Effects of Vagotomy on Autonomic Balance

originally presented by Eppinger and Hess in 1910 described a physiological condition in which there was a harmonious balancing of tonic stimulation of various internal organs by the sympathetic and parasympathetic branches of the autonomic nervous system. Disruption of this balance was believed to lead to numerous disorders, the characteristics of which depended upon whether sympa-thetic or parasympathetic activity predomi-nated. Valid and reliable measures of the relative level of sympathetic versus parasym-pathetic activity proved difficult to achieve and during the period from 1920 to 1940 the concept of autonomic balance gradually dis-appeared from the literature. In 1938, however, Wenger,6'7 using the statistical technique of factor analysis, derived a method of estimating the relative level of parasympathetic activity as compared to sym-pathetic nervous system activity. An index, the autonomic factor score (A), can be com-puted for any individual from measurements of certain physiological functions. Since