A randomised double blind trial of the effect of pre-emptive epidural ketamine on persistent pain after lower limb amputation

[Treatment and prevention phantom pain syndrome in mine-explosive injuries]

Phantom pain syndrome significantly impairs the quality of life and effectiveness of surgical treatment after limb amputations. The authors consider possible strategies for treatment and prevention in elective surgical intervention and mine-explosive injuries.

Postamputation Residual Limb Pain Severity and Prevalence: A Systematic Review and Meta-Analysis

Background: Individuals with an extremity amputation are predisposed to persistent pain that reduces their quality of life. Residual limb pain is defined as pain that is felt in the limb after amputation. Methods: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review of 5 databases from inception to June 2020 was performed and is registered under the PROSPERO ID: CRD42020199297. Included studies were clinical trials with residual limb pain assessed at a minimum follow-up of 1 week. Meta-analyses of residual limb pain prevalence and severity were performed with subgroups of extremity and amputation etiology. Results: Twenty clinical trials met criteria and reported on a total of 1347 patients. Mean patient ages ranged from 38 to 77. Residual limb pain prevalence at 1 week, 1 month, 3 months, 6 months, 1 year, and 2 years, respectively, was 50%, 11%, 23%, 27%, 22%, and 24%. Mean residual limb pain severity at the 6 months or longer follow-up was 4.19 out of 10 for cancer amputations, 2.70 for traumatic amputations, 0.47 for vasculopathy amputations, 1.01 for lower extremity amputations, and 3.56 for upper extremity amputations. Conclusions: Residual limb pain severity varies according to the etiology of amputation and is more common after upper extremity amputation than lower extremity amputations. The most severe pain is reported by patients undergoing amputations due to cancer, followed by traumatic amputations, while vascular amputation patients report lower pain severity. Promising methods of reducing long-term pain are preoperative pain control, nerve or epidural blocks, use of memantine, calcitonin-containing blocks, and prophylactic nerve coaptations.

The effect of intravenous ketamine on depressive symptoms after surgery: A systematic review

STUDY OBJECTIVE

The development of depressive symptoms is an important complication experienced by patients postoperatively and is associated with poor clinical outcomes. Ketamine is a feasible treatment option for depressive symptoms after surgery due to its known antidepressant effect. This meta-analysis aimed to evaluate the current body of research regarding the effects of intravenous ketamine on depressive symptoms after surgery.

DESIGN

A meta-analysis of randomized controlled trials.

SETTING

Perioperative care area.

PATIENTS

Adult surgical patients.

MEASUREMENTS

Systematic literature search was performed in the CENTRAL, MEDLINE, and EMBASE databases, for randomized controlled trials comparing the effect of intravenous ketamine versus placebo on postoperative depressive symptoms as the primary outcome, with no language restrictions. Two independent reviewers screened records for inclusion, extracted data, and assessed risk of bias. Random effects models were used to pool overall estimates. Postoperative pain intensity was also examined. The GRADE approach was used to assess the quality of evidence.

MAIN RESULTS

Out of 834 records screened, 9 studies met our inclusion criteria, comprising a total of 2468 patients. Compared with the control group, ketamine provided significant reduction of postoperative depression scale scores, by a standardized mean difference (SMD) of -0.89 (95% CI [-1.23, -0.73], P = 0.33, I² = 13%; 4 studies) on postoperative day (POD) 1, SMD -0.51 (95% CI [-0.99, -0.04], P < 0.001, I² = 93%; 4 studies) on POD 3, suggesting clinically relevant reduction in postoperative depressive symptoms. Postoperative depression scale scores on POD 7 were also reduced in patients receiving ketamine compared to the control group, with SMD -0.33 (95% CI [-0.52, -0.14], P = 0.36, I² = 2%; 3 studies), but the minimal clinical difference of 0.5 SMD was not reached. No significant difference was observed in the postoperative depression scale over the long term at 30 days' follow-up (SMD -0.13, 95% CI [-0.25, 0.00], P = 0.07, I² = 52%; 5 studies). A significant reduction of postoperative pain intensity on POD 1 was identified in patients following ketamine administration (SMD -1.29, 95% CI [-2.57, -0.01], P = 0.05, I² = 98%; 5 studies). However, administration of ketamine resulted in a significantly increased risk of nausea and vomiting (RR 1.71, 95% CI [1.25, 2.33], P = 0.17, I² = 35%; 6 studies), headache (RR 4.88, 95% CI [1.97, 12.06], P = 0.83, I² = 0%; 4 studies), and hallucination (RR 34.94, 95% CI [8.59, 142.17], P = 0.44, I² = 0%; 4 studies).

CONCLUSIONS

The current evidence supports intravenous ketamine administration for the treatment of depressive symptoms after surgery. While ketamine administration has clinically significant side effects, future studies are needed in surgical populations at high risk of complications.

AAAPT Diagnostic Criteria for Acute Neuropathic Pain

OBJECTIVE

Acute neuropathic pain is a significant diagnostic challenge, and it is closely related to our understanding of both acute pain and neuropathic pain. Diagnostic criteria for acute neuropathic pain should reflect our mechanistic understanding and provide a framework for research on and treatment of these complex pain conditions.

METHODS

The Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership with the U.S. Food and Drug Administration (FDA), the American Pain Society (APS), and the American Academy of Pain Medicine (AAPM) collaborated to develop the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) for acute pain. A working group of experts in research and clinical management of neuropathic pain was convened. Group members used literature review and expert opinion to develop diagnostic criteria for acute neuropathic pain, as well as three specific examples of acute neuropathic pain conditions, using the five dimensions of the AAAPT classification of acute pain.

RESULTS

AAAPT diagnostic criteria for acute neuropathic pain are presented. Application of these criteria to three specific conditions (pain related to herpes zoster, chemotherapy, and limb amputation) illustrates the spectrum of acute neuropathic pain and highlights unique features of each condition.

CONCLUSIONS

The proposed AAAPT diagnostic criteria for acute neuropathic pain can be applied to various acute neuropathic pain conditions. Both the general and condition-specific criteria may guide future research, assessment, and management of acute neuropathic pain.

Surgical prevention of terminal neuroma and phantom limb pain: a literature review

The incidence of extremity amputation is estimated at about 200,000 cases annually. Over 25% of patients suffer from terminal neuroma or phantom limb pain (TNPLP), resulting in pain, inability to wear a prosthetic device, and lost work. Once TNPLP develops, there is no definitive cure. Therefore, there has been an emerging focus on TNPLP prevention. We examined the current literature on TNPLP prevention in patients undergoing extremity amputation. A literature review was performed using Ovid Medline, Cochrane Collaboration Library, and Google Scholar to identify all original studies that addressed surgical prophylaxis against TNPLP. The search was conducted using both Medical Subject Headings and free-text using the terms “phantom limb pain,” “amputation neuroma,” and “surgical prevention of amputation neuroma.” Fifteen studies met the inclusion criteria, including six prospective trials, two comprehensive literature reviews, four retrospective chart reviews, and three case series/technique reviews. Five techniques were identified, and each was incorporated into a target-based classification system. A small but growing body of literature exists regarding the surgical prevention of TNPLP. Targeted muscle reinnervation (TMR), a form of physiologic target reassignment, has the greatest momentum in the academic surgical community, with multiple recent prospective studies demonstrating superior prevention of TNPLP. Neurorrhaphy and transposition with implantation are supported by less robust evidence, but merit future study as alternatives to TMR.

Clinical updates on phantom limb pain

Phantom limb pain is highly prevalent after amputation. Treatment results will probably benefit from an interdisciplinary team and individually adapted surgical, prosthetic and pain medicine approaches.

Introduction:

Most patients with amputation (up to 80%) suffer from phantom limb pain postsurgery. These are often multimorbid patients who also have multiple risk factors for the development of chronic pain from a pain medicine perspective. Surgical removal of the body part and sectioning of peripheral nerves result in a lack of afferent feedback, followed by neuroplastic changes in the sensorimotor cortex. The experience of severe pain, peripheral, spinal, and cortical sensitization mechanisms, and changes in the body scheme contribute to chronic phantom limb pain. Psychosocial factors may also affect the course and the severity of the pain. Modern amputation medicine is an interdisciplinary responsibility.

