Body Image Measured via the Fremantle Awareness Questionnaire in Individuals With and Without Pain: A Systematic Review and Meta-Analysis.

Research suggests that pain negatively affects body image, and body image may also influence reported pain levels. This review aims to summarize the literature on differences in body image distortion between individuals with pain compared to pain-free individuals. The review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020 statement and an a priori preregistered protocol. The literature was searched using 5 electronic databases. Studies assessing body image with the Fremantle Awareness Questionnaire (FAQ) in individuals with and without pain were eligible for inclusion. Screening and selection of eligible studies were performed by independent reviewers. Methodological quality was assessed with the Joanna Briggs Institute critical appraisal tool. Meta-analyses, meta-correlations, and metamean analyses were performed using random-effect models. The primary outcome was the FAQ score; secondary outcomes were reported pain variables. Data from individuals with pain (n = 2277) and without pain (n = 615) were summarized. Significant body image distortions were found in individuals with pain compared to individuals without pain. Compared to pain-free individuals, the pain group rated significantly higher in the FAQ when experiencing back pain (standardized mean differences=1.33, 95% confidence interval=.88-1.77) or other body parts (standardized mean differences=1.25, 95% confidence interval=.51-1.99). The results of meta-correlation analyses confirmed the positive relationship between body image distortion and pain intensity (r = .31), pain at rest (r = .31), or pain during movement (r = .36), but not for pain duration. A difference in mean FAQ results was observed between individuals with pain in different areas (knee and back). PERSPECTIVE: This review confirms differences in body image distortion between pain and pain-free individuals. Pain intensity was correlated with altered body perception, but not pain duration. A moderate correlation was observed between body image distortion and reported pain variables. Body image was more impaired by knee pain than back pain. REGISTERED PROTOCOL AT PROSPERO: CRD42022309937; https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022309937.

Spatial summation of pain is associated with pain expectations: Results from a home-based paradigm.

The purpose of this study was to reproduce the previously observed spatial summation of pain effect (SSp) using non-laboratory procedures and commercial equipment. An additional aim was to explore the association between expectations and SSp. The Cold Pressor Task (CPT) was used to induce SSp. Healthy participants (N = 68) immersed their non-dominant hands (divided into 5 segments) into cold water (CPT). Two conditions were used 1) gradual hand immersion (ascending condition) and 2) gradual hand withdrawal (descending condition). Pain intensity was measured on a Visual Analogue Scale (VAS). Psychological factors, such as the participants' expectations of pain intensity were also measured on a VAS. Results showed significant SSp (χ2(4) = 116.90, p < 0.001), reproduced with non-laboratory equipment in a home-based set-up. Furthermore, two novel findings were observed: i) there was a significant correlation between expectations and perceived pain, indicating a link between pain expectations and SSp, ii) spatial summation increased with the increase in duration exposure to the noxious stimulus (Wald χ2(8) = 80.80, p < 0.001). This study suggests that SSp is associated with pain expectations and can be formed by a mixture of excitatory and inhibitory mechanisms potentially driven by temporal characteristics of neural excitation. Moreover, this study proposes a new feasible way to induce SSp using a home-based set-up.

Tactile Precision Remains Intact When Acute Neck Pain Is Induced.

A growing body of evidence suggests that chronic pain is associated with perceptual changes, such as impaired tactile acuity and laterality judgements. A recent study on low back pain showed that tactile acuity was decreased immediately after acute pain induction. Biologically, acute pain should lead to enhanced rather than disruptive changes in tactile acuity to meaningfully respond to potentially damaging nociceptive stimuli. In this double-blinded experiment, 30 healthy volunteers attended 3 experimental sessions (injection, sham injection, and control condition) separated by 1 week each, to investigate the effect of acute nociception on tactile precision and laterality judgements. In the real injection condition, acute pain was induced by hypertonic saline solution injected into the mid portion of the trapezius muscle. Tactile acuity (2-point discrimination and an estimation task) and laterality judgements were measured before and during pain perception. In the sham condition, the injection was mimicked by a sham procedure (without piercing the skin), and in the control condition no intervention took place. Results showed that tactile acuity remained intact (P = .92), indicating that experimentally induced neck pain did not affect tactile precision. The time needed to complete the laterality judgement task improved over time in all conditions, reflecting a learning effect (P = .05). We conclude that acute neck pain does not result in perceptual distortions, possibly reflecting a higher protection demand for the neck, a body region in close anatomic proximity to neural centers responsible for vital functions. These data-in the context of existing evidence-indicates that tactile acuity may respond differently to noxious stimulation in different anatomic regions. PERSPECTIVE: In this study, a sensory adaptation to acute neck pain was investigated. It was found that experimental neck pain did not elicit changes in the sensory axis, leaving tactile acuity intact in otherwise healthy participants. These data support site-specific sensory adaptation to pain.