The efficacy of gabapentin/pregabalin in improving pain after tonsillectomy: A meta-analysis

Tranexamic acid in bleeding reduction and operative time of nasal surgeries: systematic review and meta-analysis

PURPOSE

Our study goal is to review the efficacy of tranexamic acid in reducing blood loss and operative time in nasal surgeries.

METHODS

We included randomized clinical trials using oral or intravenous tranexamic acid, excluded non-randomized studies, topic administration, coagulopathy, and using other drugs interfering in the coagulation cascade. Online databases, National Library of Medicine (MEDLINE-PubMED), Latin American and Caribbean Literature on Health Sciences (Lilacs), Cochrane Library, Embase and Google Scholar were used to perform the search. The review was registered in PROSPERO by no CRD42022310977. Two authors, independently, selected the articles meeting the inclusion criteria. They extracted the data and used RevMan 5 software to perform the meta-analysis.

RESULTS

Our search resulted in 16 RCTs that were included in the meta-analysis totalizing 1108 patients. Studies were evaluated resulting in a low risk of bias for the five domains. The use of tranexamic acid resulted in significant reduction in duration of surgery (DOS) and intraoperative blood loss (IBL) had significant reduction. The level of evidence according to GRADE System was high in all studies and variables.

CONCLUSION

Tranexamic acid has an important role in reducing intraoperative blood loss and duration of surgery. Our study has some limitations due to the low number of RCTs available in the literature.

Pain management after microtia repair with costal cartilage: De-escalation and opioid use reduction

OBJECTIVE

Complex and invasive postoperative pain regimens for microtia reconstruction with costal cartilage are often utilized. These generate added costs and invasiveness. We evaluated the effectiveness of a de-escalated pain regimen without use of invasive interventions.

METHODS

Case series of patients who underwent stage 1 microtia reconstruction with a modified Nagata/Firmin technique from 2017 to 2020 at a pediatric tertiary care hospital. Patients received intraoperative bupivacaine intercostal blocks and scheduled acetaminophen. Adjunct medications administered and pain scores (Wong-Baker FACES and FLACC-Face, Legs, Activity, Cry, Consolability) at intervals 2-72 h postoperatively were recorded. Narcotic use, peak and median pain scores, and length of stay were compared with published values.

RESULTS

Twenty patients were included. Mean age of 12 and length of stay of 2.8 days. Average postoperative FACES scores between 0 and 72 h ranged between 0.7 and 4.0. The average peak pain score was 6.1 (±2.0). FLACC scores were low. Narcotics (0.59 ±0 .35 Morphine Milligram Equivalents/kg) were given to 17 patients. Compared to Shaffer et al. (paravertebral catheter-based infusion), total narcotics use (p = 0.03), peak pain (p = 0.0001), and length of stay (p = 0.001) were less. Compared to Woo et al. (intercostal catheter-based infusion), median pain scores at identical time intervals were lower (p = 0.04).

CONCLUSION

Intraoperative intercostal nerve blocks followed by scheduled, weight-based acetaminophen, adjunctive medications (ibuprofen and lidocaine patches), and rescue narcotics are effective in managing pain following microtia repair with autologous costal cartilage. It results in decreased narcotic usage, shorter length of stay, and lower pain scores compared to more complex regimens.

Pain management after tonsillectomy-by demand or by-the-clock-is there a difference?

PURPOSE

To improve pain management after tonsillectomy (TE) by comparing individual analgesic management by demand versus a fixed-scheduled analgesic treatment protocol in a prospective trial.

PATIENTS AND METHODS

Forty consecutive patients received individual pain treatment by demand (control group) followed by 40 patients who were treated by a fixed-scheduled four-staged escalating analgesic protocol (intervention group) after TE. Minimum and maximum pain as well as pain on ambulation (NRS 0-10) on the first postoperative day were defined as primary objectives. Secondary endpoints comprised the analgesic score, treatment-related side effects/pain-associated impairments, wish for more pain medication, and patient satisfaction. Patients were surveyed using the standardized and validated "Quality Improvement in Postoperative Pain Treatment" (QUIPS) questionnaire.

RESULTS

Patients of the control group reported comparable minimum (2.03 ± 1.42 vs 2.38 ± 1.79, P = 0.337, r = 0.110) and maximum pain (6.65 ± 2.10 vs 6.93 ± 1.86, P = 0.536, r = 0.07) and pain on ambulation (4.73 ± 2.26 vs 5.18 ± 2.19, P = 0.370, r = 0.10) compared to the intervention group. Patients in both groups were comparably well satisfied with the pain treatment (7.53 ± 2.40 vs 7.73 ± 2.30, P = 0.704, r = 0.04), experienced similar side effects and functional impairments (P > 0.050, Φ < 0.3), and did not ask for much more analgesic medication (P = 0.152, Φ = 0.160).

CONCLUSION

Pain control following TE was not distinctly affected by applying a fixed-scheduled analgesic treatment protocol compared to individual analgesic therapy. In conclusion, analgesic treatment after TE remains unsatisfying. Consequently, further efforts are needed to achieve a standardized and effective approach to the underlying pathophysiological causes of pain following TE.

