Goals

To provide adequate anesthesia to a digit in situations where injury or infection is present. Local infiltration of a digit requires numerous injections and may create increased swelling and distortion of the wound.

Background

A digital nerve block provides regional anesthesia by injecting an anesthetic agent into the base of a finger or toe. Types of digital nerve blocks include:

• Web-space block
• Transthecal block
• 3-sided digital block
• 4-sided ring block

This procedure will outline the steps for the web-space block. The technique for digital nerve block is the same for both fingers and toes, except the great toe. The 3-sided digital block is used for the great toe (steps outlined in the Procedure Steps section).

The web-space block is indicated for any minor procedure of the digits such as lacerations, lacerations involving the nail or the nail bed, ingrown nails, felon or paronychia, subungual hematoma, and digit dislocation or fracture.

Each digit is innervated by four digital nerves and all nerves must be blocked to achieve adequate anesthesia. Basic anatomy of the fingers and toes is reviewed below.

Upper extremity: Each finger is innervated by nerves arising from the median, ulnar, and radial nerves. The nerves divide in the palm into the palmer (or volar) branches. The nerves are accompanied by blood vessels and both the nerve and blood vessel run medially and laterally to the finger along the flexor tendon sheath. The palmar nerves innervate all of the finger and the nail bed. The dorsal digital nerve runs along the dorsolateral aspect of each finger and innervates the dorsum of the finger.

Lower extremity: Each toe is innervated by nerves arising from the tibial and peroneal nerves. The terminal branches of these nerves run medially and laterally to each toe. The great toe can be anesthetized using the three-sided digital block as there are additional nerves along the dorsal aspect that may be missed of anesthetic is only injected medially and laterally.

Benefits of a digital nerve block include less painful injection sites as the palmar aspect of the finger is more sensitive, and a larger, more consistent anesthesia for the duration of the procedure. The most common risks for performing a digital nerve block include bleeding, infection, or distal paresthesia if a nerve is damaged.

Contraindications

• Allergy to the anesthesia agent
• Decreased digital circulation
• Infection in the tissue of the injection sites