Ultrasonographic guided block of the median nerve

Abstract

Summary Median nerve anaesthesia is sometimes indicated in the diagnosis of forelimb lameness in the horse in conjunction with the ulnar nerve block, but the localisation of the nerve to perform a precise deposition of the anaesthetic solution around and close to the nerve is difficult to achieve using the conventional blind technique. The objectives of this paper are to describe the ultrasonographic anatomy of the median nerve and the technique for performing an ultrasound‐guided anaesthetic block of the nerve. The median nerve is imaged using a microconvex (or linear) probe in transverse section performed proximally to the chestnut on the medial aspect of the forearm. Distribution of the anaesthetic solution around the nerve is done by initially inserting the needle caudally and then cranially to the nerve and injecting 4–6 mL at each site. Control of the needle penetration avoids erroneous intravascular or intramuscular injections or sudden horse reaction. Ultrasound‐guided injection has the potential to safely and accurately block the median nerve.

Comparison of 2% mepivacaine and a solution of 2% lidocaine/epinephrine administered for median and ulnar nerve blocks in horses with naturally occurring forelimb lameness

“…The same individual performed all blocks to try to minimize the chance of technical errors. An ultrasound-guided technique is described and was considered; 33,34 however as the blind technique is the most commonly utilized in clinical practice, the blind technique was utilized to make results most useful for the diagnostician. The VS was reduced by 80% at 60 min after blocking with lidocaine/epinephrine.…”

Ultrasound‐guided perineural injection of the tibial nerve in the horse versus a ‘blind’ technique

“…Ultrasound (US)-guided technique is the accepted gold standard for perineural analgesia in human medicine (Kruisselbrink & Chin, 2015) and is increasingly used in veterinary medicine (Beaumont et al, 2020;Denoix et al, 2020;Portela et al, 2018aPortela et al, , 2018b. Injection under US guidance is reported to increase the accuracy of needle placement compared to 'blind' injection techniques, potentially reducing complications associated with inaccurate deposition of injectate or inadvertent damage to surrounding structures (Jarosinski et al, 2020;Schneeweiss et al, 2012).…”

“…Injection under US guidance is reported to increase the accuracy of needle placement compared to ‘blind’ injection techniques, potentially reducing complications associated with inaccurate deposition of injectate or inadvertent damage to surrounding structures (Jarosinski et al, 2020; Schneeweiss et al, 2012). Therefore, the use of US guidance for perineural analgesia in lameness investigation of the horse could result in an increased success rate of injection, the more prompt onset of analgesia and increased operator and patient safety (Beaumont et al, 2020; Denoix et al, 2020; Kruisselbrink & Chin, 2015).…”