Lesser Known Uses of γ-Aminobutyric Acid Analogue Medications in Otolaryngology

OBJECTIVES/HYPOTHESIS

In otolaryngology, γ-aminobutyric acid (GABA) analogues have been previously analyzed for their roles in neuropathic pain, chronic cough, tinnitus, and perioperative analgesia. The primary aim of this study is to comprehensively summarize and synthesize the existing evidence for lesser known uses of gabapentin and pregabalin in otolaryngology.

STUDY DESIGN

A scoping review conducted of the available English-language literature was performed by two authors through April 1, 2021.

METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analysis criteria were followed, and a quality assessment of included studies was performed using the Methodological Index for Non-Randomized Studies.

RESULTS

Ten studies met inclusion criteria. Three studies found that gabapentin may reduce gastrostomy tube usage and improve swallowing function in head and neck cancer patients undergoing radiation therapy (RT). Three studies suggested that gabapentin may help reduce opiate use when used as a primary analgesic in patients with radiation-induced mucositis. One study demonstrated that pregabalin-reduced trismus severity in patients with radiotherapy-induced trismus. One study demonstrated gabapentin may be useful in patients with phonasthenia. Two studies demonstrated that GABA analogues may be a useful adjunct in patients with globus pharyngeus in the context of likely laryngeal sensory neuropathy.

CONCLUSIONS

The most promising potential uses for GABA analogues identified in this review are for improving swallowing, trismus, and narcotic overuse after RT. The benefit of GABA analogues for improving nonorganic voice disorders is also promising while the benefit for globus pharyngeus when possibly related to laryngeal sensory neuropathy is inconclusive. Laryngoscope, 2021.

Pharmacologic management of post-tonsillectomy pain in children

Tonsillectomy is a very common procedure in children, often performed on an outpatient basis. Severe postoperative pain is common, and can be prolonged. Despite a large number of available analgesic medications, often employed in combination, achieving adequate pain control remains a persistent challenge. Research suggests a tendency among caregivers to undertreat pain, and a need for detailed care instructions and education to ensure adequate pain management. Furthermore, ongoing questions regarding the safety and efficacy of the most commonly used medications have led to wide variance in practice patterns and continuous reassessment through research that yields sometimes conflicting results. This review summarizes the current state of the literature and presents a management approach which attempts to maximize pain control while minimizing potential harm with combinations of medications and modification based on patient-specific factors.

Impact of a revised postoperative care plan on pain and recovery trajectory following pediatric tonsillectomy

BACKGROUND

A previous cohort of adenotonsillectomy patients at our institution demonstrated moderate-severe post-tonsillectomy pain scores lasting a median (range) duration of 6 (0-23) days and postdischarge nausea and vomiting affecting 8% of children on day 1 following surgery. In this subsequent cohort, we evaluate the impact of changes to our discharge medication and parental education on post-tonsillectomy pain and recovery profile.

METHODS

In this follow-on, prospective observational cohort study, all patients undergoing tonsillectomy at our institution during the study period were discharged with standardized analgesia. Parents received a revised education package and a medication diary which were not provided to the previous cohort. Pain scores, rates of nausea and vomiting, medication usage and unplanned representation rates were collected by telephone from parents.

RESULTS

Sixty-nine patients were recruited. Moderate-severe pain lasted a median (range) of 5 (0-12) days. Twenty-nine (42%) had pain scores ≥4/10 beyond postoperative day 7. By postoperative day 5, only 37 (53%) parents continued to administer regular analgesia. The median number of oxycodone doses used was 5 (0-22), and only 28 (41%) parents had disposed of leftover oxycodone within 1 month of surgery. Twenty-four (35%) patients experienced nausea or vomiting postdischarge. The median (range) time for return to normal activities was 6 (0-14) days. Thirty-two/sixty-nine (46%) patients had unplanned medical representations. Most occurred between postoperative day 5 and 7. Pain contributed to 16 (35%) representations.

CONCLUSIONS

Despite extensive changes to our discharge protocols parents continued to report a prolonged period of pain, post operative nausea and vomiting, and behavioral changes. Further work is required to examine barriers to compliance with simple analgesia and education in appropriate methods of opioid disposal.

What the blogosphere has to say about adult tonsillectomy

OBJECTIVES

Tonsillectomy has generated extensive comment on the internet, but this content has not been examined in a scientific manner. This study aimed to determine what the blogosphere has to say about adult tonsillectomy and to report whether this information can be used to improve post-surgical care.

METHODS

The internet was searched to find personal blogs relating to tonsillectomy. A retrospective review of data collected on these blogs was carried out and the blogs were conceptually analysed by the authors.

RESULTS

Fifty blogs were included. Seventy per cent of patients had read blogs prior to their procedure. The average pain score where available was 7.2. Complications occurred in 10 per cent of patients. Only 1 patient (2 per cent) regretted having a tonsillectomy.

CONCLUSION

It is important for otolaryngologists to stay in tune with the blogosphere as this unregulated and easily accessible source of information is both friend and foe but will ultimately help in pre-operative counselling and post-operative management.

Effectiveness, cost-effectiveness and safety of gabapentin versus placebo as an adjunct to multimodal pain regimens in surgical patients: protocol of a placebo controlled randomised controlled trial with blinding (GAP study)

INTRODUCTION

Gabapentin is an antiepileptic drug currently licensed to treat epilepsy and neuropathic pain but has been used off-label to treat acute postoperative pain. The GAP study will compare the effectiveness, cost-effectiveness and safety of gabapentin as an adjunct to standard multimodal analgesia versus placebo for the management of pain after major surgery.

