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Roland Staud – One of the best experts on this subject based on the ideXlab platform.

  • analgesic and anti hyperalgesic effects of muscle injections with lidocaine or saline in patients with fibromyalgia syndrome
    European Journal of Pain, 2014
    Co-Authors: Roland Staud, Donald D Price, Elizabeth E Weyl, Emily J Bartley, Michael E Robinson
    Abstract:

    Background Patients with musculoskeletal pain syndrome including fibromyalgia (FM) complain of chronic pain from deep tissues including muscles. Previous research suggests the relevance of Impulse Input from deep tissues for clinical FM pain. We hypothesized that blocking abnormal Impulse Input with intramuscular lidocaine would decrease primary and secondary hyperalgesia and FM patients’ clinical pain.

  • Evidence for Shared Pain Mechanisms in Osteoarthritis, Low Back Pain, and Fibromyalgia
    Current Rheumatology Reports, 2011
    Co-Authors: Roland Staud
    Abstract:

    Osteoarthritis (OA), low back pain (LBP), and fibromyalgia (FM) are common chronic pain disorders that occur frequently in the general population. They are a significant cause of dysfunction and disability. Why some of these chronic pain disorders remain localized to few body areas (OA and LBP), whereas others become widespread (FM) is unclear at this time. Genetic, environmental, and psychosocial factors likely play an important role. Although patients with OA, LBP, and FM frequently demonstrate abnormalities of muscles, ligaments, or joints, the severity of such changes is only poorly correlated with clinical pain. Importantly, many patients with these chronic pain disorders show signs of central sensitization and abnormal endogenous pain modulation. Nociceptive signaling is actively regulated by the central nervous system to allow adaptive responses after tissue injuries. Thus, abnormal processing of tonic peripheral tissue Impulse Input likely plays an important role in the pathogenesis of OA, LBP, or FM. Tonic and/or intense afferent nociceptive barrage can result in central sensitization that depends on facilitatory Input from brainstem centers via descending pain pathways to the spinal cord. Abnormal endogenous control of these descending pathways can lead to excessive excitability of dorsal horn neurons of the spinal cord and pain. Ineffective endogenous pain control and central sensitization are important features of OA, LBP, and FM patients.

  • pain variability in fibromyalgia is related to activity and rest role of peripheral tissue Impulse Input
    The Journal of Pain, 2010
    Co-Authors: Roland Staud, Michael E Robinson, Elizabeth E Weyl, Donald D Price
    Abstract:

    Abstract Because fibromyalgia (FM) patients frequently report activity-dependent deep tissue pains, Impulse Input from painful body regions may be relevant for their musculoskeletal complaints. In addition, peripheral Impulse Input may induce and maintain thermal and mechanical hyperalgesia of FM patients. If so, activity and rest may alternately enhance and diminish intensity of FM pain. However, the effects of exercise on pain are ambiguous in studies of FM. Whereas exercise-only studies demonstrated increased pain and hyperalgesia during and after physical activity, some exercise studies that included rest periods resulted in decreased FM pain and increased function. To further clarify these effects, we examined the effects of alternating exercise with rest on clinical pain and thermal/mechanical hyperalgesia of 34 FM patients and 36 age-matched healthy controls (NC). Using an ergometer, all subjects performed arm exercise to exhaustion twice alternating with 15-minute rest periods. Although strenuous muscle activity was reported as painful by most FM subjects, overall clinical pain consistently decreased during the rest periods. Additionally, FM subjects’ pain sensitivity to mechanical pressure decreased after each exercise and rest session. Conclusion: Alternating strenuous exercise with brief rest periods not only decreased overall clinical pain of FM subjects but also their mechanical hyperalgesia. No prolonged worsening of overall FM pain and hyperalgesia occurred despite vigorous muscle activity. Our findings contribute further evidence that FM pain and hyperalgesia are at least partially maintained by muscle Impulse Input, and that some types of exercises may be beneficial for FM. Perspective FM is a pain-amplification syndrome that depends at least in part on peripheral tissue Impulse Input. Whereas muscle activity increased overall pain, short rest periods produced analgesic effects.

