Pain
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The perception threshold for epidural spinal cord stimulation in chronic pain management was analyzed on 3,923 testing data obtained from 136 implanted patients. The initial areas of paresthesiae due to stimulation were recorded and reported as the stimulation map according to the location of electrodes. Measurement of dorsal thickness of the cerebrospinal fluid (CSF) layer was obtained from 26 subjects using magnetic resonance imaging (MRI). ⋯ The medially placed electrodes caudal to the mid-cervical levels have a higher perception threshold than more laterally placed ones. The electrodes at high and mid-cervical levels, however, have a smaller perception threshold if placed medially. The information obtained from this investigation has important implications for the design of a new-generation stimulation system and clinical application to maximize the longevity of the power source.
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Case Reports
Intrathecal morphine and clonidine in the management of spinal cord injury pain: a case report.
Neuropathic pain following spinal cord injury (SCI) can be difficult to manage using currently available pain management techniques. We describe a case of chronic pain following SCI which failed to respond to a variety of approaches including intrathecal administration of morphine. Use of clonidine in addition to the morphine resulted in a marked decrease in pain. The use of intrathecal clonidine with or without opioids may present an effective alternative in the management of intractable SCI pain and other forms of neuropathic pain.
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Clinical Trial
Catastrophizing, depression and the sensory, affective and evaluative aspects of chronic pain.
Research has shown that catastrophizing is related to increased depression and chronic pain. However, some researchers have questioned the utility of catastrophizing as a separate construct, suggesting that it may just be a symptom of depression. The present investigation used path analysis to determine if catastrophizing was related to McGill Pain Questionnaire scores when controlling for depression as assessed by the Beck Depression Inventory in a group of 85 chronic pain patients. ⋯ The resulting path coefficients appear to support these predictions. The results suggest that catastrophizing is a separate construct which may impact on pain perception and treatment. The data also provide some support for Field's neurobiological model of the relationship between depression and pain.
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The experimental arthritis of the knee joint used in the present study leads to joint swelling, increased joint temperature, limping, guarding, and a decrease in paw withdrawal latency (PWL) to radiant heat (hyperalgesia) within hours in rats. Unexpectedly, administration of the non-NMDA receptor antagonist, CNQX, in the spinal cord 4 h after initiation of the arthritis significantly reduced the degree of joint inflammation and returned PWL times to baseline. Therefore, the present results indicate that established joint swelling and hyperalgesia can be reduced significantly by CNQX.
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The rat foot withdrawal response to noxious radiant heat has been used as a model of nociception that is particularly useful for measurements of unilateral changes in nociceptive responses. The purpose of these studies was to characterize the foot withdrawal response to graded rates of noxious skin heating. Response latencies and both surface and subsurface temperatures produced by 6 different intensities of radiant heat were measured to determine whether response latency is an appropriate measure of nociceptive threshold. ⋯ These results and published reports of nociceptive afferent recordings which used similar skin heating parameters, indicate that nociceptive foot withdrawal responses occur at about the same skin temperature as the activation of nociceptors. These results also indicate that since constant intensity heating produces linear increases in the subsurface temperature, then response latency can be used as an accurate measure of changes in nociceptive threshold produced by drug treatments. These observations lead to the conclusion that the foot withdrawal response latency is a valid and useful measure of nociceptive threshold in rodents.