VIRUS DISEASES OF THE CENTRAL NERVOUS SYSTEM: AIREVIEW BY

CLASSIFICATION The virus diseases of the central nervous system are of growing importance. Some are apparently increasing in incidence, others are newly recognized. Even in a country like Great Britain the more exotic types may be seen in these days when air travel has brought the remotest parts of the tropics within one or two days ' travelling time of North-western Europe. They may be classified into two main groups (Rhodes, 1948): A. Primary neurotropic virus infections with recognized clinical syndromes, whose character-istic sigis and symptoms result from involvement of the central nervous system. B. Secondary infections due to ordinarily nori-neurotropic viruses, in which involvement of the central nervous system occurs as a complica-tion of a primary infection elsewhere in the body. A. PRxMARY NEUROTROPIC VIRUS INFECTIONS The primary neurotropic virus infections may be differentiated on the serological reactions of the viruses, of which about forty antigenic types are known. A more useful classification is based on the anatomical incidence of the pathological lesions, with gubdivisions,-some based on the antigenic structure of the causative viruses, thus: Virus meningitis and meningo-encephalitis Lymphocytic choriomeningitis Pseudolymphocytic choriomeningitis Meningo-encephalitis due to the virus of mumps Durand's disease-Virus encephaliti