validated and reliable data collection instrument.

PERSPECTIVE

Chronic pain with neuropathic features appears to be more common in the general population than previously suggested. This type of pain is more severe than other chronic pain but distributed similarly throughout sociodemographic groups.

Can pain can be more or less neuropathic? Comparison of symptom assessment tools with ratings of certainty by clinicians

Chronic pain is generally regarded as being divided into two mutually exclusive pain mechanisms: nociceptive and neuropathic. Recently, this dichotomous approach has been questioned and a model of chronic pain being 'more or less neuropathic' has been suggested. To test whether such a spectrum exists, we examined responses by patients with chronic pain to validated neuropathic pain assessment tools and compared these with ratings of certainty about the neuropathic origin of pain by their specialist pain physicians. We examined 200 patients (100 each with nociceptive and neuropathic pain) and administered the self-complete Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS score) and the Neuropathic Pain Scale (NPS). Clinicians were asked to rate their certainty of the presence of neuropathic pain mechanisms on a 100 mm visual analogue scale (VAS) (0='not at all neuropathic in origin' to 100='completely neuropathic in origin'). The whole sample was divided into tertiles based on ascending ratings of diagnostic certainty by clinicians using the VAS and labelled 'unlikely', 'possible' and 'definite' neuropathic pain. There were significant differences in median S-LANSS and NPS composite scores between all tertile groups. There were also significant differences between many S-LANSS and NPS item scores between groups. We have shown that higher scores on both the S-LANSS and the NPS are indicative of greater clinician certainty of neuropathic pain mechanisms being present. These data support the theoretical construct that pain can be more or less neuropathic and that pain of predominantly neuropathic origin may be a useful clinical concept.

Lidocaine 5% Patch: An Open-Label Naturalistic Chronic Pain Treatment Trial and Prediction of Response: Table 1

OBJECTIVE

There have been a few open-label nonplacebo reports on the successful use of lidocaine 5% patch (L5P) for other types of pain besides postherpetic neuralgia, such as chronic low back pain. With the these reports, we began to utilize L5P routinely for chronic pain patients (CPPs) with various pain diagnoses. The purpose of this report was to describe the results of a retrospective review of this open-label naturalistic L5P chronic pain treatment trial and to attempt to delineate predictors of perceived clinical response.

DESIGN

Consecutive CPPs were selected for this clinical trial according to the following inclusion criteria: the CPPs with pain greater than 6-month duration and either a hyperalgesic pain area or trigger point, which could be covered by one L5P, were offered a 3-day L5P naturalistic treatment trial. The purpose of this trial was to determine which CPPs would perceive improvement and continue using L5P. CPPs entering the trial completed the neuropathic pain scale (NPS) at entrance and completion of the trial. The senior author also completed a baseline information tool on each CPP entering this naturalistic trial. At the completion of the 3-day trial, the CPPs were asked if they perceived pain improvement with the use of L5P. In the retrospective review, the CPPs were thus segregated into two groups, those with and without perceived clinical improvement, and were statistically compared for available clinical variables. Logistic regression was then utilized to determine which significant independent variables contributed to the correct prediction of perceived improvement.

SETTING

Multidisciplinary pain facility.

PATIENTS

Patients with chronic pain.

RESULTS

Of 362 consecutive CPPs, 114 or 31.5% were deemed candidates for this naturalistic trial. None of the CPPs refused or fulfilled exclusion criteria eliminating them from the trial. The total sample (N = 114) showed statistical improvement on all 10 NPS scales (except scales 4 and 6) plus the NPS 4, NPS nonallodynic 8, and NPS 10. The perceived clinically improved group (N = 87, 76.3% of those entering the trial), also showed perceived improvement on all preceding scales except 4 and 6. The perceived clinically nonimproved group (N = 27, 23.7% of those entering the trial) showed statistical improvement on scales B and NPS 10. Perceived improvement was predicted by the following variables: pain wakes patient up, patch placement not low back, and not in litigation. These variables explained 9.8%, 20%, and 14% of the variance, respectively. Overall, 44.5% of the variance was explained.

CONCLUSIONS

A significant percentage of CPPs exposed to an L5P 3-day naturalistic trial perceived clinical improvement. However, this can only be concluded as an initial effect, and whether or not this effect is attributable to L5P cannot be derived from our data as the effect could have been nonspecific. The apparent CPP perceived clinical improvement was not associated with any particular useful clinical indicator. As such, at present, no variable can be recommended for use in selecting CPPs for such a naturalistic L5P clinical treatment trial. However, this study indicates that such a trial can be useful in selecting CPPs who may perceive benefit from L5P.