Methods:

This review aims to provide an interdisciplinary overview of recent evidence-based and clinical knowledge.

Results:

The scientific evidence for best practice is weak and contrasted by various clinical reports describing the polypragmatic use of drugs and interventional techniques. Approaches to restore the body scheme and integration of sensorimotor input are of importance. Modern techniques, including apps and virtual reality, offer an exciting supplement to already established approaches based on mirror therapy. Targeted prosthesis care helps to obtain or restore limb function and at the same time plays an important role reshaping the body scheme.

Discussion:

Consequent prevention and treatment of severe postoperative pain and early integration of pharmacological and nonpharmacological interventions are required to reduce severe phantom limb pain. To obtain or restore body function, foresighted surgical planning and technique as well as an appropriate interdisciplinary management is needed.

Effect of Perioperative Ketamine on Postoperative Mood and Depression: A Review of the Literature

Introduction: Ketamine is being increasingly utilized in a variety of patient care settings, ranging from high acuity inpatient scenarios to the outpatient management of select mental health diagnoses. Postoperative patients are at an increased risk of developing a depressed state, and though ketamine's ability to improve mood is well documented in the literature, the relationship between perioperative ketamine and postoperative mood has not been fully elucidated. Areas covered: The purpose of this review was to determine ketamine's ability to improve mood and depression scores in the perioperative setting. A comprehensive literature review was conducted using PubMed, MEDLINE, Scopus, ProQuest, Web of Science, and CINAHL using the following search terminology: 'ketamine' AND 'perioperative' OR 'surgery' AND 'mood' OR 'depression.' Seven clinical trials are evaluated in this review. Expert opinion: As the use of ketamine continues to expand, clinicians must be cognizant of the fact that many of its desired effects are likely to overlap. Patients outside of the perioperative setting may benefit from using ketamine as an analgesic or sedative, as appropriate, to mitigate mood and depression. Ketamine, when administered as an anesthetic in the perioperative setting, seemingly has effect on postoperative mood and depression. Further studies that are sufficient.

Peripheral Nerve Blockade with Combined Standard and Liposomal Bupivacaine in Major Lower-Extremity Amputation

BACKGROUND AND OBJECTIVES

Optimizing perioperative analgesia for patients undergoing major lower-extremity amputation remains a considerable challenge. The utility of liposomal bupivacaine as a component of peripheral nerve blockade for lower-extremity amputation is unknown.

METHODS

We conducted an observational study comparing three different perioperative analgesic techniques for adults undergoing major lower-extremity amputation under general anesthesia between 2012 and 2017 at an academic medical center: (1) no regional anesthesia, (2) peripheral nerve blockade with standard bupivacaine, and (3) peripheral nerve blockade with a mixture of standard and liposomal bupivacaine. The primary outcome of cumulative opioid oral morphine milligram equivalent utilization in the first 72 hours postoperatively was compared across groups utilizing multivariable linear regression.

RESULTS

A total of 631 unique anesthetics were included for 578 unique patients, including 416 (66%) without regional anesthesia, 131 (21%) with peripheral nerve blockade with a mixture of standard and liposomal bupivacaine, and 84 (13%) with peripheral nerve blockade with standard bupivacaine alone. Cumulative morphine equivalents were lower in those receiving peripheral nerve blockade with combined standard and liposomal bupivacaine compared with those not receiving regional anesthesia (multiplicative increase 0.67; 95% CI 0.50 to 0.90; P = 0.007). There were no significant differences in opioid utilization between peripheral nerve blockade groups (P = 0.59).

CONCLUSIONS

Peripheral nerve blockade is associated with reduced opioid requirements after lower-extremity amputation compared with general anesthesia alone. However, the incorporation of liposomal bupivacaine is not significantly different to blockade employing only standard bupivacaine.

Analysis of SCN9A Gene Variants for Acute and Chronic Postoperative Pain and Morphine Consumption After Total Hysterectomy

BACKGROUND

Single nucleotide polymorphisms (SNPs) of the voltage-gated sodium channel alpha subunit gene (SCN9A) have been associated with pain in various settings. The aim of this study was to investigate the association of the SNPs to evaluate the influence of common gene variants on chronic postoperative pain (CPSP) and other related pain variables in a cohort of patients who underwent a scheduled hysterectomy.

METHODS

DNA samples from a cohort of 1,075 patients who underwent a scheduled total hysterectomy in our hospital were genotyped for three common SCN9A SNPs using TaqMan assays. Multivariate logistic regression models were used to quantify the association between independent covariates such as pain threshold, pain endurance, pain scores, morphine use, and the presence of chronic pain.

RESULTS

Frequencies of the minor alleles were different between the different ethnic groups. There was a statistically significant association of rs16851799 with morphine consumption and self-reported postoperative pain for the 1,038 subjects genotyped, with the TT genotype reporting higher pain and using more morphine. For the subpopulation of 446 subjects with chronic pain data, there was a similar association with self-reported postoperative pain and tolerance of pressure pain. Univariate analysis also showed a statistically significant association of rs16851799 with CPSP, whereas multivariable analysis revealed a similar association of rs4387806 with this outcome. There were three haplotypes with different relative frequencies for the CPSP and non-CPSP groups.

CONCLUSIONS

Our results showed that SCN9A polymorphisms could play a role in acute pain perception and the susceptibility to chronic pain.

Chronic Post-Surgical Pain in the Frail Older Adult

Older adults are the fastest growing segment of the population and surgical procedures in this group increase each year. Chronic post-surgical pain is an important consideration in the older adult as it affects recovery, physical functioning, and overall quality of life. It is increasingly recognized as a public health issue but there is a need to improve our understanding of the disease process as well as the appropriate treatment and prevention. Frailty, delirium, and cognition influence post-operative outcomes in older adults and have been implicated in the development of chronic post-surgical pain. Further research must be conducted to fully understand the role they play in the occurrence of chronic post-surgical pain in the older adult. Additionally, careful attention must be given to the physiologic, cognitive, and comorbidity differences between the older adult and the general population. This is critical for elucidating the proper chronic post-surgical pain treatment and prevention strategies to ensure that the older adult undergoing surgical intervention will have an appropriate and desirable post-operative outcome.

The Effect of Once-Daily Gabapentin Extended Release Formulation in Patients With Postamputation Pain

Objectives

To compare gabapentin extended-release, a gastro-retentive formulation, in relieving postamputation pain among gabapentin-experienced and gabapentin-naïve patients.

Design

Open-labeled pilot study.

Subjects

Sixteen patients with postamputation pain (8 patients in the gabapentin-experienced and 8 patients in the gabapentin-naïve groups).

Methods

Patients were started on gabapentin extended-release and were followed up for 8 weeks. Patients reported their pain severity during rest and movement using a numeric rating scale (NRS), interference of pain with daily activities using the modified brief pain inventory (MBPI) questionnaire, and treatment satisfaction using the treatment satisfaction questionnaire for medication (TSQM).

Results

Patients from both gabapentin-experienced and gabapentin-naïve groups achieved a significant and sustainable pain relief over the course of therapy. The pain scores at rest decreased in both gabapentin-experienced and gabapentin-naïve groups from 5.88 ± 1.36 and 4.88 ± 2.95 to 1.88 ± 0.99 and 1.38 ± 1.51, respectively. An average percent of pain relief with gabapentin extended-release was noted to be significant (p < 0.01) after 8 weeks of therapy among gabapentin-experienced (81.25 ± 16.42%) and gabapentin-naïve groups (85 ± 17.73%) when compared to baseline for gabapentin-experienced (31.25 ± 29%) and gabapentin-naïve groups (36.25 ± 34.2%), respectively. Gabapentin-experienced and gabapentin-naïve groups had no significant difference in global satisfaction from treatment (79.14 ± 10.47 and 83.3 ± 20.82), convenience of treatment (73.78 ± 19.04 and 90.44 ± 11.66), effectiveness of treatment (72.6 ± 10.1 and 79.73 ± 11.6). The only statistically significant difference among gabapentin-experienced and gabapentin-naïve groups was found in adverse event tolerability (65.78 ± 10.36 and 85.8 ± 10.14, p < 0.01).