METHODS AND ANALYSIS

The GAP study is a multicentre, double-blind, randomised controlled trial in patients aged 18 years and over, undergoing different types of major surgery (cardiac, thoracic or abdominal). Patients will be randomised in a 1:1 ratio to receive either gabapentin (600 mg just before surgery and 600 mg/day for 2 days after surgery) or placebo in addition to usual pain management for each type of surgery. Patients will be followed up daily until hospital discharge and then at 4 weeks and 4 months after surgery. The primary outcome is length of hospital stay following surgery. Secondary outcomes include pain, total opioid use, adverse health events, health related quality of life and costs.

ETHICS AND DISSEMINATION

This study has been approved by the Research Ethics Committee . Findings will be shared with participating hospitals and disseminated to the academic community through peer-reviewed publications and presentation at national and international meetings. Patients will be informed of the results through patient organisations and participant newsletters.

TRIAL REGISTRATION NUMBER

ISRCTN63614165.

PROSPECT guideline for tonsillectomy: systematic review and procedure-specific postoperative pain management recommendations

Tonsillectomy is one of the most frequently performed surgical procedures; however, pain management remains challenging. Procedure‐specific efficacy as well as specific risks of treatment options should guide selection of pain management protocols based on evidence and should optimise analgesia without harm. The aims of this systematic review were to evaluate the available literature and develop recommendations for optimal pain management after tonsillectomy. A systematic review utilising preferred reporting items for systematic reviews and meta‐analysis guidelines with procedure‐specific postoperative pain management (PROSPECT) methodology was undertaken. Randomised controlled trials published in the English language up to November 2019 assessing postoperative pain using analgesic, anaesthetic or surgical interventions were identified. Out of the 719 potentially eligible studies identified, 226 randomised controlled trials met the inclusion criteria, excluding the studies examining surgical techniques. Pre‐operative and intra‐operative interventions that improved postoperative pain were paracetamol; non‐steroidal anti‐inflammatory drugs; intravenous dexamethasone; ketamine (only assessed in children); gabapentinoids; dexmedetomidine; honey; and acupuncture. Inconsistent evidence was found for local anaesthetic infiltration; antibiotics; and magnesium sulphate. Limited evidence was found for clonidine. The analgesic regimen for tonsillectomy should include paracetamol; non‐steroidal anti‐inflammatory drugs; and intravenous dexamethasone, with opioids as rescue analgesics. Analgesic adjuncts such as intra‐operative and postoperative acupuncture as well as postoperative honey are also recommended. Ketamine (only for children); dexmedetomidine; or gabapentinoids may be considered when some of the first‐line analgesics are contra‐indicated. Further randomised controlled trials are required to define risk and combination of drugs most effective for postoperative pain relief after tonsillectomy.

Effects of Gabapentin Suspension and Rectal Acetaminophen on Postoperative Pain of Adenotonsillectomy in Children

Introduction

Adenotonsillectomy is the main treatment for symptomatic tonsillar hypertrophy with postoperative pain as the most common associated complication. The present study aimed to compare the efficacy of gabapentin with that reported for acetaminophen on the postoperative pain of adenotonsillectomy in children.

Materials and Methods

In this double-blind clinical trial, a total of 60 children within the age range of 7-15 years undergoing adenotonsillectomy were randomly allocated to two groups of gabapentin (n=30) and acetaminophen (n=30). The first group received a 10 mg/kg dose of gabapentin suspension preoperatively and placebo (suppository) after the intubation. The second group received a 40 mg/kg dose of acetaminophen suppository and placebo suspension simultaneous with that in the case group. Using the pain scale (based on the score of visual analog scale, prescribed drugs, dosage as well as incidence of postoperative nausea and vomiting were recorded 0, 2, 4, 6, 12, and 24 h after the surgery. The data were analyzed using SPSS software (version 22.0). A p-value less than 0.05 was considered statistically significant.

Results

There was no significant difference between the two groups considering the pain scores at 0, 2, 4, 6, 12, and 24 h after the surgery. In addition, the trend of pain intensity statistically decreased within 0 to 24 h in both acetaminophen (P<0.001) and gabapentin (P<0.001) groups. No statistically significant difference was observed between the two groups regarding the postoperative incidence of nausea and vomiting.

Conclusion

The obtained results of the present study showed that the administration of gabapentin and acetaminophen significantly reduced the postoperative pain of tonsillectomy and need for narcotics in these patients after the surgery. However, in this study, there was no particular reported superiority for any of the two groups in terms of the effects of gabapentin suspension and rectal acetaminophen.

Postoperative pain after tonsillectomy - the value of standardized analgesic treatment protocols

OBJECTIVE

To alleviate pain after tonsillectomy (TE) with escalating gradual treatment protocols in a prospective trial.

MATERIALS & METHODS

Following TE, 83 consecutive adult patients were treated with two different four-staged escalating analgesic protocols. Metamizole served as basic medication in protocol 1 (PT1; n = 44), whereas with protocol 2 (PT2; n = 39) ibuprofen was applied as baseline analgesic. Both protocols were escalated according to the patient´s needs to metamizole and ibuprofen vice versa and additional weak to strong opioids. The primary efficacy endpoint was defined as the minimum and maximum pain as well as pain on ambulation (NRS, 0-10). Secondary endpoints comprised analgesic score, patient satisfaction and treatment-related side-effects.

