Pain
-
Dilute capsaicin produces a differential effect on incision-related pain behaviors depending upon the test; it reduces heat hyperalgesia and guarding pain but not mechanical hyperalgesia. This suggests that common mechanisms for heat hyperalgesia and guarding pain occur, and distinct mechanisms exist for mechanical hyperalgesia. The purpose of the present study was to evaluate the effect of capsaicin treatment on the activity of cutaneous nociceptors sensitized by incision to understand the mechanisms for the selective action of dilute capsaicin on incisional pain. ⋯ Neither mechanical hyperalgesia nor mechanosensitivity of nociceptors was affected by capsaicin, suggesting that the concentration of capsaicin used in this study did not cause fiber degeneration. These results demonstrate that nociceptors desensitized by capsaicin contribute to heat hyperalgesia and guarding pain after plantar incision. These putative TRPV1-expressing C-fibers are sensitized to heat and acid after incision, and the transduction of heat and chemical stimuli after plantar incision is impaired by dilute capsaicin.
-
Both cyclooxygenase-1 and -2 are expressed in the spinal cord, and the spinal COX product prostaglandin E(2) (PGE(2)) contributes to the generation of central sensitization upon peripheral inflammation. Vice versa spinal COX inhibition is considered an important mechanism of antihyperalgesic pain treatment. Recently, however, COX-2 was shown to be also involved in the metabolism of endocannabinoids. ⋯ During established inflammation all COX inhibitors reduced release of spinal PGE(2) almost equally but only the COX-2 inhibitor prevented breakdown of 2-AG. The reversal of spinal hyperexcitability by COX-2 inhibitors was prevented or partially reversed by AM-251, an antagonist at the cannabinoid-1 receptor. We conclude that inhibition of spinal COX-2 not only reduces PG production but also endocannabinoid breakdown and provide evidence that reversal of inflammation-evoked spinal hyperexcitability by COX-2 inhibitors is more related to endocannabinoidergic mechanisms than to inhibition of spinal PG synthesis.
-
Randomized Controlled Trial Clinical Trial
High-frequency, high-intensity transcutaneous electrical nerve stimulation as treatment of pain after surgical abortion.
The aim of the study was to compare the pain-relieving effect and the time spent in the recovery ward after treatment with high-frequency, high-intensity transcutaneous electrical nerve stimulation (TENS) or intravenous (IV) conventional pharmacological treatment after surgical abortion. Two-hundred women who underwent surgical abortion and postoperatively reported a visual analogue scale (VAS) pain score3 were included. The patients were randomised to TENS or conventional pharmacological treatment for their postoperative pain. ⋯ The number of patients who needed additional analgesics in the recovery ward was comparable in both groups, as was the reported VAS pain score upon leaving the hospital (TENS=2.0 vs. conventional pharmacological treatment=1.8, NS). These results suggest that the pain-relieving effect of TENS seems to be comparable to conventional pharmacological treatment with IV opioids. Hence, TENS may be a suitable alternative to conventional pain management with IV opioids after surgical abortion.
-
There is an increasing number of studies of acceptance, mindfulness, and values-based action in relation to chronic pain. Evidence from these studies suggests that these processes may be important for reducing the suffering and disability arising in these conditions. Taken together these processes entail an overarching process referred to as "psychological flexibility." While these processes have been studied in people with chronic pain contacted in specialty treatment centers, they have not yet been investigated in primary care. ⋯ In these regression equations pain intensity accounted for an average of 9.2% of variance while psychological flexibility accounted for 24.1%. These data suggest that psychological flexibility may reduce the impact of chronic pain in patients with low to moderately complex problems outside of specialty care. Due to a particularly conservative recruitment strategy the overall response rate in this study was low and the generality of these results remains to be established.
-
Questions remain concerning effectiveness and risks of spinal cord stimulation (SCS) for chronic back and leg pain after spine surgery ("failed back surgery syndrome" [FBSS]). This prospective, population-based controlled cohort study evaluated outcomes of workers' compensation recipients with FBSS who received at least a trial of SCS (SCS group, n=51) versus those who (1) were evaluated at a multidisciplinary pain clinic and did not receive SCS (Pain Clinic, n=39) or (2) received neither SCS nor pain clinic evaluation (Usual Care, n=68). Patients completed measures of pain, function, medication use, and work status at baseline and 6, 12, and 24 months later. ⋯ Patients who received a permanent spinal cord stimulator did not differ from patients who received some pain clinic treatment on the primary outcome at any follow-up (<10% successful in each group at each follow-up) and 19% had them removed within 18 months. Both trial and permanent SCS were associated with adverse events. In sum, we found no evidence for greater effectiveness of SCS versus alternative treatments in this patient population after 6 months.