No abstract

No abstract

Experiences of childhood trauma (abuse and neglect) are disproportionately higher in those with opioid use disorder (OUD). Childhood trauma may affect the reinforcing and rewarding properties of opioid drugs and responses to pain, potentially via developmental changes to the endogenous opioid system. This has been supported by preclinical research, yet this has not been investigated in non‐addicted humans. Physically healthy participants with either a history of severe childhood trauma or no previous history of childhood trauma attended two sessions where they received either an intramuscular active dose of morphine (0.15 mg/kg) or a very low dose control (0.01 mg/kg) in a randomised, double‐blind crossover design. Sessions were held 1 week apart. Participants' physical pain threshold and tolerance were measured pre‐ and post‐drug administration using the cold water pressor test, alongside acute subjective and behavioural responses over 2.5 h. The trauma group reported liking the effects of morphine, feeling more euphoric and wanting more of the drug over the session, as well as feeling less nauseous, dizzy, and dislike of the effects of morphine compared to the non‐trauma comparison group. Morphine increased pain threshold and tolerance, yet this did not differ between the groups. Childhood trauma may therefore sensitise individuals to the pleasurable and motivational effects of opioids and reduce sensitivity to the negative effects, providing compelling evidence for individual differences in opioid reward sensitivity. This may explain the link between childhood trauma and vulnerability to OUD, with consequent implications on interventions for OUD, the prescribing of opioids, and reducing stigmas surrounding OUD.

The use of ultrasound in regional anaesthesia is well established; however, its use in chronic pain management is relatively new. There are very few randomized controlled trials involving patients, and the majority of the supporting evidence consists of case reports, and studies relating to the practicalities and performance of techniques.Nevertheless, the application of ultrasound in chronic pain management is very attractive. Traditional teaching and practice of chronic pain procedures relies heavily on the use of landmark techniques, fluoroscopy, and occasionally computed tomography (CT) or magnetic resonance imaging (MRI). Fluoroscopy involves the use of bony landmarks and spread of contrast media as an endpoint for needle placement, and the detection of intravascular injection. Such practices expose patients and staff to radiation, risks contrast allergy, and requires a range of specialist resources and dedicated personnel.Ultrasound can be performed at the bedside, and avoids radiation and contrast exposure. Good resolution of muscle, nerves, vessels, connective tissues, and viscera can be seen on ultrasound, and visualization of the target structure and needle movement can be seen in real time, as opposed to intermittent scanning.With this in mind, the use of ultrasound before performing a procedure allows appropriate planning and avoidance of important structures. Real-time observation of local anaesthetic deposition may allow smaller therapeutic doses to be used, and limit or prevent side-effects and complications associated with increased spread.Thus, the use of ultrasound may improve the specificity and diagnostic accuracy of procedures that have poor endpoints with conventional fluoroscopy. In addition, a reduction in dosage and volume of local anaesthetic required may produce a more isolated and selective block.Limitations of ultrasound include technical factors, patient factors, and operator factors.Technical factors include the acoustic shadow artefact produced by bone, a reduction in image resolution with increasing depth, and reduced needle visibility with a steep angle of insertion. Patient factors include abnormal anatomy, degenerative changes or body habitus, and operator factors include technical skill and experience. Shadowing by bone and decreased resolution may hinder the identification of injectate spread and intravascular injection, limiting the applicability of ultrasound in certain procedures, as the risk vs benefit profile may be more favourable with conventional techniques.This review considers the application of ultrasound in chronic pain management focusing on axial structures and sympathetic blocks. A further review will examine the role of ultrasound in pain interventions involving peripheral nerves and the musculoskeletal system.

No abstract