RESULTS

Both patient groups exhibited similar demographic characteristics (PT1: Ø 28.8 years; 64% ♀ and PT2: Ø 26.6 years; 56% ♀). Maximum pain (6.7 ± 1.9 vs. 7.6 ± 1.6, t₍₈₁₎ = -2.254, p = 0.027) and pain on ambulation (5.0 ± 1.8 vs. 5.8 ± 1.8, t₍₈₁₎ = -2.114, p = 0.038) were significantly higher with PT2. 68.2% of patients with PT1 needed an escalation of analgesic treatment compared to 100% with PT2 (p < 0.001). The opioid consumption was also significantly higher with PT2 (43.2% vs. 71.8%, p < 0.001). There were no significant differences regarding functional impairments, side-effects and patient satisfaction (7.0 ± 2.0 vs. 7.4 ± 2.4, t₍₇₉₎ = -0.897, p = 0.373).

CONCLUSION

Both treatment protocols yielded in a high degree of patient satisfaction but dissatisfactory pain relief following TE. Metamizole can be recommended as a basic medication allowing for improved pain relief. Reported pain intensities were independent of the amount of opioid intake. Further research is mandatory to standardize and improve analgesic treatment after TE.

Methodological Quality of Systematic Reviews and Meta-analyses Published in High-Impact Otolaryngology Journals

OBJECTIVE

To assess the methodological quality of intervention-focused systematic reviews (SRs) and meta-analyses (MAs) published in high-impact otolaryngology journals.

DATA SOURCES

Ovid Medline, Embase, and Cochrane Library.

REVIEW METHODS

A comprehensive search was performed for SR and MA citations from 2012 to 2017 in the 10 highest impact factor otolaryngology journals. Abstracts were screened to identify published manuscripts in which the authors indicated clearly that they were performing an SR or MA. Applying a modified typology of reviews, 4 reviewers characterized the review type as SR, MA, or another review type. A simplified version of the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews 2) tool was used to assess the reporting and methodological quality of the SRs and MAs that were focused on interventions.

RESULTS

Search and abstract screening generated 499 manuscripts that identified themselves as performing an SR or MA. A substantial number (85/499, 17%) were review types other than SRs or MAs, including 34 (7%) that were literature reviews. In total, 236 SRs and MAs focused on interventions. Over 50% of these SRs and MAs had weaknesses in at least 3 of the 16 items in the AMSTAR 2, and over 40% had weaknesses in at least 2 of the 7 critical domains. Ninety-nine percent of SRs and MAs provided critically low confidence in the results of the reviews.

CONCLUSION

Intervention-focused SRs and MAs published in high-impact otolaryngology journals have important methodological limitations that diminish confidence in the results of these reviews.

Perioperative Analgesia for Patients Undergoing Thyroidectomy and Parathyroidectomy: An Evidence-Based Review

Objective:

To perform an evidence-based systematic review evaluating perioperative analgesia, including opioid alternatives, used for patients undergoing thyroidectomy and parathyroidectomy.

Methods:

A comprehensive literature search from 1997 to January 2018 of Pubmed, Cochrane, and EmBase libraries was performed for studies reporting analgesic administration following thyroid or parathyroid surgery. This systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Studies were evaluated for level of evidence and given a Jadad score to assess for risk of bias. Outcomes gathered included postoperative pain scores, time to rescue analgesia, rescue analgesic consumption, and adverse events.

Results:

Thirty-eight randomized controlled trials met inclusion criteria. The GRADE criteria determined the overall evidence to be moderate-high. Studies utilizing NSAIDs reported reduced requirements for rescue analgesics. Acetaminophen studies presented with conflicting data on effectiveness. Gabapentinoid studies demonstrated lower pain scores and an increased time to rescue analgesic. Local anesthetics were effective at decreasing Visual Analogue Scale (VAS) and Numeric Rating Scale (NRS) pain scores while also reducing rescue analgesic consumption. Ketamine was shown to increased postoperative nausea and vomiting. NSAIDs and local anesthetic studies had an aggregate grade of evidence A, while all others had grade B evidence.

Conclusion:

There is significant evidence supporting the use of NSAIDs and local anesthetics in the perioperative period for pain management for thyroid and parathyroid surgeries. Acetaminophen, gabapentinoid and ketamine have some supporting evidence and may serve as adequate alternatives. Further multi-institutional RCTs are warranted to delineate optimal analgesic regimens.

Level of Evidence:

NA

Update review of pain control methods of tonsil surgery

Pain after tonsil surgery is troublesome because it causes discomfort. In addition, handling patients with postoperative pain is challenging to otolaryngologists. Many laboratory studies have assessed the use of analgesics and surgical techniques to discover methods for effective control of postoperative pain associated with tonsil surgery. In this review article, we summarize and provide a comprehensive overview of current methods for the control of pain after tonsil surgery based on findings of recent studies. Although powered intracapsular tonsillotomy is not popular yet, it seems to be an effective option among various surgical techniques. More discussion about powered intracapsular tonsillotomy should be done in the future. On the other hand, surgery with a harmonic scalpel, fibrin glue, or cryoanalgesia seems ineffective. When reviewing medical treatment methods, the use of nonsteroidal anti-inflammatory drugs, steroids, and/or gabapentin/pregabalin seems to be effective. However, the use of opioid (especially codeine) for children should be avoided because of possible respiratory insufficiency. Ketorolac is dangerous because of the risk of hemorrhage. We should continue to focus on the development of novel postoperative pain control techniques with no or low complications.

