How To Do an Ulnar Nerve Block

Laceration or other surgically treated lesion of the volar or dorsal surface of the ulnar (medial) half of the hand, including the little finger and ulnar half of the ring finger*

Ring removal from the little finger or ring finger

History of allergy to the anesthetic agent or delivery vehicle (choose a different anesthetic)

Absence of anatomic landmarks needed to guide needle insertion (eg, due to trauma)

Infection in the path of needle insertion: Use procedural sedation How To Do Procedural Sedation and Analgesia Procedural sedation and analgesia (PSA) is the administration of a short-acting sedative-hypnotic or dissociative agent, with or without an analgesic, for patients undergoing anxiety-provoking... read more or other anesthesia.

Coagulopathy*: When feasible, correct prior to procedure, or use a different means of analgesia.

Adverse reaction to the anesthetic or delivery vehicle Local anesthesia for laceration treatment (eg, allergic reaction to the anesthetic [rare] or to methylparaben [a preservative])

Toxicity due to anesthetic overdose (eg, seizure, cardiac arrhythmias) or sympathomimetic effects due to epinephrine (if using an anesthetic-epinephrine mixture)

Intravascular injection of anesthetic or epinephrine

Hematoma

Neuritis

Spread of infection, by passing the needle through an infected area

Nonsterile gloves

Barrier precautions as indicated (eg, face mask, safety glasses or face shield, cap and gown)

Antiseptic solution (eg, chlorhexidine, povidone-iodine, alcohol)

Injectable local anesthetic* such as lidocaine 2% with epinephrine† 1:100,000, or for longer-duration anesthesia, bupivacaine 0.5% with epinephrine† 1:200,000

Syringe (eg, 10 mL) and needle (eg, 25 or 27 gauge, 3.5 cm long).

For ultrasonography: Ultrasound machine with high frequency (eg, 7.5 MHz or higher) linear array probe (transducer); probe cover (eg, transparent sterile dressing, single-use probe cover); sterile, water-based lubricant, single-use packet (preferred over multi-use bottle of ultrasound gel)

Document any preexisting nerve deficit before doing a nerve block.

Stop the nerve block procedure if you are unsure where the needle is or if the patient is uncooperative. Consider sedation How To Do Procedural Sedation and Analgesia Procedural sedation and analgesia (PSA) is the administration of a short-acting sedative-hypnotic or dissociative agent, with or without an analgesic, for patients undergoing anxiety-provoking... read more for patients who are unable to cooperate.

The ulnar nerve lies along the ulnar aspect of the wrist, medial (ulnar) to the ulnar artery.

The artery and the nerve are deep to the flexor carpi ulnaris tendon, which inserts on the pisiform.

The dorsal cutaneous branches of the nerve wrap around the ulna to innervate the dorsum of the ulnar side of the hand.

Position the patient with the arm resting with the palm facing up.

Check sensation and motor function of the ulnar nerve.

Wear gloves and use appropriate barrier precautions.

Locate the flexor carpi ulnaris tendon by palpating just proximal to the pisiform bone as the patient flexes the wrist against resistance.

The needle-entry site: The needle will be inserted horizontally into the ulnar side of the wrist at the proximal flexor crease, under the flexor carpi ulnaris tendon and distal to the ulnar styloid.

Cleanse the site with antiseptic solution.

Place a skin wheal of anesthetic, if one is being used, at the needle-entry site.

Insert the needle horizontally, under the flexor carpi ulnaris tendon, and advance it about 1 to 1.5 cm laterally (radially) toward the ulnar nerve. If paresthesia occurs during insertion, withdraw the needle 1 to 2 mm.

Aspirate to exclude intravascular placement and then slowly (ie, over 30 to 60 seconds) inject 3 to 5 mL of anesthetic.

Next, anesthetize the dorsal branches of the ulnar nerve: Withdraw the needle, then reinsert it dorsally and slowly infiltrate an additional 5 to 6 mL of anesthetic subcutaneously from the lateral border of the flexor carpi ulnaris tendon to the dorsal midline.

Allow about 5 to 10 minutes for the anesthetic to take effect.

Ensure hemostasis at the injection site.

Instruct patient regarding anticipated time to anesthesia resolution.

To minimize the risk of needle breakage, do not bend a needle, insert it to its full depth (ie, to the hub), or attempt to change direction of the needle while it is inserted.

To help prevent nerve injury or intraneural injection, instruct patients to report paresthesias or pain during the procedure.

To help prevent intravascular injections, aspirate before injecting.

Always maintain ultrasound visualization of the needle tip during insertion.

If using ultrasound, always maintain ultrasound visualization of the needle tip during insertion.

Minimize the pain of injection Local anesthesia for laceration treatment by injecting slowly (eg, 30 to 60 seconds), warming the anesthetic solution to body temperature, and buffering the anesthetic.

Some clinicians prefer to use an insulin syringe and volar approach for a landmark-based ulnar nerve block, inserting the needle just lateral (radial) to the flexor carpi ulnaris tendon between the proximal and distal flexor wrist creases; however, this technique may increase the risk of ulnar arterial injection.