Analgesic Mechanisms of Antidepressants for Neuropathic Pain

An overview of the non-procedural treatment options for peripheral neuropathic pain

Peripheral neuropathic pain is common in patients with peripheral nerve injury and can significantly impact both their function and quality of life. There is a wide variety of non-interventional treatment approaches, including pharmacologic therapy, physical/occupational therapy, modalities (therapeutic, mechanical, thermal, etc.), psychology, and lifestyle modification. First line pharmacologic therapy for peripheral neuropathic pain includes gabapentinoids, tricyclic antidepressants, and serotonin-norepinephrine reuptake inhibitors. Other classes of medications, such as topical treatments, opioids, and cannabinoids, have more limited usefulness in treatment but remain part of a treatment regimen. Physical and occupational therapy, psychological interventions, and lifestyle medicine are important adjuncts in the treatment and prevention of future peripheral neuropathic pain. The strength of the evidence supporting each intervention varies, with that for pharmacologic intervention being the strongest. A combination of these options tailored to the individual needs of the patient likely will result in the best treatment outcome for peripheral neuropathic pain.

Mechanisms and Therapeutic Prospects of Microglia-Astrocyte Interactions in Neuropathic Pain Following Spinal Cord Injury

Neuropathic pain is a prevalent and debilitating condition experienced by the majority of individuals with spinal cord injury (SCI). The complex pathophysiology of neuropathic pain, involving continuous activation of microglia and astrocytes, reactive gliosis, and altered neuronal plasticity, poses significant challenges for effective treatment. This review focuses on the pivotal roles of microglia and astrocytes, the two major glial cell types in the central nervous system, in the development and maintenance of neuropathic pain after SCI. We highlight the extensive bidirectional interactions between these cells, mediated by the release of inflammatory mediators, neurotransmitters, and neurotrophic factors, which contribute to the amplification of pain signaling. Understanding the microglia-astrocyte crosstalk and its impact on neuronal function is crucial for developing novel therapeutic strategies targeting neuropathic pain. In addition, this review discusses the fundamental biology, post-injury pain roles, and therapeutic prospects of microglia and astrocytes in neuropathic pain after SCI and elucidates the specific signaling pathways involved. We also speculated that the extracellular matrix (ECM) can affect the glial cells as well. Furthermore, we also mentioned potential targeted therapies, challenges, and progress in clinical trials, as well as new biomarkers and therapeutic targets. Finally, other relevant cell interactions in neuropathic pain and the role of glial cells in other neuropathic pain conditions have been discussed. This review serves as a comprehensive resource for further investigations into the microglia-astrocyte interaction and the detailed mechanisms of neuropathic pain after SCI, with the aim of improving therapeutic efficacy.

The Use of Tricyclic Antidepressants for Postherpetic Neuralgia - A Case Series

Postherpetic neuralgia (PHN) is one of the most debilitating forms of neuropathic pain that can occur after a herpes zoster infection. PHN can significantly impair patients' quality of life due to persistent neuropathic pain. Current first-line treatments for PHN include anticonvulsants like gabapentin and pregabalin, topical agents such as lidocaine patches, and opioids in severe cases. However, many patients fail to achieve adequate pain control with these medications. Tricyclic antidepressants (TCAs) such as amitriptyline and nortriptyline may be considered as a second-line option, providing relief for patients with refractory pain. TCAs act by modulating neurotransmitters involved in pain pathways, offering analgesia in neuropathic conditions like PHN. This case series reviews four patients with PHN who found significant pain relief with the addition of TCAs after failing multiple other treatments. The patients, aged between 66 and 71, presented with severe PHN and had tried various treatments, including acetaminophen (APAP), nonsteroidal anti-inflammatory drugs (NSAIDs), lidocaine patches, gabapentinoids, and opioids, without achieving adequate pain relief. Each patient was prescribed a TCA, either amitriptyline or nortriptyline, alongside other pain medications. All four patients experienced notable reductions in pain intensity on the Numeric Rating Scale (NRS), resulting in improved daily function and better pain tolerance. Side effects were minimal, with only one patient reporting mild sedation and another reporting transient dry mouth, both of which were manageable. This case series underscores the potential of TCAs in managing PHN, particularly when other medications fail. While the results are promising, further research is needed to confirm the long-term efficacy and safety of TCAs in this patient population.

The 5-HT Descending Facilitation System Contributes to the Disinhibition of Spinal PKCγ Neurons and Neuropathic Allodynia via 5-HT2C Receptors

Neuropathic pain, often featuring allodynia, imposes significant physical and psychological burdens on patients, with limited treatments due to unclear central mechanisms. Addressing this challenge remains a crucial unsolved issue in pain medicine. Our previous study, using protein kinase C gamma (PKCγ)-tdTomato mice, highlights the spinal feedforward inhibitory circuit involving PKCγ neurons in gating neuropathic allodynia. However, the regulatory mechanisms governing this circuit necessitate further elucidation. We used diverse transgenic mice and advanced techniques to uncover the regulatory role of the descending serotonin (5-HT) facilitation system on spinal PKCγ neurons. Our findings revealed that 5-HT neurons from the rostral ventromedial medulla hyperpolarize spinal inhibitory interneurons via 5-HT2C receptors, disinhibiting the feedforward inhibitory circuit involving PKCγ neurons and exacerbating allodynia. Inhibiting spinal 5-HT2C receptors restored the feedforward inhibitory circuit, effectively preventing neuropathic allodynia. These insights offer promising therapeutic targets for neuropathic allodynia management, emphasizing the potential of spinal 5-HT2C receptors as a novel avenue for intervention.

The "brain-gut" mechanism of postherpetic neuralgia: a mini-review

Postherpetic neuralgia (PHN), a representative type of neuropathic pain, has attracted much research on its diagnosis and therapy at the molecular level. Interestingly, this study based on the brain-gut axis provided a novel point of view to interpret the mechanism of PHN. Past neuroanatomical and neuroimaging studies of pain suggest that the prefrontal cortex, anterior cingulate cortex, amygdala, and other regions of the brain may play crucial roles in the descending inhibition of PHN. Dominant bacterial species in patients with PHN, such as Lactobacillus, generate short-chain fatty acids, including butyrate. Evidence indicates that disturbance of some metabolites (such as butyrate) is closely related to the development of hyperalgesia. In addition, tryptophan and 5-HT in the intestinal tract act as neurotransmitters that regulate the descending transmission of neuropathic pain signals. Concurrently, the enteric nervous system establishes close connections with the central nervous system through the vagus nerve and other pathways. This review aims to investigate and elucidate the molecular mechanisms associated with PHN, focusing on the interplay among PHN, the gut microbiota, and relevant metabolites while scrutinizing its pathogenesis.

Evaluating amitriptyline's role in chronic TMD management: a placebo-controlled trial

BACKGROUND

To assess the effectiveness of low-dose amitriptyline in reducing pain and improving oral health-related quality of life in individuals with chronic temporomandibular disorders (TMD) over a 2-month period, compared to placebo.

METHODS

Forty participants were randomly assigned to receive either 25 mg of amitriptyline or a placebo pill for 2 months. The primary outcome was pain intensity, measured using a visual analogue scale (VAS). The secondary outcome was the impact of pain on oral health-related quality of life, assessed by the Oral Health Impact Profile questionnaire (OHIP-14). Evaluations were conducted at baseline and after the 1st and 2nd months of treatment.

RESULTS

No statistically significant differences were observed between the treatment groups at baseline (p > 0.05). After 2 months of treatment participants in amitriptyline group experienced a significantly greater reduction in spontaneous pain, with a 63.3% decrease in VAS scores. Participants in placebo group showed a much smaller reduction in spontaneous pain, with only a 16.2% decrease in VAS scores. Additionally, the amitriptyline group demonstrated a significant improvement in OHIP-14 scores (p < 0.001), whereas the placebo group showed no significant change in oral health-related quality of life (p = 0.184).

CONCLUSION

This study highlights low-dose amitriptyline as an effective treatment for chronic TMD, showing significant pain reduction and improved quality of life, underscoring its value in a multimodal approach despite the need for further research to personalize care.

TRIAL REGISTRATION

This study was registered retrospectively in ISRCTNregistry under the number ISRCTN17622685, on 01/10/2024.

Pathophysiology, Assessment, and Management of Pain Associated with Chronic Pancreatitis

Chronic pancreatitis (CP) is a fibroinflammatory disease, with pain as its most prominent symptom. This article provides a comprehensive review of the pathophysiology, assessment methodologies, and management strategies pertaining to pain in CP. Pathophysiological mechanisms include inflammatory and neuropathic components, including peripheral and central sensitization. Pain assessment can include unidimensional and multidimensional pain assessment scales, neurophysiological assessments, and advanced imaging techniques. Management strategies include a spectrum from lifestyle modifications, pharmacologic interventions, and interventional procedures to neuromodulatory techniques and other experimental treatments.

The Association of Pain Medication Usage and Quantitative Sensory Testing Outcomes in Fibromyalgia Patients: A Secondary Data Analysis

BACKGROUND

Fibromyalgia syndrome (FMS), a chronic pain syndrome affecting 0.2-6.6% of the general population, is known for its challenging diagnosis and treatment. The known dysregulation in the Endogenous Pain Modulatory System (EPMS) characteristic of the pathology contributes to enhanced pain sensitivity. Fibromyalgia patients, who are often overmedicated, may experience, in addition to the drug-related known adverse effects, effects on fibromyalgia sensory-related outcomes. Therefore, the focus of this analysis is to explore the bidirectional drug-sensory outcome interactions, indexed by the conditioned pain modulation (CPM), an important assessment element in regard to an EPMS's efficacy.

