39 research outputs found
Pain Mechanisms in Adolescent Females with Chronic Low Back Pain Compared with Healthy Controls
No full textIntroduction: Chronic low back pain (CLBP) is a multifactorial entity encompassing a biopsychosocial model. Changes in pain mechanisms have been reported in adult populations as an increase in peripheral and central sensitization. Muscle hypertonicity is present in other chronic pain conditions, however it is unknown to what extent it plays a role in CLBP. Pain catastrophizing (PC) is a comorbidity to CLBP. Most of the literature regarding pain mechanisms in CLBP patients is directed towards adults. There is a lack of knowledge regarding pain mechanisms, muscle tone and PC in adolescents with CLBP. Method: 33 females between 15-19 years (CLBP n = 22) participated. Handheld pressure algometry and computerized pressure algometry (CPA) was used to investigate the presence of local and widespread hyperalgesia. CPA was used to investigate temporal summation (TS) and conditioned pain modulation (CPA). A myotonometer was used to investigate muscle tone. The Pain Catastrophizing Scale (PCS) was used to control for the impact of psychosocial factors on pain. Results: The CLBP group has lower pressure pain thresholds (PPT) compared with the control group. There was significantly higher muscle tone in the left m. gluteus medius in the CLBP group compared with the control group. TS and CPM was present in both the CLBP group and the control group, but there was no significant difference between the two groups. PC scores were significantly higher in the CLBP group than in the control group. There was no significant correlation between PC and TS and CPM. Conclusion: Adolescent females with CLBP share some of the pain mechanisms seen in adults in terms of peripheral sensitisation and widespread hyperalgesia; however, there is a need for further research regarding the impact that PC may have on the development of TS and CPM. It appears that muscle hypertonicity in the left gluteus medius muscle could be a risk factor for developing CLBP and further studies should investigate this relationship
Evidence for a central mode of action for etoricoxib (COX-2 Inhibitor) in patients with painful knee osteoarthritis
No full textThe COX-2 inhibitor etoricoxib modulates the peripheral and central nociceptive mechanisms in animals. This interaction has not been studied in pain patients. This randomized, double-blind, placebo-controlled, 2-way crossover, 4-week treatment study investigated the pain mechanisms modulated by etoricoxib in patients with painful knee osteoarthritis.Patients were randomized to group A) (60 mg/day etoricoxib followed by placebo), or B) (placebo followed by 60 mg/day etoricoxib). The quantitative, mechanistic pain biomarkers were pressure pain thresholds (PPTs), temporal summation (TS), and conditioning pain modulation (CPM). Clinical readouts were Brief Pain Inventory (BPI), WOMAC, PainDetect Questionnaire (PDQ), time and pain intensity during walking and stair climbing.Etoricoxib as compared with placebo significantly modulated the PPTs (P=0.012, localized sensitization) at the knee and leg (control site) (P=0.025, spreading sensitization) and temporal summation assessed from the knee (P=0.038) and leg (P=0.045). CPM was not modulated. The BPI (pain scores), PDQ, WOMAC, walking and stair climbing tests were all significantly improved by etoricoxib. Based on a minimum of 30% or 50% pain alleviation (day 0 to day 28), responders and non-responders were defined. The non-responders showed a significant association between increased facilitation of TS and increased pain alleviation. None of the other parameters predicted the degree of pain alleviation. Generally, a responder to etoricoxib has the most facilitated TS.In conclusion, etoricoxib 1) modulated central pain modulatory mechanisms, and 2) improved pain and function in painful osteoarthritis. Stronger facilitation of temporal summation may indicate a better response to etoricoxib supporting the central mode-of-action of the drug.SUMMARY: Etoricoxib significantly modulates peripheral/central sensitization and temporal summation in patients with painful knee osteoarthritis.</p
Short-term cortical plasticity induced by conditioning pain modulation
No full textTo investigate the effects of homotopic and heterotopic conditioning pain modulation (CPM) on short-term cortical plasticity. Glutamate (tonic pain) or isotonic saline (sham) was injected in the upper trapezius (homotopic) and in the thenar (heterotopic) muscles. Intramuscular electrical stimulation was applied to the trapezius at pain threshold intensities, and somatosensory evoked potentials were recorded with 128 channel EEG. Pain ratings were obtained during glutamate and sham pain injection. Short-term cortical plasticity to electrical stimulation was investigated before, during, and after homotopic and heterotopic CPM versus control. Peak latencies at N100, P200, and P300 were extracted and the location/strength of corresponding dipole current sources and multiple dipoles were estimated. Homotopic CPM caused hypoalgesia (P = 0.032, 30.6% compared to baseline) to electrical stimulation. No cortical changes were found for homotopic CPM. A positive correlation at P200 between electrical pain threshold after tonic pain and the z coordinate after tonic pain (P = 0.032) was found for homotopic CPM. For heterotopic CPM, no significant hypoalgesia was found and a dipole shift of the P300 z coordinate (P = 0.001) was found between glutamate versus sham pain (P = 0.009). This generator was located in the cingulate. A positive correlation at P300 between pain ratings to glutamate injection and the x coordinate during tonic pain (P = 0.016) was found for heterotopic CPM. Heterotopic CPM caused short-term cortical plasticity within the cingulate that was correlated to subjective pain ratings. The degree of long-term depressive effect to homotopic CPM was correlated to the change in location of the P200 dipole
Volunteers with high versus low alpha EEG have different pain-EEG relationship:a human experimental study
No full textUdgivelsesdato: MA
A coordination model based control of functional arm manipulation by RBF neural networks
No full textA randomized, double-blind, placebo-controlled 2-way crossover clinical experimental study to investigate the mechanism of action of etoricoxib in patients with knee osteoarthritis
No full textAutomatic determination of synergies by radial basis function artificial neural networks for the control of a neural prosthesis
No full textUdgivelsesdato: DE
