Does pain hypervigilance further impact the lack of habituation to pain in individuals with chronic pain? A cross-sectional pain ERP study

Individual differences in response to repeated painful stimulation: Habituation, sensitization, and nocebo effects

The present study analyzes habituation, sensitization, and nocebo effects based on individual differences in response to painful stimulation. Habituation and sensitization to pain show two opposite patterns that may occur during repeated painful stimulation. Negative expectations such as a nocebo manipulation have been shown to increase pain ratings, but it is unclear to what extent they can influence habituation and sensitization to pain. In this preregistered study, we investigate the effects of repeated painful stimulation across time with pain intensity and unpleasantness ratings, individual differences in the response trajectories, and the impact of a nocebo manipulation in the context of habituation and sensitization response subgroups. We included 60 participants (26 male, 34 female, age 18-60) who received repeated painful electrical stimulation across four runs. Half of the participants received a negative verbal expectation (i.e., nocebo manipulation) after the third run. Participants provided both intensity and unpleasantness ratings after each stimulus. The results demonstrated large individual variability in responses. On the group level, participants showed sensitization to pain which decreased across runs. Individual slopes across and within-runs varied greatly, starting with mostly sensitization and ending with habituation profiles. Habituation of pain intensity and unpleasantness was highly correlated. The nocebo manipulation resulted in a significant nocebo effect, demonstrating a large increase in pain and unpleasantness ratings. In summary, this study showed large individual differences and the impact of a nocebo manipulation on the background of different response profiles. PERSPECTIVE: Repeated painful stimulation resulted in patterns of habituation and sensitization, with large individual variability that differed for across and within-run analyses. Pain intensity and unpleasantness ratings were highly correlated. A nocebo manipulation demonstrated increased intensity and unpleasantness reports, even after habituation and sensitization patterns were established.

Exploring the connectivity of dorsolateral prefrontal cortex and the modulatory impact of transcranial magnetic stimulation in adolescents with depression: a focus on pain-related cognitive processing

BACKGROUND

Abnormal cognitive response to pain is consistently associated with deleterious outcomes among adolescents with depression. Highly relevant to both pain and cognition, dorsolateral prefrontal cortex (DLPFC) is important to understanding pain cognition. Our study aimed to characterize the circuit of DLPFC and the efficacy of transcranial magnetic stimulation (TMS) over DLPFC on pain cognition in adolescents with depression.

METHODS

Using neuroimaging data, we first compared functional connectivity (FC) of DLPFC between 60 adolescents with depression and 65 controls. The patients were then divided into add-on TMS group (N = 30) and Sertraline group (N = 30). Clinical outcome was determined using Pain Vigilance and Awareness Questionnaire (PVAQ) and Pain Catastrophizing Scale (PCS). Finally, we conducted regression analysis to assess the effect that FC of DLPFC contributes to in predicting clinical outcome.

RESULTS

FC analysis showed that compared to controls, patients displayed hyperconnection of left DLPFC - left triangular part of inferior frontal gyrus (IFG), which was significantly correlated with higher PCS total-, magnification- and helplessness-scores. Patients also showed hyperconnection of right DLPFC - right supramarginal gyrus (SMG), which was correlated with lower PCS total- and rumination- scores. After intervention, the add-on TMS group displayed significantly decreased score on PVAQ, PCS total and rumination. FC of left DLPFC - bilateral triangular part of IFG, - right SMG, as well as right DLPFC - left putamen, could predict the improvement of pain vigilance and magnification.

CONCLUSION

Our results point to a key role of DLPFC acting as a connection linking cognitive control and pain processing in adolescents with depression.

TRIAL REGISTRATION

The study is registered in https://www.chictr.org.cn/ with a registration number ChiCTR2000039503 (date: 10.30.2020).

Hypervigilance to pain and sleep quality are confounding variables in the infrared thermography examination of the temporomandibular joint and temporal and masseter muscles

OBJECTIVES

Verify whether hypervigilance to pain (HP) and sleep quality (SQ) are confounding variables in the infrared thermography (IT) examination of the temporomandibular joint and temporal and masseter muscles.

