Pain mechanisms in complex regional pain syndrome: a systematic review and meta-analysis of quantitative sensory testing outcomes

Visuotactile integration in individuals with fibromyalgia

Our brain constantly integrates afferent information, such as visual and tactile information, to perceive the world around us. According to the maximum-likelihood estimation (MLE) model, imprecise information will be weighted less than precise, making the multisensory percept as precise as possible. Individuals with fibromyalgia (FM), a chronic pain syndrome, show alterations in the integration of tactile information. This could lead to a decrease in their weight in a multisensory percept or a general disruption of multisensory integration, making it less beneficial. To assess multisensory integration, 15 participants with FM and 18 pain-free controls performed a temporal-order judgment task in which they received pairs of sequential visual, tactile (unisensory conditions), or visuotactile (multisensory condition) stimulations on the index and the thumb of the non-dominant hand and had to determine which finger was stimulated first. The task enabled us to measure the precision and accuracy of the percept in each condition. Results indicate an increase in precision in the visuotactile condition compared to the unimodal conditions in controls only, although we found no intergroup differences. The observed visuotactile precision was correlated to the precision predicted by the MLE model in both groups, suggesting an optimal integration. Finally, the weights of the sensory information were not different between the groups; however, in the group with FM, higher pain intensity was associated with smaller tactile weight. This study shows no alterations of the visuotactile integration in individuals with FM, though pain may influence tactile weight in these participants.

Impact of different CRPS phenotypes and diagnostic criteria on quantitative sensory testing outcomes: systematic review and meta-analysis

OBJECTIVES

This review and meta-analysis evaluated the impact of diagnostic criteria and clinical phenotypes on quantitative sensory testing (QST) outcomes in patients with complex regional pain syndrome (CRPS).

METHODS

Eight databases were searched based on a previously published protocol. Forty studies comparing QST outcomes between CRPS-I vs II, warm vs cold CRPS, upper vs lower limb CRPS, males vs females, or using Budapest vs older IASP criteria were included.

RESULTS

Studies investigating QST differences between CRPS-I vs II (n = 4), between males vs females (n = 2), and between upper and lower limb CRPS (n = 2) showed no significant differences. Four studies compared QST outcomes in warm vs cold CRPS, showing heat hyperalgesia in warm CRPS, with thermal and mechanical sensory loss in cold CRPS. Although CRPS diagnosed using the Budapest criteria (24 studies) vs 1994 IASP criteria (13 studies) showed similar sensory profiles, there was significant heterogeneity and low quality of evidence in the latter.

CONCLUSIONS

Based on the findings of this review, classifying CRPS according to presence or absence of nerve lesion into CRPS-I and II, location (upper or lower limb) or according to sex might not be clinically relevant as all appear to have comparable sensory profiles that might suggest similar underlying mechanisms. In contrast, warm vs cold phenotypes exhibited clear differences in their associated QST sensory profiles. To the extent that differences in underlying mechanisms might lead to differential treatment responsiveness, it appears unlikely that CRPS-I vs II, CRPS location, or patient sex would prove useful in guiding clinical management.

Arthroscopic ankle surgery in people with haemophilia

INTRODUCTION

People with haemophilia (PWH) not administered primary haematological prophylaxis since childhood, that is, those treated haematologically on demand or not treated at all, often experience the degeneration of the ankles, leading to pain and functional impairment.

AIM

To analyse the outcomes and complications of arthroscopic ankle surgery performed on PWH.

METHODS

For this narrative review of the literature, a search was conducted in PubMed on 2, December 2023, using the keywords "haemophilia", "ankle" and "arthroscopy". Of the 29 articles identified, 15 specifically related to ankle arthroscopy in PWH were selected (inclusion criterion). The remaining articles did not meet this requirement (exclusion criterion) and were therefore eliminated.

RESULTS

Arthroscopic procedures (arthroscopic synovectomy, debridement and arthrodesis of the ankle) are increasingly used in the surgical treatment of haemophilic ankle arthropathy. Although arthroscopic ankle surgery offers good outcomes in patients with haemophilia, the procedure is not free of complications, which range from 7.9% for arthroscopic ankle debridement to 13.1% in arthroscopic ankle synovectomy and 17.8% in arthroscopic ankle arthrodesis, respectively. The non-union rate of arthroscopic ankle arthrodesis is 7.1% (2/28).

CONCLUSION

Although arthroscopic interventions in the haemophilic ankle (synovectomy, debridement, arthrodesis) offer good functional outcomes, they are associated with a non-negligible rate of complications. Arthroscopic ankle surgery in PWH is major surgery and should be treated as such.