METHODS

Baseline data from a randomized, double-blind, single-center (Boston-based tertiary hospital) clinical trial (NCT03371225) were analyzed. Participants aged 18-65 with an FMS diagnosis and resistance to common analgesics were included. Demographic, clinical, and sensory variables, including CPM, temporal summation, and Pain-60 outcomes, were collected alongside a pain medication diary. Multivariable regression models adjusted for confounders were applied to explore associations between medication classes and quantitative sensory outcomes.

RESULTS

Out of 101 recruited FMS patients, we categorized the use of the following medications: antidepressants with 50% use (n = 50), muscle relaxants with 26% use (n = 26), and gabapentin with 25% use (n = 25). The results showed that antidepressant use correlated with worsened CPM, Odds Ratio = 0.39 (95% CI = 0.17-0.91), while muscle relaxants were linked to increased TSPS, β coefficient = 0.72 (95% CI = 0.0021-1.4431). On the other hand, gabapentin use was associated with elevated Pain-60, OR = 2.68 (95% CI = 0.98-7.31). Interestingly, the use of low doses of opioids was not associated with altered sensory measures.

CONCLUSION

This cross-sectional analysis suggests that common pain medications may affect quantitative sensory outcomes in FMS patients. We provided important insights into bidirectional drug-sensory outcome interactions and their influence on pain medicine.

Tocochromanols in the Leaves of Plants in the Hypericum and Clusia Genera

Now under Clusiaceae and Hypericaceae, Clusia and Hypericum were previously categorized under one family until they were divided in 2003 by the APG III system. The Clusia genus is characterized by the presence of tocotrienol derivatives with antiangiogenic properties, and only Hypericum perforatum tocochromanol content has been studied in the Hypericum genus. Twelve species were analyzed: H. aegypticum, H. calycinum, H. empetrifolium, H. lancasteri, H. olympicum f. minus 'Sulphureum', H. perforatum, H. xylosteifolium, C. fluminensis, C. minor, C. odorata, C. palmicida, and C. tocuchensis. Plant leaves were analyzed for their tocochromanol (α-, β-, γ-, and δ-tocotrienol and tocopherol) contents using a reverse-phase high-performance liquid chromatography with fluorescent light detector (RP-HPLC-FLD) method. While α-tocopherol (α-T) was present in the highest proportion, the leaves had significant tocotrienol (T3) contents. Following α-T, δ-T3 was present in most Clusia samples, and γ-T3 in most Hypericum samples, except H. olympicum, in which α-T3 followed. C. minor had the highest α-T (112.72 mg 100 g-1) and total tocochromanol (141.43 mg 100 g-1) content, followed by C. palmicida (65.97 and 82.96 mg 100 g-1, respectively) and H. olympicum (α-T 32.08, α-T3 30.68, and total tocochromanols 89.06 mg 100 g-1). The Hypericum genus is a valuable source of tocotrienols, with potential use after purification.

Tocotrienols in Eleven Species of Hypericum Genus Leaves

Saint John's worts or goatweeds are mostly perennial flowering plants in the Hypericaceae family, formerly under the Clusiaceae family. Teas and macerations of the plants are common in traditional medicines and modern depression and cancer therapies. The most notable bioactive compounds in Hypericum are hyperforin and hypericin. While Hypericum contains a variety of carotenoid and phenolic compounds, which are well documented, there is little available information on tocopherols and almost none on tocotrienols. Considering the frequency of tocotrienol derivatives in Clusiaceae species, this study investigates and reports the presence of tocotrienols in eleven Hypericum species' leaves: H. hircinum, H. hookerianum, H. calycinum, H. xylosteifolium, H. densifolium, H. prolificum, H. kalmianum, H. frondosum, H. olympicum, and two hybrids: H. × moserianum and H × 'Rowallane'. Eight tocopherol and tocotrienol forms (α, β, γ, δ) were detected in the leaves, predominantly containing α-tocopherol. Tocotrienol content was most significant in Myriandra section species and was highest in H. prolificum (22.90 ± 0.63 mg 100 g-1), while the highest tocotrienol proportion was observed in H. × 'Rowallane' (54.12% of total tocochromanols) and H. prolificum (37.27% of total tocochromanols). The results demonstrated significant tocochromanol accumulation in Hypericum leaves.

A Study on Subjective Symptoms and Plantar Temperature Imbalance in Lumbar Spinal Stenosis: A Preliminary Study

Background Symptoms of lumbar spinal stenosis (LSS) are associated with changes in blood flow to lower limbs. These changes in blood flow can be perceived as temperature variations, which can be visualized using thermography. We compared the relationship between the subjective symptoms of LSS and temperature variations before and after surgical intervention and investigated the associated patient factors. Methods Patients who underwent laminectomy for LSS were included. Plantar temperature was measured preoperatively and postoperatively using thermography. Subjective symptoms and patient backgrounds were assessed through interviews and medical records. Temperature differences were evaluated using the parameter ΔT, defined as the temperature of the limb with stronger symptoms minus the temperature of the limb with weaker symptoms. The analyses were performed based on these parameters. Results The symptoms improved following laminectomy, and ΔT showed a significant increase. Pain and ΔT were positively correlated preoperatively, whereas ΔT and numbness and neuropathic pain scores were negatively correlated postoperatively. Cauda equina symptoms were associated with a decrease in ΔT both preoperatively and postoperatively, whereas age and disease duration were associated with a postoperative decrease in ΔT. Conclusion The postoperative increase in ΔT, resulting from the alleviation of nerve compression, suggests a relationship between nerve dysfunction and decreased temperature. The preoperative correlation between pain and ΔT may be attributed to vasodilation mediated by calcitonin gene-related peptide. The postoperative correlation between ΔT and neurological symptoms may reflect an association between the extent of nerve damage and reduced blood flow. In particular, cauda equina symptoms may lead to decreased blood flow through dysfunction of the S region, causing a relatively sympathetic-dominant state due to impaired parasympathetic function. Our findings suggest the potential of using temperature measurements to visualize and objectively evaluate subjective symptoms.

Metabotropic Glutamate Receptor 5: A Potential Target for Neuropathic Pain Treatment

Neuropathic pain, a multifaceted and incapacitating disorder, impacts a significant number of individuals globally. Despite thorough investigation, the development of efficacious remedies for neuropathic pain continues to be a formidable task. Recent research has revealed the potential of metabotropic glutamate receptor 5 (mGlu5) as a target for managing neuropathic pain. mGlu5 is a receptor present in the central nervous system that has a vital function in regulating synaptic transmission and the excitability of neurons. This article seeks to investigate the importance of mGlu5 in neuropathic pain pathways, analyze the pharmacological approach of targeting mGlu5 for neuropathic pain treatment, and review the negative allosteric mGlu5 modulators used to target mGlu5. By comprehending the role of mGlu5 in neuropathic pain, we can discover innovative treatment approaches to ease the distress endured by persons afflicted with this incapacitating ailment.

Anesthetic- and Analgesic-Related Drugs Modulating Both Voltage-Gated Na+ and TRP Channels

Nociceptive information is transmitted by action potentials (APs) through primary afferent neurons from the periphery to the central nervous system. Voltage-gated Na+ channels are involved in this AP production, while transient receptor potential (TRP) channels, which are non-selective cation channels, are involved in receiving and transmitting nociceptive stimuli in the peripheral and central terminals of the primary afferent neurons. Peripheral terminal TRP vanilloid-1 (TRPV1), ankylin-1 (TRPA1) and melastatin-8 (TRPM8) activation produces APs, while central terminal TRP activation enhances the spontaneous release of L-glutamate from the terminal to spinal cord and brain stem lamina II neurons that play a pivotal role in modulating nociceptive transmission. There is much evidence demonstrating that chemical compounds involved in Na+ channel (or nerve AP conduction) inhibition modify TRP channel functions. Among these compounds are local anesthetics, anti-epileptics, α2-adrenoceptor agonists, antidepressants (all of which are used as analgesic adjuvants), general anesthetics, opioids, non-steroidal anti-inflammatory drugs and plant-derived compounds, many of which are involved in antinociception. This review mentions the modulation of Na+ channels and TRP channels including TRPV1, TRPA1 and TRPM8, both of which modulations are produced by pain-related compounds.

Antinociceptive Potential of Ximenia americana L. Bark Extract and Caffeic Acid: Insights into Pain Modulation Pathways

Background/Objectives: This study evaluated the antinociceptive effect of the Ximenia americana L. bark extract (HEXA) and its primary component, caffeic acid (CA), through in vivo assays. Methods: The antinociceptive properties were assessed using abdominal writhing, hot plate, and Von Frey tests. Additionally, the study investigated the modulation of various pain signaling pathways using a pharmacological approach. Results: The results demonstrated that all doses of the HEXA significantly increased latency in the hot plate test, decreased the number of abdominal contortions, reduced hyperalgesia in the Von Frey test, and reduced both phases of the formalin test. Caffeic acid reduced licking time in the first phase of the formalin test at all doses, with the highest dose showing significant effects in the second phase. The HEXA potentially modulated α2-adrenergic (52.99%), nitric oxide (57.77%), glutamatergic (33.66%), vanilloid (39.84%), cyclic guanosine monophosphate (56.11%), and K+ATP channel-dependent pathways (38.70%). Conversely, CA influenced the opioid, glutamatergic (53.60%), and vanilloid (34.42%) pathways while inhibiting nitric oxide (52.99%) and cyclic guanosine monophosphate (38.98%). Conclusions: HEXA and CA exhibit significant antinociceptive effects due to their potential interference in multiple pain signaling pathways. While the molecular targets remain to be fully investigated, HEXA and CA demonstrate significant potential for the development of new analgesic drugs.

