Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (718 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Suffering, Physical; Physical Suffering; Physical Sufferings; Sufferings, Physical; Ache; Aches; Pain, Burning; Burning Pain.
Where it fits in the MeSH classification
- Broader topics
- Neurologic Manifestations; Sensation
- Narrower topics
- Abdominal Pain; Acute Pain; Arthralgia; Back Pain; Breakthrough Pain; Cancer Pain; Chest Pain; Chronic Pain; Earache; Eye Pain; Facial Pain; Flank Pain; Glossalgia; Headache
- See also
- Analgesia; Pain Insensitivity, Congenital; Analgesics; Hyperalgesia; Palliative Care
Related concepts
- Nerve Endings
- Nociceptive Neurons
Research landscape
PubMed indexes 508,879 records tagged with the MeSH heading “Pain” (counts retrieved 2026-10-29). 113,504 of them (22.3%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 150,931 records.
Reviews account for 71,124 records (14.0%) and meta-analyses for 9,325. Randomized controlled trials number 50,330 (9.9%) as a share of all records on the topic. Randomized trials make up a comparatively large share of this literature, which means many treatment questions have been tested directly.
Show the data
| Period | Records |
|---|---|
| through 1999 | 139,113 |
| 2000-2009 | 105,331 |
| 2010-2019 | 150,931 |
| 2020 onward | 113,504 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 71,124 | 14.0% |
| Meta-analyses | 9,325 | 1.8% |
| Randomized controlled trials | 50,330 | 9.9% |
Method: PubMed query "Pain"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in neuroscience
Neuroscience draws on tools with different strengths: cellular and animal work can manipulate circuits directly, while human imaging and electrophysiology observe the living brain at lower resolution. Small imaging studies are prone to false positives, and findings in animals do not always carry over to people. Clinical neurology and psychiatry rely on trials and cohort studies whose outcomes are often symptom scales. Check the species, the sample size, how the outcome was measured and whether results were replicated.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| TRPM2 is a direct pain transducer | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42748138 · DOI · PMC13598259 |
| Astrocytes in Neuropathic Pain: Mechanistic and Global Insights | 2026 | Review article Design not recorded in structured metadata | 1 | cc by PMID 42760823 · DOI · PMC13589199 |
| Bibliometric Analysis of Patient-Controlled Intravenous Analgesia Research From 2014 to April 2026: Global Trends, Hotspot Evolution, and Future Directions | 2026 | Review article Design not recorded in structured metadata | 1 | cc by PMID 42740600 · DOI · PMC13575643 |
TRPM2 is a direct pain transducer [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Chronic pain results from maladaptive interaction between the immune and nervous systems.
- Closing excerpt
- We conclude that neuronal TRPM2 is a convergent direct pain transducer independently of inflammation, representing an appealing target for alleviating chronic pain.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (204 words)
Chronic pain results from maladaptive interaction between the immune and nervous systems. TRPM2 channels in immune cells (immune TRPM2) are believed to facilitate chronic pain by indirectly promoting immune-inflammatory responses, whereas TRPM2 in sensory neurons (neuronal TRPM2) acts as a warmth sensor critical to sense innocuous warm temperatures. However, neuronal TRPM2 mediates the warmth sensitivity of less than 3.5% of sensory neurons. The functions of the vast majority of TRPM2+ neurons are unknown. Here, we show that neuronal TRPM2 functions as a pain sensor responsible for directly transducing acute and chronic pain independently of immune TRPM2. Both chronic arthritis pain and neuropathic pain were markedly reduced in TRPM2-knockout mice, and the pain deficit was recapitulated by sole deletion of neuronal TRPM2. However, immune and inflammatory responses were largely similar between wild-type and neuronal TRPM2-deficient mice. Moreover, antagonizing TRPM2 rapidly reversed arthritis pain and neuropathic pain. Notably, TRPM2 is activated by PGE2 and IgG immune complex (IgG-IC) through coupling to GαoA and FcγRI, respectively, independently of conventional signaling messengers. Consistently, acute pain induced by PGE2 and IgG-IC was abolished in TRPM2 mutant mice. We conclude that neuronal TRPM2 is a convergent direct pain transducer independently of inflammation, representing an appealing target for alleviating chronic pain.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42748138 · DOI · PMC13598259
Astrocytes in Neuropathic Pain: Mechanistic and Global Insights [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundNeuropathic pain (NP) is a debilitating chronic pain condition caused by injury or disease of the somatosensory nervous system.
