"According to the predominant pathological characteristics, three types of cerebral syphilis may be distinguished, viz.: (a) Meningitic, (b) Endarteritic, and (c) Gummatous. The lines of demarcation between these types are not, however, sharp ones. We practically always find in the endarteritic and gummatous types a certain amount of meningitis.
"The acute meningitic form is the most frequent type of cerebral syphilis and gives little trouble in diagnosis; many of these cases do not reach state hospitals. In most cases after prodromal symptoms (headache, dizziness, etc.) there is a rapid development of physical signs, usually cranial nerve involvement, and a mental picture of dulness or confusion with few psychotic symptoms except those related to a delirious or organic reaction.
"In the rarer chronic meningitic forms which are apt to occur a long time after the syphilitic infection, usually in the period in which we might expect general paralysis, the diagnostic difficulties may be considerable.
"In the endarteritic forms the most characteristic symptoms are those resulting from focal vascular lesions.
"In the gummatous forms the slowly developing focal and pressure symptoms are most significant.
"In all forms of cerebral syphilis the psychotic manifestations are less prominent than in general paralysis and the personality is much better preserved as shown by the social reactions, ethical sense, judgment and general behavior. The grandiose ideas and absurd trends of the general paralytic are rarely encountered in these cases."
It is only of comparatively late years that the hospitals of this country have shown the frequency of psychoses due to cerebral syphilis in their reports. Statistical studies indicate that such mental conditions are quite unusual as compared with other well recognized clinical entities. In a total of 49,640 first admissions reported by the New York state hospitals during a period of eight years only 342, or .67 per cent, were reported as mental diseases due to cerebral syphilis. The Massachusetts hospitals during 1919 reported only twenty-seven cases, a percentage of .89. Twenty-one hospitals in fourteen other states, in a total of 18,336 admissions, showed only 124 cases (.67 per cent) of cerebral syphilis. This represents, therefore, a total of 70,987 admissions with only 493 diagnosed as psychoses due to cerebral syphilis,—a percentage of .69. When this is compared with eleven per cent as shown by the admissions for general paresis it is probably a very fair index of the comparative frequency of the two diseases in our institutions. It is interesting to note that the incidence of cerebral syphilis as shown by the hospitals of the various states is almost exactly the same. The admission rate for the Casa de Orates in Santiago, Chili, in 1918, as shown by Letelier, was .90 per cent.