Conclusion

Once-daily dosing of gabapentin-extended release showed significant improvement in pain severity and functional status, with no difference found between gabapentin-experienced versus gabapentin-naïve patients.

Efficacy and safety of epidural, continuous perineural infusion and adjuvant analgesics for acute postoperative pain after major limb amputation - a systematic review

BACKGROUND AND AIMS

Treatment of pain following major limb amputations is often a clinical challenge in a patient population consisting mainly of elderly with underlying diseases. Literature on management of acute post-amputation pain is scarce. We performed a systematic review on this topic to evaluate the efficacy and safety of analgesic interventions for acute pain following major limb amputation.

METHODS

A literature search was performed in PubMed, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews using the following key words: [(amputation) AND (pain OR analgesi* OR pain relief)] AND (acute OR postoperative). Randomized controlled studies (RCTs) and observational studies investigating treatment of acute pain following major amputations for any indication (peripheral vascular disease, malignant disease, trauma) were included. The review was performed according to the standards described in the PRISMA statement. The Cochrane quality assessment tool was used to evaluate the risk of bias in the RCTs.

RESULTS

Nineteen studies with total of 949 patients were included. The studies were generally small and heterogeneous on outcomes, study designs and quality. There were 16 studies on epidural or continuous perineural analgesia (CPI). Based on five RCTs (n=268) and two observational studies (n=49), epidural analgesia decreased the intensity of acute stump pain as compared to systemic analgesics, during the first 24 h after the operation. Based on one study epidural analgesia caused more adverse effects like sedation, nausea and motor block than continuous perineural local anesthetic infusion. Based on one RCT (n=21) and eight observational studies (n=501) CPI seemed to decrease opioid consumption as compared to systemic analgesics only, on the first three postoperative days, and was well tolerated. Only three trials investigated systemic analgesics (oral memantine, oral gabapentine, iv ketamine). Ketamine did not decrease acute pain or opioid consumption after amputation as compared to other systemic analgesics. Gabapentin did not decrease acute pain when combined to epidural analgesia as compared to epidural analgesia and opioid treatment, and caused adverse effects.

CONCLUSIONS

The main finding of this systematic review is that evidence regarding pain management after major limb amputation is very limited. Epidural analgesia may be effective, but firm evidence is lacking. Epidural causes more adverse effects than CPI. The results on efficacy of CPI are indecisive. The data on adjuvant medications combined to epidural analgesia or CPI is limited. Studies on efficacy and adverse effects of systemic analgesics for amputation pain, especially concentrating on elderly patients, are needed.

Pain Management in Athletes With Impairment: A Narrative Review of Management Strategies

OBJECTIVE

To review the literature related to different treatment strategies for the general population of individuals with amputation, spinal cord injury, and cerebral palsy, as well as how this may impact pain management in a correlated athlete population.

DATA SOURCES

A comprehensive literature search was performed linking pain with terms related to different impairment types.

MAIN RESULTS

There is a paucity in the literature relating to treatment of pain in athletes with impairment; however, it is possible that the treatment strategies used in the general population of individuals with impairment may be translated to the athlete population. There are a wide variety of treatment options including both pharmacological and nonpharmacological treatments which may be applicable in the athlete.

CONCLUSIONS

It is the role of the physician to determine which strategy of the possible treatment options will best facilitate the management of pain in the individual athlete in a sport-specific setting.

Pain management in patients with vascular disease

Vascular disease covers a wide range of conditions, including arterial, venous, and lymphatic disorders, with many of these being more common in the elderly. As the population ages, the incidence of vascular disease will increase, with a consequent increase in the requirement to manage both acute and chronic pain in this patient population. Pain management can be complex, as there are often multiple co-morbidities to be considered. An understanding of the underlying pain mechanisms is helpful in the logical direction of treatment, particularly in chronic pain states, such as phantom limb pain or complex regional pain syndrome. Acute pain management for vascular surgery presents a number of challenges, including coexisting anticoagulant medication, that may preclude the use of regional techniques. Within the limited evidence base, there is a suggestion that epidural analgesia provides better pain relief and reduced respiratory complications after major vascular surgery. For carotid endarterectomy, there is again some evidence supporting the use of local anaesthetic analgesia, either by infiltration or by superficial cervical plexus block. Chronic pain in vascular disease includes post-amputation pain, for which well-known risk factors include high pain levels before amputation and in the immediate postoperative period, emphasizing the importance of good pain control in the perioperative period. Complex regional pain syndrome is another challenging chronic pain syndrome with a wide variety of treatment options available, with the strongest evidence being for physical therapies. Further research is required to gain a better understanding of the underlying pathophysiological mechanisms in pain associated with vascular disease and the best analgesic approaches to manage it.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 39 studies, enrolling a total of 3027 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Local anaesthetics and regional anaesthesia versus conventional analgesia for preventing persistent postoperative pain in adults and children

BACKGROUND

Regional anaesthesia may reduce the rate of persistent postoperative pain (PPP), a frequent and debilitating condition. This review was originally published in 2012 and updated in 2017.

OBJECTIVES

To compare local anaesthetics and regional anaesthesia versus conventional analgesia for the prevention of PPP beyond three months in adults and children undergoing elective surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to December 2016 without any language restriction. We used a combination of free text search and controlled vocabulary search. We limited results to randomized controlled trials (RCTs). We updated this search in December 2017, but these results have not yet been incorporated in the review. We conducted a handsearch in reference lists of included studies, review articles and conference abstracts. We searched the PROSPERO systematic review registry for related systematic reviews.

SELECTION CRITERIA

We included RCTs comparing local or regional anaesthesia versus conventional analgesia with a pain outcome beyond three months after elective, non-orthopaedic surgery.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial quality and extracted data and adverse events. We contacted study authors for additional information. We presented outcomes as pooled odds ratios (OR) with 95% confidence intervals (95% CI), based on random-effects models (inverse variance method). We analysed studies separately by surgical intervention, but pooled outcomes reported at different follow-up intervals. We compared our results to Bayesian and classical (frequentist) models. We investigated heterogeneity. We assessed the quality of evidence with GRADE.

MAIN RESULTS

In this updated review, we identified 40 new RCTs and seven ongoing studies. In total, we included 63 RCTs in the review, but we were only able to synthesize data on regional anaesthesia for the prevention of PPP beyond three months after surgery from 41 studies, enrolling a total of 3143 participants in our inclusive analysis.Evidence synthesis of seven RCTs favoured epidural anaesthesia for thoracotomy, suggesting the odds of having PPP three to 18 months following an epidural for thoracotomy were 0.52 compared to not having an epidural (OR 0.52 (95% CI 0.32 to 0.84, 499 participants, moderate-quality evidence). Simlarly, evidence synthesis of 18 RCTs favoured regional anaesthesia for the prevention of persistent pain three to 12 months after breast cancer surgery with an OR of 0.43 (95% CI 0.28 to 0.68, 1297 participants, low-quality evidence). Pooling data at three to 8 months after surgery from four RCTs favoured regional anaesthesia after caesarean section with an OR of 0.46, (95% CI 0.28 to 0.78; 551 participants, moderate-quality evidence). Evidence synthesis of three RCTs investigating continuous infusion with local anaesthetic for the prevention of PPP three to 55 months after iliac crest bone graft harvesting (ICBG) was inconclusive (OR 0.20, 95% CI 0.04 to 1.09; 123 participants, low-quality evidence). However, evidence synthesis of two RCTs also favoured the infusion of intravenous local anaesthetics for the prevention of PPP three to six months after breast cancer surgery with an OR of 0.24 (95% CI 0.08 to 0.69, 97 participants, moderate-quality evidence).We did not synthesize evidence for the surgical subgroups of limb amputation, hernia repair, cardiac surgery and laparotomy. We could not pool evidence for adverse effects because the included studies did not examine them systematically, and reported them sparsely. Clinical heterogeneity, attrition and sparse outcome data hampered evidence synthesis. High risk of bias from missing data and lack of blinding across a number of included studies reduced our confidence in the findings. Thus results must be interpreted with caution.