- Closing excerpt
- Current trends underscore the integration of mechanistic insights with translational relevance, thereby informing future therapeutic and mechanistic advancements in NP.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (263 words)
BackgroundNeuropathic pain (NP) is a debilitating chronic pain condition caused by injury or disease of the somatosensory nervous system. Accumulating evidence indicates that astrocytes play a central role in neuroinflammatory regulation and synaptic remodeling, thereby critically influencing the initiation and persistence of NP. However, a comprehensive overview of research trends and knowledge structures in this field is still lacking.MethodsThe analysis was conducted based on publications retrieved from the Web of Science Core Collection (WoSCC) and Scopus, covering the period from 2000 to 2025. Studies focusing on astrocytes and NP were systematically identified. Visualization and network analyses were performed using CiteSpace, VOSviewer, and the R package bibliometrix. Collaboration networks, cocitation patterns, keyword co-occurrence, and thematic evolution were analyzed to delineate research hotspots, developmental trajectories, and scholarly contributions across countries, institutions, authors, and journals.ResultsA total of 1828 publications were included, showing a 15% average annual growth in output, which accelerated post-2010. The United States and China led in research and international collaboration, with studies concentrated in North American and East Asian institutions. Author productivity was uneven, with key researchers (Ji RR, Zhang Y, Watkins LR) contributing heavily to publications and citations. Pain and Molecular Pain were the core journals. Key themes included spinal astrocytic mechanisms, glial activation, and therapeutic modulation, with the focus evolving from injury models/markers to astrocytic activation and targeted pathways.ConclusionOur analysis shows a substantial growth in astrocyte-related NP research over the past 25 years, underscoring astrocytes' key role in chronic pain pathophysiology. Current trends underscore the integration of mechanistic insights with translational relevance, thereby informing future therapeutic and mechanistic advancements in NP.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42760823 · DOI · PMC13589199
Bibliometric Analysis of Patient-Controlled Intravenous Analgesia Research From 2014 to April 2026: Global Trends, Hotspot Evolution, and Future Directions [3]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundPatient-controlled intravenous analgesia (PCIA) remains a cornerstone in managing moderate to severe postoperative pain.
- Closing excerpt
- ConclusionThis study delineates the global scientific landscape and the evolution of research hotspots in PCIA, providing bibliometric evidence to inform future study design, strengthen cross-regional collaboration, and shape individualized perioperative analgesic strategies.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (251 words)
BackgroundPatient-controlled intravenous analgesia (PCIA) remains a cornerstone in managing moderate to severe postoperative pain. The shift toward multimodal analgesia, opioid-sparing protocols, and enhanced recovery after surgery has steadily broadened the scope of PCIA-related investigation. Despite this growth, a clear synthesis of the global research landscape, underlying knowledge structure, and the trajectory of emerging themes is still lacking.MethodsThe Web of Science Core Collection was searched for English-language original articles and reviews on PCIA published between January 1, 2014, and April 6, 2026. Bibliometric and visualization analyses were performed using Microsoft Excel, VOSviewer, CiteSpace, Bibliometrix, and SCImago Graphica to examine publication trends, contributing countries/regions, institutions, authors, journals, keywords, and cocited references.ResultsThe full dataset retrieved through April 6, 2026, included 492 publications involving 33 countries/regions, 607 institutions, and 2675 authors. In the analysis of complete publication years from 2014 to 2025, PCIA-related research showed a