Topical amitriptyline and ketamine in neuropathic pain syndromes: an open-label study

Twenty eight subjects with refractory, moderate to severe peripheral neuropathic pain participated in an open label prospective trial examining perceived analgesic effect, patient satisfaction, and safety of topical amitriptyline 2%/ketamine 1% cream. Outcome measures included an 11-point numerical rating scale for pain intensity (NRS-PI), a 5-point satisfaction scale, blood chemistry screen, drug and metabolite levels, urinalyses, electrocardiogram (ECG), and physical examination. Adverse events were monitored. Twenty-one subjects completed the trial. At 6 months, subjects reported an average long-term reduction in pain of 34% (standard deviation [SD] = 37%); 5 subjects (25%) achieved 50% or greater reduction in pain and 1 subject (5%) achieved 100% reduction in pain. At 12 months, the average reduction in pain was 37% (SD = 40%); 7 subjects (40%) achieved 50% or greater pain reduction. At the end of the study, 89% of subjects rated their satisfaction as 3/5 or greater and 2 subjects (10%) were pain free. Minimal adverse events were reported and there were no serious medication related adverse events. Blood levels revealed minimal systemic absorption. In conclusion, topical 2% amitriptyline/ 1% ketamine cream was associated with long-term reduction (6-12 months) in perceived pain, moderate to complete satisfaction, and was well tolerated in treatment of neuropathic pain. There was no significant systemic absorption of amitriptyline or ketamine.

PERSPECTIVE

This study demonstrates that topical 2% amitriptyline/1% ketamine, given over 6-12 months, is associated with long-term perceived analgesic effectiveness in treatment of neuropathic pain. Antidepressants and ketamine both produce multiple pharmacologic effects that may contribute to peripheral analgesia; such actions include block of peripheral N-methyl-D-aspartate receptors, local anesthetic properties, and interactions with adenosine systems.

The pharmacotherapy of chronic pain: a review

The past two decades have contributed a large body of preclinical work that has assisted in our understanding of the underlying pathophysiological mechanisms that cause chronic pain. In this context, it has been recognized that effective treatment of pain is a priority and that treatment often involves the use of one or a combination of agents with analgesic action. The current review presents an evidence-based approach to the pharmacotherapy of chronic pain. Medline searches were done for all agents used as conventional treatment in chronic pain. Published papers up to June 2005 were included. The search strategy included randomized, controlled trials, and where available, systematic reviews and meta-analyses. Further references were found in reference sections of papers located using the above search strategy. Agents for which there were no controlled trials supporting efficacy in treatment of chronic pain were not included in the present review, except in cases where preclinical science was compelling, or where initial human work has been positive and where it was thought the reader would be interested in the scientific evidence to date.

Topical agents for the treatment of chronic pain

Unlike systemic analgesics, topical analgesics exert their analgesic activity locally and without significant systemic absorption. This is in contrast to transdermal analgesics, which require systemic absorption for clinical benefit. The mechanism of action of a particular topical analgesic is unique to the specific medication being used as a topical analgesic. Topical analgesics have been studied in an increasing number of painful clinical conditions, and the results of some of these studies are summarized in this article. The potential role of topical analgesics acting peripherally in affecting the central processing of pain as well as painful states considered to be "central," not "peripheral," also are reviewed.

Algorithm for neuropathic pain treatment: an evidence based proposal

New studies of the treatment of neuropathic pain have increased the need for an updated review of randomized, double-blind, placebo-controlled trials to support an evidence based algorithm to treat neuropathic pain conditions. Available studies were identified using a MEDLINE and EMBASE search. One hundred and five studies were included. Numbers needed to treat (NNT) and numbers needed to harm (NNH) were used to compare efficacy and safety of the treatments in different neuropathic pain syndromes. The quality of each trial was assessed. Tricyclic antidepressants and the anticonvulsants gabapentin and pregabalin were the most frequently studied drug classes. In peripheral neuropathic pain, the lowest NNT was for tricyclic antidepressants, followed by opioids and the anticonvulsants gabapentin and pregabalin. For central neuropathic pain there is limited data. NNT and NNH are currently the best way to assess relative efficacy and safety, but the need for dichotomous data, which may have to be estimated retrospectively for old trials, and the methodological complexity of pooling data from small cross-over and large parallel group trials, remain as limitations.

