How To Do a Digital Nerve Block

• Laceration or other surgically treated lesion of a finger*

• Ring removal

A digital nerve block has advantages over local anesthetic infiltration; it typically causes less pain, provides better anesthesia, and does not distort wound edges, which is important because there is little extra space in the fingers.

* This includes fracture, dislocation, fingernail removal, infection.

Absolute contraindications

• 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)

Relative contraindications

• Infection in the path of needle insertion: Use procedural sedation or other anesthesia.

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

* Therapeutic anticoagulation (eg, for pulmonary embolism) increases the risk of bleeding with nerve blocks, but this must be balanced against the increased risk of thrombosis (eg, stroke) if anticoagulation is reversed. Discuss any contemplated reversal with the clinician managing the patient's anticoagulation and then with the patient.

• Adverse reaction to the anesthetic or delivery vehicle (eg, allergic reaction to the anesthetic [rare] or to methylparaben [a preservative])

• Hematoma

• Neuritis

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

Most complications result from inaccurate needle placement.

• Nonsterile gloves

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

• Syringe (eg, 3 mL) and needle (eg, 25 or 27 gauge) for anesthetic injection

* Local anesthetics are discussed in Lacerations.

• 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 for patients who are unable to cooperate.

• Each finger is innervated by 4 nerves: bilateral dorsal and palmar digital.

• The palmar digital nerves originate from the medial and ulnar nerves.

• The dorsal digital nerves originate from the cutaneous branches of the ulnar and radial nerves that wrap around to innervate the dorsum of the hand.

• Digital nerve blocks are traditionally placed in the web space adjacent to the metacarpal head, with one needle insertion on each side of the finger.

• The middle 3 fingers can be anesthetized by blocking only the palmar digital nerves of those fingers.

• The thumb and little finger are anesthetized by blocking both their palmar and dorsal digital nerves.

• Position the patient with the arm supported. The hand is supinated for volar injections and pronated and flat for dorsal injections (eg, ring block).

• Check sensation of the finger (palmar and dorsal surfaces).

• Wear gloves and use appropriate barrier precautions.

• Cleanse the site with antiseptic solution.

• Ensure hemostasis at the injection site.

• Instruct patient regarding anticipated time to anesthesia resolution.

• To minimize the risk of needle breakage, do not bend the 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.

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

1. 1.Cannon B, Chan L, Rowlinson JS, et al: Digital anaesthesia: One injection or two? Emerg Med J 27:533-536, 2010. doi:10.1136/emj.2009.072850