METHODS

A cross-sectional and analytical study was conducted, collecting HP and SQ data from 80 participants without temporomandibular disorders (TMD), performing their IT and another 40 participants with TMD. For the selection of participants with and without TMD, the TMD Pain Screener questionnaire and axis I of the Diagnostic Criteria for Temporomandibular Disorders were applied. SQ was verified using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. For the HP assessment the Pain Vigilance and Awareness Questionnaire (PVAQ) was applied. And the IT was performed through a FLIR infrared sensor camera, model T650 Infrared.

RESULTS

No significant correlations were found between SQ and the temperatures of the areas of interest (P > .05), and regarding HP, a statistically significant positive correlation was found with the dimensionless (ρ = 0.289) and non-dimensionless (ρ = 0.223) asymmetries of temporal muscle temperatures. In the temperature comparisons between the participants without TMD and the participants with TMD, significant differences were found (P < .05), also when the group without TMD was controlled according to both HP and SQ (P < .05), with higher temperatures found in the TMD group.

CONCLUSIONS

HP and SQ can be considered confounding variables in IT examination of the temporomandibular region.

Modulation of attention to pain by goal-directed action: a somatosensory evoked potentials approach

Background

Attentional processes are modulated by current goal pursuit. While pursuing salient cognitive goals, individuals prioritize goal-related information and suppress goal-irrelevant ones. This occurs in the context of pain too, where nonpain cognitive goal pursuit was found to have inhibitory effects on pain-related attention. Crucially, how pursuing nonpain motor goals affects pain-related somatosensory attention is still unknown. The aim of this study was to investigate whether nonpain motor goal pursuit would attenuate pain-related somatosensory attention.

Methods

Healthy volunteers (N = 45) performed a robotic arm conditioning task where movements were paired with conflicting (pain and reward), threatening (only pain) or neutral (no pain and no reward) outcomes. To increase the motivational value of pursuing the nonpain motor goal, in the conflicting condition participants could receive a reward for a good motor performance. To examine somatosensory attention during movement, somatosensory evoked potentials (SEPs; N120 and P200) were obtained in response to innocuous tactile stimuli administered on a pain-relevant or pain-irrelevant body location. We expected that the threat of pain would enhance somatosensory attention. Furthermore, we expected that the possibility of getting a reward would inhibit this effect, due to pain-reward interactions.

Results

Against our predictions, the amplitude of the N120 did not differ across movement types and locations. Furthermore, the P200 component showed significantly larger SEPs for conflicting and threat movements compared to neutral, suggesting that the threat of pain increased somatosensory attention. However, this effect was not modulated by nonpain motor goal pursuit, as reflected by the lack of modulation of the N120 and P200 in the conflicting condition as compared to the threat condition. This study corroborates the idea that pain-related somatosensory attention is enhanced by threat of pain, even when participants were motivated to move to obtain a reward.

Dosage matters: Uncovering the optimal duration of pain neuroscience education to improve psychosocial variables in chronic musculoskeletal pain. A systematic review and meta-analysis with moderator analysis

The aim was to examine the moderator effect of duration of PNE (total minutes) on changes in psychosocial variables after treatment in people with chronic musculoskeletal pain. PubMed/MEDLINE, Embase, Web of Science, Scopus and CINHAL databases were systematically searched from inception to 6 February 2023. A mixed-effects meta-regression was performed to determine the moderator effect of PNE duration. Twenty-three studies involving 2352 patients were included. Meta-analysis revealed a statistically significant effect in favour of PNE on pain neurophysiology knowledge, anxiety symptoms, catastrophizing and kinesiophobia. The total duration of PNE ranged from 40 to 720 min. A linear relationship was observed between longer duration of PNE (total minutes) and changes of psychosocial variables. In addition, a dose of 100, 200 and 400 min of PNE was estimated to exceed the minimum clinically important difference described in the literature for kinesiophobia (mean difference = -8.53 points), anxiety symptoms (mean difference = -1.88 points) and catastrophizing (mean difference = -7.17 points). Clinicians should provide a more tailored PNE to address psychosocial variables.