Diagnosis and treatment of neuropathic pain

PURPOSE OF REVIEW

Neuropathic pain accounts for 25-50% of pain clinic visits with an estimated prevalence of 4 million. Neuropathic pain is often difficult to diagnose and treat with few pharmacologic options currently available. This review summarizes the latest research on the pathophysiology, diagnosis and treatment of neuropathic pain.

RECENT FINDINGS

The diagnosis of neuropathic pain relies on an evaluation of information given by the patient and physical findings obtained by the health provider. There are several validated questionnaires that can be used. Neuropathic pain is associated with a number of different cellular and molecular mechanisms. These include abnormalities in ion channels; exaggerated responses to cytokines, enzymes and neuropeptides; and abnormal communications between large/small fibers and sympathetic/small fibers. An understanding of these mechanisms has led to mechanistic directed treatments including topical treatments, antiepileptics, antidepressants, opioids and other drugs in development that are more mechanistically driven.

SUMMARY

Neuropathic pain is common, underdiagnosed and undertreated. Diagnosing and understanding the basic mechanisms of neuropathic pain will lead to better treatments of this difficult health care problem.

Lidocaine Patch Treatment in Patients with Low Back Pain: Results of an Open-Label, Nonrandomized Pilot Study

This prospective, 6-week, multicenter, open-label, nonrandomized pilot study was designed to assess the effectiveness and safety of a lidocaine patch 5% in patients with low back pain (LBP). Patients with moderate to severe LBP, defined as acute/subacute (< 3 months, n = 21), short-term chronic (3-12 months, n = 33), or long-term chronic (> 12 months, n = 77), were recruited from 5 clinics; participants applied < or = 4 patches (560 cm total) once daily to area of maximal LBP as add-on treatment through week 2, with the option to taper concomitant analgesics during weeks 3-6. Scores on Brief Pain Inventory (BPI) were obtained at weeks 2 and 6. Safety analyses included reports of adverse events (AEs) and skin sensitivity to pinprick/light touch. Significant improvements in average daily pain intensity on the BPI were noted at weeks 2 and 6 (P < or = 0.001). Significant improvements in pain interference with quality of life (QOL) were noted for all BPI measures of QOL at weeks 2 and 6 for the acute/subacute (P < or = 0.007) and long-term chronic LBP groups (P < 0.0001) and for 5 of 7 BPI measures for the short-term chronic LBP group (P < or = 0.042). Fifty-eight percent of patients reported being "satisfied" or "very satisfied" with treatment. The lidocaine patch was well tolerated. Most common AEs were dizziness and rash (n = 5, 3.8%), and most AEs (80%) were mild to moderate in intensity. Significant improvement in pain intensity and QOL in this cohort of LBP patients was noted during treatment with the lidocaine patch 5%. Controlled clinical trials are warranted.

The S-LANSS score for identifying pain of predominantly neuropathic origin: validation for use in clinical and postal research

This article describes the development and validation of the S-LANSS score, a self-report version of the Leeds Assessment of Neuropathic Symptoms and Signs pain scale. The S-LANSS aims to identify pain of predominantly neuropathic origin, as distinct from nociceptive pain, without the need for clinical examination. Two hundred patients with chronic pain were asked to complete the S-LANSS unaided. A researcher then administered the S-LANSS scale and the Neuropathic Pain Scale (NPS) in interview format. An independent clinician determined the pain type (neuropathic versus nociceptive) and rated his or her certainty about diagnosis. The S-LANSS scale was also incorporated into a chronic pain questionnaire that was sent to 160 community patients and 150 newly referred patients waiting for pain clinic assessment. The S-LANSS scale correctly identified 75% of pain types when self-completed and 80% when used in interview format. Sensitivity for self-completed S-LANSS scores ranged from 74% to 78%, depending on the cutoff score. There were significant associations between NPS items and total score with S-LANSS score. In the postal survey, completed questionnaires were returned by 57% of patients (n = 174). Internal consistency and convergent validity of the survey S-LANSS scores were confirmed. The findings support the S-LANSS scale as a valid and reliable self-report instrument for identifying neuropathic pain and it is also acceptable for use in postal survey research. Establishing valid measures of symptoms and signs in neuropathic pain will allow standardized comparisons with other investigational measures. This might lead to new insights into the relationship between pathophysiologic mechanisms and clinical manifestations of pain.