Duloxetine for individuals with chronic back pain: A systematic review and meta‑analysis of randomized controlled trials

The current study aimed to assess the efficacy of duloxetine in reducing pain and improving the quality of life of individuals with chronic low back pain (CLBP). An extensive literature search was conducted to identify relevant studies that examined the efficacy of duloxetine in CLBP management. The primary objective of the present study was to assess the role of duloxetine use on pain levels, as well as improvements in quality of life, using validated instruments. The results were synthesized using a random-effects model. A total of 8 studies were included in the analysis. Duloxetine demonstrated clear benefits in pain reduction, evidenced by improvements across multiple scales including the visual analogue scale, brief pain inventory-interference (BPI), BPI-severity, weekly worst pain over 24 hours and Roland-Morris Disability Questionnaire scores. Quality of life improved with duloxetine treatment, as indicated by the 36-item short form survey (SF-36). However, there was no significant impact on the physical function component of SF-36. The present study provides evidence to affirm the efficacy of duloxetine in treating CLBP. Further research is required to validate these findings and to establish whether combining duloxetine with other CLBP treatments yields superior outcomes.

Decrypting the multifaceted peripheral neuropathy based on molecular pathology and therapeutics: a comprehensive review

CONTEXT

Peripheral neuropathy (PN) is a multifaceted complication characterized by nerve damage due to oxidative stress, inflammatory mediators, and dysregulated metabolic processes. Early PN manifests as sensory changes that develop progressively in a "stocking and glove" pattern.

METHODS AND MECHANISMS

A thorough review of literature has been done to find the molecular pathology, clinical trials that have been conducted to screen the effects of different drugs, current treatments and novel approaches used in PN therapy. Diabetic neuropathy occurs due to altered protein kinase C activity, elevated polyol pathway activity in neurons, and Schwann cells-induced hyperglycemia. Other causes involve chemotherapy exposure, autoimmune ailments, and chronic ethanol intake.

CONCLUSION

Symptomatic treatments for neuropathic pain include use of tricyclic antidepressants, anticonvulsants, and acetyl-L-carnitine. Patients will have new hope if clinicians focus on novel therapies including gene therapy, neuromodulation techniques, and cannabidiol as an alternative to traditional medications, as management is still not ideal.

Profiling Human iPSC-Derived Sensory Neurons for Analgesic Drug Screening Using a Multi-Electrode Array

Chronic pain is a major global health issue, yet effective treatments are limited by poor translation from preclinical studies to humans. To address this, we developed a high-content screening (HCS) platform for analgesic discovery using hiPSC-derived nociceptors. These cells were cultured on multi-well micro-electrode arrays to monitor activity, achieving nearly 100% active electrodes by week two, maintaining stable activity for at least two weeks. After maturation (28 days), we exposed the nociceptors to various drugs, assessing their effects on neuronal activity, with excellent assay performance (Z' values >0.5). Pharmacological tests showed responses to analgesic targets, including ion channels (Nav, Cav, Kv, TRPV1), neurotransmitter receptors (AMPAR, GABA-R), and kinase inhibitors (tyrosine, JAK1/2). Transcriptomic analysis confirmed the presence of these drug targets, although expression levels varied compared to primary human dorsal root ganglion cells. This HCS platform facilitates the rapid discovery of novel analgesics, reducing the risk of preclinical-to-human translation failure.

Motivation

Chronic pain affects approximately 1.5 billion people worldwide, yet effective treatments remain elusive. A significant barrier to progress in analgesic drug discovery is the limited translation of preclinical findings to human clinical outcomes. Traditional rodent models, although widely used, often fail to accurately predict human responses, while human primary tissues are limited by scarcity, technical difficulties, and ethical concerns. Recent advancements have identified human induced pluripotent stem cell (hiPSC)-derived nociceptors as promising alternatives; however, current differentiation protocols produce cells with inconsistent and physiologically questionable phenotypes.To address these challenges, our study introduces a novel high-content screening (HCS) platform using hiPSC-derived nociceptors cultured on multi-well micro-electrode arrays (MEAs). The "Anatomic" protocol, used to generate these nociceptors, ensures cells with transcriptomic profiles closely matching human primary sensory neurons. Our platform achieves nearly 100% active electrode yield within two weeks and demonstrates sustained, stable activity over time. Additionally, robust Z' factor analysis (exceeding 0.5) confirms the platform's reliability, while pharmacological validation establishes the functional expression of critical analgesic targets. This innovative approach improves both the efficiency and clinical relevance of analgesic drug screening, potentially bridging the translational gap between preclinical studies and human clinical trials, and offering new hope for effective pain management.

Unraveling the Complexity of Chikungunya Virus Infection Immunological and Genetic Insights in Acute and Chronic Patients

Background: The chikungunya virus (CHIKV), transmitted by infected Aedes mosquitoes, has caused a significant number of infections worldwide. In Brazil, the emergence of the CHIKV-ECSA genotype in 2014 posed a major public health challenge due to its association with more severe symptoms. Objectives/Methods: This study aimed to shed new light on the host immune response by examining the whole-blood transcriptomic profile of both CHIKV-acute and chronically infected individuals from Feira de Santana, Bahia, Brazil, a region heavily affected by CHIKV, Dengue, and Zika virus epidemics. Results: Our data reveal complex symptomatology characterized by arthralgia and post-chikungunya neuropathy in individuals with chronic sequelae, particularly affecting women living in socially vulnerable situations. Analysis of gene modules suggests heightened metabolic processes, represented by an increase in NADH, COX5A, COA3, CYC1, and cap methylation in patients with acute disease. In contrast, individuals with chronic manifestations exhibit a distinct pattern of histone methylation, probably mediated by NCOA3 in the coactivation of different nuclear receptors, KMT2 genes, KDM3B and TET2, and with alterations in the immunological response, majorly led by IL-17RA, IL-6R, and STAT3 Th17 genes. Conclusion: Our results emphasize the complexity of CHIKV disease progression, demonstrating the heterogeneous gene expression and symptomatologic scenario across both acute and chronic phases. Moreover, the identification of specific gene modules associated with viral pathogenesis provides critical insights into the molecular mechanisms underlying these distinct clinical manifestations.

Low-value interventions to deimplement: A secondary analysis of a systematic review of low back pain clinical practice guidelines

OBJECTIVE

To perform a secondary review of low back pain (LBP) clinical practice guidelines (CPG) identified in a recently conducted systematic review and to synthesize and summarize low-value recommendations as practices that may be candidates for deimplementation.

LITERATURE SURVEY

LBP (subacute or chronic) CPGs in English (symptom based, created by a governmental or professional society, published between January 1990 and May 2020) were previously identified using MEDLINE, EMBASE, CINAHL, Ortho Guidelines, CPG Infobase, Emergency Care Research Institute, Guidelines International Network, National Institute of Health and Care Excellence, and Scottish Intercollegiate Guideline Network.

METHODOLOGY

Twenty-one CPGs were reviewed from a systematic review (previously published). Full-text review of all 21 CPGs was conducted, and three recommendation categories indicative of low value (recommend strongly against, recommend weakly against, inconclusive/insufficient evidence) were identified using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) language and approach.

SYNTHESIS

One hundred thirty-five low-value recommendations were identified and classified under eight intervention categories: orthotics/support, traction, physical modalities, pharmacological interventions, injections, surgery, bed rest, and miscellaneous. Traction, transcutaneous electrical nerve stimulation (TENS), therapeutic ultrasound (TUS), and selective serotonin reuptake inhibitors (SSRI) had the most CPGs recommend strongly against their usage. Opioids were recommended strongly against by four CPGs. No significant difference (p > .05) was found between CPG quality and a specific deimplementation recommendation or between CPG quality and the number of strongly against, weakly against, and inconclusive/insufficient evidence recommendations.

CONCLUSIONS

Clinicians managing patients with chronic LBP should consider deimplementing these low-value interventions (traction, TENS, TUS, and SSRI).

Antidepressants for pain management in adults with chronic pain: a network meta-analysis

Background

Chronic pain is common and costly. Antidepressants are prescribed to reduce pain. However, there has not been a network meta-analysis examining all antidepressants across all chronic pain conditions, so effectiveness and safety for most antidepressants for pain conditions remain unknown.

Objective

To assess the efficacy and safety of antidepressants for chronic pain (except headache) in adults. Our primary outcomes were as follows: substantial pain relief (50%), pain intensity, mood and adverse events. Our secondary outcomes were as follows: moderate pain relief (30%), physical function, sleep, quality of life, Patient Global Impression of Change, serious adverse events and withdrawal.

Design

This was a systematic review with a network meta-analysis. We searched CENTRAL, MEDLINE, EMBASE, CINAHL, LILACS, AMED and PsycINFO databases for randomised controlled trials of antidepressants for chronic pain conditions up until 4 January 2022. The review was registered in PROSPERO (CRD42020171855), and the protocol was published in the Cochrane Library (https://doi.org/10.1002/14651858.CD014682).

Setting

We analysed trials from all settings.

Participants

We included trials in which participants had chronic pain, defined as longer than 3 months, from any condition excluding headache.

Interventions

We included all antidepressants.

Main outcome measures

Our primary outcome was substantial pain relief, defined as a reduction ˃ 50%. We also measured pain intensity, mood and adverse events. Secondary measures included moderate pain relief (above 30% reduction), physical function, sleep, quality of life, Global Impression of Change, serious adverse events, and withdrawal from trial.

Results

We identified 176 studies with a total of 28,664 participants. Most studies were placebo-controlled (n = 83) and parallel armed (n = 141). The most common pain conditions examined were fibromyalgia (59 studies), neuropathic pain (49 studies) and musculoskeletal pain (40 studies). The average length of randomised controlled trials was 10 weeks. Most studies measured short-term outcomes only and excluded people with low mood and other mental health conditions. Across efficacy outcomes, duloxetine was consistently the highest-ranked antidepressant with moderate- to high-certainty evidence. Standard dose was equally efficacious as high dose for the majority of outcomes. Milnacipran was often ranked as the next most efficacious antidepressant, although the certainty of evidence was lower than that for duloxetine. There was insufficient evidence to draw robust conclusions for the efficacy and safety of any other antidepressant for chronic pain.

