Nerve Blocks for Hand Injuries

Lidocaine, bupivacaine, or a combination of the two solutions can be
used. Add bicarbonate if it is available. Epinephrine should not be used
for anesthetizing the hand and fingers.
Digital Block
A digital block is the best way to evaluate and treat a wound on the
finger. The digital nerves supply sensation to the volar and dorsal surfaces
of the finger.
Anatomy. Each finger and the thumb have two digital nerves that
travel with the digital vessels along the lateral and medial sides of the
digit. Look at your own finger from the side, bend it at the two joints
(distal interphalangeal [DIP] and proximal interphalangeal [PIP]
joints). The line that connects the joint creases is a good estimate of
where each digital nerve runs.


Digital nerve block, dorsal approach. Care must be taken to ensure that the
anesthetic is not injected entirely circumferentially around the finger.
(Illustration by Elizabeth Roselius. From Green DP, et al: Operative Hand Surgery,
4th ed. New York, Churchill Livingstone, 1999, with permission.)

Procedure
1. The injection is done from the dorsal (not volar) surface near the
metacarpophalangeal (MCP) knuckle.
2. Insert the needle into the web space, when present (the thumb and
little finger are not bordered on both sides by web spaces).
3. Aim the needle toward the MCP joint of the affected finger, moving
in a volar direction.
4. Be careful not to inject too superficially on the volar side, or your injection
will miss the area around the nerve.
5. Inject 2–3 ml of solution into each side of the affected finger.
6. Infiltrate 1–2 ml along the dorsal skin of the digit, just distal to the
MCP knuckle.


Pattern of sensory innervation of major peripheral nerves. (From Jurkiewicz
MJ, et al (eds): Plastic Surgery: Principles and Practice. St. Louis, Mosby,
1990, with permission.)

Wrist Block
Three nerves supply sensation to the hand: the median nerve, ulnar
nerve, and superficial branch of the radial nerve. If you infiltrate around
all three nerves, you effectively anesthetize the entire hand. If an injury
is within the distribution of any one or two nerves, simply infiltrate
around the nerves that you need to anesthetize, based on the injury.
Median Nerve
The median nerve supplies sensation to the volar surface of the hand,
from the lateral half of the ring finger to the thumb, and to the dorsal
aspect of the fingers distal to the PIP joint, from the lateral half of the
ring finger to the thumb.
Anatomy. At the wrist the median nerve lies between the palmaris
longus (PL) and flexor carpi radialis (FCR) tendons. If the PL is absent
(15% of the population), the landmark for injection is just medial to the
FCR tendon.


Wrist block, median nerve. PL = palmaris longus, FCR = flexor carpi radialis.
(Illustration by Elizabeth Roselius. From Green DP, et al (eds): Operative Hand
Surgery, 4th ed. New York, Churchill Livingstone, 1999, with permission.)

Procedure
1. Have the patient flex the wrist. The FCR and PL (if present) become
noticeable in the distal forearm; the FCR is the more lateral of the
two tendons.
2. Insert the needle just proximal to the wrist crease and medial to the
FCR tendon.
3. Draw back on the syringe and slowly inject 3–5 ml of anesthetic in the tissues
deep to the skin.
4. If the patient describes minor tingling, the needle is in the proper
position. If the patient describes electric shocks or severe pain, the
needle may be in the nerve. Stop injecting the anesthetic, and back
the needle out a few mm before continuing to inject the anesthetic
solution. Do not inject the anesthetic directly into the nerve.
Ulnar Nerve
The ulnar nerve supplies the remainder of the volar surface of the hand
and the volar and dorsal surfaces of the ring and little fingers. The
dorsal ulnar side of the hand is innervated by a branch of the ulnar
nerve that comes off proximal to the wrist in the distal forearm.
Anatomy. At the wrist, the ulnar nerve lies with the ulnar artery lateral
to the flexor carpi ulnaris (FCU) tendon. The artery is lateral to the
nerve.


Procedure
1. Have the patient flex the wrist. The FCU is palpable along the
medial edge of the distal forearm.
2. Insert the needle just proximal to the wrist crease and just lateral to
the FCU tendon.
3. Draw back on the syringe before injecting the anesthetic to ensure that the
needle is not in the ulnar artery. If blood is drawn back, remove the
needle and hold pressure over the area for several minutes.
4. Slowly inject 1–2 ml of local anesthetic.
5. To block the nerve branch that supplies sensation to the dorsal
aspect of the hand, inject 1 ml of local anesthetic subcutaneously in
the tissues overlying the ulnar nerve.
6. Advance the needle onto the dorsum of the wrist, and inject another
3–4 ml. Go about halfway around the wrist on the dorsal surface.
Superficial Branch of the Radial Nerve
The superficial branch of the radial nerve supplies sensation to the
dorsum of the hand from the ring finger to the thumb; the dorsum of
the thumb; and the dorsum of the index, middle, long, and ring fingers
to the PIP joint.
Anatomy. The superficial branch of the radial nerve often has several
branches traveling in the tissues of the dorsolateral surface of the distal
forearm and wrist.

Procedure
1. Feel for the radial artery pulse in the distal forearm, approximately
2 cm proximal to the wrist crease.
2. Insert the needle laterally to the point where you feel the pulse, and
inject 1–2 ml of local anesthetic subcutaneously. Draw back on the syringe
before injection.
3. Advance the needle into the tissues on the dorsum of the distal forearm.
4. Inject an additional 3–4 ml of solution halfway around the dorsal
surface of the wrist.