Position Paper on Post-Traumatic Headache: The Relationship Between Head Trauma, Stress Disorder, and Migraine

Piperine-hydroxybenzoate as phytochemistry antiosteoarthritis combination: Structural, solubility, and in vivo antiinflammatory study

This study discusses the composition and structure determination of a new multicomponent system from antiinflammatory natural ingredients, consisting of piperine (Pip) and 4-hydroxybenzoic acid (HBA), named Pip-HBA. In addition, this research studied its solubility and anti-inflammatory activity. After screening the stoichiometric proportions, this multicomponent system formation reaction was carried out using the solvent-dropped grinding and evaporation methods. Characterizations using solid analysis including differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), and Fourier transform infrared spectroscopy (FTIR), confirmed the formation of Pip-HBA. These multicomponent systems showed different thermograms and diffractograms. Furthermore, the FTIR spectrum of Pip-HBA multicomponent system differs from the physical mixture and its constituent components. Single crystal diffractometry (SCXRD) determined Pip-HBA to be a new multicomponent system structure in three dimensions. Pip-HBA showed increased solubility and anti-inflammatory activity compared to single piperine. Therefore, Pip-HBA multicomponent system has quite potential for further preparation development.

Frequency and predictors of headache in the first 12 months after traumatic brain injury: results from CENTER-TBI

BACKGROUND

Headache is a prevalent and debilitating symptom following traumatic brain injury (TBI). Large-scale, prospective cohort studies are needed to establish long-term headache prevalence and associated factors after TBI. This study aimed to assess the frequency and severity of headache after TBI and determine whether sociodemographic factors, injury severity characteristics, and pre- and post-injury comorbidities predicted changes in headache frequency and severity during the first 12 months after injury.

METHODS

A large patient sample from the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) prospective observational cohort study was used. Patients were stratified based on their clinical care pathway: admitted to an emergency room (ER), a ward (ADM) or an intensive care unit (ICU) in the acute phase. Headache was assessed using a single item from the Rivermead Post-Concussion Symptoms Questionnaire measured at baseline, 3, 6 and 12 months after injury. Mixed-effect logistic regression analyses were applied to investigate changes in headache frequency and associated predictors.

RESULTS

A total of 2,291 patients responded to the headache item at baseline. At study enrolment, 59.3% of patients reported acute headache, with similar frequencies across all strata. Female patients and those aged up to 40 years reported a higher frequency of headache at baseline compared to males and older adults. The frequency of severe headache was highest in patients admitted to the ICU. The frequency of headache in the ER stratum decreased substantially from baseline to 3 months and remained from 3 to 6 months. Similar trajectory trends were observed in the ICU and ADM strata across 12 months. Younger age, more severe TBI, fatigue, neck pain and vision problems were among the predictors of more severe headache over time. More than 25% of patients experienced headache at 12 months after injury.

CONCLUSIONS

Headache is a common symptom after TBI, especially in female and younger patients. It typically decreases in the first 3 months before stabilising. However, more than a quarter of patients still experienced headache at 12 months after injury. Translational research is needed to advance the clinical decision-making process and improve targeted medical treatment for headache.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02210221.

Changes in Outpatient Healthcare Utilization and Costs Following Mild Traumatic Brain Injury Among Service Members in the Military Health System by Preexisting Behavioral Health Condition Status

OBJECTIVE

To evaluate changes in healthcare utilization and cost following an index mild traumatic brain injury (mTBI) diagnosis among service members (SMs). We hypothesized that differences in utilization and cost will be observed by preexisting behavioral health (BH) diagnosis status.

SETTING

Direct care outpatient healthcare facilities within the Military Health System.

PARTICIPANTS

A total of 21 984 active-duty SMs diagnosed with an index mTBI diagnosis between 2017 and 2018.

DESIGN

This retrospective study analyzed changes in healthcare utilization and cost in military treatment facilities among SMs with an index mTBI diagnosis. Encounter records 1 year before and after mTBI were assessed; preexisting BH conditions were identified in the year before mTBI.

MAIN MEASURES

Ordinary least squares regressions evaluated difference in the average change of total outpatient encounters and costs among SMs with and with no preexisting BH conditions (eg, posttraumatic stress disorder, adjustment disorder). Additional regressions explored changes in utilization and cost within clinic types (eg, mental health, physical rehabilitation).