Systematic review of analgesics and dexamethasone for post-tonsillectomy pain in adults

BACKGROUND

Intense pain can last several days after tonsillectomy. It is often undertreated and improved analgesic strategies that can be safely used at home are needed.

METHODS

We conducted a systematic review and meta-analysis on the effectiveness of systemic medications used for post-tonsillectomy pain in adult and adolescent (13 yr old) patients. Studies were identified from PubMed, the Cochrane Library, and by hand searching reference lists from studies and review articles. Randomised, double-blind, placebo-controlled studies reporting on pain intensity or use of rescue analgesia were included.

RESULTS

Twenty-nine randomised controlled trials representing 1816 subjects met the inclusion criteria. Follow-up time was ≤24 h in 15 studies, in which the majority were taking nonsteroidal anti-inflammatory drugs. Thirteen studies were suitable for meta-analysis. In pooled analysis, paracetamol, dexamethasone, and gabapentinoids reduced pain intensity on the day of operation. In individual studies, ketoprofen, ibuprofen, lornoxicam, parecoxib, rofecoxib, indomethacin and dextromethorphan reduced pain intensity, need for rescue analgesics, or both on the day of operation. Oral celecoxib for 2 postoperative weeks or i.v. ketamine on the day of operation were not effective at the studied doses. Dexamethasone in multiple doses provided analgesia beyond 1 postoperative day. Pain was moderate to strong in both study and control groups during the first postoperative week.

CONCLUSIONS

Single analgesics and dexamethasone provide only a weak to moderate effect for post-tonsillectomy pain on the day of operation and thus a multimodal analgesic strategy is recommended. Short follow-up times and clinical heterogeneity of studies limit the usefulness of results.

Efficacy of tranexamic acid on operative bleeding in endoscopic sinus surgery: A meta-analysis and systematic review

OBJECTIVES

Tranexamic acid might help control bleeding during surgery because of antifibrinolytic characteristics. We aimed to evaluate the effectiveness of systemic tranexamic acid compared to control in blood loss, operative time, and surgical field and incidence of postoperative emesis and thromboembolism in endoscopic sinus surgery.

METHODS

Two authors independently searched six databases (PubMed, SCOPUS, Embase, the Web of Science, Google Scholar, and the Cochrane database) from their inception to July 2018. The included studies compared perioperative tranexamic acid administration (treatment group) with a placebo, and the outcomes of interest were intraoperative morbidities, including surgical time, operative bleeding, and hypotension; postoperative morbidities such as nausea and vomiting; and coagulation profiles.

RESULTS

Seven studies comprising 562 participants were reviewed in this study. Operative time (standardized mean difference (SMD) = -0.60; 95% confidence interval (CI)[-0.93, -0.29]) and intraoperative blood loss (SMD = -0.66; 95% CI [-0.86, -0.46]) were statistically lower in the treatment group than placebo group; and the quality of the surgical field (SMD = -0.80; 95% CI [-1.12; -0.48]) and surgeon satisfaction (SMD = 1.74; 95% CI [1.36; 2.13]) were statistically higher in the treatment group than the placebo group. By contrast, there were no significant differences in the hemodynamic (SMD = 0.08; 95% CI [-0.20; 0.37]) and coagulation profiles (SMD = -0.18; 95% CI [-0.42, 0.07]) of the two groups. Additionally, tranexamic acid had no significant effect on emetic or thrombotic events compared to placebo.

CONCLUSION

This meta-analysis showed that the systemic administration of tranexamic acid could decrease operative time and blood loss intraoperatively, increasing the satisfaction of surgeons. It did not provoke intraoperative hemodynamic instability, postoperative emetic events, or coagulation profile abnormality. Only a small number of studies were enrolled, so further trials are needed to confirm the results of this study. Laryngoscope, 129:800-807, 2019.

Gabapentin prevents synaptogenesis between sensory and spinal cord neurons induced by thrombospondin-4 acting on pre-synaptic Cav α2 δ1 subunits and involving T-type Ca2+ channels

BACKGROUND AND PURPOSE

Nerve injury induces concurrent up-regulation of the voltage-gated calcium channel subunit Cav α2 δ1 and the extracellular matrix protein thrombospondin-4 (TSP4) in dorsal root ganglia and dorsal spinal cord, leading to the development of a neuropathic pain state. Interactions of these proteins promote aberrant excitatory synaptogenesis that contributes to neuropathic pain state development through unknown mechanisms. We investigated the contributions of Cav α2 δ1 subunits and TSP4 to synaptogenesis, and the pathways involved in vitro, and whether treatment with gabapentin could block this process and pain development in vivo.

EXPERIMENTAL APPROACH

A co-culture system of sensory and spinal cord neurons was used to study the contribution from each protein to synaptogenesis and the pathway(s) involved. Anti-synaptogenic actions of gabapentin were studied in TSP4-injected mice.

KEY RESULTS

Only presynaptic, but not postsynaptic, Cav α2 δ1 subunits interacted with TSP4 to initiate excitatory synaptogenesis through a pathway modulated by T-type calcium channels. Cav α2 δ1 /TSP4 interactions were not required for maintenance of already formed synapses. In vivo, early, but not delayed, treatment with low-dose gabapentin blocked this pathway and the development of the pain state.

