Effects of Anesthesia and Nociceptive
Stimulation in an Experimental Model of Brachial Plexus Avulsion
Š. VACULÍN, R. ROKYTA
Department of Normal, Pathological and Clinical Physiology, Third Faculty
of Medicine, Charles University, Prague, Czech Republic
Received January 6, 2003
Accepted April 25, 2003
Summary
Unilateral dorsal rhizotomy of brachial plexus nerves (C5-Th1) performed
under general anesthesia is known to induce self-mutilation in rats. The
aim of this study was to determine the effect of different anesthetic
agents, and of pre-rhizotomy nociceptive stimulation on the appearance of
self-mutilation. Self-mutialtion appeared in 78 % of animals after
rhizotomy had been performed under pentobarbital anesthesia. When ketamine
was used as the general anesthetic, self-mutilation was almost suppressed
(13 %) and consisted of superficial erosions. Mechanical nociceptive
stimulation, when applied just before the induction of ketamine anesthesia
and subsequent rhizotomy, provoked self-mutilation in 91 % of rats.
Furthermore, a serious type of self-mutilation consisting of total
amputation of the distal part of the forepaw was present in 28 % of all
self-mutilating animals after previous nociceptive stimulation. In terms
of self-mutilation, these results suggest 1) the crucial role of
anesthesia, especially that which involved NMDA receptors (ketamine), and
2) the need of an additional factor to chronic deafferentation, formed
either by activity of nociceptive pathways just before rhizotomy
(nociceptive stimulation preceding ketamine anesthesia) or by injury
discharges (pentobarbital anesthesia).
Key words
Rhizotomy • Deafferentation • Autotomy • Neuropathic Pain • Prior
Nociception
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