Neuronal Pathways as Determining Factors in Dissemination of Poliomyelitis in the Central Nervous System. ∗

Abstract

There has been hitherto no clear-cut evidence regarding the mode of progression of the virus of poliomyelitis from the portal of entry into and through the central nervous system (CNS) of man. In the experimental animal more information is available and there is now a general belief, supported by considerable evidence, that the principal rôle in the dissemination of the virus is played by neuronal pathways rather than by humoral ones, and that within the CNS there occurs a progression of the virus from the point of entry to certain susceptible regions, especially the motor centers in the hind-brain and spinal cord, where the most serious effects of the virus-host reaction become apparent. Little is known as yet concerning the determining factors in the transmission and localization of the virus throughout the CNS, although studies of some of the neuronal pathways involved have been made by Fairbrother and Hurst, 1 and by others. In this report, additional evidence bearing on these problems will be presented.

The material examined up to the present time consists of some 50 brains of Rhesus monkeys in preparalytic and paralytic stages of poliomyelitis, induced by introduction of the MV virus intra-nasally, intracerebrally, intraocularly and intraneurally. In a few-cases the Wallingford strain (Trask and Paul 2 ), inoculated intracerebrally and by skin rub, was used. The brains were prepared under optimal conditions for histological study chiefly by the gallocyanin method of Einarson, 3 which satisfactorily demonstrates nerve cells, neuroglia, and inflammatory cells. In some cases various experimental procedures, such as section of the olfactory tracts, the corpus callosum, the bulbar pyramids, or the spinal cord, were carried out in order to modify if possible the mode of dissemination of the virus.