Ultrasonographic appearance of intraneural injections in the porcine model.

Background: Ultrasonographic (US) images of apparent intraneural injection of local anesthetic solutions have been reported. We aimed to define US signs of intraneural (ie, subepineural) injection using a histologic standard in an animal model and compare these signs with other potential markers of intraneural injection, including low nerve stimulation current thresholds and high injection pressures.

Methods: In 6 anesthetized adult swine, bilateral brachial plexus and femoral nerves were contacted by needles and penetrated.