TUMORS OF THE BASE strictly limited to the anterior fossa would affect the olfactory nerves, but by extending back ward into the middle fossa they may cause unilateral loss of sight or some form of hemianopsia. Mental symptoms are usually present on account of press ure on the anterior lobes. A tumor in the middle fossa, if situated near the sphenoidal fissure, may paralyze all the motor nerves to one eye and compress the first division of the fifth, causing uni lateral ophthalmoplegia, ansthesia, and pain in the region of distribution of this division of the trigeminal nerve, together with trophic changes in the eye. The Gasserian ganglion and all the divisions of the fifth nerve—as well the second, third, fourth, and sixth nerves—are ex posed to the invasion of tumors in the middle fossa. Tumors of the posterior fossa injure the cranial nerves, pons, and medulla, and give rise to many of the symptoms of tumor of the lions and me dulla, with these differences: that tumors in this fossa affect the nerves before they do the pons or medulla; in paralysis of the sixth nerve from injury to its trunk the conjugate fibres of the internal rectus of the other eye are not affected, as in nuclear paralysis of this nerve; and the seventh and eighth nerves are usually in volved by the same lesion, as they all lie near together at the base.
Multiple Tumors.—According to Dana, about one-seventh of all brain-tumors are multiple. The tubercular, cancerous, and melanotic varieties are most com monly multiple. I have found seven tubercular nodules of considerable size in one brain, situated in widely different portions of the brain.
In only a comparatively small number of cases is it possible to determine the exact nature of the growth, and often the conclusion at which one arrives is little more than a shrewd guess. Secondary growths in the brain usually are of the same nature as the primary one in other portions of the body. Evidences of syph ilis or tuberculosis in a person suffering from tumor of the brain points to the probable nature of the growth. Inher ited syphilis very rarely gives rise to tumor of the brain. The most common cerebral growths in children are the tubercular, and these may occur in child hood without the signs of tuberculosis in other portions of the body. The cere
bellum, comparatively speaking, is re markably exempt from syphilitic tumors, but the tubercular and the gliomatous are the most frequent here. Growths in the cortex are usually syphilitic, tuber cular, or sarcomatous. Gliomata and sarcomata frequently occur in the cen trum ovale, and may subsequently in volve the cortex. The symptoms of most growths of the brain are at first favorably modified by active antisyphilitic treat ment. If the improvement is very great and can be maintained by such treat ment, it is strong evidence in favor of the syphilitic nature of the growth.
Etiology.— PREDISPOSING CAUSES. — Cerebral growths may occur at any time of life. The third decade furnishes the largest number, about 20 per cent.; first and fourth about 1S.5 per cent. and the second and fifth about 14 per cent. each. They are rare in extreme old age. Steffen has reported a case of tumor of the brain in an infant four weeks old.
The character of the tumor varies considerably with the different periods of life. Tubercular, cystic, gliomatous, and sarcomatous varieties are frequent in childhood and early adult life. The tubercular largely predominating in childhood. Syphilitic growths are most common in young and middle-aged adults. The gliomatous, sarcomatous, and gliosarcomatous are most frequent during the latter period. In my experi ence I have found cystic growths much more frequent in adults than in child hood, although this is contrary to the results obtained from a study of tabular statistics. Carcinomatous growths are found most commonly during the de generative period of life.
Scx.—After the age of fifty tumor of the brain is found with about equal fre quency in the two sexes, but before this time, not excluding early childhood, the male sex suffers nearly twice as often as the female. It seems, then, that the ex planation for the increased liability of the male sex to suffer from tumor of the brain must be sought in conditions per taining to the developmental and active periods of sexual life.