RESULTS

There was a 39.5% increase in overall healthcare utilization during the following year, representing a 34.8% increase in total expenditures. Those with preexisting BH conditions exhibited smaller changes in overall utilization (β, -4.9; [95% confidence interval (CI), -6.1 to -3.8]) and cost (β, $-1873; [95% CI, $-2722 to $-1024]), compared with those with no BH condition. The greatest differences were observed in primary care clinics, in which those with prior BH conditions exhibited an average decreased change of 3.2 encounters (95% CI, -3.5 to -3) and reduced cost of $544 (95% CI, $-599 to $-490) compared with those with no prior BH conditions.

CONCLUSION

Despite being higher utilizers of healthcare services both pre- and post-mTBI diagnosis, those with preexisting BH conditions exhibited smaller changes in overall cost and utilization. This highlights the importance of considering prior utilization and cost when evaluating the impact of mTBI and other injury events on the Military Health System.

Headache comorbidity in refugees and migrants with post-traumatic stress disorder

BACKGROUND

Headache is often comorbid with post-traumatic stress disorder yet overlooked in health assessments of refugees.

OBJECTIVES

To describe prevalence of severe headache among refugees with post-traumatic stress disorder and compare severity of post-traumatic stress disorder symptoms and treatment outcomes among those with and without severe headache.

METHODS

This follow-up study used data from the Danish Database on Refugees with Trauma. Participants were recruited from 2009 to 2015 at a specialized psychiatric clinic. Prevalence of severe headache was computed by age, sex, and history of head injury or torture. Severe headache was defined as maximum headache scores on the Hopkins Symptom Checklist, Symptom Checklist-90 or the Visual Analogue Scale. Groups with and without severe headache were described according to validated questionnaires before and after 12-18 months of multidisciplinary treatment for post-traumatic stress disorder. Regression analyses were used to analyze associations between headache at start of treatment and symptom burden post-treatment, controlled for pre-treatment scores and possible confounders.

RESULTS

Among 403 female and 489 male participants, nearly all (97.5%) complained of headaches. Severe headache prevalence was 31.4% to 50.0% (depending on which questionnaire was used) and was significantly more common among females and those aged 30-49 years. There was no clear relationship between headache and head injury or torture. Participants with severe headache had heavier symptom burdens compared to those without severe headache. Post-treatment, headache prevalence by age and sex did not change significantly. Those without severe headache showed a tendency toward improvement in outcome measures; this was not seen among those with severe headache. Pre-treatment headache scores were correlated with all outcome measures. Regression analyses controlled for pre-treatment scores of the outcome variables showed associations between pre-treatment headache scores (Hopkins Symptom Checklist or Symptom Checklist-90) and post-treatment scores for intrusion, numbing, hyperarousal, anxiety, disability, and quality of life (all p < 0.02).

CONCLUSION

Headache is a prevalent comorbid condition among refugees with post-traumatic stress disorder. Measures of pre-treatment headache severity appear to predict post-traumatic stress disorder treatment outcomes. Severe headache adversely affects post-traumatic stress disorder prognosis. Assessment and treatment options should be studied further.

A multicenter, longitudinal survey of headaches and concussions among youth athletes in the United States from 2009 to 2019

OBJECTIVE/ BACKGROUND

Chronic headaches and sports-related concussions are among the most common neurological morbidities in adolescents and young adults. Given that the two can overlap in presentation, studying the effects of one on another has proven difficult. In this longitudinal study, we sought to assess the relationship between chronic headaches and concussions, analyzing the role of historic concussions on chronic headaches, as well as that of premorbid headaches on future concussion incidence, severity, and recovery.

METHODS

This multi-center, longitudinal cohort study followed 7,453 youth athletes who were administered demographic and clinical surveys as well as a total of 25,815 Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) assessments between 2009 and 2019. ImPACT was administered at baseline. Throughout the season concussions were examined by physicians and athletic trainers, followed by re-administration of ImPACT post-injury (PI), and at follow-up (FU), a median of 7 days post-concussion. Concussion incidence was calculated as the total number of concussions per patient years. Concussion severity and recovery were calculated as standardized deviations from baseline to PI and then FU in Symptom Score and the four neurocognitive composite ImPACT scores: Verbal Memory, Visual Memory, Processing Speed, and Reaction Time. Data were collected prospectively in a well-organized electronic format supervised by a national research-oriented organization with rigorous quality assurance. Analysis was preformed retrospectively.