Habituation to Pain in Patients with Chronic Pain: Clinical Implications and Future Directions

In this review, the latest insights into habituation to pain in chronic pain are summarized. Using a systematic search, results of studies on the evidence of habituation to (experimental) pain in migraine, chronic low back pain, fibromyalgia, and a variety of chronic pain indications are presented. In migraine, reduced habituation based on self-report and the EEG-based N1 and N2-P2 amplitude is reported, but the presence of contradictory results demands further replication in larger, well-designed studies. Habituation to pain in chronic low back pain seems not to differ from controls, with the exception of EEG measures. In fibromyalgia patients, there is some evidence for reduced habituation of the N2-P2 amplitude. Our analysis shows that the variability between outcomes of studies on habituation to pain is high. As the mechanisms underlying habituation to pain are still not fully understood and likely involve several pathways, it is now too early to conclude that habituation to pain is related to clinical outcomes and can be used as a diagnostic marker. The review ends with a discussion on future directions for research including the use of standard outcome measures to improve comparisons of habituation to pain in patients and controls, as well as a focus on individual differences.

The interpersonal-psychological theory of suicide and the role of psychological pain during the COVID-19 pandemic: A network analysis

INTRODUCTION

Among the most investigated theories explaining suicidal behavior there are the interpersonal-psychological theory of suicide (IPTS) by Thomas E. Joiner and the one focused on the construct of psychological pain (or psychache, or mental pain).

OBJECTIVE

Since it remains unclear whether these two different theories correlate with each other in the explanation of suicidal risk, we used a network analysis approach to investigate the complex interplay between both IPTS and psychological pain theories and history of suicidal planning and/or suicide attempt (SP/SA).

METHODS

A sample of 1,586 university students from various Italian universities was recruited between April 24th, 2020 and February 23rd, 2021, hence during the COVID-19 pandemic. To be included subjects should have been university students and aged between 18 and 35 years old.

RESULTS

Within a network that included the core factors from both models (IPTS and psychological pain), higher fearlessness about death (Acquired Capability for Suicide Scale-Fearlessness About Death, ACSS-FAD) and higher psychological pain (Psychache Scale) were the variables most strongly associated with history of SP/SA.

CONCLUSIONS

Considering a large number of variables, history of SP/SA was explained in particular by fearlessness about death and psychological pain in university students. Hence these aspects should be targeted in the treatment for suicide prevention.

Auditory change-related cortical response is associated with hypervigilance to pain in healthy volunteers

Background

Patients with chronic pain exhibit hypervigilance (heightened responsiveness to stimuli) to innocuous auditory stimuli as well as noxious stimuli. “Generalized hypervigilance” suggests that individuals who show heightened responsiveness to one sensory system also show hypervigilance to other modalities. However, research exploring the existence of generalized hypervigilance in healthy subjects is limited.

Methods

We investigated whether hypervigilance to pain is associated with auditory stimuli in healthy subjects using the pain vigilance and awareness questionnaire (PVAQ) and auditory change‐related cortical responses (ACRs). ACRs are thought to reflect a change detection system, based on preceding sensory memory. We recorded ACRs under conditions that varied in terms of the accumulation of sensory memory as follows: short‐ACR, with short preceding continuous stimuli and long‐ACR, with long preceding continuous stimuli. In addition, the attention to pain (PVAQ‐AP) and attention to changes in pain (PVAQ‐ACP) subscales were evaluated.

Results

Amplitudes of long‐ACR showed significant positive correlations with PVAQ‐ACP, whereas those of short‐ACR did not show any significant correlations.

Conclusions

Generalized hypervigilance may be observed even in healthy subjects. ACR may be a useful index to evaluate the hypervigilance state in the human brain.

Esophageal hypervigilance is prevalent across gastroesophageal reflux disease presentations

BACKGROUND

There is a need to identify factors outside of abnormal reflux that contribute to gastroesophageal reflux disease (GERD). Esophageal hypervigilance is a psychological process impacting symptom experience in esophageal disease. However, little is known about the presence of hypervigilance in GERD phenotypes, especially in those with abnormal acid exposure or symptom index scores. The primary aim was to assess differences in self-reported esophageal hypervigilance across different GERD presentations. The secondary aim was to evaluate esophageal hypervigilance as a predictor of symptom severity.

