European journal of pain : EJP
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Comparative Study
Effects of intrathecal morphine, baclofen, clonidine and R-PIA on the acute allodynia-like behaviours after spinal cord ischaemia in rats.
The present study assessed the efficacy and potency of intrathecal (i.t.) administration of the opiate morphine, the gamma-aminobutyric acid-B (GABA(B)) receptor agonist baclofen, the alpha2-adrenoceptor agonist clonidine and the adenosine A1-receptor agonist R-phenylisopropyl-adenosine (R-PIA) on the acute allodynia-like behaviour after photochemically induced spinal cord injury (SCI) in rats. Rats displaying allodynia-like behaviours to brushing, von Frey hairs and cold stimulation 1-2 days after photochemically induced SCI were studied. In a cumulative dose regime, morphine (0.1-10 micrcog), baclofen (0.1-1 microg), clonidine (0.1-10 microg) and R-PIA (0.01-10 nmol) were administered i.t. through an implanted catheter at the lumbar spinal cord. ⋯ For the mechanical allodynia, morphine appeared to be most effective, whereas baclofen, clonidine and R-PIA only provided a partial alleviation. For the cold allodynia, morphine and baclofen were more effective than clonidine and R-PIA. In relieving acute mechanical and cold allodynia-like behaviours in rats 1-2 days after SCI, i.t. morphine and baclofen were superior to clonidine and R-PIA.
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There is continuing reluctance to prescribe strong opioids for the management of chronic non-cancer pain due to concerns about side-effects, physical tolerance, withdrawal and addiction. Randomized controlled trials have now provided evidence for the efficacy of opioids against both nociceptive and neuropathic pain. However, there is considerable variability in response rates, possibly depending on the type of pain, the type of opioid and its route of administration, the time to follow-up, compliance and the development of tolerance. ⋯ There were no withdrawal effects or addictive behaviour on treatment cessation, regardless of duration of the treatment. In conclusion, strong opioids may provide prolonged effective pain relief in selected patients with nociceptive and neuropathic non-cancer pain. Transdermal fentanyl treatment can often be temporary and can easily be stopped following adequate pain relief without withdrawal effects or any evidence of addictive behaviour.
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Clinical Trial Controlled Clinical Trial
The assessment of radiating low back pain by thermal sensory testing.
Low back pain radiating into the legs is a common pain syndrome. However, neurological examination, imaging and electromyographic studies are of limited value for prognosis or therapy. The origin of the pain remains unknown. ⋯ We propose that these findings indicate selective damage to the Adelta fibres which are involved in transmission of cold sensation and pain, presumably by root compression. We found no evidence of involvement of C fibres, which transmit warm sensation and pain. Thermal testing should be considered among the testing modalities that are capable of demonstrating objective findings in patients with radiating low back pain.
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Eighty-eight patients (58 women and 30 men; mean age 53.4 years) with chronic non-cancer pain present on average for 9.8 years were evaluated following treatment with intrathecal opioids for an average duration of 36.2 months. Outcome measures were global pain relief, physical activity levels, medication consumption, work status, intrathecal opioid side-effects, proportion of patients who ceased therapy and patient satisfaction. The most common diagnosis in this group was lumbar spinal or radicular pain after failed spinal surgery (n= 55, 63%). ⋯ Drug administration systems were permanently removed in five patients (6%). Intrathecal opioid therapy appears to have a place in the management of chronic non-cancer pain. Therapy does not seem to be significantly inhibited by the development of tolerance.
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This study compared the pain sensitivity in healthy women at the abdomen and lower back (presumed referral areas of menstrual pain), thigh and arm (control areas), in the menstrual, ovulatory, luteal and premenstrual phases of confirmed ovulatory cycles, with that of males. The pressure pain threshold (PPT) and pinch pain threshold (PiPT) was determined by an electronic pressure algometer, heat pain threshold (HPT) by a contact thermode and tactile threshold (TT) with von Frey hairs. The abdominal PPT was significantly lower in females in all menstrual phases as compared to the control sites ( p<0.0007). ⋯ During the ovulatory phase, the HPT was significantly reduced at the abdomen and the PPT at the back compared with the menstrual, luteal and premenstrual phases (p<0.0002). There were no within-menstrual phase variations in the PiPT and TT at any site, or for the HPT and PPT at the control areas. The reduced thresholds in menstruating women may be due to the presence of latent uterine algogenic stimuli, and the increased levels of oestrogen and leuteinizing hormone at ovulation may enhance nociception by acting both at the peripheral and central level, resulting in the hypersensitivity changes at the abdomen and lower back areas.