RESULTS

Of the eligible athletes, 1,147 reported chronic headaches (CH) at the start of the season and 6,306 reported no such history (NH). Median age of the cohort was 15.4 ± 1.6 years, and students were followed for an average of 1.3 ± 0.6 years. A history of concussions (OR 2.31, P < 0.0001) was associated with CH. Specifically, a greater number of past concussions (r2 = 0.95) as well as concussions characterized by a loss of consciousness (P < 0.0001) were associated with more severe headache burden. The CH cohort had a greater future incidence of concussion than the NH cohort (55.6 vs. 43.0 per 100 patient-years, P < 0.0001). However, multivariate analysis controlling for demographic, clinical, academic, and sports-related variables yielded no such effect (OR 0.99, P = 0.85). On multivariable analysis the CH cohort did have greater deviations from baseline to PI and FU in Symptom Score (PI OR per point 1.05, P = 0.01, FU OR per point 1.11, P = 0.04) and Processing Speed (OR per point 1.08, P = 0.04), suggesting greater concussion severity and impaired symptomatic recovery as compared to the NH cohort.

CONCLUSION

A history of concussions was a significant contributor to headache burden among American adolescents and young adults. However, those with chronic headaches were not more likely to be diagnosed with a concussion, despite presenting with more severe concussions that had protracted recovery. Our findings not only suggest the need for conservative management among youth athletes with chronic headaches, they also indicate a potential health care gap in this population, in that those with chronic headaches may be referred for concussion diagnosis and management at lower rates than those with no such comorbidity.

Remotely supervised at-home tDCS for veterans with persistent post-traumatic headache: a double-blind, sham-controlled randomized pilot clinical trial

Background

Currently, there are no FDA approved therapies for persistent post-traumatic headache (PPTH) secondary to traumatic brain injury (TBI). As such neither headache nor TBI specialists have an effective means to manage PPTH. Thus, the objective of the present pilot trial was to evaluate the feasibility and preliminary efficacy of a four-week at-home remotely supervised transcranial direct current stimulation (RS-tDCS) intervention for veterans with PPTH.

Methods

Twenty-five (m = 46.6 ± 8.7 years) veterans with PPTH were randomized into two groups and received either active (n = 12) or sham (n = 13) RS-tDCS, with anodal stimulation over left dlPFC and cathodal over occipital pole. Following a four-week baseline, participants completed 20-sessions of active or sham RS-tDCS with real-time video monitoring over a period of four-weeks. Participants were assessed again at the end of the intervention and at four-weeks post-intervention. Primary outcomes were overall adherence rate (feasibility) and change in moderate-to-severe headache days per month (efficacy). Secondary outcomes were changes in total number of headache days, and PPTH-related functional outcomes.

Results

Adherence rate was high with 88% of participants (active = 10/12; sham = 12/13) fully completing tDCS interventions. Importantly, there was no significant difference in adherence between active and sham groups (p = 0.59). Moderate-to-severe headache days were significantly reduced within the active RS-tDCS group (p = 0.004), compared to sham during treatment (-2.5 ± 3.5 vs. 2.3 ± 3.4), and 4-week follow-up (-3.9 ± 6.4 vs. 1.2 ± 6.5). Total number of headache days was significantly reduced within the active RS-tDCS (p = 0.03), compared to sham during-treatment (-4.0 ± 5.2 vs. 1.5 ± 3.8), and 4-week follow-up (-2.1 ± 7.2 vs. -0.2 ± 4.4).

Conclusion

The current results indicate our RS-tDCS paradigm provides a safe and effective means for reducing the severity and number of headache days in veterans with PPTH. High treatment adherence rate and the remote nature of our paradigm indicate RS-tDCS may be a feasible means to reduce PPTH, especially for veterans with limited access to medical facilities.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT04012853].

Total tenderness score and pressure pain thresholds in persistent post-traumatic headache attributed to mild traumatic brain injury

Objective

To investigate whether persistent post-traumatic headache attributed to mild traumatic brain injury (TBI) is associated with more pronounced pericranial tenderness and lower pressure pain thresholds (PPTs) in the head and neck region, compared with healthy controls.