Donald D Price – One of the best experts on this subject based on the ideXlab platform.

  • analgesic and anti hyperalgesic effects of muscle injections with lidocaine or saline in patients with fibromyalgia syndrome
    European Journal of Pain, 2014
    Co-Authors: Roland Staud, Donald D Price, Elizabeth E Weyl, Emily J Bartley, Michael E Robinson
    Abstract:

    Background Patients with musculoskeletal pain syndrome including fibromyalgia (FM) complain of chronic pain from deep tissues including muscles. Previous research suggests the relevance of Impulse Input from deep tissues for clinical FM pain. We hypothesized that blocking abnormal Impulse Input with intramuscular lidocaine would decrease primary and secondary hyperalgesia and FM patients’ clinical pain.

  • pain variability in fibromyalgia is related to activity and rest role of peripheral tissue Impulse Input
    The Journal of Pain, 2010
    Co-Authors: Roland Staud, Michael E Robinson, Elizabeth E Weyl, Donald D Price
    Abstract:

    Abstract Because fibromyalgia (FM) patients frequently report activity-dependent deep tissue pains, Impulse Input from painful body regions may be relevant for their musculoskeletal complaints. In addition, peripheral Impulse Input may induce and maintain thermal and mechanical hyperalgesia of FM patients. If so, activity and rest may alternately enhance and diminish intensity of FM pain. However, the effects of exercise on pain are ambiguous in studies of FM. Whereas exercise-only studies demonstrated increased pain and hyperalgesia during and after physical activity, some exercise studies that included rest periods resulted in decreased FM pain and increased function. To further clarify these effects, we examined the effects of alternating exercise with rest on clinical pain and thermal/mechanical hyperalgesia of 34 FM patients and 36 age-matched healthy controls (NC). Using an ergometer, all subjects performed arm exercise to exhaustion twice alternating with 15-minute rest periods. Although strenuous muscle activity was reported as painful by most FM subjects, overall clinical pain consistently decreased during the rest periods. Additionally, FM subjects’ pain sensitivity to mechanical pressure decreased after each exercise and rest session. Conclusion: Alternating strenuous exercise with brief rest periods not only decreased overall clinical pain of FM subjects but also their mechanical hyperalgesia. No prolonged worsening of overall FM pain and hyperalgesia occurred despite vigorous muscle activity. Our findings contribute further evidence that FM pain and hyperalgesia are at least partially maintained by muscle Impulse Input, and that some types of exercises may be beneficial for FM. Perspective FM is a pain-amplification syndrome that depends at least in part on peripheral tissue Impulse Input. Whereas muscle activity increased overall pain, short rest periods produced analgesic effects.

  • enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent Input a randomized double blind placebo controlled study
    Pain, 2009
    Co-Authors: Roland Staud, Michael E Robinson, Susann Nagel, Donald D Price
    Abstract:

    Fibromyalgia (FM) syndrome is characterized by pain and widespread hyperalgesia to mechanical, thermal, and electrical stimuli. Despite convincing evidence for central sensitization of nociceptive pain pathways, the role of peripheral tissue Impulse Input in the initiation and maintenance of FM is unclear. Therefore this randomized, double-blind, placebo-controlled trial of 22 female normal controls (NCs) and 28 female FM subjects tested the effects of trapezius muscle (TrapM) tender point injections with 1% lidocaine on local pain thresholds as well as on remote heat hypehyperalgesia at the forearm. Prior to muscle injections shoulder pain was standardized by tonic mechanical muscle stimulation, resulting in local pain ratings of 4.0 ± 0.5 VAS units. Tonic muscle stimulation was interrupted for the TrapM injections but was continued afterwards at the same level. NC as well as FM subjects experienced significant increases of TrapM pressure pain thresholds from lidocaine injections but not from placebo injections (p < 0.001). Additionally, heat hypehyperalgesia of FM participants was significantly reduced at areas remote from the injection site (forearm) by lidocaine but not by placebo (p = 0.02). Neither lidocaine nor saline injections significantly affected clinical FM pain ratings, a result most likely due to the very low dose of lidocaine (50 mg) used in this trial. Conclusion: Lidocaine injections increased local pain thresholds and decreased remote secondary heat hypehyperalgesia in FM patients, emphasizing the important role of peripheral Impulse Input in maintaining central sensitization in this chronic pain syndrome; similar to other persistent pain conditions such as irritable bowel syndrome and complex regional pain syndrome.

