Perineural versus intravenous dexamethasone as adjuncts to local anaesthetic brachial plexus block for shoulder surgery.

This randomised, double-blind, placebo-controlled study compared the effect of perineural with intravenous dexamethasone, both administered concomitantly with interscalene brachial plexus block for shoulder surgery. Patients received 8 mg dexamethasone mixed with ropivacaine in the block injection (n = 42), 8 mg dexamethasone intravenously at the time of the block (n = 37), or intravenous saline (n = 41) at the time of the block. Perineural and intravenous dexamethasone resulted in prolonged mean (SD) duration of block to 16.9 (5.2) h and 18.2 (6.4) h, respectively, compared with 13.8 (3.8) h for saline (p = 0.001). Mean (SD) opioid consumption (morphine equivalents) during the first 24 h after postanaesthesia recovery arrival was 12.2 (9.3) mg in the perineural dexamethasone, 17.1 (15.9) mg in the intravenous dexamethasone and 24.1 (14.3) mg in the saline groups (p = 0.001). Dexamethasone via either route reduced anti-emetic use (p = 0.046). There was no effect on patient satisfaction. These results suggest that both perineural and intravenous dexamethasone are useful adjuncts to ropivacaine interscalene block, with the intravenous route preferred as this avoids the possibility of neural toxicity of dexamethasone.

Response to occipital nerve block is not useful in predicting efficacy of occipital nerve stimulation.

Occipital nerve stimulation (ONS) may be effective for the treatment of headaches that are recalcitrant to medical therapy. The objective of this study was to determine if response to occipital nerve block (ONB) predicts response to ONS in patients with chronic, medically intractable headaches. We evaluated 15 patients who underwent placement of occipital nerve stimulators for the treatment of chronic headaches. Data were collected regarding analgesic response to ONB and to ONS. Nine of 15 patients were ONS responders (> or =50% reduction in headache frequency or severity). Thirteen patients had ONB prior to stimulator implantation. Ten of 13 who had ONB had significant relief of head pain lasting at least 24 h, and three were ONB non-responders. Of the three ONB non-responders, two were ONS responders. Of the two patients who did not have ONB prior to ONS, one was an ONS responder and one was an ONS non-responder. In conclusion, analgesic response to ONB may not be predictive of the therapeutic effect from ONS in patients with medically refractory chronic headaches.

Occipital nerve stimulation for chronic headache--long-term safety and efficacy.

The aim of this study was to examine the safety and efficacy of occipital nerve stimulation for medically intractable headache. Electrical stimulation of large sensory afferents has an antinociceptive effect. Occipital nerve stimulation may be effective for the treatment of medically intractable headache. Retrospective analysis was performed of 15 patients with medically refractory headache who underwent implantation of an occipital nerve stimulator. Pre- and postimplant data regarding headache frequency, severity, disability, depression and poststimulator complications were collected. Twelve patients were female and three male. Ages ranged from 21 to 52 years (mean 39 years). Eight patients had chronic migraine, three chronic cluster, two hemicrania continua and two had post-traumatic headache. Eight patients underwent bilateral and seven had unilateral lead placement. Patients were measured after 5-42 months (mean 19). All six mean headache measures improved significantly from baseline (P < 0.03). Headache frequency per 90 days improved by 25 days from a baseline of 89 days; headache severity (0-10) improved 2.4 points from a baseline of 7.1 points; MIDAS disability improved 70 points from a baseline of 179 points; HIT-6 scores improved 11 points from a baseline of 71 points; BDI-II improved eight points from a baseline of 20 points; and the mean subjective percent change in pain was 52%. Most patients (60%) required lead revision within 1 year. One patient required generator revision. Occipital nerve stimulation may be effective in some patients with intractable headache. Surgical revisions may be commonly required. Safety and efficacy results from prospective, randomized, sham-controlled studies in patients with medically refractory headache are needed.

Brachial plexus neuropathy following attempt at subclavian vein catheterization. Case report.

BACKGROUND AND OBJECTIVES: The subclavian vein is often used for placement of central venous catheters, and the possibility exists of nerve injury as a complication of the procedure. METHODS: A 58-year-old woman undergoing subclavian central catheter placement sustained a brachial plexus injury. A review of the English-language literature revealed no reports of brachial plexus injury during placement of a subclavian central catheter, although three reports were found in the non-English-language literature. RESULTS: The anatomic relationship of the subclavian artery, vein, and brachial plexus at the supraclavicular triangle is described, and suggestions are given as to how to avoid this problem. CONCLUSIONS: Brachial plexus injury can occur with placement of subclavian central catheters, but proper technique should minimize this complication.

Mediation of serotonin-induced analgesia by the 5HT2 receptor in the pentobarbital anesthetized mouse model.

Serotonin can induce analgesia when injected directly into the brain, but analgesia after peripheral administration has been more difficult to show. The pentobarbital anesthetized mouse (PAM) model, developed to alleviate some of the problems involved in the measurement of tail flick latency, was used to assess the action of peripherally administered serotonin. Mice were anesthetized with about 65 mg/kg of sodium pentobarbital IP and their tail flick latencies measured while they were in stage III anesthesia. In these anesthetized mice, IP serotonin induced a significant analgesia that was much more robust than that found in awake mice. The analgesic effect was dose-dependent from 0.25 mg/kg to 10 mg/kg but was not blocked by the antiopiate naltrexone. Of several psychotropic agents tested, only amitriptyline, mianserin, and trazodone had significant effects on analgesia in the PAM model. The analgesic effect of serotonin was reproduced by the 5HT2 agonist DOI and totally blocked by the 5HT2 antagonist NPP. These results show the utility of the PAM model in studying nonopiate analgesia and suggest that the analgesic action of serotonin is mediated primarily through the 5HT2 receptor.

The general anesthesia induced by various drugs differentially affects analgesia and its variability.

Responses to noxious stimuli in awake animals are not totally consensual but are influenced by environmental factors. We considered the possibility that the influence of the environment could be reduced by induction of general anesthesia. We, therefore, compared responses to nociceptive thermal stimuli by measuring tail flick latency, a spinal reflex, in anesthetized and awake mice. All anesthetics tested decreased the intraindividual variability in the measurement of response, suggesting that environmental factors may account for much of this variability in the awake mouse. Mice treated with pentobarbital showed a graded response to increasing levels of heat but were unresponsive to either morphine or naloxone. In mice anesthetized with pentobarbital, increases in latencies occurred only at very deep levels of anesthesia, while urethane nociceptive effect of ketamine was reversed by morphine. Thus, the various anesthetics could show differential effects towards opiate action. The decrease in statistical variability, the differential effects of general anesthetics on tail flick latency, and the distinctive effects of the different anesthetics on opiate action suggest that the anesthetized animal may be a useful tool in the study of nociception.