AUTHORS' CONCLUSIONS

We conclude that there is moderate-quality evidence that regional anaesthesia may reduce the risk of developing PPP after three to 18 months after thoracotomy and three to 12 months after caesarean section. There is low-quality evidence that regional anaesthesia may reduce the risk of developing PPP three to 12 months after breast cancer surgery. There is moderate evidence that intravenous infusion of local anaesthetics may reduce the risk of developing PPP three to six months after breast cancer surgery.Our conclusions are considerably weakened by the small size and number of studies, by performance bias, null bias, attrition and missing data. Larger, high-quality studies, including children, are needed. We caution that except for breast surgery, our evidence synthesis is based on only a few small studies. On a cautionary note, we cannot extend our conclusions to other surgical interventions or regional anaesthesia techniques, for example we cannot conclude that paravertebral block reduces the risk of PPP after thoracotomy. There are seven ongoing studies and 12 studies awaiting classification that may change the conclusions of the current review once they are published and incorporated.

Spinal or general anaesthesia for lower-limb amputation in peripheral artery disease - a retrospective cohort study

BACKGROUND

The present study aimed to determine which method of anaesthesia (spinal anaesthesia or general anaesthesia) is better in reducing post-operative analgesic requirements in patients undergoing major limb amputation for lower-limb ischaemia. Another aim was to find out if anaesthesiologists use neuraxial anaesthesia in high-risk patients despite abnormal coagulation profile or use of anticoagulation.

METHODS

The study was a retrospective cohort study. All patients undergone above-the-knee amputation or below-the-knee amputation due to peripheral artery disease between 1996 and 2010 were reviewed to evaluate post-operative opioid consumption and complications.

RESULTS

A total of 434 amputations in 323 patients were included in the study. The number of surgical complications, the need for surgical revision and the number of intensive care unit admissions were significantly higher in the general anaesthesia group. The need for post-operative opioid medication was significantly lower in patients with above-the-knee amputation and spinal anaesthesia. The use of post-operative epidural analgesia did not reduce analgesic requirements. In the present study, there were patients who received neuraxial anaesthesia despite abnormal coagulation profile or uninterrupted warfarin or clopidogrel. There were no reported cases of spinal or epidural haematoma.

CONCLUSION

Patients with spinal anaesthesia had a lower rate of surgical complications, re-operations and intensive care unit admissions. Patients with above-the-knee amputation and spinal anaesthesia had a lesser need for opioid medication in the post-operative period than patients with general anaesthesia. Anaesthesiologists performed neuraxial anaesthesia and/or analgesia in high-risk patients despite abnormal coagulation profile or ongoing anticoagulation, but no adverse outcomes were reported.

Strategies for prevention of lower limb post-amputation pain: A clinical narrative review

Postamputation limb pain or phantom limb pain (PLP) develops due to the complex interplay of peripheral and central sensitization. The pain mechanisms are different during the initial phase following amputation as compared with the chronic PLP. The literature describes extensively about the management of established PLP, which may not be applicable as a preventive strategy for PLP. The novelty of the current narrative review is that it focuses on the preventive strategies of PLP. The institution of preoperative epidural catheter prior to amputation and its continuation in the immediate postoperative period reduced perioperative opioid consumption (Level II). Optimized preoperative epidural or intravenous patient-controlled analgesia starting 48 hours and continuing for 48 hours postoperatively decreased PLP at 6 months (Level II). Preventive role of epidural LA with ketamine (Level II) reduced persistent pain at 1 year and LA with calcitonin decreased PLP at 12 months (Level II). Peripheral nerve catheters have opioid sparing effect in the immediate postoperative period in postamputation patients (Level I), but evidence is low for the prevention of PLP (Level III). Gabapentin did not reduce the incidence or intensity of postamputation pain (Level II). The review in related context mentions evidence regarding therapeutic role of gabapentanoids, peripheral nerve catheters, and psychological therapy in established PLP. In future, randomized controlled trials with long-term follow-up of patients receiving epidural analgesia, perioperative peripheral nerve catheters, oral gabapentanoids, IV ketamine, or mechanism-based modality for prevention of PLP as primary outcome are required.

Perioperative Pain Management Strategies for Amputation: A Topical Review

Objective

To review acute pain management strategies in patients undergoing amputation with consideration of preoperative patient factors, pharmacologic/interventional modalities, and multidisciplinary care models to alleviate suffering in the immediate post-amputation setting.

Background

Regardless of surgical indication, patients undergoing amputation suffer from significant residual limb pain and phantom limb pain in the acute postoperative phase. Most studies have primarily focused on strategies to prevent persistent pain with inclusion of immediate postoperative outcomes as secondary measures. Pharmacologic agents, including gabapentin, ketamine, and calcitonin, and interventional modalities such as neuraxial and perineural catheters, have been examined in the perioperative period.

Design

Focused Literature Review.

Results

Pharmacologic agents (gabapentin, ketamine, calcitonin) have not shown consistent efficacy. Neuraxial analgesia has demonstrated both an opioid sparing and analgesic benefit while results have been mixed regarding perineural catheters in the immediate post-amputation setting. However, several early studies of perineural catheters employed sub-optimal techniques (distal surgical placement), and prolonged use of perineural catheters may provide a sustained benefit. Regardless of analgesic technique, a multidisciplinary approach is necessary for optimal care.

Conclusion

Patient-tailored analgesic regimens utilizing catheter-based techniques are essential in the acute post-amputation phase and should be implemented in all patients undergoing amputation. Future research should focus on improved measurement of acute pain and comparisons of effective analgesic regimens instead of single techniques.

Intervention for phantom limb pain: A randomized single crossover study of mirror therapy

INTRODUCTION

Mirror therapy suggested to help relieve phantom limb pain (PLP) by resolving the visual- proprioceptive dissociation in the brain, but studies so far either had shorter follow-up or smaller sample size.

MATERIALS AND METHODS

In this randomized single crossover trial, 64 amputees with PLP in the age group of 15-75 years of age were distributed into test and control groups by simple randomization method. Of these 28 in control and 32 in test groups, respectively, completed the 4 weeks of mirror therapy and 12 weeks of follow-up assessments. A standardized set of exercises for 15 min/day for 4 and 8 weeks in test and control groups (in the first 4 weeks, the mirror was covered), respectively, was administered under supervision of one of the authors. All were assessed using the visual analog scale and Short-Form McGill Pain Questionnaire on day 0 and at 4, 8, and 12 weeks after therapy. In control group for the initial 4 weeks, the mirror was covered. The assessing author was blinded to the group to which the participants belonged.

RESULTS

Significant reduction in PLP was noted in the test group at 4 weeks compared to the control group (P < 0.0001). Significant reduction was seen in control group also after the switchover and sustained for 12 weeks in both. No harm was reported.

CONCLUSION

Mirror therapy is effective in relieving the intensity, duration, frequency, and overall PLP, and improvement is maintained up to 12 weeks' posttherapy.

