Pain
-
The alpha2A and alpha2C adrenergic receptor (AR) subtypes mediate antinociception when activated by the endogenous ligand norepinephrine. These receptors also produce antinociceptive synergy when activated concurrently with opioid receptor activation. The involvement of the opioid receptors in the mechanisms governing transcutaneous electrical nerve stimulation (TENS) has been well described. ⋯ The alpha2 adrenergic receptor selective antagonist, SK&F 86466, reversed TENS-mediated antihyperalgesia when delivered intra-articularly, but not when delivered intrathecally or intracerebroventricularly. These data suggest that peripheral alpha2 ARs contribute, in part, to TENS antihyperalgesia. This pharmacodynamic response is consistent with previous anatomical observations that alpha2A ARs are expressed on primary afferent neurons and macrophages near injured tissue.
-
Statistics and prescription database studies show that analgesics are widely utilized, but do not tell anything about either the factors behind analgesic use or how over-the-counter (OTC) analgesics are being used. We aimed to study the prevalence of frequent use of prescribed and OTC analgesics. We also investigated the background factors related to frequent analgesic use and assessed rationality of analgesic usage patterns. ⋯ Low mood and not being employed also increased the probability for daily analgesic use. Frequent analgesic use seems to be common at population level. Concomitant use of both prescribed and OTC analgesics can be considered irrational, as it increases the risk of adverse events.
-
Comparative Study
The ontogeny of neuropathic pain: postnatal onset of mechanical allodynia in rat spared nerve injury (SNI) and chronic constriction injury (CCI) models.
Neuropathic pain is known to occur in children but remains poorly understood and treated. The aim here was to establish a model of neuropathic pain in neonatal and young rodents. In the adult the spared nerve injury (SNI) model produced robust mechanical allodynia measured as a fall in cutaneous sensory threshold to 16% of controls, within one postoperative day and lasting at least 28 days. ⋯ A similar lack of neuropathic pain behaviour in younger animals was observed using the chronic constriction injury (CCI) model, which produced a clear allodynia in adult rats but no change in hindpaw sensitivity when performed at 10 days of age. Mechanical allodynia can be evoked in very young animals with inflammatory pain, so this developmental profile is selective for peripheral neuropathic pain and suggests a remarkable ability in young animals to compensate for the sensory consequences of nerve injury. The results are consistent with human neonatal responses to nerve injury; further study of underlying mechanisms are likely to yield important information about the pathogenesis and treatment of neuropathic pain.
-
Chronic pain following whiplash injury and non-specific arm pain (NSAP, previously termed diffuse repetitive strain injury) present clinicians with problems of diagnosis and management. In both patient groups there are clinical signs of altered nerve movement and increased nerve trunk mechanosensitivity. Previous studies of NSAP patients have identified altered median nerve movement at the wrist. ⋯ In the whiplash patients the pattern of transverse median nerve movement at the proximal carpal tunnel was significantly different to controls (patient mean=2.57+/-0.80 mm (SEM) in a radial direction; control mean=0.39+/-0.52 mm in an ulnar direction). Signs of neural mechanosensitivity (i.e. painful responses to median nerve trunk and brachial plexus pressure and stretch) were apparent in both patients groups. Change in nerve tension and neural mechanosensitivity may contribute to symptoms in whiplash and NSAP patients.
-
Multicenter Study Clinical Trial
Possible selves in chronic pain: self-pain enmeshment, adjustment and acceptance.
The aim of this study was to test whether enmeshment of self and pain predicted adjustment (depression and acceptance) in a chronic pain population. 89 chronic pain patients completed standardized self-report measures of depression and acceptance and generated characteristics describing their current actual self, hoped-for self and feared-for self, and made judgments about the degree to which their future possible selves (hoped-for and feared-for) were dependent on the absence or presence of pain, i.e. enmeshed with pain. Hierarchical multiple regression analyses showed that after accounting for the influence of demographics (age, gender), pain characteristics and the degree of role interference attributable to pain, the proportion of hoped-for self characteristics that could be achieved even with the presence of pain predicted the magnitude of depression and acceptance scores. The findings are discussed with reference to the enmeshment hypothesis and theories of self-discrepancy, self-regulation and hopelessness.