CONCLUSIONS AND IMPLICATIONS

Cav α2 δ1 /TSP4 interactions were critical for the initiation, but not for the maintenance, of abnormal synapse formation between sensory and spinal cord neurons. This process was blocked by early, but was not reversed by delayed, treatment with gabapentin. Early intervention with gabapentin may prevent the development of injury-induced chronic pain, resulting from Cav α2 δ1 /TSP4-initiated abnormal synapse formation.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

Injury-induced maladaptation and dysregulation of calcium channel α2 δ subunit proteins and its contribution to neuropathic pain development

Voltage-gated calcium channels (VGCCs) play important roles in physiological functions including the modulation of neurotransmitter release, neuronal network activities, intracellular signalling pathways and gene expression. Some pathological conditions, including nerve injuries, can cause the dysregulation of VGCCs and their subunits. This in turn can lead to a functional maladaptation of VGCCs and their subunits, which can contribute to the development of disorders such as pain sensations. This review has summarized recent findings related to maladaptive changes in the dysregulated VGCC α2 δ1 subunit (Cav α2 δ1 ) with a focus on exploring the mechanisms underlying the contribution of Cav α2 δ1 to pain signal transduction. At least under neuropathic pain conditions, the dysregulated Cav α2 δ1 can modulate VGCC functions as well as other plasticity changes. The latter includes abnormal excitatory synaptogenesis resulting from its interactions with injury-induced extracellular matrix glycoprotein molecule thrombospondins, which is independent of the VGCC functions. Blocking Cav α2 δ1 with gabapentinoids can reverse neuropathic pain significantly with relatively mild side effects, but only in a small population of neuropathic pain patients due to reasons yet to be explored. There are emerging data suggesting that early preventive treatment with gabapentinoids can prevent aberrant excitatory synapse formation and the development of chronic pain. If these findings are confirmed clinically, this could be an attractive approach for neuropathic pain management.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

Gabapentin in the Management of Pain following Tonsillectomy: A Randomized Double-Blind Placebo-Controlled Trial

Objective To determine if a single dose of oral gabapentin given prior to tonsillectomy decreases postoperative morbidity. Study Design Prospective randomized double-blind placebo-controlled trial. Setting Southern District Health Board University Hospitals, New Zealand, over a 10-month period. Subjects and Methods Seventy-three adults undergoing tonsillectomy were randomized to receive either a single preoperative dose of oral gabapentin (600 mg) or placebo. A standard analgesic protocol was prescribed for 14 postoperative days. The primary outcome was a patient-assigned visual analog scale pain score during rest and swallow; secondary outcomes were analgesic consumption, nausea, vomiting, and return to normal diet and activities. Complications and adverse effects were also recorded. Results Thirty-seven participants were allocated to the placebo group and 36 to the gabapentin group. After withdrawals, data were analyzed from 31 in the placebo group and 27 in the gabapentin group. Pain scores between groups were not significantly different within the first 6 hours. The gabapentin group recorded significantly higher pain scores between days 5 and 10 (maximal difference, day 8: 17.6 mm; effect size, -8.87; P = .03; 95% CI, -16.883 to -0.865). There was no significant difference in swallow pain scores or early postoperative fentanyl consumption. Consumption of paracetamol ( P = .01 at day 13 and P = .004 at day 14) and codeine ( P < .05 at days 3-5, 7, 8, 10, 14) was higher in the gabapentin group. No significant difference between groups was found for the other outcomes. Conclusions Preemptive gabapentin (600 mg) was associated with greater postoperative pain scores and analgesic consumption following adult tonsillectomy when compared with placebo.

The efficacy of pregabalin for the management of postoperative pain in primary total knee and hip arthroplasty: a meta-analysis

Objective

A systematic review of randomized controlled trials (RCTs) was conducted to evaluate the efficacy of pregabalin for the management of postoperative pain in patients undergoing primary total knee arthroplasty (TKA) and primary total hip arthroplasty (THA).

Method

The PubMed, Embase, Cochrane Central Register of Controlled Trials, and Google Scholar databases were searched for related articles using search strategy. RevMan 5.3 software was selected to conduct the meta-analysis.

Results

Seven RCTs were included in our meta-analysis. There were significant differences in visual analogue scale (VAS) at 24 and 48 h with rest, knee flexion degree, mean morphine consumption, and postoperative side effects (nausea, vomiting, pruritus, and dizziness) when comparing the pregabalin group to the placebo group after TKA and THA. However, the differences in VAS at 72 h with rest and at 24 h on movement were not significant between the two groups.

Conclusions

Pregabalin was found to improve pain control at 24 and 48 h with rest, reduce morphine consumption, improve the knee flexion degree, decrease the incident rate of nausea, vomiting, and pruritus, and increase the incident rate of dizziness after TKA and THA but could not improve the pain control at 72 h with rest. In summary, the use of pregabalin may be a valuable asset in pain management within the first 48 h after TKA and THA. However, future studies regarding doses and pregabalin medication are required.

A Meta-Analysis on the Use of Gabapentinoids for the Treatment of Acute Postoperative Pain Following Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty is a painful procedure, with approximately half of patients reporting severe pain during the early postoperative period. Gabapentinoids are used as an adjunct for the management of acute pain in approximately half of enhanced recovery programs. We performed a meta-analysis to assess the effectiveness and safety of gabapentinoids for the treatment of acute postoperative pain following total knee arthroplasty.

