The evaluation and brain representation of pleasant touch in chronic and subacute back pain

The association of spouse interactions and emotional learning in interference related to chronic back pain

Social interactions affect individual behaviours, preferences, and attitudes. This is also critical in the context of experiencing pain and expressing pain behaviours, and may relate to learned emotional responses. In this respect, individual variability in the medial prefrontal cortex (mPFC), which is involved in adjusting an organism's behaviour to its environment by evaluating and interpreting information within the context of past experiences, is important. It is critical for selecting suitable behavioural responses within a social environment and may reinforce maladaptation in chronic pain. In our study, we used brain imaging during appetitive and aversive pavlovian conditioning in persons with chronic back pain (CBP), subacute back pain (SABP), and healthy controls (HC), together with information on spouse responses to pain behaviours. We also examined the relationship of these responses with pain-related interference in the patients. Our findings yielded a significant negative association between mPFC responses to appetitive and aversive learning in CBP. We also observed a significant negative association for mPFC responses during aversive learning and distracting spouse responses, and a significant positive association between mPFC responses during appetitive learning and solicitous spouse responses in CBP. Both significantly predicted pain-related interference in the CBP group (explained variance up to 53%). Significant associations were not found for SABP or HC. Our findings support an association between appetitive and aversive pavlovian learning, related brain circuits and spouse responses to pain in CBP, where appetitive and aversive learning processes seem to be differentially involved. This can inform prevention and early intervention in a mechanistic approach.

The analgesic power of pleasant touch in individuals with chronic pain: Recent findings and new insights

This mini-review covers recent works on the study of pleasant touch in patients with chronic pain (CP) and its potential use as a treatment. While experiments have demonstrated that pleasant touch, through the activation of CT-afferents and the brain regions involved in its affective value, might reduce the unpleasantness and intensity of induced pain, the interaction between pleasant touch and CP remains under-examined. Some experiments show that CP might disrupt the positive aspects of receiving pleasant touch, while in other studies the perception of pleasantness is preserved. Moreover, only a few attempts have been made to test whether touch can have a modulatory effect on CP, but these results also remain inconclusive. Indeed, while one recent study demonstrated that CT-touch can diminish CP after a short stimulation, another study suggested that pleasant touch might not be sufficient. Future studies should further investigate the psychological and neural interplay between pleasant touch and CP. In the conclusion of this mini-review, we propose a new tool we have recently developed using immersive virtual reality (IVR).

A Case-Series of Dry Needling as an Immediate Sensory Integration Intervention

BACKGROUND

Chronic low back pain (CLBP) has been associated with altered cortical mapping in the primary somatosensory cortex. Various sensory discrimination treatments have been explored to positively influence CLBP by targeting cortical maps.

OBJECTIVES

To determine if dry needling (DN) applied to patients with CLBP would yield changes in two-point discrimination (TPD) and left-right judgment (LRJ) tasks for the low back. Secondary measurements of pain and limited range of motion (ROM) was also assessed.

METHODS

A sample of 15 patients with CLBP were treated with DN to their low back. Prior to and immediately after DN, TPD, LRJ tasks, low back pain, spinal ROM, and straight leg raise (SLR) were measured.

RESULTS

Following DN, there was a significant (p < 0.005) improvement in LRJ for low back images in all measures, except accuracy for the right side. TPD significantly improved at the L3 segment with a moderate effect size. A significant improvement was found for pain and trunk ROM after DN with a large effect in changing pain of 3.33 points and improving SLR by 9.0 degrees on average, which exceeds the minimal detectable change of 5.7 degrees.

CONCLUSIONS

This is the first study to explore if DN alters TPD and LRJ tasks in patients with CLBP. Results show an immediate significant positive change in TPD and LRJ tasks, as well as pain ratings and movement.

Pleasant touch perception in borderline personality disorder and its relationship with disturbed body representation

BACKGROUND

Borderline personality disorder (BPD) is characterized by altered perception of affective stimuli, including abnormal evaluation of nociceptive input. However, whether or not perceptual alterations are present for its positive counterpart, i.e. pleasant touch (PT), has not yet been examined.

METHODS

In the present study, we applied standardized PT stimuli to the hands of 25 patients with BPD and 25 healthy controls (HC) and compared their perception. We used the affect-modulated acoustic startle response as a physiological correlate of affective processing. We further explored the effect of PT stimulation on dissociative experiences in BPD.

RESULTS

Compared to HC, BPD perceived PT as less pleasant and less intense. The effect on perceived valence of touch was large even after controlling for the effect of reduced perceived intensity of touch (ƞ² = .29). We further found qualitative alterations in touch perception in BPD, who rated the touch as significantly rougher and firmer compared to HC. There was a positive correlation between perceived valence of touch and changes in dissociative experiences in terms of body ownership of the stimulated body part from pre to post stimulation, suggesting that a more negative evaluation of touch is associated with an increase in body-related dissociative experiences, while a positive perception of touch might be related to a reduction of these dissociative experiences.

CONCLUSIONS

Our results confirm BPD-associated disturbances in the processing of affective somatosensory stimuli and indicate that not only pain perception but also pleasant touch perception is diminished in BPD. We discuss the role of altered touch perception for BPD psychopathology and its potential role for new treatment approaches.

