Sources of variation in assessing male and female responses to pain

Female and Younger Orthopaedic Sport Medicine Patients Are More Negatively Affected by COVID-19-Related Health Care Closures

Purpose

To determine if sex or age influence whether COVID-19 health care closures affect the health, recovery, and access to resources of pre- and post-operative orthopaedic sport medicine patients.

Methods

Electronic questionnaires assessing physical and emotional health, the value of virtual care, and access to resources were distributed to patients with postponed (PP) orthopaedic restorative surgeries and those within three-months post-operative (PO) at the time of the COVID-19 health care closures. The EQ-5D-3L was included as a standardized measure of general health. Chi-square tests compared responses between sexes and age groups. Unpaired t-tests compared the EQ VAS by sex, and a one-way analysis of variance (ANOVA) compared the EQ VAS by age.

Results

Females in the PO group were more likely to report that their recovery was delayed (49.5% vs 36%) and that closures had negatively affected their recovery (p = 0.013). Females in the PP group reported more symptoms of pain/discomfort on the EQ-5D-3L (p = 0.023). In the PP group, patients aged 25 to 44 years were most likely to identify pain as a concern (p = 0.54). In the PO group, patients younger than 45 years reported a significantly lower mean EQ VAS health state ( p = 0.017). For the final analysis, there were 115 subjects in the PP group and 198 in the PO group.

Conclusion

This study demonstrated significant sex- and age-specific differences in health and recovery among orthopaedic sport medicine patients as a result of the COVID-19 health care closures. Females reported significantly more pain, anxiety, and delay in their rehabilitation, while younger patients reported greater negative impacts and worse overall health state.

Level of Evidence

IV.

Effect of Age, Sex and Gender on Pain Sensitivity: A Narrative Review

Introduction:

An increasing body of literature on sex and gender differences in pain sensitivity has been accumulated in recent years. There is also evidence from epidemiological research that painful conditions are more prevalent in older people. The aim of this narrative review is to critically appraise the relevant literature investigating the presence of age and sex differences in clinical and experimental pain conditions.

Methods:

A scoping search of the literature identifying relevant peer reviewed articles was conducted on May 2016. Information and evidence from the key articles were narratively described and data was quantitatively synthesised to identify gaps of knowledge in the research literature concerning age and sex differences in pain responses.

Results:

This critical appraisal of the literature suggests that the results of the experimental and clinical studies regarding age and sex differences in pain contain some contradictions as far as age differences in pain are concerned. While data from the clinical studies are more consistent and seem to point towards the fact that chronic pain prevalence increases in the elderly findings from the experimental studies on the other hand were inconsistent, with pain threshold increasing with age in some studies and decreasing with age in others.

Conclusion:

There is a need for further research using the latest advanced quantitative sensory testing protocols to measure the function of small nerve fibres that are involved in nociception and pain sensitivity across the human life span.

Implications:

Findings from these studies should feed into and inform evidence emerging from other types of studies (e.g. brain imaging technique and psychometrics) suggesting that pain in the older humans may have unique characteristics that affect how old patients respond to intervention.

Differences according to gender in reporting physical symptoms during echocardiographic screening in healthy teenage athletes

BACKGROUND

Many studies have suggested that more women then men present with physical symptoms. There is no data available, however, on the differences in reporting of physical symptoms between teenage male and female athletes. Our objective was to evaluate the differences according to gender in physical symptoms in healthy teenage athletes.

METHODS

A total of 1,465 high school athletes, between the ages of 13 and 19 years participated in a mass echocardiographic screening programme for detection of cardiac abnormalities. Screening was conducted using a hand-carried cardiac ultrasound device (OptiGo, Philips). All participants were actively involved in a high school sport programme. Each athlete was required to fill out a questionnaire before the screening. The athletes were asked to report the occurrence of physical symptoms with activity or exercise. A physical examination was not performed during screening.

RESULTS

There were 1,031 (70.4%) male and 434 (29.6%) female participants. Significantly more female teenage athletes reported physical symptoms (190/434, 43.8% versus 267/1,031, 25.9%, odds ratio: 2.28, confidence interval: 1.76-2.81, p less than 0.001). Symptoms did not correlate with any echocardiographically identified cardiac abnormalities in either gender. The differences in the reporting of symptoms were significant for all physical symptoms addressed by the questionnaire.

CONCLUSION

There is a high prevalence of reporting physical symptoms in young healthy athletes without any relation to cardiac abnormalities. Young female athletes report physical symptoms nearly twice as often as their male counterparts.

Does experimental pain response vary across the menstrual cycle? A methodological review

The findings on sex differences in human experimental pain research are inconsistent. One possible factor contributing to the inconsistent findings is the female hormonal cycle, as hormone levels may affect pain sensitivity. A number of studies suggest that women's responses to experimentally evoked pain vary across the menstrual cycle. However, at least an equal number of studies suggest a lack of variability. The purpose of this article is to review the literature with emphasis on what we believe could be the reasons for the inconsistent findings, namely, differences in populations sampled, timing of experimental sessions across the menstrual cycle, and nomenclature used to identify the time (phases) in the cycle when measurements were done, nature of the pain stimuli chosen, and outcomes measured. These inconsistencies and other methodological problems associated with most experimental pain studies make it difficult to draw inferences from this literature. For the science to improve, replication of significant findings using standardized timing of sessions, pain stimulus procedures, outcomes, and hormonal assessment is necessary.