Michael E Robinson – One of the best experts on this subject based on the ideXlab platform.

  • analgesic and anti hyperalgesic effects of muscle injections with lidocaine or saline in patients with fibromyalgia syndrome
    European Journal of Pain, 2014
    Co-Authors: Roland Staud, Donald D Price, Elizabeth E Weyl, Emily J Bartley, Michael E Robinson
    Abstract:

    Background Patients with musculoskeletal pain syndrome including fibromyalgia (FM) complain of chronic pain from deep tissues including muscles. Previous research suggests the relevance of Impulse Input from deep tissues for clinical FM pain. We hypothesized that blocking abnormal Impulse Input with intramuscular lidocaine would decrease primary and secondary hyperalgesia and FM patients’ clinical pain.

  • pain variability in fibromyalgia is related to activity and rest role of peripheral tissue Impulse Input
    The Journal of Pain, 2010
    Co-Authors: Roland Staud, Michael E Robinson, Elizabeth E Weyl, Donald D Price
    Abstract:

    Abstract Because fibromyalgia (FM) patients frequently report activity-dependent deep tissue pains, Impulse Input from painful body regions may be relevant for their musculoskeletal complaints. In addition, peripheral Impulse Input may induce and maintain thermal and mechanical hyperalgesia of FM patients. If so, activity and rest may alternately enhance and diminish intensity of FM pain. However, the effects of exercise on pain are ambiguous in studies of FM. Whereas exercise-only studies demonstrated increased pain and hyperalgesia during and after physical activity, some exercise studies that included rest periods resulted in decreased FM pain and increased function. To further clarify these effects, we examined the effects of alternating exercise with rest on clinical pain and thermal/mechanical hyperalgesia of 34 FM patients and 36 age-matched healthy controls (NC). Using an ergometer, all subjects performed arm exercise to exhaustion twice alternating with 15-minute rest periods. Although strenuous muscle activity was reported as painful by most FM subjects, overall clinical pain consistently decreased during the rest periods. Additionally, FM subjects’ pain sensitivity to mechanical pressure decreased after each exercise and rest session. Conclusion: Alternating strenuous exercise with brief rest periods not only decreased overall clinical pain of FM subjects but also their mechanical hyperalgesia. No prolonged worsening of overall FM pain and hyperalgesia occurred despite vigorous muscle activity. Our findings contribute further evidence that FM pain and hyperalgesia are at least partially maintained by muscle Impulse Input, and that some types of exercises may be beneficial for FM. Perspective FM is a pain-amplification syndrome that depends at least in part on peripheral tissue Impulse Input. Whereas muscle activity increased overall pain, short rest periods produced analgesic effects.

  • enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent Input a randomized double blind placebo controlled study
    Pain, 2009
    Co-Authors: Roland Staud, Michael E Robinson, Susann Nagel, Donald D Price
    Abstract:

