The journal of pain : official journal of the American Pain Society
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Pulsed radiofrequency, in which short bursts of radiofrequency energy are applied to nervous tissue, has been recently described as an alternative technique devoid of nerve injury, a subsequent side effect of thermal lesions created by continuous radiofrequency lesioning. Yet the mechanism of this effect remains unclear. In this study we compared the acute effects of pulsed versus continuous radiofrequency energy on impulse propagation and synaptic transmission in hippocampal slice cultures and on cell survival in cortical cultures. ⋯ In addition, although both continuous radiofrequency and pulsed radiofrequency treatments induced a distance-dependent tissue destruction under the stimulating needle, the effect was more pronounced in the continuous radiofrequency group. These findings suggest that the acute effects of pulsed radiofrequency are more reversible and less destructive in nature than the classic continuous radiofrequency mode, even in normothermal conditions. This model might help elucidate the importance of various parameters for the clinical application of radiofrequency lesioning and might open new horizons for the role of pulsed radiofrequency lesioning in cases of neuropathic pain.
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Comparative Study
Gonadal hormones do not account for sexual dimorphism in vagal modulation of nociception in the rat.
Subdiaphragmatic vagotomy produces a decrease in mechanical nociceptive threshold that is greater in male rats and an enhancement of bradykinin hyperalgesia that is greater in female rats. To examine the role of gonadal hormones in these sex differences, we evaluated the effect of gonadectomy, with or without gonadal hormone replacement, on vagal modulation of nociceptive threshold and bradykinin hyperalgesia by using the Randall-Selitto paw withdrawal test. Gonadectomy (before sexual maturation) plus vagotomy decreased nociceptive threshold in male rats more than either lesion alone, whereas neither lesion nor in combination had an effect on nociceptive threshold in female rats. ⋯ Testosterone replacement in vagotomized males and 17 beta-estradiol in vagotomized females reversed the effect of gonadectomy. Dihydrotestosterone replacement in vagotomized males also reversed the effect of gonadectomy on bradykinin hyperalgesia, although to a lesser degree than testosterone. We conclude that although gonadal hormones and other gonadal-dependent mechanisms influence nociception, they do not account for sexual dimorphism in vagal modulation of mechanical nociceptive threshold or bradykinin hyperalgesia.
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Comparative Study
Race and chronic pain: A comparative study of young black and white Americans presenting for management.
Chronic pain is a debilitating problem for many Americans. It affects physical, social, and emotional health. This study addresses the potential differential effects of chronic pain cross-culturally in younger Americans. ⋯ They also experience a higher prevalence of self-identified comorbidities, including dizziness, chest pain, and high blood pressure. In conclusion, considerable diminution in the overall physical and emotional health of black Americans 18 to 50 years of age with chronic pain was noted. These data support the need for further study of the chronic pain experiences of racial and ethnicity minority persons.
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Review
Transcutaneous electrical nerve stimulation: basic science mechanisms and clinical effectiveness.
Transcutaneous electrical nerve stimulation (TENS) is used clinically by a variety of health care professionals for the reduction of pain. Clinical effectiveness of TENS is controversial, with some studies supporting whereas others refute its clinical use. Although used by health professionals for decades, the mechanisms by which TENS produces analgesia or reduces pain are only recently being elucidated. ⋯ We also review the clinical literature on TENS effectiveness and elucidate the problems with clinical research studies to date. In conclusion, TENS is a noninvasive modality that is easy to apply with relatively few contraindications. However, the clinical efficacy of TENS will remain equivocal until the publication of sufficient numbers of high quality, randomized, controlled clinical trials.
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Randomized Controlled Trial Clinical Trial
The heat/capsaicin sensitization model: a methodologic study.
The heat/capsaicin sensitization model induces cutaneous sensitization by using a combination of heat and topical capsaicin. It has been suggested that the stability and duration of the cutaneous sensitization are due to a synergistic effect between heat and capsaicin. The aim of this study was to evaluate a possible synergistic effect between heat and capsaicin in inducing cutaneous sensitization. ⋯ The within day reproducibility was better with heat/capsaicin than with either stimulation alone. There was no synergistic or additive effect between heat and capsaicin in inducing cutaneous sensitization. Rekindling seems to be the important factor in maintaining stable and long-lasting cutaneous sensitization.