METHODS

Randomized controlled trials of patients undergoing elective primary total knee arthroplasty that compared the use of the gabapentinoid class of drugs (gabapentin [Neurontin; Pfizer]) or pregabalin [Lyrica; Pfizer]) with that of placebo were retrieved, with 12 studies meeting inclusion criteria. The primary outcome was pain intensity with activity at 48 hours following the surgical procedure. The secondary outcomes included pain intensity at other time points, opioid consumption, knee function, incidence of chronic pain, and adverse events.

RESULTS

No difference in pain score at 12, 24, 48, or 72 hours following the surgical procedure was seen between gabapentin and placebo. Although pregabalin was associated with reduced pain scores at 24 and 48 hours, this corresponded to a reduction of 0.5 point (95% confidence interval, 0 to 1.0 point) at 24 hours and 0.3 point (95% confidence interval, 0 to 0.6 point) at 48 hours on an 11-point numeric rating scale, which was assessed as not clinically important. Overall, no clinically relevant reduction in pain scores was associated with the use of gabapentinoids. Likewise, gabapentinoids were associated with a small, but not clinically important, reduction in cumulative opioid consumption at 48 hours (mean difference, -23.2 mg [95% confidence interval, -40.9 to -5.4 mg]). There was no difference in knee flexion at 48 hours (p = 0.63) or in the incidence of chronic pain at 3 months (p = 0.31) or 6 months (p = 0.54) associated with the use of gabapentinoids. Although gabapentinoids were associated with a significant reduction in the incidence of nausea (risk ratio, 0.7 [95% confidence interval, 0.6 to 0.9]; p < 0.001), pregabalin was also associated with a significant, clinically relevant increase in the risk of sedation (risk ratio, 1.4 [95% confidence interval, 1.1 to 1.9]; p = 0.02).

CONCLUSIONS

On the basis of this meta-analysis, we found no evidence to support the routine use of gabapentinoids in the management of acute pain following total knee arthroplasty.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Gabapentin for Perioperative Analgesia in Otorhinolaryngology-Head and Neck Surgery: Systematic Review

OBJECTIVE

Recent research has investigated the role of gabapentin in perioperative pain relief in otorhinolaryngology-head and neck surgery. This review aims to identify whether sufficient evidence exists for the routine use of gabapentin in the perioperative setting.

DATA SOURCES

MEDLINE, Cochrane CENTRAL, EMBASE, and Google Scholar.

REVIEW METHODS

A comprehensive systematic search was performed with keywords for articles up to November 2015. The systematic review included all randomized, placebo-, and active-controlled trials investigating the role of perioperative gabapentin for pain in otorhinolaryngology-head and neck surgery. The studies were assessed for risk of bias and selected and reviewed by the main author. Selected trials were required to have data in the form of pain intensity scores, analgesic consumption, adverse effects, or return to normal function.

RESULTS

A total of 14 randomized controlled trials were included, of which 4 had an active control. The placebo-controlled trials included 4 for tonsillectomy, 3 for rhinology, and 3 for thyroidectomy. These studies were not suitable for meta-analysis. Trial quality involving gabapentin in tonsillectomy surgery is variable. The higher-quality studies reported significantly reduced analgesic consumption in the gabapentin groups, with the effect on pain scores less clear. There was a significant benefit, within the first 24 hours, in pain and analgesic consumption as compared with placebo favoring the gabapentin groups following rhinologic and thyroid surgery.

CONCLUSION

Overall, gabapentin appears to have a significant beneficial effect on perioperative pain relief and analgesic consumption in otorhinolaryngology-head and neck surgery procedures within the first 24 hours.

The use of gabapentin in the management of postoperative pain after total hip arthroplasty: a meta-analysis of randomised controlled trials

Background

Pain management after total hip arthroplasty (THA) varies and has been widely studied in recent years. Gabapentin as a third-generation antiepileptic drug that selectively affects the nociceptive process has been used for pain relief after THA. This meta-analysis was conducted to examine the efficacy of gabapentin in THA.

Methods

An electronic-based search was conducted using the following databases: PubMed, EMBASE, Ovid MEDLINE, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials (CENTRAL). Randomised controlled trials (RCTs) involving gabapentin and a placebo for THA were included. The meta-analysis was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Results

Five trials met the inclusion criteria. The cumulative narcotic consumption and the visual analogue scale (VAS) scores at 24 and 48 h postoperatively were used for postoperative pain assessment. There was a significant decrease in morphine consumption at 24 h (P = 0.00). Compared with the control group, the VAS score (at rest) at 48 h was less in the gabapentin group (P = 0.00).

Conclusion

The administration of gabapentin is effective in decreasing postoperative narcotic consumption and the VAS score.