    Fibromyalgia (FM) syndrome is characterized by pain and widespread hyperalgesia to mechanical, thermal, and electrical stimuli. Despite convincing evidence for central sensitization of nociceptive pain pathways, the role of peripheral tissue Impulse Input in the initiation and maintenance of FM is unclear. Therefore this randomized, double-blind, placebo-controlled trial of 22 female normal controls (NCs) and 28 female FM subjects tested the effects of trapezius muscle (TrapM) tender point injections with 1% lidocaine on local pain thresholds as well as on remote heat hyperalgesia at the forearm. Prior to muscle injections shoulder pain was standardized by tonic mechanical muscle stimulation, resulting in local pain ratings of 4.0 ± 0.5 VAS units. Tonic muscle stimulation was interrupted for the TrapM injections but was continued afterwards at the same level. NC as well as FM subjects experienced significant increases of TrapM pressure pain thresholds from lidocaine injections but not from placebo injections (p < 0.001). Additionally, heat hyperalgesia of FM participants was significantly reduced at areas remote from the injection site (forearm) by lidocaine but not by placebo (p = 0.02). Neither lidocaine nor saline injections significantly affected clinical FM pain ratings, a result most likely due to the very low dose of lidocaine (50 mg) used in this trial. Conclusion: Lidocaine injections increased local pain thresholds and decreased remote secondary heat hyperalgesia in FM patients, emphasizing the important role of peripheral Impulse Input in maintaining central sensitization in this chronic pain syndrome; similar to other persistent pain conditions such as irritable bowel syndrome and complex regional pain syndrome.

Izuru Takewaki – One of the best experts on this subject based on the ideXlab platform.

  • critical response of single degree of freedom damped bilinear hysteretic system under double Impulse as substitute for near fault ground motion
    Frontiers in Built Environment, 2018
    Co-Authors: Hiroki Akehashi, Kotaro Kojima, Izuru Takewaki
    Abstract:

    A double Impulse Input is used as a substitute for near-fault earthquake ground motions. A closed-form expression is derived in the maximum elastic-plastic response of a single-degree-of-freedom (SDOF) damped structure with bilinear hysteresis under the ‘critical double Impulse Input’ which causes the maximum response for variable Impulse interval with the Input level kept constant. Since only the free-vibration exists under the double Impulse, the energy balance approach for the kinetic energy, hysteretic and strain energies, and damping energy plays a key role in the derivation of the closed-form expression of a complicated damped bilinear hysteretic response. It is shown that the critical elastic-plastic defodeformation and the corresponding critical Impulse timing can be derived depending on the Input level. The accuracy of the proposed simplified but smart methodology is confirmed through the comparison with the response analysis to the critical double Impulse and the corresponding one-cycle sine wave as a representative for the near-fault earthquake ground motion.

  • critical steady state response of single degree of freedom bilinear hysteretic system under multi Impulse as substitute of long duration ground motion
    Frontiers in Built Environment, 2017
    Co-Authors: Kotaro Kojima, Izuru Takewaki
    Abstract:

    A set of multiple Impulses is introduced as a substitute of many-cycle harmonic waves which represent the long-duration earthquake ground motion. A closed-form expression is derived of the elastic-plastic response of a single-degree-of-freedom (SDOF) structure with bilinear hysteresis under the ‘critical multiple Impulse Input’. As in the case of elastic-perfectly plastic models, an advantageous feature can be used such that only the free-vibration exists under the multiple ground motion Impulse and the energy balance approach plays a key role in the derivation of the closed-form expression of a complicated elastic-plastic response. It is demonstrated that the critical inelastic maximum deformation and the corresponding critical Impulse timing can be obtained depending on the Input level. The validity and accuracy of the proposed theory are confirmed through the comparison with the response analysis to the corresponding sine wave as a representative of the long-duration earthquake ground motion.

  • robustness of sdof elastoplastic structure subjected to double Impulse Input under simultaneous uncertainties of yield deformation and stiffness
    International Journal of Non-linear Mechanics, 2017
    Co-Authors: Yoshihiro Kanno, Kohei Fujita, Keisuke Yasuda, Izuru Takewaki
    Abstract:

    Abstract A series of Impulse-type Inputs has been extensively used to evaluate the critical response of an elastoplastic structure subjected to diverse types of pulse-type Inputs, including a near-fault ground motion. In this paper, we consider the critical double-Impulse Input for a single-degree-of-freedom elastic–perfectly plastic structure, and study effects of structural uncertainties. When the natural frequency (or, equivalently, the stiffness) is fixed, the critical response of the structure does not necessarily decrease as the yield deformation (or, equivalently, the yield force) increases. As the first contribution, we give through investigation of this non-monotonicity property. Moreover, we present a systematic method for finding the worst-case scenario when the yield deformation and the stiffness of a structure assumed to be uncertain simultaneously. Numerical examples are presented to illustrate that the robustness of a structure does not necessarily improve when the yield deformation and/or the yield force is increased.