fluctuating but overall upward trend. China, South Korea, and the United States emerged as the leading contributors. Although China produced the largest volume of publications, the United States held a more central position within the international collaboration network. The most prolific journals were Medicine, BMC Anesthesiology, and Journal of Pain Research. Research hotspots have progressively moved beyond opioid analgesia and efficacy evaluation to multimodal analgesia, opioid-sparing strategies, safety optimization, integration with regional blocks, procedure-specific analgesia, and patient-centered outcomes.ConclusionThis study delineates the global scientific landscape and the evolution of research hotspots in PCIA, providing bibliometric evidence to inform future study design, strengthen cross-regional collaboration, and shape individualized perioperative analgesic strategies.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42740600 · DOI · PMC13575643
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Opioid-free vs. opioid-inclusive anaesthesia with or without regional anaesthesia for postoperative pain: a systematic review with network meta-analysis of randomised controlled trials [4]
- Research article Chronic pain and risk of cognitive impairment: a meta-analysis of longitudinal cohort studies [5]
- Research article Effectiveness of Pain Neuroscience Education in Reducing Pain, Disability, Kinesiophobia, and Catastrophizing in Patients with Chronic Low Back Pain: A Systematic Review and Meta-Analysis [6]
- Research article Human assumed central sensitization in interictal migraine: a systematic review and meta-analysis [7]
- Research article Is Endometriosis Staging Related to the Type and Intensity of Patients' Complaints? A Systematic Review and Meta-Analysis [8]
- Research article Cannabis-based medicines for chronic neuropathic pain in adults [9]
References
- Varghese L, Alizada M, Yang J, Feng Y, Yuan X, Malhotra M, et al.. TRPM2 is a direct pain transducer. . 2026. PMID 42748138 · DOI · PMC13598259
- Xue L, Yuan H, Yang J, Yuan Q, Fan H. Astrocytes in Neuropathic Pain: Mechanistic and Global Insights. . 2026. PMID 42760823 · DOI · PMC13589199
- Duan ZY, Zhu SY, Li QJ, Cao XY, Wang XC, Xiao QX, et al.. Bibliometric Analysis of Patient-Controlled Intravenous Analgesia Research From 2014 to April 2026: Global Trends, Hotspot Evolution, and Future Directions. . 2026. PMID 42740600 · DOI · PMC13575643
- de Carvalho CC, El-Boghdadly K, Guedes IHL, Dantas MVM, Tomé DPB, Ramos IB, et al.. Opioid-free vs. opioid-inclusive anaesthesia with or without regional anaesthesia for postoperative pain: a systematic review with network meta-analysis of randomised controlled trials. Anaesthesia. 2026. PMID 41487040 · DOI · PMC13065899
- Qiu D, Zhou ZB, Li XY, Hashimoto K, Yang JJ, Wang XM. Chronic pain and risk of cognitive impairment: a meta-analysis of longitudinal cohort studies. Transl Psychiatry. 2026. PMID 41792103 · DOI · PMC12976088
- Medina-Viedma L, Cortés-Pérez I, Obrero-Gaitán E, Osuna-Pérez MC, Díaz-Fernández Á, López-Ruiz MDC, et al.. Effectiveness of Pain Neuroscience Education in Reducing Pain, Disability, Kinesiophobia, and Catastrophizing in Patients with Chronic Low Back Pain: A Systematic Review and Meta-Analysis. Med Sci (Basel). 2025. PMID 41440522 · DOI · PMC12734988
- Cnockaert E, Meeus M, Cagnie B, Chys M, Steverlynck C, Moerkerke M, et al.. Human assumed central sensitization in interictal migraine: a systematic review and meta-analysis. Neurol Sci. 2026. PMID 41667877 · DOI
- Alves JS, Meneses T, Mariano M, Serra SS, Costa T, Martins JP, et al.. Is Endometriosis Staging Related to the Type and Intensity of Patients' Complaints? A Systematic Review and Meta-Analysis. J Minim Invasive Gynecol. 2026. PMID 41338448 · DOI
- Ateş G, Welsch P, Klose P, Phillips T, Lambers B, Häuser W, et al.. Cannabis-based medicines for chronic neuropathic pain in adults. Cochrane Database Syst Rev. 2026. PMID 41548880 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-29.
See how EvidenceLib is built. Spotted an error? Email support@evidencehelix.com.
Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.