Methods

Patients with persistent post-traumatic headache (n = 100) and age- and gender-matched healthy controls (n = 100) were included between July 2018 and June 2019. Total tenderness score (TTS) was used to assess pericranial tenderness by bilateral manual palpation in eight muscles or tendon insertions. Summation was then used to calculate a TTS from 0 to 48 based on individual right- and left-sided scores; higher TTS score indicated more pronounced pericranial tenderness. PPTs were examined in m. temporalis and m. trapezius (upper and middle part) using an electronic pressure algometer that applies increasing blunt pressure at a constant rate.

Results

The TTS score was higher in patients with persistent post-traumatic headache (median, 21; IQR, 12–31), compared with healthy controls (median, 10; IQR, 6–17; P < .001). PPTs were lower in patients with persistent post-traumatic headache than in controls in both the left-sided m. temporalis (mean ± SD, 157.5 ± 59.9 vs. 201.1 ± 65.2; P < .001) and right-sided m. temporalis (mean ± SD, 159.5 ± 63.8 vs. 212.3 ± 61.9; P < .001). Furthermore, patients with persistent post-traumatic headache also had lower left- and right-sided PPTs in the upper as well as middle part of m. trapezius, compared with healthy controls; all P values were .05 or less.

Conclusions

Among patients with persistent post-traumatic headache, pericranial tenderness was more pronounced and PPTs in the head and neck region were lower than in healthy controls free of headache and mild TBI. Further research is needed to better understand the involvement of pericranial myofascial nociceptors in the disease mechanisms underlying post-traumatic headache.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01457-1.

Artificial intelligence analysis to explore synchronize exercise, cobalamin, and magnesium as new actors to therapeutic of migraine symptoms: a randomized, placebo-controlled trial

INTRODUCTION

Migraine is recognized as a complex neurological disorder that has imposed a social burden. We assessed the signaling pathways and molecular mechanisms based on the in silico analysis and predicted drug candidates by the biomedicine approach. Moreover, we evaluated high-intensity interval training and vitamin B12 + magnesium on women's migraine attacks and inflammatory status.

METHODS

This study computed differential gene expression in migraine syndrome and the dimension network parameters visualized by software. Moreover, we proposed the functional mechanism and binding energy of essential micronutrients on macromolecules based on drug discovery. In this clinical trial, 60 cases were randomized to four groups, including applied high-intensity interval training (HIIT), cases consumed supplementation vitamin B12 and magnesium (Supp), cases applied high-intensity interval training, and consumed supplementation (HIIT + Supp), and migraine cases for 2 months. Serum levels of calcitonin gene-related peptide (CGRP) were measured at baseline and at the end of the study. In addition, migraine disability assessment score (MIDAS), frequency, intensity, and duration were recorded before and during interventions.

RESULTS

In silico study revealed the association between inflammation signaling pathways and pathogenesis of migraine attacks as a remarkable pathomechanism in this disorder. Furthermore, serum concentrations of CGRP were significantly declined in the HIIT + Supp compared with other groups. In addition, MIDAS, frequency, intensity, and duration were reduced in the HIIT + Supp group compared with the other groups.

CONCLUSION

We found that the synergistic effects of cobalamin and magnesium followed by regular exercise could silence the inflammation signaling pathway, and a combination of HIIT + Supp could ameliorate migraine pain.

TRIAL REGISTRATION

This study was registered in the Iranian Registry of Clinical Trials; IRCT code: IRCT20170510033909N12. Approval Data: 2021/06/02.

Post-traumatic headache: Pathophysiology and management - A review

Background

Post-traumatic headache (PTH) is a common secondary headache due to traumatic brain injury. In the past, significant research has been conducted to understand the pathophysiology and treatment options for PTH. However, PTH still lacks evidence-based treatment, and most of the management depends on the primary phenotype observed in the patient.

Objective

The main objective of this review is to provide a single reference that covers the current understanding of the pathophysiology and the treatment options available for PTH.

Methods

A detailed literature search on PubMed was performed, and a narrative review was prepared.

