Search results for "Nociception"
showing 10 items of 110 documents
Complex regional pain syndrome–up-to-date
2017
The pathophysiology of complex regional pain syndromes includes inflammation and central reorganisation. The treatment should be adjusted to the prevailing pathophysiology including possible psychosocial factors.
Multiple mechanisms of secondary hyperalgesia
2000
Publisher Summary This chapter discusses the multiple mechanisms of secondary hyperalgesia. The chapter defines the minimal conditions of complexity that must be fulfilled by a model of plasticity of spinal nociceptive transmission in order to explain clinical and psychophysical observations in humans. Secondary hyperalgesia is characterized by a leftward shift of the stimulus-response function for noxious mechanical stimuli. In order to define the afferent pathways involved in inducing central sensitization and in mediating the hyperalgesia to noxious mechanical stimuli, several psychophysical experiments using selective nerve block techniques is performed. Secondary hyperalgesia is likely…
Within-session sensitization and between-session habituation: A robust physiological response to repetitive painful heat stimulation
2011
Habituation and sensitization are important behavioural responses to repeated exposure of painful stimuli. Whereas within-session response dynamics to nociceptive stimuli is well characterized, little is known about long-term behaviour due to repetitive nociceptive stimulation. We used a standardized longitudinal heat pain paradigm in 66 healthy participants, 21 patients with chronic low back pain and 22 patients with depression who received daily sessions of 60 suprathreshold heat stimuli (48 °C each) for eight consecutive days. All three groups showed the same response: Repeated painful stimulation over several days resulted in substantially decreased pain ratings to identical painful sti…
Brain processing during mechanical hyperalgesia in complex regional pain syndrome: a functional MRI study.
2005
Complex Regional Pain Syndromes (CRPS) are characterized by a triad of sensory, motor and autonomic dysfunctions of still unknown origin. Pain and mechanical hyperalgesia are hallmarks of CRPS. There are several lines of evidence that central nervous system (CNS) changes are crucial for the development and maintenance of mechanical hyperalgesia. However, little is known about the cortical structures associated with the processing of hyperalgesia in pain patients. This study describes the use of functional magnetic resonance imaging (fMRI) to delineate brain activations during pin-prick hyperalgesia in CRPS. Twelve patients, in whom previous quantitative sensory testing revealed the presence…
The Adequate Stimulus
2008
The term adequate stimulus describes that class of environmental phenomena that requires the least amount of energy to elicit a percept mediated by a particular sensory system, implying that the receptive organs of that sensory system are specialized to detect those phenomena. It was difficult to transfer this concept to the perception of pain and to the nociceptive system. Many different stimuli may cause pain (pin prick, burn injury, freeze injury, inflammation, etc.), none of which needs particularly low amounts of energy. The common denominator of those stimuli is that they threaten to cause tissue damage (in Greek: νoξη Noxe). Hence the adequate stimulus to elicit pain is traditionally…
Chapter 33 Experimental human models of neuropathic pain
2006
Publisher Summary This chapter reviews human surrogate models of neuropathic pain that focus on the mechanisms of symptom generation. A vast array of human surrogate models exists for ongoing symptoms, for positive sensory symptoms, and for sensory loss. The chapter discusses that by design, human surrogate models of neuropathic pain involve a reversible modulation of the properties of the nociceptive system such as its acute plasticity (phase 2). They usually do not create a long-lasting and potentially irreversible modification (phase 3). The denervation and ectopic activity of phase 3 can be modeled to a certain extent by transient nerve compression–ischemia and by topical capsaicin. By …
Neck Pain Rehabilitation
2016
Neck pain is par excellence one of the most common disorders of the musculoskeletal system, second only to low back pain. It constitutes 40 % of all backache. The International Association for the Study of Pain (IASP) defines pain of cervical origin coming from an area between the nuchal line and another imagi-nary line that passes through the lower end of the spinous process of the first thoracic vertebra and the sagittal plans tangent to the side edges of the neck. This definition considers therefore posterior pain which in turn can be divided into high pain, up to C3, and lower pain, down from C4. Also, as all diseases, it can be divided into acute and chronic neck pain, merely according…
Histone post-translational modifications as potential therapeutic targets for pain management
2021
Effective pharmacological management of pain associated with tissue pathology is an unmet medical need. Transcriptional modifications in nociceptive pathways are pivotal for the development and the maintenance of pain associated with tissue damage. Accumulating evidence has shown the importance of the epigenetic control of transcription in nociceptive pathways via histone post-translational modifications (PTMs). Hence, histone PTMs could be targets for novel effective analgesics. Here, we discuss the current understanding of histone PTMs in the modulation of gene expression affecting nociception and pain phenotypes following tissue injury. We also provide a critical view of the translationa…
Heat-induced action potential discharges in nociceptive primary sensory neurons of rats.
2009
Although several transducer molecules for noxious stimuli have been identified, little is known about the transformation of the resulting generator currents into action potentials (APs). Therefore we investigated the transformation process for stepped noxious heat stimuli (42-47 degrees C, 3-s duration) into membrane potential changes and subsequent AP discharges using the somata of acutely dissociated small dorsal root ganglion (DRG) neurons (diameteror=32.5 microm) of adult rats as a model for their own peripheral terminals. Three types of heat-induced membrane potential changes were differentiated: type 1, heat-induced AP discharges (approximately 37% of the neurons); type 2, heat-induce…
Effects of Anandamide and Noxious Heat on Intracellular Calcium Concentration in Nociceptive DRG Neurons of Rats
2007
As an endogenous agonist at the cannabinoid receptor CB1 and the capsaicin-receptor TRPV1, anandamide may exert both anti- and pronociceptive actions. Therefore we studied the effects of anandamide and other activators of both receptors on changes in free cytosolic calcium ([Ca2+]i) in acutely dissociated small dorsal root ganglion neurons (diameter: ≤30 μm). Anandamide (10 μM) increased [Ca2+]iin 76% of the neurons. The EC50was 7.41 μM, the Hill slope was 2.15 ± 0.43 (mean ± SE). This increase was blocked by the competitive TRPV1-antagonist capsazepine (10 μM) and in Ca2+-free extracellular solution. Neither exclusion of voltage-gated sodium channels nor additional blockade of voltage-gate…