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Ultrasound- or Nerve Stimulation-Guided Wrist Blocks for Carpal Tunnel Release: A Randomized Prospective Comparative Study
  1. Philippe Macaire, M.D.a,*,
  2. François Singelyn, M.D., Ph.D.b,
  3. Patrick Narchi, M.D.b and
  4. Xavier Paqueron, M.D., Ph.D.b
  1. aDepartment of Anesthesiology, Dubai Medical Suites, Dubai Healthcare City, UAE
  2. bDepartment of Anaesthesiology and Intensive Care, Centre Clinical, Soyaux, France.
  3. *Reprint requests: Philippe Macaire, M.D., Department of Anaesthesiology - PO Box 505150, Dubai Healthcare City, Dubai, AE. E-mail: phmacaire{at}


Background and Objectives: We hypothesized that ultrasound-guided wrist blocks may be faster to perform, and may increase success rate, compared with nerve stimulation-guided wrist blocks.

Methods: Sixty patients undergoing ambulatory endoscopic carpal tunnel release were randomly allocated to receive median and ulnar nerve blocks using either sensory-motor nerve stimulation (n = 30) or ultrasound guidance (n = 30). Four mL of mepivacaine 1.5% was injected around each nerve. Performance time and onset time of complete sensory block were assessed.

Results: Median time to perform both median (ultrasound, 55 [48-60] vs. nerve stimulation, 100 [65-150] seconds, P = .002) and ulnar (ultrasound, 57 [50-70] vs. nerve stimulation, 80 [60-105] seconds, P = .02) nerve blocks were significantly shorter in the ultrasound group. Onset time of complete sensory block in the median (ultrasound, 370 [278-459] vs. nerve stimulation, 254 [230-300] seconds, P = .02) and ulnar (ultrasound, 367 [296-420] vs. nerve stimulation, 241 [210-300] seconds, P = .01) nerve areas were shorter in the nerve stimulation group. The success rate was 93% in both groups.

Conclusions: This randomized prospective study demonstrates that ultrasound-guided wrist nerve blocks are as efficient as those performed with nerve stimulation.

  • Wrist blocks
  • Ultrasound
  • Nerve stimulation
  • Subepineurium injection

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