Human Studies

Early tactile and nociceptive (pain) mechanisms in children with global developmental delay at risk for intellectual and developmental disability are not well understood. Sixteen children with global developmental delay (mean age = 5.1 years, SD = 1.4; 50% male) completed a modified quantitative sensory testing (mQST) protocol, an epidermal (skin) punch biopsy procedure, and parent-endorsed measures of pain. Children with reported chronic pain had significantly greater epidermal nerve fiber density (ENFd) compared to children without chronic pain. Based on the mQST trials, ENFd values were associated with increased vocal reactivity overall and specifically during the light touch and cool thermal stimulus trials. The findings support the feasibility of an integrative biobehavioral approach to test nociceptive and tactile peripheral innervation and behavioral reactivity during a standardized sensory test in a high-risk sample for which there is often sensory dysfunction and adaptive behavior impairments.

Wrist arthroplasties have not achieved clinical outcomes comparable to those of shoulders and knees, being offered low-demand patients due to a high failure rate. In the 90s, there were no wrist arthroplasties available for high-demand patients. An experimental setup for the development of a new wrist arthroplasty intended for all wrist patients were done. A long-term final follow-up to evaluate the performance of the experimental arthroplasty was performed. A novel uncemented modular wrist prosthesis with conical threaded fixation, metal-on-metal coupling and ball-and-socket articulation was developed. In an experimental study, eight patients (7 men, 53 years of age) were operated between 2001 and 2003, to treat non-inflammatory primary or secondary osteoarthritis. Published mid-term results (7-9 years) demonstrated satisfactory function, but two arthroplasties were converted to arthrodesis due to infection. At final follow-up 15-20 years after primary surgery, the remaining six patients still had a wrist arthroplasty (in three the original) in situ. The clinical results were good. Low pain (median = 0), Quick Disability of Arm, Shoulder and Hand (QDASH median 11) and Patient Rated Wrist and Hand Evaluation (PRWHE median = 14) scores were reported. Wrist active range of motion (AROM) was 64% and grip strength 86% compared to the opposite side. None regretted choosing arthroplasty knowing the outcome. Despite technical errors and the implementation of an incomplete prototype, this new concept for arthroplasty has demonstrated promising long-term fixation, a stable articulation with good range of motion, satisfactory function and pain reduction in high-demand patients. Level IV (Therapeutic).

An important part of providing pain science education is to first assess baseline knowledge and beliefs about pain, thereby identifying misconceptions and establishing individually-tailored learning objectives. The Concept of Pain Inventory (COPI) was developed to support this need. This study aimed to characterize concept of pain in care-seeking youth and their parents, to examine its clinical and demographic correlates, and to identify conceptual gaps.

The use of high definition transcranial direct current stimulation (HD-tDCS) has shown analgesic effects in some chronic pain patients, but limited anti-nociceptive effects in healthy asymptomatic subjects. This double-blinded sham-controlled study assessed the effects of HD-tDCS applied on three consecutive days on central pain mechanisms in healthy participants with (N=40) and without (N=40) prolonged experimental pain induced by intramuscular injection of nerve growth factor into the right hand on Day1. Participants were randomly assigned to Sham-tDCS (N=20 with pain, N=20 without) or Active-tDCS (N=20 with pain, N=20 without) targeting simultaneously the primary motor cortex and dorsolateral prefrontal cortex for 20 min with 2mA stimulation intensity. Central pain mechanisms were assessed by cuff-algometry on the legs measuring pressure pain sensitivity, temporal summation of pain (TSP) and conditioned pain modulation (CPM), at baseline and after HD-tDCS on Day2 and Day3. Based on subject's assessment of received HD-tDCS (sham or active) they were effectively blinded. Compared with Sham-tDCS, Active-tDCS did not significantly reduce the average NGF-induced pain intensity. Tonic pain-induced temporal summation at Day2 and Day3 was significantly lower in the NGF-pain group under Active-tDCS compared to the pain group with Sham-tDCS (P≤0.05). No significant differences were found in the cuff pressure pain detection/tolerance thresholds or CPM effect across the 3 days of HD-tDCS in any of the four groups. HD-tDCS reduced the facilitation of TSP caused by tonic pain suggesting that efficacy of HD-tDCS might depend on the presence of sensitized central pain mechanisms.

The SARS-CoV-2 Omicron (B.1.1.529) variant has been associated with less severe acute disease, however, concerns remain as to whether long-term complaints persist to a similar extent as for earlier variants. Studying 1 323 145 persons aged 18-70 years living in Norway with and without SARS-CoV-2 infection in a prospective cohort study, we found that individuals infected with Omicron had a similar risk of post-covid complaints (fatigue, cough, heart palpitations, shortness of breath and anxiety/depression) as individuals infected with Delta (B.1.617.2), from 14 to up to 126 days after testing positive, both in the acute (14 to 29 days), sub-acute (30 to 89 days) and chronic post-covid (≥90 days) phases. However, at ≥90 days after testing positive, individuals infected with Omicron had a lower risk of having any complaint (43 (95%CI = 14 to 72) fewer per 10,000), as well as a lower risk of musculoskeletal pain (23 (95%CI = 2-43) fewer per 10,000) than individuals infected with Delta. Our findings suggest that the acute and sub-acute burden of post-covid complaints on health services is similar for Omicron and Delta. The chronic burden may be lower for Omicron vs Delta when considering musculoskeletal pain, but not when considering other typical post-covid complaints.

To characterize the altered brain function in patients with vestibular migraine (VM) using resting-state functional magnetic resonance imaging (fMRI).

Bodily pain is a common presentation in several chronic diseases, yet the influence of sedentary behaviour, common in ageing adults, is unclear. Television-viewing (TV) time is a ubiquitous leisure-time sedentary behaviour, with a potential contribution to the development of bodily pain. We examined bodily pain trajectories and the longitudinal relationships of TV time with the bodily pain severity; and further, the potential moderation of the relationships by type 2 diabetes (T2D) status.

Opioid analgesics are the most effective pharmacological agents for moderate and severe pain. However, opioid use has several limitations such as opioid-induced hyperalgesia (OIH), which refers to the increased pain sensitivity that occurs once analgesia wears off after opioid administration. Several pharmacological interventions have been suggested for OIH, but the current literature does not provide guidelines on which interventions are the most effective and whether they differ depending on the opioid that induces hyperalgesia. This scoping review aimed to identify and describe all the preclinical trials investigating pharmacological interventions for OIH caused by remifentanil, fentanyl, or morphine as the first step towards evaluating whether the most effective OIH interventions are different for different opioids.