Effect of thoracic epidural bupivacaine on somatosensory evoked potentials after dermatomal stimulation

Anesth Analg. 1987 Aug;66(8):731-4.


The effect of epidural bupivacaine (9 ml 0.5%) analgesia on early (less than 500 msec) somatosensory evoked potentials (SEPs) with electrical stimulation of the T-10 and L-1 dermatomes was examined in eight patients. Cortical amplitudes decreased only insignificantly after stimulation of both dermatomes, despite the presence of sensory analgesia (pin prick) from T-3.5 +/- 0.4 to L-2.9 +/- 0.4 (mean +/- SEM). Latency of the SEP components remained unchanged and sensory threshold increased only insignificantly during blockade. We conclude that thoracic epidural analgesia with conventional doses of bupivacaine provides only a limited blockade of fast conducting afferent nerve fibers.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anesthesia, Epidural*
  • Bupivacaine / administration & dosage*
  • Bupivacaine / pharmacology
  • Electric Stimulation
  • Evoked Potentials, Somatosensory / drug effects*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neural Conduction / drug effects
  • Skin / innervation
  • Spinal Nerve Roots / physiology
  • Thorax


  • Bupivacaine