Extraneural vs Intraneural Supraclavicular Block

Study Summary

This study highlights the fact that intraneural needle placement cannot be excluded by a minimum current threshold during neurostimulation. On the other hand, a minimum current threshold of 0.2mA or less strongly suggests that the needle tip may be intraneural. Further work is needed to determine if this is applicable to all peripheral nerves or only to the supraclavicular brachial plexus. There appears to be no single wholly reliable indicator of intraneural needle placement. Instead, practitioners should look at a combination of factors including paresthesia or pain, reistance to local anesthetic injection, nerve distension on ultrasound, and the minimum threshold current for neurostimulation.