Although we are as yet ignorant of the exact route followed by the Spirochaeta pallida in its invasion of the central nervous system, we know definitely that in many cases this invasion occurs with the generalization of the infection preceding secondary manifestations. In other words, the onset of neurosyphilis coincides in most instances with the onset of syphilis. Apparently the only exceptions are those instances in which central nervous system invasion takes place during subsequent periods of generalization of the infection, such as are believed to precede recurrent outbreaks of a secondary type; or by direct extension from an intimately associated focus of syphilitic bone or vascular disease. We may conclude that in untreated or inadequately treated cases more than one invasion of the central nervous system may occur. Ample proof of the early invasion may be found in studies of the cerebrospinal fluid in primary and early secondary syphilis.
ALBERT KEIDEL, JOSEPH EARLE MOORE. STUDIES IN ASYMPTOMATIC NEUROSYPHILISI. A TENTATIVE CLASSIFICATION OF EARLY ASYMPTOMATIC NEUROSYPHILIS. Arch NeurPsych. 1921;6(3):286–291. doi:10.1001/archneurpsyc.1921.02190030033004