Ulnar Nerve Block

Aka: Ulnar Nerve Block, Regional Anesthesia of the Ulnar Nerve, Ulnar Nerve Block at Wrist, Forearm Ulnar Nerve Block

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II. Indications

  1. Anesthesia of Ulnar Nerve distribution distal to wrist (medial hand)
  2. Consider in combination with Median Nerve Block at Wrist and Radial Nerve Block at Wrist for Complete Hand Anesthesia
    1. See Complete Hand Anesthesia

III. Contraindications

  1. See Regional Anesthesia

IV. Anatomy: Landmarks at medial or ulnar wrist

  1. Ulnar styloid (proximal) or Pisiform Bone (distal)
  2. Flexor Carpi Ulnaris tendon (medial or ulnar aspect)
    1. Palpate at region proximal to Pisiform Bone
    2. Better defined during wrist flexion
  3. Ulnar Vein
  4. Ulnar Nerve
  5. Ulnar Artery (lateral or radial aspect)

V. Precautions

  1. Avoid injecting directly into Ulnar Nerve
  2. Avoid injection into ulnar artery
  3. Confirm adequate Anesthesia at palmar 4th and 5th fingers

VI. Preparation

  1. Needle: 27 gauge 1.5 inch
  2. Skin Preparation (e.g. Hibiclens or Betadine)
    1. See Regional Anesthesia
  3. Anesthetic
    1. See Regional Anesthesia for Anesthetic options
    2. Local Anesthetic 2-5 ml (Ultrasound) or 5-10 ml (landmark)

VII. Technique: Forearm (Ultrasound, preferred location compared with wrist)

  1. Images
    1. forearmMedianUlnarNerveBlock.jpg
  2. Ultrasound-Guidance
    1. High frequency linear probe in short axis
    2. Use standard Ultrasound-guided Regional Anesthesia technique
    3. Linear probe is transverse to mid-Forearm
    4. Median Nerve, Ulnar artery and Ulnar Nerve lie in a plane between the superficial and deep flexors
      1. Ultrasound at wrist can easily identify ulnar artery and Ulnar Nerve
      2. Slide probe up Forearm, proximally, until Ulnar Nerve and ulnar artery separate
  3. Needle Insertion
    1. Both Ulnar Nerve and Median Nerve can be blocked in same Ultrasound view, with needle redirection
    2. Approaching from ulnar aspect, rounded Forearm edge allows needle to be perpendicular to probe

VIII. Technique: Wrist Ultrasound Guided

  1. Images
    1. ulnarNerveBlockWristUltrasound.jpg
  2. Position
    1. Patient seated
    2. Forearm supinated (palm up)
  3. Ultrasound Probe Position
    1. Transverse to Forearm, over the wrist crease
    2. See Landmarks above
  4. Injection
    1. Insert needle at proximal palmar wrist crease
    2. Direct needle from distal to proximal at 30 degree angle, perpendicular to probe (out-of-plane)

IX. Technique: Landmark

  1. Images
    1. ulnarNerveBlockWristLandmark.jpg
  2. Position
    1. Patient seated
    2. Forearm supinated (palm up)
  3. Injection site 1: Palmar branch of the Ulnar Nerve (typical insertion site)
    1. Direct needle from ulnar aspect of wrist towards radial wrist at 45 degree angle
    2. Insert at proximal wrist crease (or 1-2 cm proximal), between flexor carpi ulnaris tendon and ulnar artery
    3. Inject under flexor carpi ulnaris tendon
    4. Advance needle deeper towards ulna and inject additional 3 ml of Anesthetic while withdrawing needle
  4. Injection site 2: Dorsal branch of the Ulnar Nerve
    1. Distal aspect of ulnar styloid process (dorsum)
    2. Infiltrate 3-4 ml subcutaneously
  5. Warning: Distal Paresthesias with needle with injection
    1. Indicates needle is at Ulnar Nerve
    2. Do not inject here!
    3. Remove needle and reposition

X. References

  1. Pfenninger (1994) Procedures, Mosby, p. 1036-54
  2. Warrington and Sanders (2018) Crit Dec Emerg Med 32(7): 41
  3. Salam (2004) Am Fam Physician 69(4):896 [PubMed]
  4. Yurgil (2020) Am Fam Physician 101(11):654-64 [PubMed]

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