Der Schmerz
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Two cases with perineal pain caused by recurrent carcinoma of the rectum are reported. Initially both patients suffered from predominantly nociceptive pain, which was treated adequately with spinal opioids. Tumor growth with epidural spread and infiltration of the plexus lumbosacralis caused severe neuropathic pain. ⋯ Bradycardia and hypotension occurred with initial dose titration and after dose increases and were treated with parasympathicolytic drugs and vasopressor agents. Both patients were given spinal clonidine until their death 4 1/2 and 4 months later. In the final stages, adjuvant systemic administration of morphine was necessary to control dyspnea.
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Chronic pain is often associated with an array of general psychological dimensions such as depression, somatic symptoms, anxiety, anger and a loss of quality of life. Part VIII describes various instruments concerning each dimension and comments on their applicability within a diagnostic routine for chronic pain patients. ⋯ Trait-anxiety and pain-unrelated state-anxiety seem not to be suitable because they lack significance for the therapy process. While the inventory for assessing anger still needs an empirical basis for chronic pain patients, quality of life inventories are not recommended for routine pain assessment.
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alpha(2)-Adrenoceptor agonists like clonidine, dexmedetomidine, and ST-91, inhibit nociceptive reflex activity predominantly by a spinal mode of action. They mimic the action of the inhibitory transmitter noradrenaline, which is released from the terminals of bulbospinal monoaminergic pathways. The inhibition by noradrenaline is due partly to hyperpolarization of the postsynaptic neuronal membrane; however, the selective antinociceptive effect of the alpha(2)-adrenoceptor agonists results from reduction of the release of the excitatory transmitters such as glutamate and substance P, blockade of the binding of substance P to spinal neurones, and enhancement of the action of the inhibitory transmitter, 5-hydroxytryptamine. ⋯ Moreover, impulse conduction in C fibres of peripheral nerves is far more reduced by these compounds than that in A fibres. Antinociceptive effects are reported to occur in various models of clinical pain, e.g. the formalin test, adjuvans-induced arthritis, autotomy following deafferentation, and "hyperalgesia" after nerve ligation. Therefore, the mechanisms involved in antinociception may also be responsible for the analgesia produced by alpha(2)-adrenoceptor agonists.