The journal of pain : official journal of the American Pain Society
-
The heat pain threshold was assessed in 32 healthy participants after a mild burn on the dorsal surface of each hand, after injection of an opioid antagonist (80 microg naloxone) or vehicle alone (0.2 mL saline) into the burnt skin of 1 hand, and after repeated painful immersion of this hand in cold water for up to 180 seconds. We hypothesized that sensitivity to heat would decrease at the burn-injured site after the immersions, due to local release of opioids into the burnt skin. Naloxone augmented cold-induced pain during the immersions in participants who tolerated the longest immersions, implying that release of endogenous opioids suppressed cold-pain. After the immersions, sensitivity to heat decreased at the burn-injured site in the immersed hand, but naloxone did not block this effect. Instead, naloxone altered sensitivity to heat in unburnt skin, implying that thermal hyperalgesia at sites of burn injury masked the modulatory effects of opioids. In particular, naloxone blocked a decrease in sensitivity to heat at an unburnt site on the contralateral hand of participants who tolerated the longest immersions, consistent with central or systemic opioid release. Naloxone reduced sensitivity to heat at unburnt sites in participants who tolerated medium-length immersions, suggesting that an increase in systemic or central opioid activity evoked thermal hyperalgesia in this group. In addition, in a small group of participants who tolerated only brief immersions, naloxone blocked decreases in sensitivity to heat at an unburnt site in the immersed hand. These findings suggest that repeated painful immersions trigger local opioid release in participants who tolerate only brief immersions, and elicit central or systemic opioid release in participants who tolerate longer immersions. ⋯ This article demonstrates that repeated immersion of the hand in painfully cold water increases opioid activity and that the increase in opioid activity exerts multiple opposing effects on sensitivity to heat. Individual differences in the response to opioids might contribute to individual differences in pain tolerance.
-
This study aimed to determine if electromyographic (EMG) diagnostic evaluation can predict functional outcome in patients undergoing transforaminal lumbar spine epidural injections. In this retrospective study, functional outcome by Oswestry Disability Index (ODI) and verbal rating scale (VRS) for current pain severity was evaluated in 39 patients undergoing lumbar transforaminal epidural spinal injections (ESI). Subjects with low back pain (mean age, 60 +/- 12.5 years) were evaluated for functional improvement post EMG and ESI. Of 39 patients tested with EMG before injection, 18 patients were positive for radiculopathy and 21 had a normal or negative examination. The patients were followed postinjection on average of 10.8 (SD +/- 3.9) weeks. Pretreatment ODI scores were not significantly different between groups showing positive (72.3 SD +/- 12.7) and negative (65.9 SD +/- 18.6, P > .05) EMG findings. There was significantly greater improvement of ODI for EMG positive radiculopathy (7.11 SD +/- 9.5) compared with negative EMG (3.2 SD +/- 17.4, P < .05). Positive radiculopathy subjects complained of more pain by VRS before ESI than subjects with negative EMG findings, 8.1 SD +/- 1.0 and 7.3 SD +/- 0.8, respectively, which was not significant (P > .05). VRS mean improvement was not significantly different in the positive EMG group (1.8 SD +/- 1.2) compared with a negative EMG (1.2 SD +/- 1.2, P > .05). ⋯ The results appear to show that patients undergoing transforaminal ESI, who have a positive radiculopathy by EMG before injection, will have significant improvement in functional outcome by ODI but not with current pain intensity by VRS. This study suggests the importance and diagnostic value of ordering electromyography studies for lumbar radiculopathy evaluation, which may lead to prediction of outcome with lumbar transforaminal epidural spinal procedures. Furthermore, the current study highlights the difficulty of pain evaluation outcome by VRS.
-
Comment Letter Case Reports
Complex regional pain syndrome-a multifaceted disorder requiring multidimensional care: case study.
-
Hypogonadotrophic hypogonadism is characteristically induced in men by intrathecal, transdermal, or sustained-action opioids. Although women receiving intrathecal opioids have similar changes, often accompanied by amenorrhea, hypogonadotrophic hypogonadism has not been documented in women receiving sustained-action, transdermal, or oral opioids. Dehydroepiandrosterone sulfate deficiency, indicating adrenal inhibition, is present in most men and women chronically consuming sustained-action oral or transdermal opioids. We recorded menstrual histories and measured gonadotrophin, androgen, and estradiol levels in 47 women ages 30 to 75 years who were consuming sustained-action oral or transdermal opioids for control of nonmalignant pain and in 68 non-opioid-consuming control subjects. Testosterone, estradiol, and dehydroepiandrosterone sulfate values were 48% to 57% lower in opioid-consuming women with intact ovarian tissue than in control subjects (P < .01-.05). Luteinizing hormone and follicle-stimulating hormone values averaged 30% lower in premenopausal and 70% lower in postmenopausal opioid consumers (P < .001). Among oophorectomized women not consuming estrogen, free testosterone levels were 39% lower in opioid consumers (P < .05), indicating impaired adrenal androgen production. Additional lowering of free testosterone levels was associated independently with oral estrogen replacement and low body mass index. Menses had often ceased soon after beginning sustained-action opioid therapy. Our observations document hypogonadotrophic hypogonadism plus decreased adrenal androgen production in most women consuming sustained-action oral or transdermal opioids. ⋯ These observations demonstrate profound inhibition of ovarian sex hormone and adrenal androgen production among women chronically consuming sustained-action opioids. Related consequences include altered menstrual flow, probable reduced fertility, and possible contributions to opioid-associated depression, osteoporosis, and hyperalgesia. Measurements of bone density, estradiol, and free testosterone may guide appropriate therapy.
-
Herpes zoster causes substantial morbidity, especially among older adults. Although the acute cutaneous manifestations can be painful and troublesome, the most important consequence of herpes zoster (shingles) is the chronic pain syndrome known as postherpetic neuralgia (PHN). Previous studies have suggested that declining varicella-zoster virus (VZV)-specific cell-mediated immune (CMI) responses account for the increased frequency of herpes zoster seen in older adults. This led to the idea that immunization designed to boost VZV-specific CMI responses might reduce the risk of herpes zoster. This hypothesis was tested in a large, randomized, placebo-controlled clinical trial called the Shingles Prevention Study (SPS). Compared with the placebo group, herpes zoster vaccine recipients had a 61.1% reduction in zoster "burden of illness" (an index incorporating incidence and severity of herpes zoster); a 66.5% reduction in the incidence of postherpetic neuralgia; and a 51.3% reduction in the incidence of herpes zoster. The incidence of serious adverse events was not different between the overall vaccine and placebo populations. The most frequently encountered adverse event among vaccine recipients was local reactogenicity, with self-limited and generally mild tenderness, warmth, or erythema occurring at the injection site in about one-half of vaccine recipients. The zoster vaccine was approved by the US Food and Drug Administration in 2006 and is indicated for prevention of herpes zoster in immunocompetent persons aged 60 years and older. ⋯ The herpes zoster vaccine provides physicians with an effective means for reducing a patient's risk for developing shingles and its attendant complications. No significant safety concerns regarding the vaccine have been identified. Indications for use of the attenuated-virus vaccine in special subpopulations continue to evolve.