The most common emergency department indication for performing median nerve blocks isto anesthetize its hand distribution (i.e. volar surface of hand) for pain control and/or to perform procedures such as laceration repair and dislocation reductions.
The median nerve is located at the proximal flexor crease of the wrist, between the palmaris longus (PL) and flexor carpi radialis (FCR) tendons. The FCR lies radial to the PL tendon.
Use a 25 or 27 gauge needle, inserted to a depth of 1 cm, to inject 3-5 mL of plain lidocaine proximal to the distal wrist flexor crease, just ulnar to the PL tendon.
If the PL tendon is absent, as is the case in 25% of people, direct the needle in line with the ring finger.
If distal paresthesias result, withdraw and reposition the needle as this suggests that the median nerve was directly struck, which should be avoided.