Comparing intensities and modalities within the sensory attenuation paradigm: Preliminary evidence

It is well-documented that the intensity of a self-generated somatosensory stimulus is perceived to be attenuated in respect to an identical stimulus generated by others. At present, it is not clear whether such a phenomenon, known as somatosensory attenuation, is based not only on feedforward motor signals but also on re-afferences towards the body. To answer this question, in the present pilot investigation on twelve healthy subjects, three types of stimulations (sensory non-nociceptive electrical – ES, nociceptive electrical – NES, and vibrotactile – VTS) and intensities (1 = sensory threshold ∗ 2.5 + 2 mA, 2 = sensory threshold ∗ 2.5 + 3 mA, 3 = sensory threshold ∗ 2.5 + 4 mA for ES and NES; 1 = sensory threshold ∗ 2 Hz, 2 = sensory threshold ∗ 3 Hz, 3 = sensory threshold ∗ 4 Hz for VTS) have been directly compared in a somatosensory attenuation paradigm. The results show that the attenuation effect emerged only with electrical stimuli and that it increased with higher intensities. These pilot findings suggest that, depending on the type and the intensity of stimulation, re-afferences can have a role in somatosensory attenuation. Additionally, it is possible to speculate the effect is present only with electrical stimuli because those stimuli are prospectively judged as potentially dangerous. This, in turn, would optimize planning successful reactions to incoming threatening stimuli.

The role of intraoperative interventions to minimise chronic postsurgical pain

Chronic postsurgical pain (CPSP) is the most common complication following surgery, with increasing evidence of both its prevalence and severity. While awareness of the various risk factors for this long-term condition is also increasing, effective prevention remains elusive. In this review, we describe the increasing evidence for preventive or 'protective' strategies. Controversies and conflicting human data are presented along with suggestions for improved future study.

A Randomized, Controlled Trial of Mirror Therapy for Upper Extremity Phantom Limb Pain in Male Amputees

Objective

Phantom limb pain (PLP) is prevalent in patients post-amputation and is difficult to treat. We assessed the efficacy of mirror therapy in relieving PLP in unilateral, upper extremity male amputees.

Methods

Fifteen participants from Walter Reed and Brooke Army Medical Centers were randomly assigned to one of two groups: mirror therapy (n = 9) or control (n = 6, covered mirror or mental visualization therapy). Participants were asked to perform 15 min of their assigned therapy daily for 5 days/week for 4 weeks. The primary outcome was pain as measured using a 100-mm Visual Analog Scale.

Results

Subjects in the mirror therapy group had a significant decrease in pain scores, from a mean of 44.1 (SD = 17.0) to 27.5 (SD = 17.2) mm (p = 0.002). In addition, there was a significant decrease in daily time experiencing pain, from a mean of 1,022 (SD = 673) to 448 (SD = 565) minutes (p = 0.003). By contrast, the control group had neither diminished pain (p = 0.65) nor decreased overall time experiencing pain (p = 0.49). A pain decrement response seen by the 10th treatment session was predictive of final efficacy.

Conclusion

These results confirm that mirror therapy is an effective therapy for PLP in unilateral, upper extremity male amputees, reducing both severity and duration of daily episodes.

Registration

NCT0030144 ClinicalTrials.gov.

Dutch evidence-based guidelines for amputation and prosthetics of the lower extremity: Amputation surgery and postoperative management. Part 1

BACKGROUND

Surgeons still use a range of criteria to determine whether amputation is indicated. In addition, there is considerable debate regarding immediate postoperative management, especially concerning the use of 'immediate/delayed fitting' versus conservative elastic bandaging.

OBJECTIVES

To produce an evidence-based guideline for the amputation and prosthetics of the lower extremities. This guideline provides recommendations in support of daily practice and is based on the results of scientific research and further discussions focussed on establishing good medical practice. Part 1 focuses on amputation surgery and postoperative management.

STUDY DESIGN

Systematic literature design.

METHODS

Literature search in five databases. Quality assessment on the basis of evidence-based guideline development.

RESULTS

An evidence-based multidisciplinary guideline on amputation and prosthetics of the lower extremity.

CONCLUSION

The best care (in general) for patients undergoing amputation of a lower extremity is presented and discussed. This part of the guideline provides recommendations for diagnosis, referral, assessment, and undergoing amputation of a lower extremity and can be used to provide patient information.

CLINICAL RELEVANCE

This guideline provides recommendations in support of daily practice and is based on the results of scientific research and further discussions focussed on establishing good medical practice.

Transcutaneous electrical nerve stimulation (TENS) for phantom pain and stump pain following amputation in adults

BACKGROUND

This is the first update of a Cochrane review published in Issue 5, 2010 on transcutaneous electrical nerve stimulation (TENS) for phantom pain and stump pain following amputation in adults. Pain may present in a body part that has been amputated (phantom pain) or at the site of amputation (stump pain), or both. Phantom pain and stump pain are complex and multidimensional and the underlying pathophysiology remains unclear. The condition remains a severe burden for those who are affected by it. The mainstay treatments are predominately pharmacological, with increasing acknowledgement of the need for non-drug interventions. TENS has been recommended as a treatment option but there has been no systematic review of available evidence. Hence, the effectiveness of TENS for phantom pain and stump pain is currently unknown.

OBJECTIVES

To assess the analgesic effectiveness of TENS for the treatment of phantom pain and stump pain following amputation in adults.

SEARCH METHODS

For the original version of the review we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, AMED, CINAHL, PEDRO and SPORTDiscus (February 2010). For this update, we searched the same databases for relevant randomised controlled trials (RCTs) from 2010 to 25 March 2015.

SELECTION CRITERIA

We only included RCTs investigating the use of TENS for the management of phantom pain and stump pain following an amputation in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We planned that where available and appropriate, data from outcome measures were to be pooled and presented as an overall estimate of the effectiveness of TENS.

MAIN RESULTS

In the original review there were no RCTs that examined the effectiveness of TENS for the treatment of phantom pain and stump pain in adults. For this update, we did not identify any additional RCTs for inclusion.

AUTHORS' CONCLUSIONS

There were no RCTs to judge the effectiveness of TENS for the management of phantom pain and stump pain. The published literature on TENS for phantom pain and stump pain lacks the methodological rigour and robust reporting needed to confidently assess its effectiveness. Further RCT evidence is required before an assessment can be made. Since publication of the original version of this review, we have found no new studies and our conclusions remain unchanged.

Preoperative and postoperative analgesic techniques in the treatment of patients undergoing transabdominal hysterectomy: a preliminary randomized trial

BACKGROUND

Although pre-emptive analgesia is commonly used for the management of postoperative pain in developed countries, no defined protocol has been carried out and widely practiced, especially in transabdominal hysterectomy. Keeping this in mind the present study aimed to investigate the effects of multimodal pre-emptive analgesia on pain management, stress response and inflammatory factors of patients undergoing transabdominal hysterectomy to find an optimized way of pre-emptive analgesia.

METHODS

One hundred patients undergoing abdominal hysterectomy were randomly divided into four groups (Trial registration: ChiCTR-IPR-15005848). Group P1 was given intravenous flurbiprofen and epidural fentanyl + ketamine before surgery; Group P2 received intravenous flurbiprofen before surgery and epidural fentanyl + ketamine after surgery; Group P3 was given epidural fentanyl + ketamine before surgery and intravenous flurbiprofen after surgery; Patients in Group C received normal saline treatment.

RESULTS

Compared with control group, the first time to request additional analgesics after surgery were significantly later (P < 0.05), 24 h dosage of analgesia were significantly less (P < 0.05), VAS score at all time periods after surgery were significantly lower (P < 0.05) in Group P1, P2, or P3. At 12 h or 24 h after surgery, VAS score in Group P1 was significantly lower than that in group P2 or P3 (P < 0.05, P < 0.05). No significant adverse effects were found among the groups (P > 0.05). At 1 or 2 days after surgery, the levels of cortisol, glucose, and IL-6, TNF-α in group P1, P2, and P3 were significantly lower than those in group C (P < 0.05); while, the levels in group P2, P3 were significantly lower than those in group P1 (P < 0.05).

CONCLUSION

Multimodal pre-emptive analgesia could significantly lower VAS score, inhibit stress response, and reduce inflammatory response in patients undergoing transabdominal hysterectomy, which can be a rational strategy for pain control in future.

TRIAL REGISTRATION

ChiCTR-IPR-15005848 on January 17, 2015.