METHODS

We conducted retrospective data analyses on a cohort of adult patients with reflux symptoms that underwent 96-hour wireless pH monitoring from 9/2015 to 9/2017. Patients were stratified into groups based on the number of days they exhibited positive acid exposure time (AET; 0 days, 1-2 days, 3+ days), and symptom index scores (SI; 0 days, 1-day, 2+ days). Esophageal hypervigilance and anxiety, and symptom frequency and severity were assessed between groups.

KEY RESULTS

A total of 123 AET cases and 116 SI cases were included for analysis. Esophageal hypervigilance and anxiety scores did not significantly differ based on the number of days of positive AET (p = 0.311) or SI (p = 0.118). Symptom severity and perceived symptom frequency differed between groups. Hypervigilance significantly predicted symptom severity, when controlling for symptom-specific anxiety.

CONCLUSIONS

Esophageal hypervigilance is persistent across patients with reflux, irrespective of acid burden and symptom index, and significantly predicts symptom severity. Hypervigilance should be considered as an independent factor contributing to esophageal symptom perception.

Motor action changes pain perception: a sensory attenuation paradigm in the context of pain

ABSTRACT

A large body of evidence indicates how pain affects motor control, yet the way the motor system influences pain perception remains unclear. We present 2 experiments that investigated sensory attenuation of pain implementing a 2-alternative forced choice paradigm. Particularly, healthy participants received painful stimuli on a moving and nonmoving hand during the execution or the preparation of reaching motor actions. At the end of each trial, they indicated on which hand they perceived the stimulus stronger. The point of subjective equality was obtained to measure sensory attenuation. The intensity (experiment 1) and the threat value (experiment 2) of the pain stimuli were manipulated between-subjects to examine their impact on sensory attenuation. Results of experiment 1 (N = 68) revealed that executing a motor action attenuates pain processing in the moving hand. Sensory attenuation during motor preparation alone occurred with stronger stimulus intensities. Sensory attenuation was not affected by the intensity of the pain stimuli. Results of experiment 2 (N = 79) replicated the phenomenon of sensory attenuation of pain during motor action execution. However, sensory attenuation was not affected by the threat value of pain. Together these findings indicate that executing, but not preparing, a motor action affects pain processing in that body part. No significant associations were found between sensory attenuation indices and inhibitory control abilities or pain catastrophizing, vigilance and rumination. These results provide insight into the inhibitory effects of motor actions on pain processing, suggesting that pain perception is a dynamic experience susceptible to individuals' actions in the environment.

C-tactile touch perception in migraineurs – a case-control study

Background

Migraine is characterized by sensory hypersensitivity and habituation deficits. Slow brushing over the skin activates C-tactile nerve fibers, which mediate pleasant touch and analgesic effects in healthy subjects. As this function is altered in painful conditions, we aimed to examine whether the C-tactile processing is disrupted in migraines.

Methods

To psychophysically assess C-tactile function, we applied optimal and suboptimal C-tactile stroking stimuli on the dorsal forearm (body reference area) and the trigeminally innervated skin of 52 interictal migraineurs and 52 matched healthy controls. For habituation testing, 60 repeated C-tactile optimal stimuli were presented in both test areas. The participants rated each stimulus on a visual analogue scale by intensity, pleasantness, and painfulness.

Results

Regarding C-tactile function, migraineurs showed unphysiological rating patterns but no significantly different pleasantness ratings than controls. During repeated stimulation, controls showed stable pleasantness ratings while migraineurs’ ratings decreased, especially in those experiencing tactile allodynia during headaches. Migraineurs taking triptans responded like controls.

Conclusion

The C-tactile function of migraineurs is subclinically altered. Repeated C-tactile stimulation leads to altered habituation but differs from previous work by the direction of the changes. Although the pathophysiology remains unknown, causative mechanisms could include central and peripheral neuronal sensitization, tactile allodynia and hedonic stimulus attributions.