Ulnar nerve blocks are relatively easy to perform and excellent for anesthetizing the ulnar nerve distribution, particularly of the hand.
Ulnar nerve blocks can be performed at the level of the wrist (dorsal or volar side) or at the elbow. Volar side blocks at the wrist tend to be easier to perform and associated with less risk.
Using a 27 gauge needle, infiltrate 2 to 3 mL's of lidocaine between the flexor carpi ulnaris tendon and the distal-most aspect of the ulnar bone. The needle should be inserted 1 to 2 cm's at about a 40 degree angle, at the proximal-most wrist crease.
Do not puncture the actual ulnar nerve or the ulnar artery. Should needle insertion cause distal hand paresthesias or blood withdrawal, do not inject and immediately remove the needle, as this suggests that the ulnar nerve or artery was struck, respectively. The objective is to allow the lidocaine to infiltrate into the nerve, not to inject it directly into the nerve.