Reporting of sample size calculations in analgesic clinical trials: ACTTION systematic review

Sample size calculations determine the number of participants required to have sufficiently high power to detect a given treatment effect. In this review, we examined the reporting quality of sample size calculations in 172 publications of double-blind randomized controlled trials of noninvasive pharmacologic or interventional (ie, invasive) pain treatments published in European Journal of Pain, Journal of Pain, and Pain from January 2006 through June 2013. Sixty-five percent of publications reported a sample size calculation but only 38% provided all elements required to replicate the calculated sample size. In publications reporting at least 1 element, 54% provided a justification for the treatment effect used to calculate sample size, and 24% of studies with continuous outcome variables justified the variability estimate. Publications of clinical pain condition trials reported a sample size calculation more frequently than experimental pain model trials (77% vs 33%, P < .001) but did not differ in the frequency of reporting all required elements. No significant differences in reporting of any or all elements were detected between publications of trials with industry and nonindustry sponsorship. Twenty-eight percent included a discrepancy between the reported number of planned and randomized participants. This study suggests that sample size calculation reporting in analgesic trial publications is usually incomplete. Investigators should provide detailed accounts of sample size calculations in publications of clinical trials of pain treatments, which is necessary for reporting transparency and communication of pre-trial design decisions.

PERSPECTIVE

In this systematic review of analgesic clinical trials, sample size calculations and the required elements (eg, treatment effect to be detected; power level) were incompletely reported. A lack of transparency regarding sample size calculations may raise questions about the appropriateness of the calculated sample size.

A systematic review and meta-analysis of ketamine for the prevention of persistent post-surgical pain

While post-operative pain routinely resolves, persistent post-surgical pain (PPSP) is common in certain surgeries; it causes disability, lowers quality of life and has economic consequences. The objectives of this systematic review and meta-analysis were to evaluate the effectiveness of ketamine in reducing the prevalence and severity of PPSP and to assess safety associated with its use. We searched the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE through December 2012 for articles in any language. We included randomized, controlled trials in adults in which ketamine was administered perioperatively via any route. Seventeen studies, the majority of which administered ketamine intravenously, met all inclusion criteria. The overall risk of developing PPSP was not significantly reduced at any time point in the ketamine group vs. placebo, nor did comparisons of pain severity scores reach statistical significance. Sensitivity analysis of exclusively intravenous ketamine studies included in this meta-analysis demonstrated statistically significant reductions in risk of developing PPSP at 3 and 6 months (P = 0.01 and P = 0.04, respectively). Adverse event rates were similar between ketamine and placebo groups. The study data from our review are heterogeneous and demonstrate efficacy of intravenously administered ketamine only in comparison with placebo. Highly variable timing and dosing of ketamine in these studies suggest that no unifying effective regimen has emerged. Future research should focus on clinically relevant outcomes, should stratify patients with pre-existing pain and possible central sensitization and should enroll sufficiently large numbers to account for loss to follow-up in long-term studies.

Ketamine for chronic pain: risks and benefits

The anaesthetic ketamine is used to treat various chronic pain syndromes, especially those that have a neuropathic component. Low dose ketamine produces strong analgesia in neuropathic pain states, presumably by inhibition of the N-methyl-D-aspartate receptor although other mechanisms are possibly involved, including enhancement of descending inhibition and anti-inflammatory effects at central sites. Current data on short term infusions indicate that ketamine produces potent analgesia during administration only, while three studies on the effect of prolonged infusion (4-14 days) show long-term analgesic effects up to 3 months following infusion. The side effects of ketamine noted in clinical studies include psychedelic symptoms (hallucinations, memory defects, panic attacks), nausea/vomiting, somnolence, cardiovascular stimulation and, in a minority of patients, hepatoxicity. The recreational use of ketamine is increasing and comes with a variety of additional risks ranging from bladder and renal complications to persistent psychotypical behaviour and memory defects. Blind extrapolation of these risks to clinical patients is difficult because of the variable, high and recurrent exposure to the drug in ketamine abusers and the high frequency of abuse of other illicit substances in this population. In clinical settings, ketamine is well tolerated, especially when benzodiazepines are used to tame the psychotropic side effects. Irrespective, close monitoring of patients receiving ketamine is mandatory, particularly aimed at CNS, haemodynamic, renal and hepatic symptoms as well as abuse. Further research is required to assess whether the benefits outweigh the risks and costs. Until definite proof is obtained ketamine administration should be restricted to patients with therapy-resistant severe neuropathic pain.

A systematic review of therapeutic interventions to reduce acute and chronic post-surgical pain after amputation, thoracotomy or mastectomy

Background

Perioperative neuropathic pain is under-recognized and often undertreated. Chronic pain may develop after any routine surgery, but it can have a far greater incidence after amputation, thoracotomy or mastectomy. The peak noxious barrage due to the neural trauma associated with these operations may be reduced in the perioperative period with the potential to reduce the risk of chronic pain.

Databases and data treatment

A systematic review of the evidence for perioperative interventions reducing acute and chronic pain associated with amputation, mastectomy or thoracotomy.

Results

Thirty-two randomized controlled trials met the inclusion criteria. Gabapentinoids reduced pain after mastectomy, but a single dose was ineffective for thoracotomy patients who had an epidural. Gabapentinoids were ineffective for vascular amputees with pre-existing chronic pain. Venlafaxine was associated with less chronic pain after mastectomy. Intravenous and topical lidocaine and perioperative EMLA (eutectic mixture of local anaesthetic) cream reduced the incidence of chronic pain after mastectomy, whereas local anaesthetic infiltration appeared ineffective. The majority of the trials investigating regional analgesia found it to be beneficial for chronic symptoms. Ketamine and intercostal cryoanalgesia offered no reduction in chronic pain. Total intravenous anaesthesia (TIVA) reduced the incidence of post-thoracotomy pain in one study, whereas high-dose remifentanil exacerbated chronic pain in another.

Conclusions

Appropriate dose regimes of gabapentinoids, antidepressants, local anaesthetics and regional anaesthesia may potentially reduce the severity of both acute and chronic pain for patients. Ketamine was not effective at reducing chronic pain. Intercostal cryoanalgesia was not effective and has the potential to increase the risk of chronic pain. TIVA may be beneficial but the effects of opioids are unclear.

Phantom limb pain: a systematic neuroanatomical-based review of pharmacologic treatment

OBJECTIVE

Review the current evidence-based pharmacotherapy for phantom limb pain (PLP) in the context of the current understanding of the pathophysiology of this condition.

DESIGN

We conducted a systematic review of original research papers specifically investigating the pharmacologic treatment of PLP. Literature was sourced from PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL). Studies with animals, "neuropathic" but not "phantom limb" pain, or without pain scores and/or functional measures as primary outcomes were excluded. A level of evidence 1-4 was ascribed to individual treatments. These levels included meta-analysis or systematic reviews (level 1), one or more well-powered randomized, controlled trials (level 2), retrospective studies, open-label trials, pilot studies (level 3), and anecdotes, case reports, or clinical experience (level 4).

RESULTS

We found level 2 evidence for gabapentin, both oral (PO) and intravenous (IV) morphine, tramadol, intramuscular (IM) botulinum toxin, IV and epidural Ketamine, level 3 evidence for amitriptyline, dextromethorphan, topiramate, IV calcitonin, PO memantine, continuous perineural catheter analgesia with ropivacaine, and level 4 evidence for methadone, intrathecal (IT) buprenorphine, IT and epidural fentanyl, duloxetine, fluoxetine, mirtazapine, clonazepam, milnacipran, capsaicin, and pregabalin.

CONCLUSIONS

Currently, the best evidence (level 2) exists for the use of IV ketamine and IV morphine for the short-term perioperative treatment of PLP and PO morphine for an intermediate to long-term treatment effect (8 weeks to 1 year). Level 2 evidence is mixed for the efficacy of perioperative epidural anesthesia with morphine and bupivacaine for short to long-term pain relief (perioperatively up to 1 year) as well as for the use of gabapentin for pain relief of intermediate duration (6 weeks).

