Pain
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Records of 313 patients who had been treated with spinal morphine via an implanted Port-A-Cath were reviewed. In 284 cases the Port-A-Cath was implanted for epidural delivery of morphine in patients with cancer-related pain. These patients were treated for a mean of 96 (range 1-1215) days. ⋯ Port-A-Caths were also implanted for delivery of spinal morphine in 12 patients with chronic pain which was not related to cancer and which failed to respond to other therapies. These patients were treated for a mean of 155 (range 2-575) days. Port-A-Caths were removed from 7 of these patients, primarily due to infection (2 cases) and inadequate pain relief and pain on injection (2 cases).
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Recent studies suggest that coping strategies play an important role in adjustment to chronic pain. Identification of factors that influence coping could potentially help clinicians facilitate the use of adaptive coping strategies by pain patients. According to social learning theory, self-efficacy beliefs (judgments regarding one's capabilities) and outcome expectancies (judgments regarding the consequences of behaviors) are significant determinants of coping behavior. ⋯ In support of social learning theory, and consistent with research in other areas, the patients' beliefs regarding their capabilities were strongly related to reported coping efforts. Beliefs about the consequences of coping efforts and their interaction with beliefs about capabilities were generally unrelated to coping. These results suggest that treatment should emphasize the actual practice and use of adaptive coping strategies over education about their outcome.
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Repetitive stimulation of small diameter primary afferent fibres produces a progressive increase in action potential discharge (windup) and a prolonged increase in the excitability of neurones in the spinal cord following the stimulus. Previous studies have demonstrated that windup is the consequence of the temporal summation of slow synaptic potentials and that the slow potentials and windup are reduced by pretreatment with N-methyl-D-aspartic acid (NMDA) antagonists. We have now examined whether primary afferent induced hypersensitivity states in flexor motoneurones are also dependent on the activation of NMDA receptors and whether windup is a possible trigger for the production of the central hypersensitivity. ⋯ When the the MK-801 and the D-CPP were administered once a state of central facilitation had been induced by prior treatment with mustard oil, they returned the facilitated reflex to its pretreatment level. These results indicate that NMDA receptors are involved in the induction and maintenance of the central sensitization produced by high threshold primary afferent inputs. Because central sensitization is likely to contribute to the post-injury pain hypersensitivity states in man, these data have a bearing both on the potential role of NMDA antagonists for pre-emptive analgesia and for treating established pain states.