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Median Nerve Block

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Median Nerve Block, Regional Anesthesia of the Median Nerve

  • Indications
  1. Anesthesia of Median Nerve distribution
  • Contraindications (Relative)
  • Precautions
  1. Avoid Median Nerve
  2. Injection is harmful if improperly done
  • Anatomic relationships
  1. Flexor carpi radialis (radial side)
  2. Median Nerve
  3. Palmaris Longus (Ulnar side)
    1. Forms palmar aponeurosis at midline of wrist
    2. Opose thumb and 5th finger to find palmaris longus
  • Preparation
  1. Needle: 27 gauge 1.5 inch
  2. Anesthetic: Lidocaine 1%: 2-5 ml
  • Technique
  1. Wrist position
    1. Dorsiflex wrist to 30 degrees resting on towel roll
  2. Ultrasound-Guidance (preferred)
    1. High frequency linear probe in short axis
    2. Start with probe over mid-Forearm
    3. Median Nerve is "starry night" ovoid structure between flexor digitorum superficialis and profundus
      1. Slide Ultrasound probe distally until a vessel is not adjacent to nerve
      2. Ultrasound-guided injection site will be proximal to landmark-guided injection
    4. Use standard Ultrasound-guided Regional Anesthesia technique
  3. Injection site
    1. Radial side of following landmark
      1. Wrist midline if palmaris longus absent or
      2. Palmaris longus tendon
        1. Find by opposing thumb with pinky or
        2. Flex middle finger against resistance
    2. Proximal wrist crease
  4. Needle insertion
    1. Apply antiseptic to skin (e.g. Betadine)
    2. Aim 45 degrees distally toward middle-ring finger
    3. Insert needle 1-2 cm until no resistance
    4. Do not inject if Paresthesias (see below)
  5. Warning: Distal Paresthesias with needle with injection
    1. Indicates needle is at Median Nerve
    2. Do not inject here!
    3. Remove needle and replace further to the ulnar side
  • References
  1. Eicken and Rempell (2016) Crit Dec Emerg Med 30(4):3-11
  2. Pfenninger (1994) Procedures, Mosby, p. 1036-54
  3. Salam (2004) Am Fam Physician 69(4):896 [PubMed]