Electrophysiological Studies on Experimental Traumatic Cervical Syndrome

Abstract

In order to elucidate the mechanism of the traumatic cervical syndrome, electrophysiological studies were conducted in rabbits. The greater occipital nerve (GON), cervical sympathetic trunk (SYMP) or both GON and SYMP (BOTH) was stimulated electrically with frequencies of the 3 Hz or 100 Hz. And diazepam (2-5 mg/kg) and pentazocine (3-6 mg/kg) were administered to observe the effect of these drugs on the cervical syndrome. The following was observed.
1) The threshold of arousal reaction and the evoked muscular discharge due to stimulation of the brain stem reticular formation increased. The change with 100 Hz stimulation was more pronounced than with 3 Hz stimulation. The change in the arousal reaction was more pronounced than that of the evoked muscular discharge. The threshold changes were inhibited following administration of diazepam but not greatly inhibited by administration of pentazocine.
2) The threshold of the evoked muscular discharge due to stimulation of t he cerebral cortex rose. The change was more prominent when BOTH was stimulated, and was inhibited following administration of diazepam.
3) The threshold of the evoked muscular discharge due to stimulation of the hippocampus declined. The change with 3 Hz stimulation of SYMP was more marked than with 100 Hz stimulation of the SYMP, and was inhibited following administration of diazepam.
4) The amplitude of the recruiting response due to stimulation of the VA with frequency of 8 Hz, increased markedly. This change disappeared following administration of diazepam, but was reversed following administration of pentazocine.
5) The amplitude of the photo-evoked eyelid microvibration (MV) either increased or decreased. These changes were more prominent when SYMP was stimulated. In the cases of inhibition, the change due to GON stimulation alone was inhibited following administration of diazepam. In the cases of facilitation, diazepam had an effect on the change due to GON, SYMP or BOTH stimulation. Pentazocine had no effect in any of the cases.
6) The amplitude of the sciatic evoked eyelid microvibration (SMV) increased. This change disappeared following administration of diazepam, and was inhibited following administration of pentazocine 6 mg/kg.
7) The amplitu de of the nociceptive reflex decreased. The change due to GON or SYMP stimulation was inhibited following administration of diazepam, but pentazocine had no effect.
8) The blood flow volume of the carotid and subclavicular arteries decreased with SYMP and BOTH stimulation, but that by GON stimulation remained almost unchanged. This change was inhibited following administration of diazepam, but was no affected by administration of pentazocine.
9) Intestinal movement decreased by stimulation of these nerves. Diazepam inhibited this change markedly but pentazocine did not.
10) In order to clarify the mechanis m of the above changes, VA and hippocampus were destroyed, and vagotomy was performed.The inhibition of, the arousal reaction and evoked muscular discharge due to stimulation of the brain stem reticular formation; evoked muscular discharge due to stimulation of the cerebral cortex; MV; and nociceptive reflex; all disappeared after VA destruction. The facilitation of, the evoked muscular discharge due to stimulation of the hippocampus; MV; and SMV; all disappeared after the widespread destruction of the hippocampus. The inhibition of intestinal movement did not disappear after vagotomy of both sides.