The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial
The Importance of the Treatment Rationale for Pain in Animal-Assisted Interventions: A Randomized Controlled Trial in Healthy Participants.
Animal-assisted interventions (AAIs) is a promising treatment approach for pain, but possible mechanisms still need to be elucidated. This study set out to investigate the analgesic effects of an animal provided with a treatment rationale in a randomized controlled trial employing a standardized experimental heat-pain paradigm. We randomly assigned 128 healthy participants to: dog treatment (DT), placebo treatment (PT), dog and placebo treatment (DPT), and no treatment (NT). ⋯ PERSPECTIVE: This study shows that the presence of an animal is not sufficient for animal-assisted interventions (AAIs) to have an analgesic effect on pain unless they are provided with a treatment rationale. This could imply that not only the animal but also contextual factors are important in AAIs. TRIAL REGISTRATION: Clinical Trials NCT04361968.
-
Classically, to electrically excite C-nociceptors, rectangular pulses are used with a duration close to the estimated chronaxie of C-fibres (about 2 ms). Recent results using slow depolarizing stimuli suggest longer chronaxies. We therefore set out to optimize C-fiber stimulation based on recordings of single C-nociceptors in-vivo and C-fiber compound-action-potentials (C-CAP) ex-vivo using half-sine shaped stimuli of durations between 1 and 250ms. ⋯ Increasing the duration from 1 to 25 ms led to a 4-fold amplitude reduction for pain-thresholds and stimuli caused an axon-reflex flare. Excitability of single polymodal nociceptors in animals paralleled human psychophysics and we conclude optimized half-sine pulses facilitate C-nociceptor activation. PERSPECTIVE: Electrical stimulation with longer lasting half-sine wave pulses preferentially activates C-nociceptors and changes in the strength duration curve may identify nociceptor hyperexcitability in patients with neuropathic pain.
-
Head and neck pain drawings have been introduced as part of the diagnostic gold standard for temporomandibular disorders (TMD). We aimed to quantify the spatial extent of pain in TMD patients and to analyze its association with further clinical findings. In a cross-sectional study, 90 patients (median age = 38 years; n women = 68) were diagnosed according to the DC/TMD. ⋯ PERSPECTIVE: Head and neck pain drawings can contribute to a stratification of TMD patients. A greater extent of pain as well as pain bilateralization is associated with higher levels of emotional distress, pain chronicity and somatization, but not with functional impairment. Unilateral reporting of pain is associated with more intra-articular disorders.
-
Projections from the periaqueductal gray (PAG) to the rostral ventromedial medulla (RVM) are known to engage in descending pain modulation, but how the neural substrates of the PAG-RVM projections contribute to neuropathic pain remains largely unknown. In this study, we showed somatostatin-expressing glutamatergic neurons in the lateral/ventrolateral PAG that facilitate mechanical and thermal hypersensitivity in a mouse model of chemotherapy-induced neuropathic pain. We found that these neurons form direct excitatory connections with neurons in the RVM region. ⋯ Thus, our findings revealed that somatostatin neurons within the PAG-RVM axial are crucial for descending pain facilitation and can potentially be exploited as a useful therapeutic target for neuropathic pain. PERSPECTIVE: We report the profound contribution of somatostatin neurons within the PAG-RVM projections to descending pain facilitation underlying neuropathic pain. These results may help to develop central therapeutic strategies for neuropathic pain.
-
Review Meta Analysis
Effectiveness of Different Electrical Stimulation Modalities for Pain and Masticatory Function in Temporomandibular Disorders: A Systematic Review and Meta-Analysis.
Temporomandibular disorders comprise a set of conditions that include alterations of the temporomandibular joint and masticatory muscles. Although different modalities of electric currents are widely used for treating temporomandibular disorders, previous reviews have suggested these are ineffective. This systematic review and meta-analysis aimed to determine the effectiveness of different electrical stimulation modalities in patients with temporomandibular disorders for reducing musculoskeletal pain, increasing the range of movement, and improving muscle activity. ⋯ PERSPECTIVE: TENS and high voltage currents are valid options for the control of pain intensity in patients suffering from temporomandibular disorder. Data suggest clinically relevant changes compared to sham. Healthcare professionals should take this into account as it is inexpensive therapy, has no adverse effects and can be self-administered by patients.