Ulnar Nerve Block
Welcome to the Ulnar Nerve Block regional anesthesia page. Here we will cover indications, contraindications, materials and steps for you to master this procedure. Let’s begin with the overview below.
Overview
Involves local anesthesia of the ulnar nerve to safely and reliably provide pain relief as well as total loss of feeling if needed for surgery. Wrist/forearm blocks are simple to perform, essentially devoid of systemic complications and can be used in an emergency department setting, office, or operating room.
Indications
While most commonly used for finger and hand surgery, wrist blocks can also be used to perform minor procedures, fracture or dislocation reductions, or provide acute pain relief.
Contraindications
There are few true contraindications to this block. They include:
- Infection (cellulitis) at the site of injection
- Allergy to local anesthetic being used
- Patient refusal
Some relative contraindications to consider:
- Patient needs a neural exam of the affected extremity
- Anticoagulation use or bleeding disorder (pressure and tourniquet can be applied to the affected area if necessary)
- Patient with prior neural lesion or active injury
Anatomy
The ulnar nerve innervates the skin of the medial one-and-a-half digits, as well as the corresponding palmer and dorsal area of the hand. Additionally, it is responsible for several intrinsic muscles in the hand, including the three hypothenar muscles, the medial two lumbrical muscles, all the interossei, the adductor pollicis, and the palmaris brevis muscle (see Figure 1).
Materials
Technique
Blocks should be performed with aseptic technique using a skin antiseptic, sterile field, and sterile equipment (i.e. ultrasound) if possible. Allow for appropriate dry time for your antiseptic. Block needles should be aspirated prior to every injection to avoid intravascular administration, and injection should be immediately stopped if the patient suddenly complains of pain or high pressure. Ideally, multiple needle insertions should be avoided as most superficial blocks can be accomplished with one or two needle insertions. Blocks can be done by landmark or ultrasound (US) guidance.
Landmark
- Place the patient’s extremity in the supinated position.
- The needle is inserted just medial to the flexor carpi ulnaris tendon, approximately 2 cm proximal to its distal attachment to the styloid process at the wrist crease (Figure 2).
- The needle should be advanced 5–10 mm radially, just deep to the tendon, where 3-5 mL of solution can be administered. As the needle is withdrawn, an additional 2-3 mL of local anesthesia can be administered subcutaneously, just above the tendon, to block the cutaneous branches of the ulnar nerve – particularly important for procedures involving the hypothenar area.
Ultrasound
- Place the patient’s extremity in the supinated position. If performing the block by the elbow, have the patient rest their arm over their head on the stretcher (Figure 3). If blocking by the wrist, supinated and on a bedside table should suffice.
- Blocking at the elbow: The ulnar nerve can be easily found in the ulnar notch with the patient’s arm abducted and flexed to 90 degrees. From this position, it can be traced distally as it travels down the forearm. The ulnar nerve can be blocked anywhere along the forearm where it is easily accessible by ultrasound (Figure 4).
Blocking at the wrist: Place the US probe on the medial forearm to identify the ulnar artery. This may be easier to accomplish by starting at the wrist crease and moving the probe proximally along the medial (ulnar) forearm. After identification of the ulnar artery, identify the ulnar nerve, which is has the “honeycomb” echogenicity and will lie medial to the ulnar artery (Figure 5). - After cleaning the area and placing a skin wheal, advance the needle into vicinity of the ulnar nerve. Aspirate as you go to avoid intravascular administration and use hydro-dissection to verify appropriate location of the needle tip (Figure 6).
- Inject 3-5 mL of local anesthetic in the area around the ulnar nerve.
Summary & Bullet Points
- This is an excellent nerve block for injuries to ulnar side of hand, including Boxer’s fractures.
- Inject blindly at the flexor carpi ulnaris, or use a linear probe to find the ulnar nerve tracing up from the wrist crease, or in the ulnar notch at the elbow tracing down the forearm.
- Block the nerve in a position where it is superficial and not surrounded by blood vessels.
Ulnar Nerve Block
Welcome to the Ulnar Nerve Block regional anesthesia page. Here we will cover indications, contraindications, materials and steps for you to master this procedure. Let’s begin with the overview below.
Overview
Involves local anesthesia of the ulnar nerve to safely and reliably provide pain relief as well as total loss of feeling if needed for surgery. Wrist/forearm blocks are simple to perform, essentially devoid of systemic complications and can be used in an emergency department setting, office, or operating room.
Indications
Contraindications
There are few true contraindications to this block. They include:
- Infection (cellulitis) at the site of injection
- Allergy to local anesthetic being used
- Patient refusal
Some relative contraindications to consider:
- Patient needs a neural exam of the affected extremity
- Anticoagulation use or bleeding disorder (pressure and tourniquet can be applied to the affected area if necessary)
- Patient with prior neural lesion or active injury
Anatomy
Materials
Technique
Landmark
1. Place the patient’s extremity in the supinated position.
2. The needle is inserted just medial to the flexor carpi ulnaris tendon, approximately 2 cm proximal to its distal attachment to the styloid process at the wrist crease (Figure 2).
3. The needle should be advanced 5–10 mm radially, just deep to the tendon, where 3-5 mL of solution can be administered. As the needle is withdrawn, an additional 2-3 mL of local anesthesia can be administered subcutaneously, just above the tendon, to block the cutaneous branches of the ulnar nerve – particularly important for procedures involving the hypothenar area.
Ultrasound
Place the patient’s extremity in the supinated position. If performing the block by the elbow, have the patient rest their arm over their head on the stretcher (Figure 3). If blocking by the wrist, supinated and on a bedside table should suffice.
Blocking at the elbow: The ulnar nerve can be easily found in the ulnar notch with the patient’s arm abducted and flexed to 90 degrees. From this position, it can be traced distally as it travels down the forearm. The ulnar nerve can be blocked anywhere along the forearm where it is easily accessible by ultrasound (Figure 4).
Blocking at the wrist: Place the US probe on the medial forearm to identify the ulnar artery. This may be easier to accomplish by starting at the wrist crease and moving the probe proximally along the medial (ulnar) forearm. After identification of the ulnar artery, identify the ulnar nerve, which is has the "honeycomb" echogenicity and will lie medial to the ulnar artery (Figure 5).
After cleaning the area and placing a skin wheal, advance the needle into vicinity of the ulnar nerve. Aspirate as you go to avoid intravascular administration and use hydro-dissection to verify appropriate location of the needle tip (Figure 6).
Inject 3-5 mL of local anesthetic in the area around the ulnar nerve.
Summary & Bullet Points
- This is an excellent nerve block for injuries to ulnar side of hand, including Boxer’s fractures.
- Inject blindly at the flexor carpi ulnaris, or use a linear probe to find the ulnar nerve tracing up from the wrist crease, or in the ulnar notch at the elbow tracing down the forearm.
- Block the nerve in a position where it is superficial and not surrounded by blood vessels.