Limitations

The evidence for antidepressants other than duloxetine is poor. For duloxetine, it is not clear whether the effect applies to groups with both pain and low mood, since these groups were excluded from trials. There is also insufficient evidence on long-term outcomes and on adverse effects.

Conclusions

There is only reliable evidence for duloxetine in the treatment of chronic pain. Duloxetine was moderately efficacious across all outcomes at standard dose. There is also promising evidence for milnacipran, although further high-quality research is needed to be confident in these conclusions. Data for all other antidepressants were of low certainty. However, the findings should not be read as an encouragement to prescribe antidepressants where other non-pharmacological intervention could be equally effective, especially in the absence of good evidence on side effects and safety.

Future work

There is a need for large, methodologically sound trials testing the effectiveness of antidepressants for chronic pain. These trials should examine long-term outcomes (> 6 months) and include people with low mood. There should also be better reporting of adverse events, tolerance of drugs, and long-term compliance.

Study registration

This study is registered as PROSPERO CRD42020171855.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR128782) and is published in full in Health Technology Assessment; Vol. 28, No. 62. See the NIHR Funding and Awards website for further award information.

Changes of melatonin secretion in the neuropathic pain induced sleep disorder model rat

Chronic pain due to peripheral neuropathy can lead to sleep disorders that significantly worsen the patient's quality of life. Previously, we conducted brain wave measurements in a rat model of neuropathic pain and identified its potential as a model for sleep disorders associated with chronic pain (reported). In this study, we quantified melatonin secretion and assessed its circadian rhythm in a rat model of pain-induced sleep disorder. To create a model of chronic constriction injury (CCI), rats were loosely tied around the sciatic nerve, with approximately 1 mm spacing, 14 days before the experiment. Rats with no ties around the sciatic nerve were used as controls. Electroencephalograms and electromyograms were recorded for 3 days, and the episodes of waking, REM sleep, and non-REM sleep were compared between the groups. The samples for microanalysis were collected every 30 min and used for melatonin analysis. Compared to the control group, the CCI model group exhibited an increase in wake episodes and a decrease in non-REM sleep episodes. Analysis of the area under the curve of melatonin secretion revealed a significant increase in melatonin secretion and a loss of circadian rhythm in the CCI model group. Melatonin secretion markedly increased accompanied by loss of circadian rhythm in a rat model of CCI. Further studies investigating the causal relationship between neuropathic pain and melatonin secretion are warranted.

Neuropathic pain, antidepressant drugs, and inflammation: a narrative review

BACKGROUND

Neuropathic pain (NP) is a chronic and disabling condition, caused by a lesion or disease of the somatosensory nervous system, characterized by a systemic inflammatory state. Signs and associated symptoms are rarely recognized, and response to usual analgesic drugs is poor. Antidepressant drugs are first-line agents for the treatment of NP. This narrative review aims to summarize the role of antidepressant drugs in treating NP and their mechanism of action, focusing on the effects on inflammatory cytokines.

MAIN TEXT

Peripheral nerve injury leads to a local inflammatory response and to the disruption of the blood-medullary barrier, allowing the influx of peripheral immune cells into the central nervous system. Antidepressants have antinociceptive effects because they recruit long-term neuronal plasticity. Amitriptyline modulates the inflammatory response due to the reduction of the mRNA of pro-inflammatory cytokines acting as an adenosine agonist and leading to the activation of the A3AR receptor. Through toll-like receptors, local inflammation determines the release of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) that drives and stimulates the hyperflammation in NP. Nortriptyline has an important antiallodynic effect in NP as it determines the recruitment of norepinephrine in the dorsal root ganglia. By modulating the β2-adrenoreceptors expressed by non-neuronal satellite cells, it inhibits the local production of TNF-α and determines a reduction of NP symptoms. Following the administration of antidepressants, there is a reduction in the production of TNF-α in the brain which in turn transforms the function of the α2-adrenergic receptor from an inhibitor to an activator of the release of norepinephrine. This is important to prevent the development of chronic pain.

CONCLUSION

Inflammatory cytokines are the main players in a bidirectional communication between the central and peripheral nervous system and the immune system in NP. Antidepressants have an important role in NP. Further research should explore the interaction between neuroinflammation in NP, the effects of antidepressants and the clinical relevance of this interaction.

Assessing suicide risk in chronic pain management: a narrative review across drug classes

INTRODUCTION

Chronic pain presents a multifaceted challenge in clinical practice, necessitating a nuanced understanding of pharmacological interventions to optimize treatment outcomes. This review provides an outline of various pharmacological agents commonly used in chronic pain management and highlights their safety considerations, particularly regarding suicide risk.

AREAS COVERED

This review discusses the role of antidepressants, anticonvulsants, GABA receptor agonists, NMDA receptor antagonists, corticosteroids, cannabis and cannabinoids, bisphosphonates, calcitonin, and alpha-2 adrenergic receptor agonists in chronic pain management. It assesses their therapeutic benefits, potential for misuse, and psychiatric adverse effects, including the risk of suicide. Each pharmacological class is evaluated in terms of its efficacy, safety profile, and considerations for clinical practice. We searched peer-reviewed English literature on the topic using the MEDLINE database without time restrictions.

EXPERT OPINION

While pharmacological interventions offer promise in alleviating chronic pain, healthcare providers must carefully weigh their benefits against potential risks, including the risk of exacerbating psychiatric symptoms and increasing suicide risk. Individualized treatment approaches, close monitoring, and multidisciplinary collaboration are essential for optimizing pain management strategies while mitigating adverse effects. Ongoing research efforts are crucial for advancing our understanding of these pharmacological interventions and refining pain management practices.

Neuropharmacology of Neuropathic Pain: A Systematic Review

Neuropathic pain, a debilitating condition, remains challenging to manage effectively. An insight into neuropharmacological mechanisms is critical for optimizing treatment strategies. This systematic review aims to evaluate the role of neuropharmacological agents based on their efficacy, involved neurotransmitters, and receptors. A manual literature search was undertaken in PubMed including Medline, Cochrane Library, Google Scholar, Plos One, Science Direct, and clinicaltrials.gov from 2013 until 2023. Out of the 13 included studies, seven evaluated the role of gabapentinoids. Two main drugs from this group, gabapentin and pregabalin, function by binding voltage-gated calcium channels, lowering neuronal hyperexcitability and pain signal transmission, thereby relieving neuropathic pain. Four of the pooled studies reported the use of tricyclic antidepressants (TCAs) including amitriptyline and nortriptyline which work by blocking the reuptake of norepinephrine and serotonin, their increased concentration is thought to be central to their analgesic effect. Three articles assessed the use of serotonin-norepinephrine reuptake inhibitors (SNRIs) and reported them as effective as the TCAs in managing neuropathic pain. They work by augmenting serotonin and norepinephrine. Three studies focused on the use of selective serotonin reuptake inhibitors (SSRIs), modulating their effect by increasing serotonin levels; however, they were reported as not a highly effective treatment option for neuropathic pain. One of the studies outlined the use of cannabinoids for neuropathic pain by binding to cannabinoid receptors with only mild adverse effects. It is concluded that gabapentinoids, TCAs, and SNRIs were reported as the most effective therapy for neuropathic pain; however, for trigeminal neuralgia, anticonvulsants like carbamazepine were considered the most effective. Opioids were considered second-line drugs for neuropathic pain as they come with adverse effects and a risk of dependence. Ongoing research is exploring novel drugs like ion channels and agents modulating pain pathways for neuropathic pain management. Our review hopes to inspire further research into patient stratification by their physiology, aiding quicker and more accurate management of neuropathic pain while minimizing inadvertent side effects.

Efficacy of Desvenlafaxine in Reducing Migraine Frequency and Severity: A Retrospective Study

Background: Migraine is characterized by sudden acute episodes of pain, with a global prevalence of 18% among all age groups. It is the second leading cause of years lived with disability worldwide. Prophylactic treatment is important in managing migraine; however, its efficacy and safety are debated. This study aimed to evaluate the efficacy of desvenlafaxine in female patients with migraine. Methods: We conducted a retrospective observational case study involving 10 women diagnosed with migraine who were treated with desvenlafaxine. We measured the number of migraine days per month, average headache duration in minutes, headache severity using a visual analog scale, use of acute medications, and frequency of acute medication use per week. Results: Desvenlafaxine significantly reduced the number of migraine days from 14.70 ± 3.68 at baseline to 2.50 ± 2.50 at follow-up (p < 0.05). The average headache duration dropped from 131.25 ± 32.81 min to 52.50 ± 44.64 min. Headache severity scores improved from 6.80 ± 1.49 at baseline to 0.80 ± 0.92 at follow up, the frequency of acute medication use per week reduced from 3.30 ± 1.49 at baseline to 0.80 ± 0.92, and the frequency of acute medication use decreased from 3.30 ± 1.49 times per week to 0.80 ± 0.92. Conclusions: Desvenlafaxine shows potential as an effective prophylactic therapy for migraine. Larger-scale studies are necessary to further explore its benefits.

