Please confirm that an ethics committee approval has been applied for or granted: Not relevant (see information at the bottom of this page)

Background and Aims Blocks of individual nerves in the forearm, is well established, either a landmark or ultrasound guided approach. A circumferential spread of LA might result in an adequate or inadequate block. Based on a cadaveric-injection study, we aspire to investigate the spread pattern and anatomic-barriers that would impede the flow of injectate

Methods In 2-THEIL based cadavers and four specimens, a total of 12-injections (one each in median, ulnar and superficial-radial nerve) were performed. The primary aim was to evaluate the spread pattern of the injected latex in all three nerves. The secondary aim was to investigate the diffusion of injectate in muscles, para-neural tissue, epineural tissue and longitudinal extent of the spread of latex. Technique- A single puncture block was administered with 50mm needle under a linear probe with an out of plane approach, at 6cm distal to the elbow crease. A 3ml latex was injected each at median(blue), radial(green) and ulnar(green). At 24th-hour forearm dissection was executed from above the elbow crease up to the mid forearm.

Results Ultrasound-guided injections were performed in the paraneural tissue of all three nerves (4 specimens and 12 injections). Open dissection at 24-hours later revealed spread-pattern as 50%,75% and 50% continuous for median, superficial-radial and ulnar nerve respectively [table 1]. Epineural spread(25%), intramuscular diffusion in the muscle group of median(25%)and ulnar( 75%)occurred respectively

Conclusions Based on our cadaveric-injection study, we recommend a forearm nerve block at ‘5cm’distal to the elbow crease. We conclude, in the forearm nerves, a non-circumferential, longitudinal spread -pattern is consistent with a ‘3ml’ latex-injection.