Results

The pathophysiology of PTH is multifactorial. Acute PTH may be attributed to increased peripheral pain sensitization with impaired pain inhibiting pathways. Chronic or persistent PTH may be due to a chronic inflammatory response and peripheral as well as central sensitization. The mechanism responsible for the transition of acute to persistent PTH is unknown. The migraine-like phenotype is reported to be the most prevalent headache type seen in PTH. New targets for preventive treatment have been identified in recent years, such as neuropeptides like calcitonin-gene-related peptide (CGRP), nitric oxide, and glutamate. The preventive pharmacological and non-pharmacological strategies employed for migraine (e.g. anti-CGRP monoclonal antibodies, onabotulinumtoxinA, physical therapy, cognitive and behavioral treatment, and neurostimulation techniques) have shown in preliminary studies that they are potentially efficacious, but large, randomized, double blind, placebo controlled trials are needed to further establish these as treatment options for PTH.

Conclusions

The lack of evidence-based treatment for PTH has created a need for future large trials to confirm the safety and efficacy of the currently employed treatments.

Post-traumatic headache after mild traumatic brain injury in a one-year follow up study - risk factors and return to work

BACKGROUND

Post-traumatic headache (PTH) is a common symptom following mild traumatic brain injury (mTBI). Patients at risk to develop acute PTH (aPTH) and further persistent PTH (pPTH) need to be recognized.

METHODS

This is a one-year follow-up of 127 patients with mTBI, aged 18 to 68, referred to outpatient clinic in the Helsinki University Hospital. Symptoms were assessed at the emergency department (ED), with structured interview at outpatient clinic visit and with Rivermead post-concussion symptom questionnaire at one, three, and 12 months after injury. Psychiatric disorders were assessed with Structured Clinical Interview for DSM-IV Axis I disorders at 3-4 months and return to work (RTW) from patient records.

RESULTS

At one month, 77/127 patients (61%) had aPTH. According to multiple logistic regression analysis, risk factors for aPTH were headache at the emergency department (ED) (OR 5.43), other pain (OR 3.19), insomnia (OR 3.23), and vertigo (OR 5.98). At three months, 17 patients (22% of aPTH patients) had developed pPTH, and at one year, 4 patients (24% of pPTH patients) still presented with pPTH. Risk factors for pPTH at three months were older age (OR 1.06) and current insomnia (OR 12.3). The frequency of psychiatric disorders did not differ between the groups. pPTH patients performed worse on their RTW.

CONCLUSIONS

Risk factors for aPTH were insomnia, headache at ED, other pain, and vertigo and for pPTH, insomnia and older age. RTW rate was lower among pPTH patients.

Computerized migraine diagnostic tools: a systematic review

BACKGROUND

Computerized migraine diagnostic tools have been developed and validated since 1960. We conducted a systematic review to summarize and critically appraise the quality of all published studies involving computerized migraine diagnostic tools.

METHODS

We performed a systematic literature search using PubMed, Web of Science, Scopus, snowballing, and citation searching. Cutoff date for search was 1 June 2021. Published articles in English that evaluated a computerized/automated migraine diagnostic tool were included. The following summarized each study: publication year, digital tool name, development basis, sample size, sensitivity, specificity, reference diagnosis, strength, and limitations. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool was applied to evaluate the quality of included studies in terms of risk of bias and concern of applicability.

RESULTS

A total of 41 studies (median sample size: 288 participants, median age = 43 years; 77% women) were included. Most (60%) tools were developed based on International Classification of Headache Disorders criteria, half were self-administered, and 82% were evaluated using face-to-face interviews as reference diagnosis. Some of the automated algorithms and machine learning programs involved case-based reasoning, deep learning, classifier ensemble, ant-colony, artificial immune, random forest, white and black box combinations, and hybrid fuzzy expert systems. The median diagnostic accuracy was concordance = 89% [interquartile range (IQR) = 76-93%; range = 45-100%], sensitivity = 87% (IQR = 80-95%; range = 14-100%), and specificity = 90% (IQR = 77-96%; range = 65-100%). Lack of random patient sampling was observed in 95% of studies. Case-control designs were avoided in all studies. Most (76%) reference tests exhibited low risk of bias and low concern of applicability. Patient flow and timing showed low risk of bias in 83%.

CONCLUSION

Different computerized and automated migraine diagnostic tools are available with varying accuracies. Random patient sampling, head-to-head comparison among tools, and generalizability to other headache diagnoses may improve their utility.

