Digital Nerve Block
Digital nerve block is used to provide quick, reliable anesthesia of a finger or toe. Nerve block avoids injection of anesthetic into injured or more sensitive distal tissues, while providing sufficient anesthesia to allow nail removal, drainage of paronychia, reduction of minor dislocations, and other emergent and urgent procedures. This chapter describes the use of the basic web-space block in both the upper and lower extremities. Alternative techniques are described in references at the end.
SCORE™, the Surgical Council on Resident Education, classified digital nerve block as an “ESSENTIAL UNCOMMON” procedure.
STEPS IN PROCEDURE
Finger Block
Position the hand with the palm down on a padded well-supported surface
Prep the web spaces on each side of the digit to be anesthetized
For the thumb:
Prep the web space between thumb and index finger
Prep lateral aspect of thumb
Prepare a 5- to 10-mL syringe with local anesthetic without epinephrine and a 15- to 30-gauge needle
Enter the web space in the loose skin overlying the dorsum of the hand (or lateral aspect of the thumb, for thumb block)
Gently inject 2- to 4-mL of local anesthetic while advancing the needle toward the palmar aspect
Take care not to pierce the skin of the palm
Repeat the procedure on the other side
Gently massage the anesthetic into the tissues
Allow several minutes to achieve an effective block
Toe Block
Position the patient with easy access to the web spaces and great toe
Prep the web spaces and inject as noted above
For the great toe:
Inject the web space between the great toe and the next digit as described above
Inject soft tissues medial to great toe
It may be necessary to use a third injection across the dorsum of the toe to achieve adequate anesthesia
HALLMARK ANATOMIC COMPLICATIONS
Digital ischemia
LIST OF STRUCTURES
Ulnar nerve
Dorsal digital branches
Median nerve
Dorsal digital branches
Radial nerve
Dorsal digital branches
Proper palmar digital nerve, artery, and vein
Superficial fibular (peroneal) nerve
Dorsal digital branches
Lateral dorsal cutaneous nerve of foot
Deep fibular (peroneal) nerve
Digital arteries
The cutaneous innervation of the hand is shown in Figure 39.1A. Note how branches of the ulnar, median, and radial nerves bifurcate in complex patterns but in general local anesthesia injected along the medial and lateral aspects of each digit will produce a nerve block for the distal portion. These dorsal digital branches course in close proximity to the proper palmar digital arteries and veins as shown in Figure 39.1B. It is this close proximity to the proper palmar digital artery that creates the potential for ischemic complications when injections are made in this region. Do not use epinephrine-containing anesthetics because these may induce arterial spasm and ischemia.
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