Nerve Block: Ulnar Nerve

Background

• Ulnar nerve block is a quick, safe, and effective means of pain reduction for hand injuries, including reduction of Boxer's Fracture

Indications

• Boxer's Fracture
• Hand Burns
• Complex Hand Injury
• Need for pain control or to perform painful procedure in distribution of ulnar nerve

Contraindications

• Infection overlying injection site

Equipment Needed

• 10 cc Syringe with a 27 Gauge Needle
• Blunt fill needle (to draw up anesthetic)
• Local Anesthetic (e.g. Lidocaine or Bupivacaine)
• Antiseptic (e.g. Chlorhexidine, Betadine)
• Sterile Gloves
• Sterile Drape and sterile ultrasound probe cover
• Linear Ultrasound Probe

Procedure

Ulnar Nerve Block at the Wrist

Ulnar Nerve at the Distal Wrist

Following the Ulnar Nerve Distally

• Obtain informed consent
  • Patient should be made aware that they will lose both sensory and motor function of the ulnar distribution until the anesthetic wears off
• Place the patient's extremity in the supinated position
• Cleanse the skin with chosen antiseptic
• Create a sterile field using sterile drape
• In a sterile fashion, apply a small wheel of local anesthetic to the area immediately medial to tendon of the Flexor Carpi Ulnaris and approximately 2 cm proximal to the wrist crease.
• The ulnar nerve should be immediately deep to the Flexor Carpi Ulnaris Tendon

Wrist Block

Non-Ultrasound Guided Technique

• Direct the Needle radially, deep to the Flexor Carpi Ulnaris
• The ulnar nerve is ulnar in relation to the ulnar artery; even still, it is important to aspirate prior to injecting anesthetic to rule out intra-arterial placement
• Discontinue and reposition should the patient report shooting "electrical" pains or numbness prior to injection
• Inject approximately 5 mL of local anesthetic

Ultrasound Guided Technique

• Have a partner help place the Linear Ultrasound Probe into the Sterile Probe Cover
• Starting mid forearm of the volar aspect in a transverse plane, locate the Ulnar Nerve
• Sliding Distally, the Ulnar Nerve and Artery should separate from each other
• Injection site is generally approximately 2 cm proximal to the wrist crease.
• In plane, visualize the needle on the Ultrasound monitor as you advance towards the Ulnar Nerve.
• Make sure to aspirate prior to injecting to rule out vascular penetration (low risk given ultrasound guidance)
• Discontinue and reposition should the patient report shooting "electrical" pains or numbness prior to injection
• Inject approximately 5 mL of local anesthetic in the area immediately surrounding the Ulnar Nerve

Complications

• Inadvertent intravascular injection
• Infection
• Bleeding/hematoma
• Neurapraxia

See Also

• Nerve blocks (main)
• Local anesthetic systemic toxicity