Intrathecal ketamine and pregabalin at sub-effective doses synergistically reduces neuropathic pain without motor dysfunction in mice

Peripheral or central nerve injury often leads to neuropathic pain. Although ketamine and pregabalin are first line options for the treatment of neuropathic pain, their clinical application is limited due to side effects such as sedation, dizziness and somnolence. We designed this study to determine whether the intrathecal (i.t.) co-treatment with ketamine and pregabalin at sub-effective low doses would elicit a sufficient pain relief without producing side effect in a neuropathic pain mouse model. At day 7 after chronic constriction injury (CCI) of sciatic nerve, dose dependent effects of i.t. ketamine (3, 10, 30, 100 µg) or i.t. pregabalin (10, 30, 100 µg) on mechanical allodynia and thermal hyperalgesia were measured. For combination treatment, 3 or 10 µg of ketamine and 30 µg of pregabalin were selected because these doses of drugs were not effective on neuropathic pain. Interestingly, combined i.t. treatment groups (ketamine 3 µg+pregabalin 30 µg and ketamine 10 µg+pregabalin 30 µg) produced strong analgesia on neuropathic pain although these doses of ketamine and pregabalin alone are not effective. Moreover, rota rod test revealed that normal motor function was not affected by combined treatment while i.t. ketamine at doses above 10 µg showed a significant motor dysfunction. Results of this study suggested that i.t. co-treatment with ketamine and pregabalin at sub-effect low doses may be a useful therapeutic method for the treatment of neuropathic pain patients.

Surgically induced neuropathic pain: understanding the perioperative process

Nerve damage takes place during surgery. As a consequence, significant numbers (10%-40%) of patients experience chronic neuropathic pain termed surgically induced neuropathic pain (SNPP). The initiating surgery and nerve damage set off a cascade of events that includes both pain and an inflammatory response, resulting in "peripheral and central sensitization," with the latter resulting from repeated barrages of neural activity from nociceptors. In affected patients, these initial events produce chemical, structural, and functional changes in the peripheral and central nervous systems (CNS). The maladaptive changes in damaged nerves lead to peripheral manifestations of the neuropathic state-allodynia, sensory loss, shooting pains, etc, that can manifest long after the effects of the surgical injury have resolved. The CNS manifestations that occur are termed "centralization of pain" and affect sensory, emotional, and other (eg, cognitive) systems as well as contributing to some of the manifestations of the chronic pain syndrome (eg, depression). Currently there are no objective measures of nociception and pain in the perioperative period. As such, intermittent or continuous pain may take place during and after surgery. New technologies including direct measures of specific brain function of nociception and new insights into preoperative evaluation of patients including genetic predisposition, appear to provide initial opportunities for decreasing the burden of SNPP, until treatments with high efficacy and low adverse effects that either prevent or treat pain are discovered.

Postamputation pain: epidemiology, mechanisms, and treatment

Postamputation pain (PAP) is highly prevalent after limb amputation but remains an extremely challenging pain condition to treat. A large part of its intractability stems from the myriad pathophysiological mechanisms. A state-of-art understanding of the pathophysiologic basis underlying postamputation phenomena can be broadly categorized in terms of supraspinal, spinal, and peripheral mechanisms. Supraspinal mechanisms involve somatosensory cortical reorganization of the area representing the deafferentated limb and are predominant in phantom limb pain and phantom sensations. Spinal reorganization in the dorsal horn occurs after deafferentataion from a peripheral nerve injury. Peripherally, axonal nerve damage initiates inflammation, regenerative sprouting, and increased "ectopic" afferent input which is thought by many to be the predominant mechanism involved in residual limb pain or neuroma pain, but may also contribute to phantom phenomena. To optimize treatment outcomes, therapy should be individually tailored and mechanism based. Treatment modalities include injection therapy, pharmacotherapy, complementary and alternative therapy, surgical therapy, and interventions aimed at prevention. Unfortunately, there is a lack of high quality clinical trials to support most of these treatments. Most of the randomized controlled trials in PAP have evaluated medications, with a trend for short-term Efficacy noted for ketamine and opioids. Evidence for peripheral injection therapy with botulinum toxin and pulsed radiofrequency for residual limb pain is limited to very small trials and case series. Mirror therapy is a safe and cost-effective alternative treatment modality for PAP. Neuromodulation using implanted motor cortex stimulation has shown a trend toward effectiveness for refractory phantom limb pain, though the evidence is largely anecdotal. Studies that aim to prevent PA P using epidural and perineural catheters have yielded inconsistent results, though there may be some benefit for epidural prevention when the infusions are started more than 24 hours preoperatively and compared with nonoptimized alternatives. Further investigation into the mechanisms responsible for and the factors associated with the development of PAP is needed to provide an evidence-based foundation to guide current and future treatment approaches.

Causes and prevention of chronic postsurgical pain

PURPOSE OF REVIEW

Surgical incision invariably causes some measure of nerve damage and inflammatory response that, in most cases, heals quickly without long-term negative consequence. However, a subset of these patients go on to develop lasting neuropathic pain that is difficult to treat and, in many cases, prevents the return to normal activities of life. It remains unknown why two patients with identical surgical interventions may go on to develop completely divergent pain phenotypes or no pain at all. Aggressive, early analgesic therapy has been shown to reduce the incidence of chronic postsurgical pain (CPSP), but no specific regional anesthetic technique or systemic pharmacologic therapy has been shown to prevent CPSP.

RECENT FINDINGS

Inflammation and glial cell activation have recently been shown to be just as important in the transition from normal acute pain to pathologic chronic pain as nerve injury itself and that central sensitization may not be solely due to repetitive nociceptive firing at the time of nerve injury. This has opened a number of new therapeutic possibilities for prevention of CPSP.

SUMMARY

Here, we discuss the causes of CPSP and current useful preventive strategies in the perioperative period. We also discuss future potential disease-modifying treatments of CPSP.

Chronic postsurgical pain: still a neglected topic?

Background

Surgical injury can frequently lead to chronic pain. Despite the obvious importance of this problem, the first publications on chronic pain after surgery as a general topic appeared only a decade ago. This study tests the hypothesis that chronic postsurgical pain was, and still is, represented insufficiently.

Methods

We analyzed the presentation of this topic in journal articles covered by PubMed and in surgical textbooks. The following signs of insufficient representation in journal articles were used: (1) the lack of journal editorials on chronic pain after surgery, (2) the lack of journal articles with titles clearly indicating that they are devoted to chronic postsurgical pain, and (3) the insufficient representation of chronic postsurgical pain in the top surgical journals.

Results

It was demonstrated that insufficient representation of this topic existed in 1981–2000, especially in surgical journals and textbooks. Interest in this topic began to increase, however, mostly regarding one specific surgery: herniorrhaphy. It is important that the change in the attitude toward chronic postsurgical pain spreads to other groups of surgeries.

Conclusion

Chronic postsurgical pain is still a neglected topic, except for pain after herniorrhaphy. The change in the attitude toward chronic postsurgical pain is the important first step in the approach to this problem.

Polyanalgesic Consensus Conference 2012: recommendations for the management of pain by intrathecal (intraspinal) drug delivery: report of an interdisciplinary expert panel

INTRODUCTION

The use of intrathecal (IT) infusion of analgesic medications to treat patients with chronic refractory pain has increased since its inception in the 1980s, and the need for clinical research in IT therapy is ongoing. The Polyanalgesic Consensus Conference (PACC) panel of experts convened in 2000, 2003, and 2007 to make recommendations on the rational use of IT analgesics based on preclinical and clinical literature and clinical experiences.

METHODS

The PACC panel convened again in 2011 to update the standard of care for IT therapies to reflect current knowledge gleaned from literature and clinical experience. A thorough literature search was performed, and information from this search was provided to panel members. Analysis of published literature was coupled with the clinical experience of panel members to form recommendations regarding the use of IT analgesics to treat chronic pain.