The efficacy of Tuina with herbal ointment for patients with post-stroke depression: study protocol for a randomized controlled trial

BACKGROUND

Post-stroke depression (PSD) is a common complication after stroke which hinders functional recovery and return to social participation of stroke patients. Efficacy of conventional drug therapies for patients with PSD is still uncertain. Therefore, many patients prefer to use complementary and alternative therapies for PSD. Tuina (traditional Chinese manual manipulation) with herbal ointment is an integration of manual therapy, and ointment is an important part of traditional Chinese medicine (TCM) therapy. Preliminary experiments have shown that the Tuina with herbal ointment can improve the mental state of patients with PSD. The purpose of this study is to observe and verify the efficacy of Tuina combined with herbal ointment for patients with post-stroke depression, and to lay a foundation for further research on its mechanism of action.

METHODS/DESIGN

In this study, a randomized controlled trial will be conducted in parallel, including two intervention groups: Tuina with herbal ointment group and herbal ointment for control group. A total of 84 eligible participants will be randomly assigned to the groups in a 1:1 ratio. All participants will receive conventional antidepressant venlafaxine treatment (75 mg QD), on which they received two different interventions. The interventions for both groups will be carried out 5 times each week for a period of 2 weeks. The primary outcome will be the Hamilton Rating Scale for Depression (HAMD). Secondary outcomes will include transcranial magnetic stimulation (TMS), as well as 36-item Short-Form Health Survey (SF-36) and Treatment Emergent Symptom Scale (TESS). They will be assessed at the baseline, at the end of the intervention (2 weeks), and during the 1 month and 3 months of follow-up by repeated measures analysis of variance. The significance level is 5%. Adverse events will be monitored at each visit to assess safety. All outcomes will be assessed and analyzed by researchers blinded to the treatment allocation. The purpose of this study will focus on observing the efficacy of Tuina with herbal ointment for patients with post-stroke depression, and to explore further the mechanisms of its effects.

DISCUSSION

This study may evaluate clinical application value and safety of Tuina with herbal ointment in PSD patients, which can provide basis for clinical research and mechanism exploration of PSD.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000033887 . Registered on 15 June 2020.

DISSEMINATION

The results will be published in peer-reviewed journals and disseminated through the study's website and conferences.

Strengths and weaknesses of affective touch studies over the lifetime: A systematic review

C-Tactile (CT) fibers are activated by slow, caress-like stimulations, and convey a specific tactile processing of hedonic and interpersonal components, defined as affective touch. Given the beneficial effects deriving from affective tactile experiences in social interactions at all ages, a systematic review of experimental studies on affective touch perception across the lifespan was performed with the aims of 1) examining whether and how affective touch has been studied in a systematic manner throughout the lifespan; 2) verifying whether the pleasantness associated to affective stimulations is found during the entire lifespan. Empirical human studies on affective touch were searched in two databases (PubMed, PsychINFO) and 112 articles were retrieved. Results indicated that most of the studies recruited participants with a mean age ranging from 18 to 40 years, whereas other age ranges came out as under-represented or not represented at all. Despite high heterogeneity across studies, affective touch was considered as a pleasant experience across the lifetime, and it was associated to specific psychophysiological patterns in infants and adults.

Altered Interoceptive Perception and the Effects of Interoceptive Analgesia in Musculoskeletal, Primary, and Neuropathic Chronic Pain Conditions

Chronic pain (CP) severely disrupts the daily life of millions. Interoception (i.e., sensing the physiological condition of the body) plays a pivotal role in the aetiology and maintenance of CP. As pain is inherently an interoceptive signal, interoceptive frameworks provide important, but underutilized, approaches to this condition. Here we first investigated three facets of interoceptive perception in CP, compared with pain-free controls. We then introduce a novel interoceptive treatment and demonstrate its capacity to reduce pain severity in CP, potentially providing complementary analgesic treatments. Study 1 measured interoceptive accuracy, confidence and sensibility in patients (N = 60) with primary, secondary musculoskeletal, and neuropathic CP. Compared with matched controls, CP participants exhibited significantly lower interoceptive accuracy and interoceptive confidence. Pain severity was predicted positively by interoceptive accuracy, anxiety and depression, and negatively by interoceptive confidence. Study 2 tested a promising new interoceptive treatment for CP, in a single-blind between-subjects design (N = 51) with primary, secondary musculoskeletal, and neuropathic CP patients. The treatment specifically activates the C-Tactile system, by means of controlled stimulation of interoceptive unmyelinated afferents, at 3 cm/s with a force of 2.5 mN. This treatment led to significant pain reduction (mean 23%) in the CP treatment group after only 11 min, while CP controls who received comparable but non-interoceptive stimulation reported no change in pain intensity. These studies highlight the importance of interoceptive approaches to CP and demonstrate the potential of this novel method of C-Tactile stimulation to provide complementary analgesic treatments.

The body comes first. Embodied reparation and the co-creation of infant bodily-self

During infancy relational experiences of body-to-body exchanges (i.e., embodied interactions) contribute to the infant's bodily perception. Early embodied interactions are based on countless multimodal reciprocal exchanges, in which mother and infant contribute to interpersonal rhythmic cycles of co-regulation (i.e., attunement). However, it remains unclear how infants and their mothers actually accomplish attunement in their exchanges. Interactions between mothers and their infants typically fluctuate between attuned and misattuned states and recovery attunement states by a process called 'reparation'. Here, we discuss recent neuroscientific evidence that provides insight into the mechanisms underpinning the concepts of attunement and misattunement in early embodied interactions. We propose that a process of embodied reparation might be achieved within the dyad through tactile contact behaviors (e.g., skin-to-skin, affectionate touch) and maternal interoceptive sensitivity (i.e., ability to perceive internal input about the state of one's own body). We describe how these elements that mothers provide during embodied interactions with their infants, might contribute not only to bodily attunement, but also to co-create the infant bodily-self.