Alpha2delta ligands, gabapentin, pregabalin and mirogabalin: a review of their clinical pharmacology and therapeutic use

INTRODUCTION

The first two alpha₂delta ligands - gabapentin (GBP) and pregabalin (PGB) - were initially synthesized as antiepileptics; however, they were later also found to be useful for the treatment of additional conditions. Areas covered: Relevant publications describing potential underlying mechanisms, clinical pharmacokinetics/pharmacokinetics, and clinical efficacy and safety of these drugs in various disease conditions were searched in PubMed and Scopus and included in this review. Expert commentary: GBP and PGB are effective for the treatment neuropathic pain, fibromyalgia and epilepsy; in addition, they may be useful for the reduction of postoperative pain. PGB is also effective for the treatment of generalized anxiety disorder and GBP for the treatment of restless legs syndrome. GBP may be considered a treatment option for pain associated with Guillain-Barré Syndrome and phantom limb and for the management of uremic pruritus. Mirogabalin (MGB), recently developed, is being investigated for the treatment of peripheral neuropathic pain and fibromyalgia, showing promising results in patients with diabetic peripheral neuropathy. Their most frequent adverse reactions are of neuropsychiatric nature and include fatigue, dizziness, sedation, somnolence, and ataxia; peripheral edema and weight gain are also frequently described. Pharmacokinetic interactions are scarce; however, pharmacodynamic interactions have been described in association with drugs with CNS-depressant effects.

The use of gabapentin in the management of postoperative pain after total knee arthroplasty: A PRISMA-compliant meta-analysis of randomized controlled trials

Pain management after total knee arthroplasty (TKA) varies and has been widely studied in recent years. Some randomized controlled studies have carried out to evaluate the effects of gabapentin on pain relief after TKA. However, no solid result was made about it. The purpose of this Meta-Analysis of Randomized Controlled Trials (RCTs) was to estimate the overall effect of pain control of gabapentin versus placebo after a TKA. An electronic-based search using the following databases: PubMed, EMBASE, Ovid MEDLINE, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trial from 1966 to June 2015. RCTs involving gabapentin and placebo for total knee arthroplasty were included. The meta-analysis was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Six trials with 859 participants met the inclusion criteria. The primary endpoint was cumulative narcotic consumption and the visual analog scale scores at 12 hours, 24 hours, and 48 hours, postoperatively. The knee flexion degree and treatment side effects were also compiled to evaluate the safety of gabapentin. After testing for the heterogeneity and publication bias among studies, data were aggregated for random-effects modeling when necessary. There was a significant decrease in morphine consumption at 12 hours (MD = -4.69, 95% CI: -7.18 to -2.21, P = 0.0002), 24 hours (MD = -5.30, 95% CI: -9.94 to -0.66, P = 0.03), and 48 hours (MD = -17.80, 95% CI: -31.95 to -3.64, P = 0.01), respectively. Compared with the control group, the rate of pruritus was less in the gabapentin group (RR 0.20, 95% CI 0.10 to 0.38, P = 0.00). In summary, the administration of gabapentin was effective in decreasing postoperative narcotic consumption and the incidence of pruritus. There was a high risk of selection bias and a higher heterogeneity of knee flexion range in this analysis. More high-quality large randomized controlled trials with long follow-up period are necessary for proper comparisons of the efficacy and safety of gabapentin with placebo.Systematic review registration number: No.

The Effect of Gabapentin on Acute Postoperative Pain in Patients Undergoing Total Knee Arthroplasty: A Meta-Analysis

The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) and non-RCTs was to evaluate the efficacy and safety of gabapentin versus placebo for pain control after total knee arthroplasty (TKA).In December 2015, a systematic computer-based search was conducted in the Medline, Embase, PubMed, Cochrane Controlled Trials Register (CENTRAL), Web of Science, Google, and Chinese Wanfang databases. This systematic review and meta-analysis were performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement criteria. The primary endpoint was the visual analogue scale (VAS) score after TKA with rest or mobilization at 24 and 48 hours, representing the efficacy of pain control after TKA. Cumulative morphine consumption via patient controlled anesthesia (PCA) was also assessed to determine the morphine-spare effect. Complications such as dizziness, pruritus, vomiting, nausea, and sedation were also compiled to assess the safety of gabapentin. Stata 12.0 software was used for the meta-analysis. After testing for publication bias and heterogeneity across studies, the data were aggregated for random-effects modeling whenever necessary.Six studies involving 769 patients met the inclusion criteria. Our meta-analysis revealed that gabapentin resulted in superior pain relief compared to the control group in terms of VAS score with rest at 24 hours (mean difference [MD] = -3.47; 95% confidence interval [CI] -6.16 to -0.77; P = 0.012) and at 48 hours postoperatively (MD = -2.25; 95% CI -4.21 to -0.30; P = 0.024). There was no statistically significant difference between the groups with respect to the VAS score at 24 hours postoperatively (MD = 1.05; 95% CI -3.31 to 5.42; P = 0.636) or at 48 hours (MD = 1.71; 95% CI -0.74 to 4.15; P = 0.171). These results indicated that the perioperative administration of gabapentin decreases the cumulative morphine consumption via PCA at 24 hours (MD = -8.28; 95% CI -12.57 to -3.99; P = 0.000) and 48 hours (MD = -4.50; 95% CI -10.98 to -3.61; P = 0.221). Furthermore, gabapentin decreased the rate of postoperative dizziness (relative risk [RR], 0.68; 95% CI 0.47-0.99, P = 0.044) and the occurrence of pruritus (RR, 0.50; 95% CI 0.37-0.67, P = 0.000).Based on the current meta-analysis, gabapentin exerts an analgesic and opioid-sparing effect in acute postoperative pain management without increasing the rate of dizziness and pruritus.