RESULTS

After a review of literature published from 2007 to 2011 and discussions of clinical experience, the panel created updated algorithms for the rational use of IT medications for the treatment of neuropathic pain and nociceptive pain.

CONCLUSIONS

The advent of new algorithmic tracks for neuropathic and nociceptive pain is an important step in improving patient care. The panel encourages continued research and development, including the development of new drugs, devices, and safety recommendations to improve the care of patients with chronic pain.

Current and future options for the management of phantom-limb pain

Phantom-limb pain (PLP) belongs among difficult-to-treat chronic pain syndromes. Treatment options for PLP are to a large degree implicated by the level of understanding the mechanisms and nature of PLP. Research and clinical findings acknowledge the neuropathic nature of PLP and also suggest that both peripheral as well as central mechanisms, including neuroplastic changes in central nervous system, can contribute to PLP. Neuroimaging studies in PLP have indicated a relation between PLP and the neuroplastic changes. Further, it has been shown that the pathological neuroplastic changes could be reverted, and there is a parallel between an improvement (reversal) of the neuroplastic changes in PLP and pain relief. These findings facilitated explorations of novel neuromodulatory treatment strategies, adding to the variety of treatment approaches in PLP. Overall, available treatment options in PLP include pharmacological treatment, supportive non-pharmacological non-invasive strategies (eg, neuromodulation using transcranial magnetic stimulation, visual feedback therapy, or motor imagery; peripheral transcutaneous electrical nerve stimulation, physical therapy, reflexology, or various psychotherapeutic approaches), and invasive treatment strategies (eg, surgical destructive procedures, nerve blocks, or invasive neuromodulation using deep brain stimulation, motor cortex stimulation, or spinal cord stimulation). Venues of further development in PLP management include a technological and methodological improvement of existing treatment methods, an implementation of new techniques and products, and a development of new treatment approaches.

Prevention of chronic pain after surgical nerve injury: amputation and thoracotomy

Although techniques for acute pain management have improved in recent years, a dramatic reduction in the incidence and severity of chronic pain following surgery has not occurred. Amputation and thoracotomy, although technically different, share the commonalities of unavoidable nerve injury and the frequent presence of persistent postsurgical neuropathic pain. The authors review the risk factors for the development of chronic pain following these surgeries and the current evidence that supports analgesic interventions. The inconclusive results from many preemptive analgesic studies may require us to reconceptualize the perioperative treatment period as a time of gradual neurologic remodeling.

Pharmacologic interventions for treating phantom limb pain

BACKGROUND

Phantom limb pain (PLP) is pain that arises in the missing limb after amputation and can be severe, intractable and disabling. Various medications have been studied in the treatment of phantom pain. Presently there is uncertainty in the optimal pharmacologic management of PLP. 

OBJECTIVES

This review aims to summarize the evidence of effectiveness of pharmacologic interventions in treating PLP.

SEARCH METHODS

We searched the Cochrane Pain, Palliative and Supportive Care Review Group (PaPaS) Trials Register, the Cochrane Controlled Trials Register (CENTRAL, The Cochrane Library), MEDLINE and EMBASE up to September 2011 for randomised and quasi-randomised trials comparing pharmacologic treatment with placebo, another active treatment, or no treatment.

SELECTION CRITERIA

We included randomised and quasi-randomised trials studying the effectiveness of pharmacologic interventions in patients with established PLP. The outcomes considered were change in pain intensity, function, mood, sleep, quality of life, satisfaction and adverse effects.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the methodologic quality of the studies and extracted the data. We reported continuous and dichotomous data on change in pain intensity, function, mood/depression scores, sleep, quality of life, satisfaction for each study, where available. Because of the wide variability in the studies, we did not perform a meta-analysis for all the interventions and outcomes but we attempted to pool the results of some studies where possible. We prepared a qualitative description and narrative summary of results and described adverse effects. We assessed clinical heterogeneity by making qualitative comparisons in terms of the populations, interventions, outcomes/outcome measures and methods.

MAIN RESULTS

From 583 references/publications, we selected 13 studies involving 255 participants. Six groups of medications were reviewed, namely, N-methyl D-aspartate (NMDA) receptor antagonists, antidepressants, anticonvulsants, anaesthetics, opioids, and calcitonin. Ten studies were of high quality and three were of moderate quality based on both Jadad and Van Tulder criteria. Because of the wide variation (heterogeneity) in the pharmacologic interventions, outcome measures, analyses, reporting of results, duration of follow-ups and study designs, it was not possible to pool the results for most of the interventions and outcomes. Morphine (oral and intravenous) was effective in decreasing pain intensity in the short-term with reported adverse effects being constipation, sedation, tiredness, dizziness, sweating, voiding difficulty, vertigo, itching, and respiratory problems. The NMDA receptor antagonists, ketamine and dextromethorphan but not memantine, had analgesic effects. The adverse effects of ketamine were more serious and included loss of consciousness, sedation, hallucinations, hearing and position impairment, and insobriety. The results for gabapentin in terms of pain relief were conflicting but combining the results showed a trend towards benefit. Gabapentin, however, did not improve function, depression score and sleep quality. Side effects experienced were somnolence, dizziness, headache and nausea. Amitryptiline was not effective in PLP with dry mouth and dizziness as side effects based on one study. The findings for calcitonin and anaesthetics were variable. Adverse effects of calcitonin were headache, vertigo, drowsiness, nausea, vomiting, and hot and cold flushes. Most of the studies were limited by their small sample sizes.

AUTHORS' CONCLUSIONS

The short- and long-term effectiveness of opioids, NMDA receptor antagonists, anticonvulsants, antidepressants, calcitonins, and anaesthetics for clinically relevant outcomes that include pain, function, mood, sleep, quality of life, satisfaction and adverse effects remains unclear. Morphine, gabapentin and ketamine demonstrate trends towards short-term analgesic efficacy. Memantine and amitriptyline were ineffective for PLP. Results, however, are to be interpreted with caution as these were based mostly on a small number of studies with limited sample sizes that varied considerably and also lacked long-term efficacy and safety outcomes. The direction of efficacy of calcitonin, anaesthetics and dextromethorphan need further clarification. Larger and more rigorous randomised controlled trials are needed to make stronger recommendations about which medications would be useful for clinical practice.

A single subanesthetic dose of ketamine relieves depression-like behaviors induced by neuropathic pain in rats

BACKGROUND

Chronic pain is associated with depression. In rodents, pain is often assessed by sensory hypersensitivity, which does not sufficiently measure affective responses. Low-dose ketamine has been used to treat both pain and depression, but it is not clear whether ketamine can relieve depression associated with chronic pain and whether this antidepressant effect depends on its antinociceptive properties.

METHODS

The authors examined whether the spared nerve injury model of neuropathic pain induces depressive behavior in rats, using sucrose preference test and forced swim test, and tested whether a subanesthetic dose of ketamine treats spared nerve injury-induced depression.

RESULTS

Spared nerve injury-treated rats, compared with control rats, showed decreased sucrose preference (0.719 ± 0.068 (mean ± SEM) vs. 0.946 ± 0.010) and enhanced immobility in the forced swim test (107.3 ± 14.6s vs. 56.2 ± 12.5s). Further, sham-operated rats demonstrated depressive behaviors in the acute postoperative period (0.790 ± 0.062 on postoperative day 2). A single subanesthetic dose of ketamine (10 mg/kg) did not alter spared nerve injury-induced hypersensitivity; however, it treated spared nerve injury-associated depression-like behaviors (0.896 ± 0.020 for ketamine vs. 0.663 ± 0.080 for control rats 1 day after administration; 0.858 ± 0.017 for ketamine vs. 0.683 ± 0.077 for control rats 5 days after administration).

CONCLUSIONS

Chronic neuropathic pain leads to depression-like behaviors. The postoperative period also confers vulnerability to depression, possibly due to acute pain. Sucrose preference test and forced swim test may be used to compliment sensory tests for assessment of pain in animal studies. Low-dose ketamine can treat depression-like behaviors induced by chronic neuropathic pain.