With the demonstration by Noguchi1 of Spirochaeta pallida in the central nervous system tissues, and with the successful use of salvarsan, paresis and locomotor ataxia have become less matters of purely neurological concern and more problems of infection, immunity and chemotherapy. Under this aspect the syphilitic disturbances of the central nervous system function have taken on a new interest alike for the student of immunity, the clinician and the psychologist. For it is now clear that the symptoms of central nervous system syphilis, be they pain, ataxia, or psychic disturbance, depend, as is the case in acute poliomyelitis, on the location of the damaging lesions.
The therapeutic problem, therefore, is fundamentally of a similar nature to that found in any infection in which the specific agent is sent to destroy the infecting organism. The agent and organism must be brought into contact. The well-known impermeability of the choroid