Imipramine Increases Norepinephrine and Serotonin in the Salivary Glands of Rats

Xerostomia induced by antidepressants such as imipramine has long been thought to be due to their anticholinergic effects. However, even antidepressants with low anticholinergic effects may have a high incidence of xerostomia. In salivary glands, norepinephrine activates alpha-adrenergic receptors in blood vessels and beta-adrenergic receptors in acinar cells, respectively, causing a decrease in the blood flow and an increase in the protein secretion, resulting in the secretion of viscous saliva with low water content and high protein content. A previous study demonstrated that perfusion of the submandibular glands of rats with serotonin significantly decreased saliva secretion. The results of the present study revealed the following: (1) that norepinephrine and serotonin, but not epinephrine nor dopamine, were detected in the interstitial fluids in rat submandibular glands; (2) that norepinephrine and serotonin concentrations in the dialysate was 4.3 ± 2.8 nM and 32.3 ± 19.6 nM at stable level, respectively; (3) that infusion with imipramine, a reuptake inhibitor of norepinephrine and serotonin, significantly and dose-dependently increased both norepinephrine and serotonin concentrations in the dialysate; and (4) that intraperitoneal administration of imipramine significantly increased both norepinephrine and serotonin concentrations in the dialysate. These results suggested that one of the mechanisms of xerostomia induced by reuptake inhibitors of norepinephrine and serotonin involves the activation of adrenergic and serotonin receptors in the salivary glands, respectively.

A Pathophysiological Approach for Selecting Medications to Treat Nociceptive and Neuropathic Pain in Servicemembers

INTRODUCTION

The prevalence of chronic pain of service members (SMs) in the U.S. is estimated to be higher (roughly 31-44%) compared to that of civilian population (26%). This higher prevalence is likely due to the high physical demands related combat and training injuries that are not immediately resolved and worsen over time. Mental Health America reports that chronic pain can lead to other mental health conditions such as severe anxiety, depression, bipolar disorder, and post-traumatic stress disorder. Such mental health conditions can negatively affect job performance, reduce readiness for military duties, and often lead to patterns of misuse of opioid after SMs entering civilian life. The primary objective of this narrative review is to present a summarized guideline for the treatment of two types of pain that likely affect SMs, namely nociceptive somatic pain and neuropathic pain. This review focused on a stepwise approach starting with nonopioid interventions prior to opioid therapy. The secondary objective of this review is to elucidate the primary mechanisms of action and pathways associated with these two types of pain.

METHODS

We followed the Scale for Assessment of Narrative Review Articles when transcribing this narrative review article to enhance the quality and brevity of this review. This Scale has 0.77% an intra-class coefficient of correlation, 95% confidence interval and 0.88 inter-rater reliability. We searched PubMed, Google Scholar, WorldCAT, and the Cochrane Library for the primary and secondary articles that targeted mechanisms of action, pathways, and pharmacological modalities for nociceptive somatic and neuropathic pain that were published from 2011 to 2022. We excluded articles related to pediatric, some specific pain conditions such as cancer-related pain, palliative care, end-of-life care, and articles that were not written in English language. For pharmacologic selection, we adopted the guidelines from the Policy for Implementation of a Comprehensive Policy on Pain Management by the Military Health Care system for the Fiscal Year 2021; the Clinical Practice Guidance for Opioid Therapy for Chronic Pain by the Department of Defense/Veterans Health Administration (2022); the (2021) Implementation of a Comprehensive Policy on Pain Management by the Military Health Care System; and the (2022) Guideline for Prescribing Opioids for Chronic Painby the Centers for Disease Control.

DISCUSSION

From the knowledge of the mechanisms of action and pathways, we can be more likely to identify the causative origins of pain. As a result, we can correctly diagnose the type of pain, properly develop an efficient and personalized treatment plan, minimize adverse effects, and optimize clinical outcomes. The guideline, however, does not serve as a substitute for clinical judgment in patient-centered decision-making. Medication choices should be individualized judiciously based on the patient's comorbid conditions, available social and economic resources, and the patient's preferences to balance the benefits and risks associated with various pain medications and to achieve optimal pain relief and improve the patient's quality of life.

Quantitative analysis of nortriptyline's analgesic properties: a comparative systematic review and meta-analysis

OBJECTIVES

This study aims to quantitatively analyse nortriptyline's analgesic potency, safety and tolerability.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

The systematic search was conducted in Scopus, Web of Science and PubMed in February 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Clinical trials evaluating the efficacy of nortriptyline in reducing pain scores (open-label studies and comparisons of nortriptyline with placebo or other analgesics) in different pain types were included.

DATA EXTRACTION AND SYNTHESIS

The data extraction procedure and the screening phases were carried out based on predetermined eligibility criteria. To pool the data, the standardised mean difference (SMD) and standardised mean change (SMC) methods, along with random-effect and fixed-effect meta-analysis, were used. The risk of bias was assessed using the Cochrane Collaboration method, and the Grading of Recommendations Assessment, Development and Evaluation criteria were used to measure the certainty of the results.

RESULTS

14 of the initial 648 studies were eventually imported. Nortriptyline was reported to significantly reduce pain severity in chronic low back pain, painful symptoms in major depressive disorder, neuropathy, chronic pelvic pain and neuropathic corneal pain. However, it was not superior to placebo in fibromyalgia and knee osteoarthritis. In comparison to placebo and various alternative analgesics, the pooled SMD for lowering pain scores was 0.43 (0.23-0.64) and -0.18 (-0.39 to 0.03), respectively. In the pretreatment and post-treatment analyses, the pooled SMC was -1.20 (-1.48 to -0.93). Although constipation and xerostomia were the most commonly reported side effects, all references indicated that the adverse events were well tolerated at the administered dosages.

CONCLUSION

While nortriptyline is effective in some chronic pains, such as neuropathies, it lacks efficacy in some other chronic pains, such as fibromyalgia and osteoarthritis. Nortriptyline is well tolerated when administered in doses intended for its analgesic effects. Moreover, several studies suggested that the analgesic effects of nortriptyline are comparable to those of amitriptyline and gabapentin.

Examination of the effects of vitexin and vitexin-loaded solid lipid nanoparticles on neuropathic pain and possible mechanisms of action

This research aims to investigate the possible antiallodynic and antihyperalgesic effects of pure vitexin and vitexin-loaded solid lipid nanoparticles (SLN) on neuropathic pain and the pathways mediating these effects. Chronic constriction nerve injury was induced in female rats, and the effects of vitexin at the doses of 5, 10, 20, 40 mg/kg were evaluated. Ketanserin, ondansetron, WAY-100635, yohimbine and bicuculin, which are antagonists of receptors on pain pathways. were used to examine the mechanisms of the effects of vitexin. Pure vitexin exhibited antiallodynic activity at all administered doses, whereas antihyperalgesic activity was not observed at 5 mg/kg vitexin dose. SLN formulation was prepared with 5 mg/kg vitexin, the lowest dose. Vitexin-loaded formulation significantly increased antiallodynic and antihyperalgesic effects. Ondansetron, WAY-100635, yohimbine, and bicuculine antagonized the antiallodynic and antihyperalgesic effects of vitexin. So, it was concluded that serotonin (5-hydroxtryptamine, 5-HT) receptor subtypes 5-HT3 and 5-HT1A, alpha-2 adrenergic, and γ-Aminobutyric acid type A (GABA-A) receptors are involved in the antiallodynic and antihyperalgesic activity of vitexin. In conclusion, vitexin and vitexin-loaded formulation have the potential for clinical use in neuropathic pain management, and different pain pathways contributed to this effect. And also, it is thought that vitexin-loaded SLN formulation is more effective than pure vitexin, which will provide an advantage in treatment.

Efficacy and safety of venlafaxine versus nortriptyline for the preventive treatment of migraine: A double-blind randomized clinical trial

OBJECTIVE

Migraine, as a primary headache disorder, stands as one of the primary causes of disability worldwide. Consequently, prophylactic treatments are highly recommended for individuals experiencing recurrent migraine episodes. Our study aimed to compare the efficacy and safety profiles of venlafaxine and nortriptyline in the prophylactic management of migraine.

METHODS

In this single-center, randomized, double-blind clinical trial, 210 migraine patients were allocated into two groups in a 1:1 ratio. One group received venlafaxine (37.5 mg, orally twice daily), while the other group administered nortriptyline (25 mg, orally once daily). A neurologist documented (1) headache intensity using the Visual Analog Scale (VAS) and 6-point Behavioral Rating Scale (BRS-6), (2) headache frequency (per month), and (3) headache duration (in hours) of participants on days 0, 45, and 90 of the intervention.

RESULTS

Following the 90-day intervention, a significant decrease was observed in VAS, BRS-6, frequency, and duration of headaches within both groups (all with p-values <0.001). No difference in VAS, BRS-6, or headache durations was observed between the two groups after 45 and 90 days of treatment (all p-values > 0.05). Although the headache frequency exhibited no difference between the groups after 45 days (p-value = 0.097), a significantly lower frequency in the venlafaxine group was observed at day 90 of the intervention (p-value = 0.011). The reductions in attack parameters in the 0-45- and 0-90-day intervals did not meet statistical significance between the two groups (p-values > 0.05). 77.0 % of the participants in the venlafaxine group and 79.2 % in the nortriptyline group experienced a minimum of 50 % improvement in all attack parameters. Venlafaxine demonstrated a statistically significant lower incidence of adverse reactions in comparison to nortriptyline (p-value = 0.005). A total of 33 adverse drug reactions were documented in the venlafaxine group and 53 in the nortriptyline group, with insomnia observed in the former and xerostomia in the latter as the most prevalent side effects.

CONCLUSIONS

Venlafaxine and nortriptyline demonstrate clinically significant and comparable therapeutic efficacy for migraine patients in reducing the intensity, frequency, and duration of headache attacks. Venlafaxine may be preferred to nortriptyline in the context of migraine preventive treatment under comparable conditions due to its lower incidence of adverse effects.

