Pain
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Comparative Study
Somatostatin modulates the transient receptor potential vanilloid 1 (TRPV1) ion channel.
Activation of peripheral somatostatin receptors (SSTRs) inhibits sensitization of nociceptors, thus having a short term or phasic effect [Pain 90 (2001) 233] as well as maintaining a tonic inhibitory control over nociceptors [J Neurosci 21 (2001) 4042]. The present study provides several lines of evidence that an important mechanism underlying SSTR modulation of nociceptors is regulation of the transient receptor potential vanilloid 1 ion channel (TRPV1, formerly the VR1 receptor). Double labeling of L5 dorsal root ganglion cells demonstrates that approximately 60% of SSTR2a-labeled cells are positive for TRPV1. ⋯ Furthermore, blockade of peripheral SSTRs with c-SOM dramatically enhances CAP-induced behaviors and nociceptor activity, demonstrating SSTR-induced tonic inhibitory modulation of TRPV1. Finally, TRPV1 does not appear to be under tonic opioid receptor control since the opioid antagonist naloxone does not change CAP-induced excitation and does not effect OCT-induced inhibition of CAP responses. These data strongly suggest that SSTRs modulate nociceptors through phasic and tonic regulation of peripheral TRPV1 receptors.
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Randomized Controlled Trial Comparative Study Clinical Trial
Pre-emptive analgesia using intravenous fentanyl plus low-dose ketamine for radical prostatectomy under general anesthesia does not produce short-term or long-term reductions in pain or analgesic use.
The aim of the study was to evaluate post-operative pain and analgesic use after pre-operative or post-incisional i.v. fentanyl plus low dose i.v. ketamine vs. a standard treatment receiving i.v. fentanyl but not ketamine. Men undergoing radical prostatectomy under general anesthesia were randomly assigned in a double-blinded manner to one of three groups. Patients received i.v. fentanyl before incision followed by an i.v. bolus dose (0.2 ml kg(-1)) and an i.v. infusion (0.0025 ml kg(-1)min(-1)) of 1 mg ml(-1) ketamine (group 1) or normal saline (groups 2 and 3). ⋯ Pain scores and von Frey pain thresholds did not differ significantly among groups. Two-week and 6-month follow-ups did not reveal significant group differences in pain incidence, intensity, disability or mental health. Pre-operative, low-dose administration of i.v. ketamine did not result in a clinically meaningful reduction in pain or morphine consumption when compared with post-incisional administration of ketamine or a saline control condition.
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To investigate neglect, extinction, and body-perception in patients suffering from complex regional pain syndrome (CRPS). So-called 'neglect-like' symptoms have been reported in CRPS, however no studies have yet analyzed this phenomenon which might substantiate the theory of the central nervous system involvement in the pathophysiology of CRPS. A total of 114 patients with CRPS of the upper limb underwent bedside neurological examination. 'Neglect-like' symptoms were determined by asking all patients what kind of feeling they had toward the affected hand (feeling of foreignness). ⋯ A large proportion of CRPS patients have disturbances of the self-perception of the hand, indicating an alteration of higher central nervous system processing. There are no indicators that classic neglect or extinction contribute to these findings. Physical therapy of such patients should take this observation into consideration.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Relative analgesic potency of fentanyl and sufentanil during intermediate-term infusions in patients after long-term opioid treatment for chronic pain.
Sufentanil, a potent mu-opioid agonist, historically has not been been given systemically to treat chronic pain. An implantable, fixed-rate osmotic pump that delivers sufentanil subcutaneously is being developed for this purpose. In that transdermal fentanyl may be a useful intermediary to estimate the appropriate sufentanil dose before implant, accurate information is needed about the relative analgesic potency of sufentanil and fentanyl during continuous infusion. ⋯ For the remaining 41 patients, target concentrations associated with adequate analgesia were achieved for both sufentanil and fentanyl. The median value for the equianalgesic concentration ratio (steady-state fentanyl infusion to steady-state sufentanil infusion) was 7.5; mean potency ratio was 7.44 (95% confidence interval 6.8-8.2). During titrated, intermediate-term infusions in patients previously treated with opioids for chronic pain, sufentanil is approximately 7.5 times as potent as fentanyl.