Pain
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Comparative Study
Spontaneous discharge and increased heat sensitivity of rat C-fiber nociceptors are present in vitro after plantar incision.
Postoperative pain is characterized by spontaneous pain at the surgical site and increased pain due to movements. To study postoperative pain mechanisms, we investigated discharge properties of mechano-heat sensitive C-fiber afferents innervating the rat glabrous hindpaw skin 1 day after plantar incision. Behaviors indicating spontaneous pain, heat and mechanical hyperalgesia were present 1 day after incision. ⋯ The mean mechanical response thresholds, measured by a servo force-controlled stimulator, were not different between groups. The total spikes evoked at supra-threshold mechanical stimulation were not increased in afferents from the incision. In conclusion, 1 day after incision, when behaviors indicating spontaneous pain, heat and mechanical hyperalgesia are present, C-fibers close to incision showed spontaneous discharge and sensitization to heat but not to mechanical stimuli, in vitro.
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Comparative Study
Pain related behaviour in two models of osteoarthritis in the rat knee.
Osteoarthritis (OA) is a major healthcare burden, with increasing incidence. Pain is the predominant clinical feature, yet therapy is ineffective for many patients. While there are considerable insights into the mechanisms underlying tissue remodelling, there is poor understanding of the link between disease pathology and pain. ⋯ Diclofenac and paracetamol were effective 3 days after arthritic induction only, coinciding with a measurable swelling of the knee. Gabapentin varied in its ability to reverse both hyperalgesia and allodynia. The iodoacetate model provides a basis for studies on the mechanisms of pain in OA, and for development of novel therapeutic analgesics.
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Tri-cyclic antidepressants (TCAs) have been widely used in treating major depressive disorders. Recent studies further demonstrated that TCAs have potent sodium channel blocking effect, and amitriptyline, one of the TCAs, has a potent spinal anesthetic effect. The aim of the study was to evaluate the spinal anesthetic effect of various TCAs and to see whether these TCAs could likewise act as local anesthetics after a single intrathecal injection. ⋯ Under this concentration, amitriptyline had a similar potency but longer duration of spinal blockade of motor, propioception, and nociception (P<0.001) than did bupivacaine, whereas several other TCAs had similar or less potencies of spinal blockade than did bupivacaine. In dose-response studies, amitriptyline had a more potent (P<0.005) and longer duration (P<0.001) of spinal blockade than did bupivacaine. We concluded that intrathecal amitriptyline had a more potent and longer duration of spinal anesthetic effect than did bupivacaine, whereas several other TCAs had similar or less potencies than did bupivacaine.
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Comparative Study
Can one predict the likely specific orofacial pain syndrome from a self-completed questionnaire?
To estimate the prevalence of orofacial pain (OFP) by specific diagnostic subgroups in the general population. Cross-sectional population study. General medical practice in South East Cheshire, UK. ⋯ The estimated prevalence in the general population of musculoligamentous/soft tissue type of OFP was 7%, dentoalveolar 7% and neurological/vascular 6%. This study has derived a statistical model to classify participants with OFP into three broad groups (musculoligamentous/soft tissue, dentoalveolar and neurological/vascular) based on questionnaire information about OFP (OFP chronicity, location and verbal descriptors of pain). It is potentially useful in large population studies of OFP, where a clinical examination is not possible, however, further validation of its performance in large populations are necessary.
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Comparative Study
Self-efficacy, fear avoidance, and pain intensity as predictors of disability in subacute and chronic musculoskeletal pain patients in primary health care.
This study examined the relations between disability, as measured by the Pain Disability Index (PDI) and self-efficacy, fear avoidance variables (kinesiophobia and catastrophizing), and pain intensity, using a prospective design. Two primary health care samples (n(1)=210; n(2)=161) of patients with subacute, chronic or recurring musculoskeletal pain completed sets of questionnaires at the beginning of a physiotherapy treatment period. Multiple hierarchial regression analyses showed that self-efficacy explained a considerably larger proportion of the variance in disability scores than the fear avoidance variables in the first sample. ⋯ Gender, age, and pain duration were not related to disability. These findings suggest that self-efficacy beliefs are more important determinants of disability than fear avoidance beliefs in primary health care patients with musculoskeletal pain. The findings also suggest that pain-related beliefs, such as self-efficacy and fear avoidance, in turn, are more important determinants of disability than pain intensity and pain duration in these patients.