Reduced risk of intraneural or worse intrafascicular injection. Likely the primary cause of serious nerve injury from peripheral nerve blocks.
Reduced risk of intravascular injection and resulting systemic local anesthetic toxicity
Reduced risk of inadvertent subarachnoid needle placement when performing proximal blocks such as the interscalene brachial plexus block. Total spinal anesthesia and devastating spinal cord syrinx formation has been reported.
Quincke tip spinal (20-22G) is a back up if a block needle is unavailable
Tips for reducing risk of needle-to-nerve injury
Only block an awake and calm patient: any paresthesias or pain with needling while using a non-block needle should be be considered high risk events prompting movement away from any nerve, ceasing any injection, and potentially aborting the procedure altogether
Use in-plane US visualization of the entire needle length
Avoid high risk blocks (interscalene brachial plexus in particular) unless you have 100% confidence in your needle visualization and anatomy
Use a stay-away technique maximizing the distance from needle to nerve