Pain
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According to myogenic models that relate abnormal EMG patterns to the experience of pain, lumbar paravertebral muscle activity has been considered to play an important role in chronic low back pain. In the present study, 40 chronic low back pain patients and 40 matched non-patient controls were compared on lumbar paravertebral EMG during mechanically stabilized static and dynamic postures. ⋯ In addition, most patients did not show the flexion-relaxation response or the expected pattern of EMG responses during trunk rotation, most likely because of restricted range of motion and/or compensatory posturing. These findings provide support for the biomechanical model of chronic pain and indicate the need for further research pertaining to pain behavior and movement-related lumbar muscle activity.
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Randomized Controlled Trial Clinical Trial
A double-blind comparison between epidural morphine and epidural clonidine in patients with chronic non-cancer pain.
In a randomised double-blind study of 20 patients with chronic pain, epidural morphine 5 mg in 5 ml of saline was compared with epidural clonidine 150 micrograms in 5 ml of saline. Thirteen patients had a clinical and radiological diagnosis of arachnoiditis, 6 had low back pain and 1 had post-operative scar pain. There were 18 females and 2 males with an average age of 52 years, range 22-76 years. ⋯ Clonidine was associated with sedation and a fall in blood pressure of greater than 20 mm Hg in all patients, 1 patient required ephedrine to treat hypotension. Twelve patients had pruritus, 7 nausea and 2 vomiting following the morphine. Statistically there was no difference found between morphine and clonidine for short-term (3 h) analgesia in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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In rats anaesthetized with urethane, we have investigated the response of neurones in the ventrobasal complex of the thalamus to noxious ischaemia of the tail, and to graded noxious thermal stimulation of the tail before and after ischaemia. In behavioural experiments conscious rats were exposed to the same experimental procedure. After ischaemia the threshold tail temperature required to elicit both a neuronal response and aversive behaviour in conscious rats, to thermal stimulation, was decreased significantly (P less than 0.01 paired t tests). ⋯ Most thalamic neurones responding to noxious thermal stimulation of the tail also increased firing rate during ischaemia. The latency of response of the thalamic neurones to ischaemia was 12.1 +/- 1.8 min and the latency of the behavioural response to the same stimulus was 11.9 +/- 2.1 min. Ventrobasal thalamic neurones, therefore, which responded to noxious thermal stimulation of the tail also responded to noxious ischaemia, and exhibited a neuronal correlate of post-ischaemic hyperalgesia which paralleled behavioural responses closely.
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Comparative Study Clinical Trial Controlled Clinical Trial
Morphine and ibuprofen compared using the cold pressor test.
The analgesic efficacy of single doses of oral morphine sulphate solution (10 mg) and ibuprofen 600 mg was compared in 12 volunteers using a double-blind, double-dummy, placebo-controlled design on the cold pressor experimental pain model. Measurement of pain intensity was made before medication and then at 30, 60, 90, 120 and 180 min; blood samples were taken at these times for measurement of morphine and glucuronide metabolites by radioimmunoassay. Sessions were at least 5 days apart. ⋯ Ibuprofen was statistically indistinguishable from placebo on all three measures of analgesia. Analgesic effect and plasma concentrations of morphine showed significant correlation (P = 0.053). The study confirmed reports of the opiate sensitivity of the cold pressor model, and the apparent insensitivity of the model to non-steroidal anti-inflammatory drugs.