Effect of thoracic epidural bupivacaine on somatosensory evoked potentials after dermatomal stimulation.
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.
D000328:Adult; D000767:Anesthesia, Epidural; D002045:Bupivacaine / Q000008:administration & dosage* / Q000494:pharmacology; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000187:drug effects; D012867:Skin / Q000294:innervation; D013126:Spinal Nerve Roots / Q000502:physiology; D013909:Thorax
D002045:Bupivacaine