Respiratory hazards of high cervical percutaneous cordotomy.

Abstract

AMILIARITY with Belmusto's and Nathan's clinical articles on the respiratory hazards of high cervical cordotomy and with Pitts' classical work on the physiology of respiration in the cat will be found useful by those who undertake percutaneous high cervical cordotomy. 2,6,7 We will not attempt to summarize these valuable contributions, but will draw attention to some of the known facts of the respiratory centers and pathways. In the cat, the respiratory center lies in the medially situated reticular formation of the medulla (Figs. 1 A and B). It does not include the dorsally- or laterally-situated cranial nerve nuclei, or the ventrally-situated olivary nucleus. In its longitudinal extent it corresponds to the cranial four-fifths of the olive. It extends from just below the striae acusticae superiorly to just below the obex inferiorly. Within this area there are two types of response to electrical stimulations, which serve to divide it into inspiratory and expiratory centers. Stimulation of the inspiratory center produces tonic inspiration, and stimulation of the expiratory center produces tonic expiration, or at least tonic cessation of inspiration, in the expiratory position. The inspiratory center lies immediately dorsal to the olive, the expiratory center lies dorsal to the inspiratory center and caps it rostrally. It does not extend quite so far caudally. At and below the lower pole of the olive, electrical stimulation produces weaker responses presumed to arise from the efferent pathways, rather than from the center itself. The area concerned with inspiratory responses lies lateral to that for expiratory responses. At the level of the first cervical vertebra, degeneration produced by lesions in the respiratory centers is found in the anterior column and in the anterior part of the lateral column (Fig. 1 C). Henderson