Prevalence of radicular neuropathic pain in idiopathic Parkinson's disease: A systematic review and meta-analysis

Parkinson's disease (PD) is estimated to impact up to 1 % of the global population aged 60 years and older. Among the non-motor manifestations of idiopathic PD, radicular neuropathic pain emerges as a noteworthy concern due to its potential for debility in affected individuals. In, this systematic review and meta-analysis we aimed to evaluate the prevalence of radicular neuropathic pain and thus provide evidence of how this painful symptom affects the lives of patients with idiopathic PD. We registered the research protocol for this study in PROSPERO (CRD42022327220). We searched the Embase, Scopus, and PubMed platforms for studies on PD and neuropathic pain until April 2023. The search yielded 36 articles considered to have a low risk of bias. The prevalence of radicular neuropathic pain in patients with PD was 12.7 %, without a difference when we consider the duration of diagnosis (cut-off < 7 years) or levodopa dosage (cut-off <600 mg/dL). Moreover, there was no variation in the prevalence of radicular neuropathic pain regarding a Hoehn and Yahr stage cut-off of <2.5 or >2.5. Of note, a limited number of patients received pain treatment (21.5 %). We also found that the source of publication bias is the use of the Ford criteria (FC), suggesting that this type of diagnostic criteria may contribute to an underdiagnosis of radicular neuropathic pain in patients with PD. This study underlines the necessity for a more discerning and comprehensive approach to the diagnosis and management of radicular neuropathic pain in patients with idiopathic PD.

Metabolomic and lipidomic profiling of the spinal cord in type 2 diabetes mellitus rats with painful neuropathy

In this paper we investigated lipid and metabolite changes in diabetic neuropathy, using untargeted lipidomics and metabolomics analyses of the spinal cords from streptozotocin-treated diabetic rats.170 metabolites and 45 lipids were dysregulated in the painful diabetic neuropathy (PDN) phase. Pathway enrichment analysis revealed perturbations in starch and sucrose, tryptophan, pyrimidine, cysteine and methionine, thiamine, tyrosine, and nucleotides. The disturbance of tyrosine, tryptophan, methionine, triacylglycerol, and phosphatidylethanolamine metabolism indicated that pathological mechanisms in the PDN involved energy metabolism, oxidative stress, and neural reparative regeneration. These revelations offered potential biomarkers for PDN and enriched the comprehension of the complex molecular mechanisms characterizing PDN, establishing a solid foundation for subsequent inquiries into neural convalescence and recovery after PDN.

The association between changes in clinical pain severity and IL-6 reactivity among patients undergoing total knee Arthroplasty: The moderating role of change in insomnia

Knee osteoarthritis (KOA) is linked to an enhanced release of interleukin-6 (IL-6). Increased levels of IL-6 are associated with greater pain and insomnia. While total knee arthroplasty (TKA) typically results in the reduction of pain, for a subgroup of patients, pain does not improve. Understanding patients' propensity to upregulate IL-6 may provide insight into variation in the clinical success of TKA for improving pain, and insomnia may play an important modulatory role. We investigated the association between pre- and post-surgical changes in clinical pain and IL-6 reactivity, and whether change in insomnia moderated this association. Patients (n = 39) with KOA came in-person before and 3-months after TKA. At both visits, patients completed validated measures of clinical pain and insomnia, as well as underwent quantitative sensory testing (QST). Blood samples were collected to analyze IL-expression both before and after QST procedures to assess changes in IL-6 in response to QST (IL-6 reactivity). Patients were categorized into two groups based on change in clinical pain from pre- to post-surgery: 1) pain decreased > 2 points (pain improved) and 2) pain did not decrease > 2 points (pain did not improve). Based on this definition, 49 % of patients had improved pain at 3-months. Among patients with improved pain, IL-6 reactivity significantly decreased from pre- to post-surgery, whereas there was no significant change in IL-6 reactivity among those whose pain did not improve. There was also a significant interaction between pain status and change in insomnia, such that among patients whose insomnia decreased over time, improved pain was significantly associated with a reduction in IL-6 reactivity. However, among patients whose insomnia increased over time, pain status and change in IL-6 reactivity were not significantly associated. Our findings suggest that the resolution of clinical pain after TKA may be associated with discernible alterations in pro-inflammatory responses that can be measured under controlled laboratory conditions, and this association may be moderated by perioperative changes in insomnia. Randomized controlled trials which carefully characterize the phenotypic features of patients are needed to understand how and for whom behavioral interventions may be beneficial in modulating inflammation, pain, and insomnia.

Corneal neuropathic pain: a review to inform clinical practice

Corneal neuropathic pain (CNP) is a poorly defined disease entity characterised by an aberrant pain response to normally non-painful stimuli and categorised into having peripheral and central mechanisms, with the former responding to instillation of topical anaesthetic. CNP is a challenging condition to diagnose due to numerous aetiologies, an absence of clinical signs and ancillary tests (in vivo confocal microscopy and esthesiometry), lacking the ability to confirm the diagnosis and having limited availability. Symptomatology maybe mirrored by severe and chronic forms of dry eye disease (DED), often leading to misdiagnosis and inadequate treatment. In practice, patients with suspected CNP can be assessed with questionnaires to elicit symptoms. A thorough ocular assessment is also performed to exclude any co-existent ocular conditions. A medical and mental health history should be sought due to associations with autoimmune disease, chronic pain syndromes, anxiety and depression. Management begins with communicating to the patient the nature of their condition. Ophthalmologists can prescribe topical therapies such as autologous serum eyedrops to optimise the ocular surface and promote neural regeneration. However, a multi-disciplinary treatment approach is often required, including mental health support, particularly when there are central mechanisms. General practitioners, pain specialists, neurologists and psychologists may be needed to assist with oral and behavioural therapies. Less data is available to support the safety and efficacy of adjuvant and surgical therapies and the long-term natural history remains to be determined. Hence clinical trials and registry studies are urgently needed to fill these data gaps with the aim to improve patient care.

Navigating Preclinical Models and Medications for Peripheral Neuropathy: A Review

Peripheral neuropathy (PN) is a multifaceted disorder characterised by peripheral nerve damage, manifesting in symptoms like pain, weakness, and autonomic dysfunction. This review assesses preclinical models in PN research, evaluating their relevance to human disease and their role in therapeutic development. The Streptozotocin (STZ)-induced diabetic rat model is widely used to simulate diabetic neuropathy but has limitations in faithfully replicating disease onset and progression. Cisplatin-induced PN models are suitable for studying chemotherapy-induced peripheral neuropathy (CIPN) and closely resemble human pathology. However, they may not fully replicate the spectrum of sensory and motor deficits. Paclitaxel-induced models also contribute to understanding CIPN mechanisms and testing neuroprotective agents. Surgical or trauma-induced models offer insights into nerve regeneration and repair strategies. Medications such as gabapentin, pregabalin, duloxetine, and fluoxetine have demonstrated promise in these models, enhancing our understanding of their therapeutic efficacy. Despite progress, developing models that accurately mirror human PN remains imperative due to its complex nature. Continuous refinement and innovative approaches are critical for effective drug discovery. This review underscores the strengths and limitations of current models and advocates for an integrated approach to address the complexities of PN better and optimise treatment outcomes.

Evaluation of lavender and rose aromatherapies on the success of inferior alveolar nerve block in symptomatic irreversible pulpitis: A randomized clinical trial

Trial design

This is a prospective, block-randomized, blinded, multiple arm and parallel-group superiority clinical trial.

Methods

Seventy-eight patients satisfying the recruitment standards, were randomly allocated into three groups as follows: Group I (n = 26) - Inferior alveolar nerve block (IANB) devoid of aromatherapy (AT); Group II (n = 26) - IANB with lavender AT and Group III - IANB with rose AT (n = 26) with the help of the ultrasonic aroma diffuser (with respective oils)for 20 min/2 h in operatories 1,2 and 3 respectively. For AT, 3-4 drops of lavender and rose-conditioned oils were added from a 100 ml solution containing 100 mg of these medicinal plants. The pre-operative (PRO) and access opening (AO) pain as well as the anxiety of patients were recorded using the Visual Analog Scale (VAS) and Modified Dental Anxiety Scale (MDAS) respectively. Data thus obtained was entered into the Excel sheet and subjected to statistical tests (analysis of variance and paired t-test). The p-value less than 0.05 was considered statistically significant.

Results

Group I showed non-significant disparity between PRO and AO for both VAS as well as MDAS (p = 0.62, p = 0.71). However, group II (p = 0.04, p = 0.02) and group III (p = 0.03, p = 0.01) revealed significant differences between PO - AO VAS and MDAS. MDAS and VAS intergroup comparison revealed a significant difference among groups I and II (p = 0.03, p = 0.04), and groups I and III (p = 0.02, p = 0.03). However non-significant disparity was observed among groups II and III (p = 0.85, 0.34). Moreover, there was a statistically significant reduction in anxiety levels in females compared to males after rose AT (p = 0.02). Nevertheless, groups I and II did not show any gender predilection for anxiety as well as pain.

Conclusion

Alleviation of dental anxiety as well as reduction in pain during AO of teeth with SIP can be achieved using Lavender and rose AT. In female patients, rose AT can be preferred over lavender AT.

