Electrophysiological evaluation of spinal reflexes during epidural anesthesia in an experimental model

• Published in: Muscle & nerve Vol. 19; no. 1; pp. 29 - 36
• Main Authors: Navarro, Xavier, Lazaro, Juan J., Buti, Miquel, Verdu, Enrique, Fabregas, Pere J., Castellano, Bernardo
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.01.1996; Wiley
• Subjects: Anesthesia; Anesthesia, Epidural; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthetics, Local - pharmacology; Animals; Biological and medical sciences; Bupivacaine - pharmacology; Electrophysiology; Electroshock; epidural anesthesia; Female; H reflex; H-Reflex - physiology; Hindlimb; Local anesthesia. Pain (treatment); Medical sciences; nerve conduction; Nociceptors - physiology; Rats; Rats, Sprague-Dawley; Reaction Time; Reflex - physiology; Spinal Cord - physiology; withdrawal reflex; Rat; Rodentia; Electrophysiology; H-Reflex; Conduction velocity; Local anesthetic; Nerve conduction; Vertebrata; Mammalia; Regional anesthesia; Animal; Extradural administration; Electromyography
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/(SICI)1097-4598(199601)19:1<29::AID-MUS5>3.0.CO;2-A

We assessed the effects of epidural anesthesia with bupivacaine in the rat by serial recordings of spinal reflexes. The H wave from plantar muscles after electrical stimulation of the sciatic nerve evaluates a large nerve fiber spinal reflex arch. The extensor reflex response recorded from quadriceps muscle after stimulation of the contralateral tibial nerve assesses a reflex arch with small fiber afferents. After epidural injection of 0.2 mL of bupivacaine (0.25%, 0.5%, and 1.0% solutions) at the L5‐L6 vertebral space, nociceptive, H, and extensor reflex responses were abolished within 1–3 min. Duration of complete blockade lasted 20–80 min, increasing with the anesthetic concentration, and complete recovery occurred after an additional period of 30–40 min. The responses recovered to amplitudes similar to preanesthesia controls, indicating that there was no damage to the nervous system. This study shows that electrophysiological recording and quantitation of nerve reflex responses is a useful and accurate method to evaluate the efficacy of local anesthetic agents. © 1996 John Wiley & Sons, Inc.