V. Rastogi – One of the best experts on this subject based on the ideXlab platform.

  • Vibration analysis for detecting failure mode and crack location in first stage gas turbine blade
    Journal of Mechanical Science and Technology, 2019
    Co-Authors: S. Rani, A.k. Agrawal, V. Rastogi
    Abstract:

    Structure frequency response testing “modal analysis” is an integral part of the development and testing of structures such as pistons, turbine blades, compressor blades, crankshafts, and connecting rods. The usefulness of this technique lies in the fact that the energy in an Impulse Input is distributed continuously in the frequency domain. Thus, an Impulse force will excite all resonances within given frequency range. To detect a fault in the structure, one may require frequency response functions (FRFs) of structures in both conditions, before (healthy structure) and after (failed structure) fault occurs. Now by extracting modal properties from collected FRFs and by comparing modal properties, one can detect and locate the structural faults. A case study is presented in order to detect failure mode and locate cracks on a 30 MW first stage gas turbine blade made of nickel based super alloy IN738LC, which has failed after rendering a useful life of 72000 h. The root causes of failure are detected by comparing the failed blade experimental model with the failed blade computational model. It is observed that the frequencies of the real failed blade experimental model are lesser than the computational model of the failed turbine blade. This is due to the metallurgical defects, which result in loosening of stiffness at the leading and trailing edges of the blade. Further, the stress concentration areas noticed on leading and trailing edges in computational model of the failed blade at the sixth mode are well corroborated with the cracked zone seen on leading and trailing edges of a real case failed turbine blade, collected from the site. It is concluded that the blade has failed due to that the resonance at sixth modal frequency. Scanning electron micrmicroscope (SEM) images reveal the presence of corrosion pits on the surfaces of the turbine blade that lead to surface degradation, which results in crack initiation and its propagation with high-cyclcycle fatigue. It is concluded that the failure of turbine blade occurs due to high cyclcycle fatigue.

  • Vibration analysis for detecting failure mode and crack location in first stage gas turbine blade
    Journal of Mechanical Science and Technology, 2019
    Co-Authors: S. Rani, A.k. Agrawal, V. Rastogi
    Abstract:

    Structure frequency response testing “modal analysis” is an integral part of the development and testing of structures such as pistons, turbine blades, compressor blades, crankshafts, and connecting rods. The usefulness of this technique lies in the fact that the energy in an Impulse Input is distributed continuously in the frequency domain. Thus, an Impulse force will excite all resonances within given frequency range. To detect a fault in the structure, one may require frequency response functions (FRFs) of structures in both conditions, before (healthy structure) and after (failed structure) fault occurs. Now by extracting modal properties from collected FRFs and by comparing modal properties, one can detect and locate the structural faults. A case study is presented in order to detect failure mode and locate cracks on a 30 MW first stage gas turbine blade made of nickel based super alloy IN738LC, which has failed after rendering a useful life of 72000 h. The root causes of failure are detected by comparing the failed blade experimental model with the failed blade computational model. It is observed that the frequencies of the real failed blade experimental model are lesser than the computational model of the failed turbine blade. This is due to the metallurgical defects, which result in loosening of stiffness at the leading and trailing edges of the blade. Further, the stress concentration areas noticed on leading and trailing edges in computational model of the failed blade at the sixth mode are well corroborated with the cracked zone seen on leading and trailing edges of a real case failed turbine blade, collected from the site. It is concluded that the blade has failed due to that the resonance at sixth modal frequency. Scanning electron micrmicroscope (SEM) images reveal the presence of corrosion pits on the surfaces of the turbine blade that lead to surface degradation, which results in crack initiation and its propagation with high-cyclcycle fatigue. It is concluded that the failure of turbine blade occurs due to high cyclcycle fatigue.