Background: Multi-injection targeted intracluster injection ultrasound-guided supraclavicular brachial plexus block has been advocated to provide a faster onset of anaesthesia compared with a double injection technique. By placing the needle within clusters of hypoechoic structures, corresponding to neural tissue, this technique may increase needle trauma and the incidence of nerve injury. This study assessed the rate of sub-perineural needle placement with a single intracluster brachial plexus injection in the supraclavicular fossa of human cadavers. Methods: A single ultrasound-guided intracluster brachial plexus injection was performed bilaterally at the supraclavicular fossa on 21 lightly embalmed clinical grade cadavers. Using an in-plane technique, an echogenic needle was positioned to target the middle or lower trunk 'cluster', where 0.2 ml black India ink was injected. An effort was taken to avoid the hypoechoic structures with the needle tip. Tissue samples were assessed histologically by two experienced reviewers. Results: All 42 injections were sonographically assessed to be within the 'main cluster'. Ink was extra-epineural in 13/41 (32%), sub-epineural but outside perineurium in 18/41 (44%), and sub-perineural in 10/41 sections (24%; 95% confidence interval, 13e41%). The histology from one injection was uninterpretable. Of the 10 sub-perineural deposits, the ink was intrafascicular in nine sections. Conclusions: We observed a high rate of sub-perineural injection with a single intracluster injection. Thus the targeted intracluster injection supraclavicular block cannot be recommended until further evidence is available regarding the safety of this technique.

No abstract

Purpose: To report on the efficacy of peripheral plexus catheters in the treatment of ischemic pain in spite of nerve stimulation with long current impulses. Clinical features:Two patients with severe neuropathic ischemic foot pain are described. A 56-yr-old man with diabetes, renal failure, and autonomic neuropathy presented with severe ischemic foot pain. Opioids produced excess sedation and hypotension. A 62-yr-old woman was admitted after femoralpopliteal bypass and developed a reperfusion pain syndrome not relieved with opioids, gabapentin, amitryptiline, and clonidine. In both patients, a sciatic plexus catheter was placed with resolution of pain. Conventional nerve stimulation, which uses a pulse duration of 0.1 msec, did not result in muscle contraction. However, by using a nerve stimulator capable of delivering a 1.0 msec impulse duration, a muscle twitch or paresthesia endpoint ensued allowing for successful catheter placement. Conclusion:Peripheral plexus catheters provide a safe alternative to systemic analgesics for pain relief in patients with ischemic foot pain. However, conventional nerve stimulation techniques may not elicit a motor response in patients with underlying neuropathy, and the use of nerve stimulators capable of delivering long current impulses is recommended.Objectif : Présenter l'efficacité des cathéters de plexus périphéri-que utilisés dans le traitement de la douleur ischémique malgré la stimulation nerveuse avec de longues impulsions de courant.

The suprascapular nerve is consistently in the path of the block needle posterior to the clavicle. This raises the possibility of risk of injury to the suprascapular nerve when using this approach to the brachial plexus. Vascular injury is also possible deep to the clavicle, and because of the noncompressible location, caution is advised in patients with disordered coagulation.