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Motor Block Outlasts Sensory Block: A Unique Characteristic of Etidocaine?
  1. Alon P. Winnie, MD,
  2. Robert W. Masters, MD,
  3. Zia Durrani, MD and
  4. Kanchan P. Patel, MD
  1. From the Department of Anesthesiology, University of Illinois College of Medicine, Chicago, Illinois


Early clinical studies with etidocaine indicated that this new local anesthetic was unique among all local anesthetics in that it produced a motor block that outlasted the sensory block. A doubleblind, randomized comparison of the onset and duration of sensory and motor blockade following subclavian perivascular brachial block carried out with 0.5% etidocaine and 1% lidocaine, both containing 1:200,000 epinephrine, indicated that the duration of paresis exceeds the duration of analgesia with both drugs, by approximately 18% with Iidocaine and etidocaine in mantle fibers and by 17% with Iidocaine and by 27% with etidocaine in core fibers. Probably the reason that this phenomenon, so apparent and alarming with etidocaine, has gone unnoticed in clinical practice with Iidocaine is due to the fact that the time during which an identifiable degree of paresis exists without analgesia is short enough with Iidocaine that the patient does not notice it, whereas the time during which the patient already has postoperative pain and still cannot move the arm is very long with etidocaine. Therefore, this phenomenon is not unique to etidocaine.

  • Brachial block
  • Motor block
  • Sensory block
  • Lidocaine
  • Etidocaine

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  • This work was carried out at the University of Illinois Medical Center in Chicago utilizing patients at both the University of Illinois Hospital and the West Side Veterans Administration Hospital.

    Address reprint requests to Dr. Winnie: Department of Anesthesiology, University of Illinois Medical Center, 1740 West Taylor Street, Chicago, IL 60612.