The real significance of all of these chronic changes remains the subject of dispute, and able authorities on either side contend, on the one hand, for the inflammatory origin of the lesions de scribed, while, on the other, degenera tion is held to lie the first step in the process. It seems, however, to the writer that the term "chronic encephalitis," ac cording to our present knowledge, should include the clinical states to which ref erence has briefly been made, and that the theories of agenesis and degenera .14 tion are very satisfactory as applied ta a great number of other chronic brain con ditions, which present analogous lesions, but in which no inflammatory stage is known to exist. Continued and careful clinical and pathological evidence is needed to limit strictly the meaning of chronic encephalitis, or positively to ex tend it so as to exclude more of these sclerotic lesions than at present we are justified in applying to it.
Diagnosis.—The diagnosis of chronic encephalitis is made from the presence of one or other of its causes and the as sociation of its symptoms. According to Gowers, in rare cases of chronic en cephalitis, chronic headache with long continued cerebral symptoms, including optic neuritis, may simulate tumor of the brain. Elughlings-Jackson has reported a case in which such symptoms existed for six months. These symptoms in these rare cases of primary chronic en cephalitis may be headache, vertigo, epi leptic attacks, transient loss of sight or other special senses, vomiting, optic neuritis, slight fever and stupor, followed by coma and death. The diagnosis from tumor would be made by noting the want of progressive nature of the lesion, commonly present in tumor, the general character of the head-pain, and other symptoms of cerebral irritation, and the more definite focal symptoms of tumor would also be wanting.
The forras of chronic encephalitis sur rounding new growths or other focal lesions need not be discussed, because their diagnosis is that of the primary condition practically.
Chronic meningo-encephalitis does not present any very distinct clinical type, except when present as thc lesion of par alytic dementia.
Prognosis.—In all forms of chronic encephalitis the prognosis is very grave; in most cases absolutely hopeless as re gards cure. All cases of paralytic de mentia end fatally, except in extremely rare instances, in which a remission last ing many years may occur. The acute forms of chronic encephalitis which have been mentioned may run prolonged courses, and death may result from in tercurrent disease, but is more usually due to the brain condition directly or indirectly.
Treatment. —The most hopeful cases of chronic encephalitis clinically are those resulting from syphilis. In such cases large doses of the iodide of potas sium combined with rest and general tonic treatment sometimes accomplishes extremely satisfactory results. The rare cases in which chronic encephalitis is suspected as a primary- condition must be treated on the general principles gov erning the treatment of chronic inflam mation. The cases associated with other focal cerebral lesions require the treat ment necessary to the primary condition present.
Prenatal Encephalitis.
The basis for belief in a prenatal form of encephalitis is chiefly the studies of Virchow, who described in 1865 whitish or yellowish-gray foci in the brain of newborn infants which he considered inflammatory in origin. These foci he describes as a fatty change in thc neu rogliar cells, with unequally-dilated and obstructed vessels and neurogliar cell proliferation along the vessels. He also refers to a peculiar kind of softening in connection with these foci. When the foci are situated in the white substance of the brain they are grayish-red in color, from congestion of the capillaries. Un less the lesions have progressed to the stage of softening the brain-consistence is unaltered. Hayem, on the contrary, regards fatty degeneration of the neu rogliar cells as inflammatory only when associated with extrenie congestion and the compound granular cell. Jastro witz considers the condition physio logical in fcetal life, basing his conclu sions upon a study of sixty-five cases. According to him, this fatty degenera tion of the neurogliar cells does not fol low inflammatory proliferation as pro claimed by Virchow, but is commonly found in certain portions of the brain, increases until the seventh month of intra-uterine life, and disappears soon after birth. Virchow's observations have been confirmed by Parrot and others, but a great difference of opinion exists re garding the primary cause of these patches. Recent studies have demon strated a form of miliary encephalitis in the newborn which is due to septic metastasis from suppuration of the um bilical cord, and other cases are reported in which this lesion has followed diph theria and aphthous stomatitis, some authorities regarding this form of en cephalitis as the primary stage of the lesions found in a proportion of the cases of spastic hemiplegia and diplegia, and in some cases of disseminated sclerosis in children.