Contemporary management of neuropathic pain for the primary care physician

Neuropathic pain (NP), caused by a primary lesion or dysfunction in the nervous system, affects approximately 4 million people in the United States each year. It is associated with many diseases, including diabetic peripheral neuropathy, postherpetic neuralgia, human immunodeficiency virus-related disorders, and chronic radiculopathy. Major pathophysiological mechanisms include peripheral sensitization, sympathetic activation, disinhibition, and central sensitization. Unlike most acute pain conditions, NP is extremely difficult to treat successfully with conventional analgesics. This article introduces a contemporary management approach, that is, one that incorporates nonpharmacological, pharmacological, and interventional strategies. Some nonpharmacological management strategies include patient education, physical rehabilitation, psychological techniques, and complementary medicine. Pharmacological strategies include the use of first-line agents that have been supported by randomized controlled trials. Finally, referral to a pain specialist may be indicated for additional assessment, interventional techniques, and rehabilitation. Integrating a comprehensive approach to NP gives the primary care physician and patient the greatest chance for success.

Pharmacologic management part 1: better-studied neuropathic pain diseases

Neuropathic pain impacts millions of people in the United States and around the world. Patients experience one of many symptoms, such as pain, paresthesia, dysesthesia, hyperalgesia, and allodynia, for many years because of unavailable or inadequate treatment. One of the major challenges in treating patients with neuropathic pain syndromes is a lack of consensus concerning the appropriate first-line treatment options for conditions associated with neuropathic pain, including postherpetic neuralgia, diabetic peripheral neuropathy, and trigeminal neuralgia. This review summarizes the published results of randomized trials involving treatment for neuropathic pain conditions. Anticonvulsants, such as gabapentin, carbamazepine, and lamotrigine, and tricyclic antidepressants, including amitriptyline and desipramine, have demonstrated efficacy in relieving pain associated with postherpetic neuralgia, diabetic peripheral neuropathy, and trigeminal neuralgia, in several studies. However, the lack of head-to-head comparison studies of these agents limits the conclusions that can be reached. Clinicians who must make decisions regarding the care of individual patients may find some guidance from the number of randomized trials with a positive outcome for each agent. Using quality-of-life study outcomes, treatment strategies must encompass the impact of therapeutic agents on the comorbid conditions of sleep disturbance and mood and anxiety disorders associated with neuropathic pain. Looking to the future, emerging therapies, such as pregabalin and newer N-methyl-D-aspartate-receptor blockers, may provide physicians and patients with new treatment options for more effective relief of pain.

Targeted peripheral analgesics therapy for neuropathic pain

The term targeted peripheral analgesics has been suggested to describe analgesics with a mechanism of action that appears to be primarily through reducing pain transmission within the peripheral nervous system. Key differences between targeted peripheral (topical) and systemic analgesics and the difference between topical and transdermal analgesics are discussed in this article. A review of the clinical conditions, which have been reported to respond to targeted peripheral analgesics, also is described in detail.

[Reduction of chronic pain for non-postherpetic peripheral neuropathies after topical treatment with a lidocaine patch]

INTRODUCTION

To clarify whether the therapeutic indication for a lidocaine patch to treat postherpetic neuralgia can be extended to include other focal peripheral neuropathic pain syndromes, we performed a subgroup analysis of a placebo-controlled, double-blind randomized study.

METHODS

The study included 16 patients with focal peripheral painful neuropathies of non-herpetic origin, pain intensity > or =40 mm (VAS), and a stable pain medication. The patients received either the lidocaine patch 5% for 1 week or a placebo patch for 12 h daily according to a crossover design. Persistent pain, mechanical allodynia, and adverse events were assessed daily by the patients. Additionally, the pain perception test, the list of physical complaints, the depression test, and the health-related quality of life (SF-36) were used. Of the enrolled patients, 12 were statistically analyzed.

RESULTS

Persistent pain was reduced by the lidocaine patch almost significantly and allodynia was reduced significantly in comparison to the placebo patch. Scores for physical complaints improved significantly with the lidocaine patch. Only mild focal skin irritations occurred.

CONCLUSIONS

As an adjuvant medication, the lidocaine patch is effective and safe for reducing chronic pain and physical complaints in focal non-herpetic neuropathies.