The bidirectional temporal relationship between headache and affective disorders: longitudinal data from the HUNT studies

Background

Few prospective population-based studies have evaluated the bidirectional relationship between headache and affective disorder. The aim of this large-scale population-based follow-up study was to investigate whether tension-type headache (TTH) and migraine had increased risk of developing anxiety and depression after 11 years, and vice-versa.

Methods

Data from the Trøndelag Health Study (HUNT) conducted in 2006-2008 (baseline) and 2017-2019 (follow-up) were used to evaluate the bidirectional relationship between migraine and TTH and anxiety and depression measured by Hospital Anxiety and depression Scale (HADS). The population at risk at baseline consisted of respectively 18,380 persons with HADS score ≤ 7 and 13,893 without headache, and the prospective data was analyzed by Poisson regression.

Results

In the multi-adjusted model, individuals with HADS anxiety (HADS-A) and depression scores (HADS-D) of ≥8 at baseline nearly doubled the risk of migraine (Risk rations (RR) between 1.8 and 2.2) at follow-up whereas a 40% increased risk (RR 1.4) was found for TTH. Vice versa, the risk of having HADS-A and HADS-D scores of ≥8 at follow-up were increased for TTH (RR 1.3) and migraine (RR 1.3-1.6) at baseline. Migraine with aura was associated with 81% (RR 1.81, 95% 1.52-2.14) increased risk of HADS-A score of ≥8.

Conclusions

In this large-scale population-based follow-up study we found a bidirectional relationship between anxiety and depression and migraine and TTH. For anxiety, this bidirectional association was slightly more evident for migraine than TTH.

Migraine and Medical Ramifications: A Comprehensive Overview Based on Observational Study Meta-Analyses

Purpose: An umbrella review was conducted for comprehensively evaluating previous review-based literature together with meta-analysis of observational investigations probing correlations between migraine and medical end-point ramifications in patients. The breadth and validity of these associations were assessed.

Methods: Multiple online scientific repositories (including PubMed, Medline, Embase, and Web of Science) were investigated (inception-August 2021) for related meta-analyses focusing on links between migraine and all possible health/medical ramification end-points. A summary effect size and 95% CIs were determined for each identified study with such links. Heterogeneity and small-study influence traces were also evaluated. The AMSTAR 2 platform was employed for evaluating standards of methodology, together with objective criteria, for assessing the standards of datasets from each medical end-point scrutinized in this study.

Results: A total of 25 scientific reports comprising 10,237,230 participants for 49 meta-analyses of observational studies were selected. Among such 49 outcomes, 30 demonstrated statistical significance (P < 0.05). Significant associations were observed in multiple diseases, including cardiovascular/cerebrovascular, cerebral, pregnancy-related and metabolic disorders, other outcomes, and mortality.

Conclusion: The results showed that migraine increased the risk of 29 health outcomes, though lowered the risk of breast cancer. However, evidence quality was graded as high only for angina. The evidence quality of ischaemic stroke, stroke, MACCE, WMAs, and asthma was graded as moderate. All remaining 24 outcomes had an evidence grade of “weak.”

Animal Models of Complex Regional Pain Syndrome Type I

Complex regional pain syndrome (CRPS) is a chronic pain disorder characterized by spontaneous or evoked regionally-confined pain which is out of proportion to the initial trauma event. The disease can seriously affect the quality of the patients’ life, increase the psychological burden, and cause various degrees of disability. Despite the awareness of CRPS among medical practitioners for over a century, its pathogenesis remains unclear, and the available treatment is still unsatisfactory. Effective animal models are the foundation of disease research, which is helpful in understanding the pathogenesis and an in-depth exploration of the appropriate therapeutic approaches. Currently, researchers have established a series of animal models of the disease. There are four main CRPSI animal models: chronic post-ischemic pain (CPIP) model, tibial fracture/cast immobilization model, passive transfer-trauma model, and the needlestick-nerve-injury (NNI) model. The modeling methods of these models are constantly improving over time. In preclinical studies, the interpretation of experimental results and the horizontal comparison between similar studies may be affected by the nature of the experimental animal breeds, sex, diet, and psychology. There is need to facilitate the choice of appropriate animal models and avoid the interference of the factors influencing animal models on the interpretation of research results. The review will provide a basic overview of the influencing factors, modeling methods, and the characteristics of CRPSI animal models.