Gender differences in patterns of cerebral activation during equal experience of painful laser stimulation

A previous functional imaging study demonstrated greater female response in the anterior insula and thalamus and left prefrontal activation in men and right prefrontal activation in women during equal heat intensity but unequal pain experience. For the current study, subjective intensities of noxious heat delivered to the back of the right hand were equalized across subjects, and regional cerebral blood flow was recorded by using positron emission tomography. The female subjects required less laser energy before reporting pain, but the difference was not significant. Correlation of regional cerebral blood flow with subjective pain experience in the whole group showed significant bilateral responses in the parietal, lateral premotor, prefrontal, secondary somatosensory, anterior cingulate and insula cortices, as well as the thalamus. There was significantly greater activation in the left, contralateral, prefrontal, primary and secondary somatosensory, parietal, and insula cortices in the male subjects compared with the female subjects and greater response in the perigenual cingulate cortex in the female subjects. Our study is the first to associate consistent pain experience with gender differences in central response. These differences may relate to differential processing of acute pain with implications for clinical disorders that show a female dominance. The subtle behavioral differences and inconsistent findings across studies, however, suggest the need for caution and further experimentation before speculating further.

Somatic symptom reporting in women and men

Women report more intense, more numerous, and more frequent bodily symptoms than men. This difference appears in samples of medical patients and in community samples, whether or not gynecologic and reproductive symptoms are excluded, and whether all bodily symptoms or only those which are medically unexplained are examined. More limited, but suggestive, literature on experimental pain, symptom reporting in childhood, and pain thresholds in animals are compatible with these findings in adults. A number of contributory factors have been implicated, supported by varying degrees of evidence. These include innate differences in somatic and visceral perception; differences in symptom labeling, description, and reporting; the socialization process, which leads to differences in the readiness to acknowledge and disclose discomfort; a sex differential in the incidence of abuse and violence; sex differences in the prevalence of anxiety and depressive disorders; and gender bias in research and in clinical practice. General internists need to keep these factors in mind in obtaining the clinical history, understanding the meaning and significance that symptoms hold for each patient, and providing symptom relief.

Affective pictures processing, attention, and pain tolerance

Two experiments were conducted to determine whether attention mediates the effects of affective distractors on cold pressor pain, or whether the cognitive processes of priming and appraisal best account for the effects. In Experiment I, 65 male respondents were exposed to either pleasant, neutral or unpleasant pictures selected from the International Affective Pictures System (IAPS). The cold-pressor test was administered simultaneously. Consistent with predictions based on priming and appraisal hypotheses, results revealed a linear trend across conditions, such that pain tolerance scores were higher as a function of picture pleasantness. A second study was conducted to examine the role of pain cues in the effects of negative affect on cold pressor pain. Thirty-nine male respondents were exposed to unpleasant pictures that either did or did not include pain-related material. Respondents who viewed pictures without pain cues tolerated the cold water for a longer period of time than respondents who viewed pictures that contained pain-related information. Priming and appraisal processes that might underlie the observed differences, and the type of affective distractors that could be meaningful for enhancing pain tolerance, are discussed.

Meta-Analysis of Thirty-Four Independent Samples Studied Using PET Reveals a Significantly Attenuated Central Response to Noxious Stimulation in Clinical Pain Patients

Chronic pain disorder is widely understood as a "biopsychosocial" phenomenon, meaning that it is influenced by psychology and certain life events. This broad understanding of chronic pain suggests that central responses during pain experience should be altered in patients compared with pain-free volunteers. A total of 34 studies are reviewed, revealing a widespread "neuromatrix" of activated regions. These regions include the brain stem, thalamus, and lentiform nucleus, and the insula, prefrontal, parietal, and anterior cingulate cortices. Meta-analysis of these studies does not reveal any single region or pattern of activity to be of particular influence during chronic pain but does reveal a generally reduced response to noxious stimulation in patients with concomitant clinical pain. The relevance of this finding remains unclear with the most parsimonious explanation being increased response variability in patients. More specific findings can be revealed when using a hypothesis-generated approach; further investigation of genetic and developmental predisposition is suggested.

Cerebral responses to pain in patients suffering acute post-dental extraction pain measured by positron emission tomography (PET)

Previous studies with normal volunteers have demonstrated distributed cortical responses to experimental heat pain within a network of structures. The network includes the insula, anterior cingulate, prefrontal, inferior parietal and somatosensory cortices. Patients suffering from chronic nociceptive pain following rheumatoid arthritis (RA) have shown damped central responses to experimental heat pain applied to the back of the right hand. In this study of patients with acute, left-sided, post-molar-extraction (surgical) pain, we assessed the cortical responses to experimental heat pain, applied to the back of the right hand, using positron emission tomography (PET), and compared the responses with a previously reported control group and the RA group. In response to the experimental heat pain, the surgical group indicated significantly increased regional cerebral blood flow in the prefrontal cortex [Brodman's area (BA) 44] ipsilateral to the heat stimulus. Contralateral increases were detected in the putamen and transverse temporal gyrus (BA 40/41/42) with bilateral increases in the insular cortex. Compared to the control and RA group, there were significantly reduced responses in the anterior cingulate (BA 24), pre-frontal medial, and orbito-frontal (BA 9/10/32/47) cortices. These results suggest that relatively discrete regions of the cerebral cortex are responsible for acute nociceptive processing during an acute inflammatory episode. The reduced frontal and anterior cingulate responses to the experimental heat pain (applied to the right hand) during acute inflammatory pain (left jaw) illustrates cortical modulation of nociceptive processing that may be related to non-somatotopic, bilateral, nociceptive inputs to these areas. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.