Use of epidurally derived evoked potentials for quantification of caudal nociception in ponies

Johannes P. A. M. van Loon Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.

Search for other papers by Johannes P. A. M. van Loon in
Current site
Google Scholar
PubMed
Close
 DVM
,
Peter J. Stienen Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.

Search for other papers by Peter J. Stienen in
Current site
Google Scholar
PubMed
Close
 PhD
,
Arie Doornenbal Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.

Search for other papers by Arie Doornenbal in
Current site
Google Scholar
PubMed
Close
, and
Ludo J. Hellebrekers Departments of Equine Sciences and Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, and Rudolf Magnus Institute of Neuroscience, Utrecht University, 3508 TD Utrecht, The Netherlands.

Search for other papers by Ludo J. Hellebrekers in
Current site
Google Scholar
PubMed
Close
 DVM, PhD

Click on author name to view affiliation information

Abstract

Objective—To determine whether epidurally derived evoked potentials (EPs) can be used to reliably assess nociception and antinociception in ponies.

Animals—7 ponies.

Procedures—EPs and electromyograms (EMGs) from the quadriceps femoris muscles were recorded simultaneously, following electrical stimulation applied to the distal portion of the hind limb. The effect of increasing stimulus intensity, conduction velocities of the stimulated nerves, effect of epidurally applied methadone, and effect of systemically administered propofol were evaluated.

Results—In the EP and EMG waveforms, 2 distinct complexes, the EP N25 and P50 and the EMG P27 and N62, respectively, were identified. On the basis of their latency and calculated conduction velocities, the EP P50 and EMG N62 were considered to be related to nociception (AD-mediated). All complexes increased significantly in amplitude with increasing stimulus intensity and decreased significantly following epidural administration of methadone or systemic administration of propofol.

Conclusions and Clinical Relevance—Although the experimental setup allowed successful discrimination between tactile- and nociceptive-associated responses, the identified EPs, considered to reflect activity in the spinal cord, could not be definitively differentiated from activity in the lumbosacral epaxial musculature. Further research is required to refine measurement techniques to allow for discrimination between these 2 signals. Similar to other species, neurophysiologic variables such as EPs could potentially become a useful additional tool in quantifying nociception in equidae.

Abstract

Objective—To determine whether epidurally derived evoked potentials (EPs) can be used to reliably assess nociception and antinociception in ponies.

Animals—7 ponies.

Procedures—EPs and electromyograms (EMGs) from the quadriceps femoris muscles were recorded simultaneously, following electrical stimulation applied to the distal portion of the hind limb. The effect of increasing stimulus intensity, conduction velocities of the stimulated nerves, effect of epidurally applied methadone, and effect of systemically administered propofol were evaluated.

Results—In the EP and EMG waveforms, 2 distinct complexes, the EP N25 and P50 and the EMG P27 and N62, respectively, were identified. On the basis of their latency and calculated conduction velocities, the EP P50 and EMG N62 were considered to be related to nociception (AD-mediated). All complexes increased significantly in amplitude with increasing stimulus intensity and decreased significantly following epidural administration of methadone or systemic administration of propofol.

Conclusions and Clinical Relevance—Although the experimental setup allowed successful discrimination between tactile- and nociceptive-associated responses, the identified EPs, considered to reflect activity in the spinal cord, could not be definitively differentiated from activity in the lumbosacral epaxial musculature. Further research is required to refine measurement techniques to allow for discrimination between these 2 signals. Similar to other species, neurophysiologic variables such as EPs could potentially become a useful additional tool in quantifying nociception in equidae.

All Time Past Year Past 30 Days
Abstract Views 29 0 0
Full Text Views 224 130 9
PDF Downloads 68 39 6
Advertisement