Central Neuromodulators in Irritable Bowel Syndrome: Why, How, and When

Irritable bowel syndrome (IBS) is responsive to treatments using central neuromodulators. Central neuromodulators work by enhancing the synaptic transmission of 5-hydroxytryptamine, noradrenalin, and dopamine, achieving a slower regulation or desensitization of their postsynaptic receptors. Central neuromodulators act on receptors along the brain-gut axis, so they are useful in treating psychiatric comorbidities, modifying gut motility, improving central downregulation of visceral signals, and enhancing neurogenesis in patients with IBS. Choosing a central neuromodulator for treating IBS should be according to the pharmacological properties and predominant symptoms. The first-line treatment for pain management in IBS is using tricyclic antidepressants. An alternative for pain management is the serotonin and noradrenaline reuptake inhibitors. Selective serotonin reuptake inhibitors are useful when symptoms of anxiety and hypervigilance are dominant but are not helpful for treating abdominal pain. The predominant bowel habit is helpful when choosing a neuromodulator to treat IBS; selective serotonin reuptake inhibitors help constipation, not pain, but may cause diarrhea; tricyclic antidepressants help diarrhea but may cause constipation. A clinical response may occur in 6-8 weeks, but long-term treatment (usually 6-12 months) is required after the initial response to prevent relapse. Augmentation therapy may be beneficial when the therapeutic effect of the first agent is incomplete or associated with side effects. It is recommended to reduce the dose of the first agent and add a second complementary treatment. This may include an atypical antipsychotic or brain-gut behavioral treatment. When tapering central neuromodulators, the dose should be reduced slowly over 4 weeks but may take longer when discontinuation effects occur.

Repetitive transcranial magnetic stimulation in central post-stroke pain: a meta-analysis and systematic review of randomized controlled trials

Background

The rehabilitation of central post-stroke pain (CPSP) is a complex clinical challenge, and repetitive transcranial magnetic stimulation (rTMS) has been widely applied in the research of neurofunctional recovery following stroke. However, there is currently no reliable evidence-based medicine supporting the efficacy of rTMS in central post-stroke pain. This review aims to evaluate the effects of rTMS on central post-stroke pain.

Methods

Following the PRISMA guidelines, we conducted searches on PubMed, Cochrane Library, Embase, Web of Science, CNKI, and Wan Fang Data Knowledge Service Platform. We searched for randomized controlled trials (RCTs) investigating the use of rTMS in treating central post-stroke pain, and conducted screening based on inclusion and exclusion criteria. Characteristics of the included RCTs were extracted. The heterogeneity of the trials was assessed using the I2 statistic. Meta-analysis was performed using Stata 17 software. Bias risk and methodological quality were evaluated using the Cochrane RoB 2 tool and the Pedro scale.

Results

A total of six randomized controlled trials involving 288 patients met our inclusion criteria. In our analysis, rTMS was more effective in treating patients with CPSP compared to the placebo group (SMD=-1.15, 95% CI: -1.69, -0.61, P < 0.001). Furthermore, results from subgroup analysis indicated no statistically significant difference in the improvement of pain for durations exceeding 6 months when comparing rTMS to conventional treatment (SMD=-0.80, 95% CI: -1.63, 0.03, P = 0.059).

Conclusion

TMS can alleviate pain in CPSP patients and improve their motor function, but its effects on depression, anxiety, and MEP-latency are not significant.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, CRD42024497530.

Neuropathic pain, mood, and stress-related disorders: A literature review of comorbidity and co-pathogenesis

Neuropathic pain can be caused by multiple factors, and its prevalence can reach 10% of the global population. It is becoming increasingly evident that limited or short-lasting response to treatments for neuropathic pain is associated with psychological factors, which include psychiatric comorbidities known to affect quality of life. It is estimated that 60% of patients with neuropathic pain also experience depression, anxiety, and stress symptoms. Altered mood, including stress, can be a consequence of several painful conditions but can also favor pain chronicization when preexisting. Despite the apparent tight connection between clinical pain and mood/stress disorders, the exact physiological mechanisms remain unclear. This review aims to provide an overview of state-of-the-art research on the mechanisms of pain related to the pathophysiology of depression, anxiety, and stress disorders.

Neuropathic pain in burn patients - A common problem with little literature: A systematic review

BACKGROUND

The prevalence of neuropathic pain (NP) in burn patients is reported in the literature to be as high as 80%1. Given the complexity of NP in burn patients and the wide range of treatments available, a systematic review of the literature is warranted to summarize our current understanding of management and treatment of NP in this population.

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The following databases were queried to identify relevant articles: PubMed, Cochrane, Embase, Scopus, Ovid, and Web of Science. The main outcome measures were incidence and management of NP. Secondary outcomes included risk factors for NP.

RESULTS

Included articles presented findings from 11 different countries, capturing outcomes for 4366 patients. Risk factors for neuropathic pain in burn patients were identified, including older age, alcohol and substance abuse, current daily smoking, greater % total body surface area burns (TBSA), and longer hospitalizations. Pharmacologic treatments included gabapentin/pregabalin (n = 7), ascorbic acid (n = 1), and lidocaine (n = 1). Overall, the studies showed varied results regarding the efficacy of pharmacological treatments. While certain studies demonstrated gabapentanoids to be effective in reducing neuropathic symptoms, others found conflicting results. With regards to non-pharmacologic treatments, electroconvulsive therapy (n = 1), electropuncture (n = 1), nerve release/reconstruction (n = 2), and somatosensory feedback rehabilitation (n = 1) were used and demonstrated promise in reducing pain intensity and improving functionality.

CONCLUSIONS

Despite NP afflicting the majority of burn patients long after their injury, this systematic review demonstrates insufficient evidence on the pathophysiology, outcomes, and risk factors in NP, as well as the efficacy of various therapies. Future prospective and randomized studies evaluating the etiology of these factors can substantially improve our treatment strategies. This can allow for the development of well-delineated and evidence-based protocols in NP management in hopes of improving quality of life and both psychological and physical function in burn patients.

Selenoprotein T, a potential treatment of attention-deficit/hyperactivity disorder and comorbid pain in neonatal 6-OHDA lesioned mice

pathological pain and Attention-deficit/hyperactivity disorder (ADHD) are two complex multifactorial syndromes. The comorbidity of ADHD and altered pain perception is well documented in children, adolescents, and adults. According to pathophysiological investigations, the dopaminergic system's dysfunction provides a common basis for ADHD and comorbid pain. Growing evidence suggests that oxidative stress may be crucial in both pathologies. Recent studies revealed that a small peptide encompassing the redox-active site of selenoprotein T (PSELT), protects dopaminergic neurons and fibers as well as lesioned nerves in animal models. The current study aims to examine the effects of PSELT treatment on ADHD-like symptoms and pain sensitivity, as well as the role of catecholaminergic systems in these effects. Our results demonstrated that intranasal administration of PSELT reduced the hyperactivity in the open field, decreased the impulsivity displayed by 6-OHDA-lesioned male mice in the 5-choice serial reaction time task test and improved attentional performance. In addition, PSELT treatment significantly increased the nociception threshold in both normal and inflammatory conditions. Furthermore, anti-hyperalgesic activity was antagonized with sulpiride pre-treatment, but not by phentolamine, or propranolol pre-treatments. The present study suggests that PSELT reduces the severity of ADHD symptoms in mice and possesses potent antinociceptive effects which could be related to the involvement of D2/D3 dopaminergic receptors.

Evaluation of New Approaches to Depression Treatment Using an Animal Model of Pharmacoresistant Depression

Depression is emerging as the predominant psychiatric disorder globally. Despite the wide availability of antidepressants, up to 30% of patients exhibit poor response to treatment, falling into the category of treatment-resistant depression (TRD). This underscores the need for the exploration of novel therapeutic options. Our work aims to study the effect of chronic administration of the pyridoindole derivative SMe1EC2M3, a triple reuptake inhibitor, and the combination of zoletil and venlafaxine under conditions of stress induced by a 4-week chronic mild stress (CMS) procedure in Wistar-Kyoto male rats as an animal model of TRD. Therefore, we investigated the possible effect of the selected compounds in four experimental groups, i.e., stress + vehicle, stress + venlafaxine, stress + zoletil + venlafaxine and stress + SMe1EC2M3. The following variables were assessed: anhedonia in sucrose preference test (SPT), spontaneous locomotion and exploration in open field test (OF), anxiety-like behavior in elevated plus maze test (EPM), motivation and depressive-like behavior in forced swim test (FST) and nociception in tail flick test. We also evaluated cognition, particularly recognition memory, in the novel object recognition test (NOR). Sucrose preference was significantly increased in the SMe1EC2M3 group (p < 0.05) in comparison with the venlafaxine animals. In the OF, we observed a significantly higher number of entries into both the central and peripheral zones in the venlafaxine (p < 0.05 central zone; p ≤ 0.05 periphery zone) and SMe1EC2M3 (p < 0.05 central zone; p < 0.05 periphery zone) groups compared to the venlafaxine + zoletil group. SMe1EC2M3 was able to significantly increase the time of climbing in FST (p < 0.05) in comparison with the venlafaxine and control groups. The NOR test revealed a significantly higher discrimination ratio in the SMe1EC2M3 group (p < 0.05) compared to the control and venlafaxine groups. Analyses of the tail flick test showed a significant increase in reaction time to painful stimuli in the SMe1EC2M3 group (p < 0.05) in comparison to both the control and venlafaxine groups. Our findings suggest that SMe1EC2M3 has the potential to ameliorate some behavioral changes associated with TRD, and the venlafaxine + zoletil combination treatment was not a promising treatment alternative in the animal model of TRD.

Serotonin norepinephrine reuptake inhibitors in managing neuropathic pain following spinal and non-spinal surgery: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

While serotonin norepinephrine reuptake inhibitors (SNRIs) offer promise in managing Post-surgical neuropathic pain (PSNP), uncertainties remain. This study aims to evaluate the effectiveness and adverse events of SNRIs in managing PSNP.

METHODS

Systematic searches of PubMed, Embase, and Cochrane databases up to January 1st 2023 identified randomized controlled trials (RCTs) comparing SNRIs to placebo for PSNP. The primary outcome measures were pain at rest and adverse events post-surgery. Subgroup analyses were conducted based on surgical type and specific SNRIs.

