Articles: hyperalgesia.
-
Chronic pain associated with inflammation is a major clinical problem, but the underlying mechanisms are incompletely understood. Recently, we reported that GRK2(+/-) mice with a approximately 50% reduction of GRK2 develop prolonged hyperalgesia following a single intraplantar injection of the pro-inflammatory cytokine interleukin-1beta (IL-1beta). Here we show that spinal microglia/macrophage GRK2 is reduced during chronic inflammation-induced hyperalgesia. ⋯ These data establish that chronic inflammatory hyperalgesia is associated with reduced GRK2 in microglia/macrophages and that low GRK2 in these cells is sufficient to markedly prolong hyperalgesia after a single intraplantar injection of IL-1beta. Ongoing hyperalgesia is maintained by spinal microglial/macrophage activity, fractalkine signaling, p38 activation and IL-1 signaling. We propose that chronic inflammation decreases spinal microglial/macrophage GRK2, which prevents silencing of microglia/macrophage activity and thereby contributes to prolonged hyperalgesia.
-
Randomized Controlled Trial
Botulinum toxin A for treatment of allodynia of complex regional pain syndrome: a pilot study.
To investigate the efficacy and tolerability of Botulinum toxin A (BoNT-A) in allodynia of patients with complex regional pain syndrome. ⋯ Intrademal and subcutaneous administration of BoNT-A into the allodynic skin of the patients with complex regional pain syndrome (CRPS) failed to improve pain and was poorly tolerated.
-
We have all encountered the following postanesthesia care unit dilemma a myriad of times. As the attending covering the postanesthesia care unit, the anesthesiologist will be confronted not infrequently with the following clinical scenario: "He needed 500 μg fentanyl in the operating room for a toe amputation and has received 20 mg morphine, and he's still complaining of severe pain…. ⋯ When assessing a patient experiencing exaggerated postoperative or chronic pain, several questions should come to mind. First, is this patient experiencing tolerance or hyperalgesia induced by opiate therapy? Second, does the management differ for the two etiologies? Third, what underlying mechanisms, both at the neuroanatomic and molecular/chemical levels, underlie the two processes? Fourth, how does the recent literature on opiate-induced hyperalgesia influence previously accepted views of pre-emptive analgesia? Fifth, what treatment modalities exist for opiate-induced hyperalgesia? Most importantly, sixth, how can opiate-induced hyperalgesia be prevented? In this literature review, we aim to address these questions and to hopefully change the current perception and management of perioperative and chronic pain states with opiates.
-
Approximately 70% of male rats receiving severe T8 spinal contusions develop allodynia in T5-7 dermatomes (at-level) beginning 2 weeks after injury. In contrast, rats having either complete transections or dorsal hemisections do not develop allodynia at-level after chronic spinal cord injury (SCI). In the present study, incomplete laceration and contusion injuries were made to test for neuroanatomical correlates between areas of white matter damage/sparing at the lesion epicenter and the presence/absence of allodynia. After incomplete laceration lesions and 6 weeks of behavioral testing, histological reconstruction and analysis of the lesion epicenters revealed a significant difference (P < .001) in the amount of ventrolateral funiculus (VLF) asymmetry between rats showing pain-like responses evoked by touch (74.5% +/- 8.4% side-to-side difference in VLF damage) versus those not responding to touch (11.3% +/- 4.4% side-to-side difference in VLF damage). A 5-week mean allodynia score for each rat that incorporates a full range of forces that are all innocuous in intact controls revealed that the degree of hypersensitivity at level is related to the extent of VLF asymmetry after SCI. No other damaged spinal white matter or gray matter area was correlated with sensitivity to touch. Similar findings were obtained for rats receiving T8 contusions, a more clinically relevant injury. These data suggest that different extents of damage/sparing between the 2 sides of VLF probably are a requisite for the development of allodynia after SCI. ⋯ A side-to-side lesion asymmetry after chronic SCI in a rodent model was found to be highly correlated with the presence and degree of allodynia. Greater insight of key factors contributing to the development and maintenance of chronic neuropathic pain is important for improving quality of life.
-
The aim was to investigate bilateral, wide-spread pressure pain hyperalgesia in symptomatic (trigeminocervical) and non-symptomatic (pain-free distant) regions in children with frequent episodic tension-type headache (FETTH). ⋯ The findings revealed bilateral, wide-spread pressure pain hypersensitivity in children with FETTH suggesting that wide-spread central sensitisation is involved in children with this headache pain condition.