Complications of ankle arthroscopy: frequency, prevention, and treatment

The complication rate of ankle arthroscopy (AA) ranges from 3.5% to 14%. To avoid such complications, it is essential to have a thorough understanding of the anatomy of the ankle, to perform the procedure very carefully and with appropriate instrumentation, and to use a non-invasive distraction technique. The most frequent complications are neurological (cutaneous nerve injuries), which are usually caused by direct injury during arthroscopic portals or by a distracting pin when using an invasive distraction technique. They usually resolve spontaneously within a few months. The iatrogenic formation of a pseudoaneurysm is a severe but extremely rare complication (an incidence of 0.008%). There are several treatments for pseudoaneurysms: external compression; direct thrombin injection, surgical intervention (resection of the damaged segment of the artery and reconstruction with a reversed long saphenous vein interposition graft), and endovascular embolisation. Other rare complications include wound infections (localised superficial infection), problems at the portal incisions (prolonged portal drainage, residual pain in the portal, portal scar dehiscence, cyst at the portal site), type I complex regional pain syndrome, instrument breakage, painful scars and nodules, and a number of other rarer complications. In conclusion, when performing AA, it is important to remember the potential complications and try to avoid them. When they do occur, it is essential to diagnose and treat them appropriately.

A Systematic Review and Meta-analysis of Non-pharmacological Methods to Manipulate Experimentally Induced Secondary Hypersensitivity

This systematic review and meta-analysis investigated the effects of non-pharmacological manipulations on experimentally induced secondary hypersensitivity in pain-free humans. We investigated the magnitude (change/difference in follow-up ratings from pre-manipulation ratings) of secondary hypersensitivity (primary outcome), and surface area of secondary hypersensitivity (secondary outcome), in 27 studies representing 847 participants. Risk of bias assessment concluded most studies (23 of 27) had an unclear or high risk of performance and detection bias. Further, 2 (of 27) studies had a high risk of measurement bias. Datasets were pooled by the method of manipulation and outcome. The magnitude of secondary hypersensitivity was decreased by diverting attention, anodal transcranial direct current stimulation, or emotional disclosure; increased by directing attention toward the induction site, nicotine deprivation, or negative suggestion; and unaffected by cathodal transcranial direct current stimulation or thermal change. Area of secondary hypersensitivity was decreased by anodal transcranial direct current stimulation, emotional disclosure, cognitive behavioral therapy, hyperbaric oxygen therapy, placebo analgesia, or spinal manipulation; increased by directing attention to the induction site, nicotine deprivation, or sleep disruption (in males only); and unaffected by cathodal transcranial direct current stimulation, thermal change, acupuncture, or electroacupuncture. Meta-analytical pooling was only appropriate for studies that used transcranial direct current stimulation or hyperbaric oxygen therapy, given the high clinical heterogeneity among the studies and unavailability of data. The evidence base for this question remains small. We discuss opportunities to improve methodological rigor including manipulation checks, structured blinding strategies, control conditions or time points, and public sharing of raw data. PERSPECTIVE: We described the effects of several non-pharmacological manipulations on experimentally induced secondary hypersensitivity in humans. By shedding light on the potential for non-pharmacological therapies to influence secondary hypersensitivity, it provides a foundation for the development and testing of targeted therapies for secondary hypersensitivity.

A multidimensional investigation of the relationship between skin-mediated somatosensory signals, emotion regulation and behavior problems in autistic children

Introduction

Autistic children may have abnormal sensory perception, emotion dysregulation and behavior problems. The aim of this cross-sectional study was to explore the relationship between skin-mediated somatosensory signals and emotion/behavior difficulties in autistic children and adolescents, in comparison typically developing peers (TDP).

Methods

Thirty-eight autistic children and adolescents and 34 TDP completed a multidimensional assessment consisting of the measurement of somatosensory thresholds of touch, pain and temperature, a task on emotion knowledge and parent-reported questionnaires on sensory reactivity, emotion regulation and behavior.

Results

Autistic children had higher pain sensitivity, less sensory reactive behaviors and more behavior problems than their TDP. In contrast to TDP, several somatosensory thresholds of autistic children correlated with emotion regulation and behavior problems.

Discussion

Sensory dysfunction may affect the development of emotional processing and behavior in autistic children and adolescents. This knowledge can lay the foundation for future studies on co-occurring alterations in corresponding neural networks and for the implementation of early interventions, including sensory rehabilitation therapy, for promoting regulated behaviors in autistic children and adolescents.