RESULTS

A total of 19 RCTs, encompassing 1440 participants (719 in the SNRI group vs 721 in the placebo group), met the inclusion criteria and were included. The pooled results demonstrated that pain scores were significantly lower in patients treated with SNRIs at 2 hours (MD:-0.26; 95%CI: -0.47 to -0.04; p=0.02), 6 hours (MD:-0.68; 95%CI: -1.01 to -0.34; p<0.0001), 24 hours (MD:-0.54; 95%CI: -0.99 to -0.09; p=0.02), and 48 hours (MD:-0.66; 95%CI: -1.23 to -0.10; p=0.02) post-surgery. In terms of adverse events, dizziness (OR:2.53; 95%CI: 1.34-4.78; p=0.004) and dry mouth (OR:2.21; 95%CI: 1.25-3.92; p=0.007) were significantly higher in the SNRIs group. Subgroup analysis showed that SNRI was found to significantly lower the 24-hour pain score after spinal surgery (MD:-0.45; 95%CI: -0.84 to -0.05; p=0.03). Duloxetine (MD:-0.63; 95%CI: -1.15 to -0.11; p=0.02) had a significant effect in lowering the 24-hour pain score at rest compared to placebo, whereas venlafaxine did not.

CONCLUSIONS

SNRIs yielded considerable pain score reductions across multiple post-surgical intervals, although accompanied by an increased incidence of dizziness and dry mouth.

Update on Treating Painful Diabetic Peripheral Neuropathy: A Review of Current US Guidelines with a Focus on the Most Recently Approved Management Options

Painful diabetic peripheral neuropathy (DPN) is a highly prevalent and disabling complication of diabetes that is often misdiagnosed and undertreated. The management of painful DPN involves treating its underlying cause via lifestyle modifications and intensive glucose control, targeting its pathogenesis, and providing symptomatic pain relief, thereby improving patient function and health-related quality of life. Four pharmacologic options are currently approved by the US Food and Drug Administration (FDA) to treat painful DPN. These include three oral medications (duloxetine, pregabalin, and tapentadol extended release) and one topical agent (capsaicin 8% topical system). More recently, the FDA approved several spinal cord stimulation (SCS) devices to treat refractory painful DPN. Although not FDA-approved specifically to treat painful DPN, tricyclic antidepressants, serotonin/norepinephrine reuptake inhibitors, gabapentinoids, and sodium channel blockers are common first-line oral options in clinical practice. Other strategies may be used as part of individualized comprehensive pain management plans. This article provides an overview of the most recent US guidelines for managing painful DPN, with a focus on the two most recently approved treatment options (SCS and capsaicin 8% topical system), as well as evidence for using FDA-approved and guideline-supported drugs and devices. Also discussed are unmet needs for this patient population, and evidence for potential future treatments for painful DPN, including drugs with novel mechanisms of action, electrical stimulation devices, and nutraceuticals.

Structure- and Cation-Dependent Mechanism of Interaction of Tricyclic Antidepressants with NMDA Receptor According to Molecular Modeling Data

Some tricyclic antidepressants (TCAs), including amitriptyline (ATL), clomipramine (CLO), and desipramine (DES), are known to be effective for management of neuropathic pain. It was previously determined that ATL, CLO, and DES are capable of voltage-dependent blocking of NMDA receptors of glutamate (NMDAR), which play a key role in pathogenesis of neuropathic pain. Despite the similar structure of ATL, CLO, and DES, efficacy of their interaction with NMDAR varies significantly. In the study presented here, we applied molecular modeling methods to investigate the mechanism of binding of ATL, CLO, and DES to NMDAR and to identify structural features of the drugs that determine their inhibitory activity against NMDAR. Molecular docking of the studied TCAs into the NMDAR channel was performed. Conformational behavior of the obtained complexes in the lipid bilayer was simulated by the method of molecular dynamics (MD). A single binding site (upper) for the tertiary amines ATL and CLO and two binding sites (upper and lower) for the secondary amine DES were identified inside the NMDAR channel. The upper and lower binding sites are located along the channel axis at different distances from the extracellular side of the plasma membrane. MD simulation revealed that the position of DES in the lower site is stabilized only in the presence of sodium cation inside the NMDAR channel. DES binds more strongly to NMDAR compared to ATL and CLO due to simultaneous interaction of two hydrogen atoms of its cationic group with the asparagine residues of the ion pore of the receptor. This feature may be responsible for the stronger side effects of DES. It has been hypothesized that ATL binds to NMDAR less efficiently compared to DES and CLO due to its lower conformational mobility. The identified features of the structure- and cation-dependent mechanism of interaction between TCAs and NMDAR will help in the further development of effective and safe analgesic therapy.

Environmental factors and their impact on chronic pain development and maintenance

It is more than recognized and accepted that the environment affects the physiological responses of all living things, from bacteria to superior vertebrates, constituting an important factor in the evolution of all species. Environmental influences range from natural processes such as sunlight, seasons of the year, and rest to complex processes like stress and other mood disorders, infections, and air pollution, being all of them influenced by how each creature deals with them. In this chapter, it will be discussed how some of the environmental elements affect directly or indirectly neuropathic pain, a type of chronic pain caused by a lesion or disease of the somatosensory nervous system. For that, it was considered the edge of knowledge in translational research, thus including data from human and experimental animals as well as the applicability of such findings.

Research of the analgesic effects and central nervous system impact of electroacupuncture therapy in rats with knee osteoarthritis

It aimed to observe the effects of TongDu TiaoShen (TDTS) electroacupuncture (EA) on the analgesia and central system of knee osteoarthritis (KOA) rats and explore its mechanism. SD rats were rolled into the blank group, model group (KOA), control group (duloxetine 500 mg/kg/d, Ctrl), conventional EA group, and TDTS-EA group. Radiometric pain measurements and the Lequesne MG scale were used to evaluate the behavioral performance of the rats. Dopamine (DA), norepinephrine (NE), 5-hydroxytryptamine (5-HT), β-endorphin (β-EP), and leucine-enkephalin (L-ENK) were detected in the midbrain and spinal cord of lumbar enlargement. Interleukin (IL)-1β protein expression was detected by Western blot. The incubation period of thermal pain and foot contraction was decreased in the KOA group versus blank group, the Lequesne MG score was increased, DA, NE, 5-HT, β-EP, and L-ENK in the midbrain and spinal cord were increased, and synovial tissue IL-1β protein expression was increased (P < 0.05). EA group and TDTS-EA group had an increased incubation period of thermal pain contraction, decreased Lequesne MG score, decreased DA, NE, etc. In the midbrain, increased 5-HT and NE in the spinal cord, and decreased IL-1β in the synovial tissue versus KOA group (P < 0.05). The Lequesne MG score and midbrain DA, NE, 5-HT, β-EP, and synovial tissue IL-1β expression were decreased in TDTS-EA group versus EA group (P < 0.05). EA can effectively improve the behavioral score of KOA and participate in central analgesia by regulating central DA, NE, 5-HT, β-EP, and L-ENK.

Factors associated with the use of traditional doses of amitriptyline for chronic pain management: A cross-sectional study

There are studies on the effect of low-dose amitriptyline on pain control, but there is a lack of studies on the use of amitriptyline for chronic pain and the factors associated with the prescription of traditional doses. We used a national sample cohort of patients aged ≥ 18 years who were prescribed amitriptyline along with chronic pain, without psychiatric disorders, between 2002 to 2015. We categorized the prescriptions into 2 groups according to the daily dose: low doses (≤25 mg) and traditional doses (>25 mg). Multivariable logistic regression models were used to identify factors associated with traditional dose prescriptions. Among 177,769 prescriptions for amitriptyline, 15,119 (8.5%) were prescribed for chronic pain. The prevalence of prescriptions and proportion of traditional doses of amitriptyline tended to decrease during the study period. Male sex (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.05-1.13); age 65-80 years (OR 1.12, 95% CI 1.08-1.16), especially ≥ 80 years (OR 1.55, 95% CI 1.45-1.65); headaches (OR 1.18, 95% CI 1.10-1.27), receiving medical aids (OR 2.58, 95% CI 2.46-2.71); and being prescribed benzodiazepines or zolpidem concomitantly (OR 1.10, 95% CI 1.06-1.15) were significantly associated with traditional dose prescriptions of amitriptyline. Although traditional dose prescriptions of amitriptyline have been declining, close monitoring is still required in the presence of the above-mentioned factors.

Differences in musculoskeletal dysfunctions and in postural alterations between chronic migraine and chronic tension type headache: A cross-sectional study

OBJECTIVE

The aim of present study is to assess postural alterations and musculoskeletal dysfunctions over all spine in patients with chronic migraine and chronic tension type headache, moreover to highlight the differences between these two forms of primary headache.

METHODS

A Cross sectional study was adopted to evaluate the musculoskeletal profile in patients with chronic migraine and with chronic tension type headache. The Bio photogrammetric evaluation was performed using the postural assessment software PAS/SAPO, while unilateral passive accessory intervertebral motion (PAIMs) were applied for manual examinations of spine segments from C0 to L5 vertebra. The One-way Analysis of Variance (ANOVA) test was used to compare the three groups with the software GraphPad InStat 3.06.

RESULTS

A total of 60 patients were recruited, 20 for chronic tension type group, 20 for chronic migraine group and 20 healthy controls. The most interesting findings was that patients with chronic primary headaches presented postural alterations in all parameters (cranio-vertebral angle and lumbar-pelvic angle) and musculoskeletal dysfunctions in all spine with respect to healthy controls. Finally, the most clinically relevant finding was that no differences were found between chronic migraine and chronic tension type headache concerning the postural alterations nor the musculoskeletal dysfunctions.

CONCLUSION

The sensitization acts as a substrate or consequence of these musculoskeletal dysfunctions in chronic primary headache. Therefore, non-pharmacological treatments targeted in the musculoskeletal system may be a good option in the management of chronic primary headache, especially when these therapies integrate various techniques that involve all spine.