1 To this article will be appended a table of one hundred cases of brain tumor. Our researches included the investigation of many more cases, four to five hundred in all. Such a table, indeed, could be indefinitely extended. Our object, however, has been not so much to present a large number of cases, and these in great detail, but rather in the most condensed manner to give a definite number, carefully selected, from which to draw conclusions. The cases have not been chosen with the view of upholding any peculiar or preconceived views as to pathology, diagnosis, localization, etc., but because of the carefulness with which they have been recorded. They have been selected also, as will be seen, with the view of determining by clinico-pathological data the possibility of localizing such growths during life. Many of our general conclusions as to pathology, symptomatology, and diagnosis have been drawn from this table.
With the exception of such merely substitutional terms as cerebral or intracranial growths, neoplasms, or adventitious products, we have no general synonyms for brain tumors.
The literature of the subject of brain tumors is second only to that of such subjects as syphilis and hysteria. Vol. ii. of the Index Catalogue of the Library of the Surgeon-General's Office, U. S. A., contains no less than 632 references to this subject: number of books, 43; articles, 589. The books and papers occur in different languages, as follows: British, 142; French, 174; German, 133; American, 91; Italian, 30; Latin, 15; Swedish, 14; miscellaneous, 33.
ETIOLOGY.—Under predisposing or constitutional causes are first to be classed such special inheritances as tuberculosis or carcinoma and tendencies to vascular degeneration. The occurrence of syphilis of course predisposes its victims to cerebral or membranous growths, as it does to other so-called tertiary forms of this disorder.
Hereditary predisposition only enters in so far as the individual inherits a general tendency to the development of such affections as cancer and tubercle. Hereditary tendency to a brain tumor per se does not exist, but the individual who is of the tuberculous or cancerous diathesis under special causes may develop an intracranial growth. As to the comparative frequency with which diathetic tumors originate, a reference to the tabular statement which will be given under Pathology will be sufficient. Gliomata are very common, but with them vie in frequency sarcomatous, tubercular, and gummatous growths. Any table, unless it includes a very large number of cases—at least a thousand or more—would be misleading as to the proportionate frequency of these different forms of intracranial constitutional diseases; but it is safe to say that syphilitic, tuberculous, and carcinomatous or sarcomatous tumors are of comparatively frequent occurrence.
Tumors of the brain occur oftener among men than women. This fact is dependent largely upon the difference between the habits and occupations of the two sexes. Men, in the first place, are much more addicted to alcoholic, venereal, and other abuses which give rise to special degenerations or constitutional infection; and secondly, they are more exposed to traumatisms. In 100 cases the tumors occurred among males in 58 cases, among females in 40 cases, and sex was not recorded in 2 cases.
Statistics show that intracranial growths are more likely to occur between puberty and middle age. Although gliomata may be found at any age, brain tumors in children are more likely to be of this character. This is what might be expected from the nature of these growths. Histologically, gliomata are most closely allied to the embryonal stage of the connective tissue, and, according to Cohnheim, tumors generally are the result of a surplusage of embryonal tissue—tissue which has remained over after the requirements of normal development have been met. Of 16 gliomata, 3 occurred in patients under ten years, 2 between the ages of ten and twenty, and 4 between twenty and thirty.
One hundred cases gave the following results as to age:
| Under 10 years | 10 | cases. |
| From 10 to 20 years | 12 | cases. |
| From 20 to 30 years | 18 | cases. |
| From 30 to 40 years | 24 | cases. |
| From 40 to 50 years | 12 | cases. |
| From 50 to 60 years | 13 | cases. |
| From 60 to 70 years | 3 | cases. |
| Over 70 years | 1 | cases. |
| Not recorded | 7 | cases. |
| 100 | cases. |
It is now generally admitted that injuries play a most important part as exciting causes of brain tumors. Frequently in our experience an apparently direct relation has existed between a head injury and the origin of the neoplasm. In 6 out of 12 cases reported by one of us,2 a history of traumatism was present, although in 5 of these a history of syphilis was also present. The great frequency with which injuries of all kinds occur must of course not be overlooked in this connection. It is said by those who oppose the idea of the direct causal relations of injury that almost every one could trace such disease to falls or blows which few escape. In some of the cases of brain tumor, however, the history of injury bears a direct relation in time to the initial symptoms of the tumor. Certain tumors, as the fibromata, osteomata, angiomata, would appear to be of more frequent occurrence as the direct result of traumatism. The part played by injuries in the production of carcinomata and sarcomata, whether in the brain or elsewhere, has not infrequently been the subject of dispute. We have no doubt that, a constitutional predisposition existing, an injury frequently leads directly to the development of some form of malignant growth. In not a few of the syphilitic cases the history would appear to show that an injury to the skull had localized the constitutional poison.