TUMORS OF THE BRAIN AND ITS MEMBRANES. 269 



paralysis in the parts supplied by the cerebral nerves (especially if 

 the paralyzed muscles do not contract on passing an electric current 

 through their nerve) renders it very probable that there is tumor of 

 the brain. The assertion that, other things being equal, paralysis of a 

 cerebral nerve favors the idea of a tumor, and that most paralyses of 

 cerebral nerves are of peripheral origin, is not actually true of the facial 

 nerve. Paralysis of the facial, as one symptom of hemiplegia, occurs 

 just as often in other local diseases of the brain as in cases of tumor, 

 and is unmistakably of central origin. What was said above is not 

 true of these cases, but of the other peripheral facial paralyses. Next 

 to the facial, among the motor-cerebral nerves, the oculo-motor and 

 abducens are most frequently attacked. Paralysis of the pars minor 

 trigemini is rare ; this is also true of complete paralysis of the hypo- 

 glossal and motor filaments of the glosso-pharyngeal ; while incom- 

 plete paralysis of these nerves, as shown by disturbances of articulation 

 and deglutition, is rather common. Peripheral facial paralysis, due 

 to tumors of the brain, is occasionally preceded by twitching of the 

 facial muscles; while twitching of the muscles of the eye precedes 

 paralysis of the oculo-motor, which is characterized by dilatation of 

 the pupil, ptosis, disturbance of mobility of the eye ; often, also, by 

 diplopia and strabismus. If the oculo-motor be unaffected, paralysis 

 of the abducens induces diplopia and strabismus convergens. Before 

 the destruction of the filaments of the trigeminus has caused anaes- 

 thesia of the half of the face, of the conjunctiva, mouth, and nose, 

 most patients complain of severe pain in all the parts supplied by the 

 nerve, and not unfrequently these pains continue during the anaesthesia 

 (anaesthesia dolorosa). Hardness of hearing, or complete deafness, 

 from destruction of the acousticus, is usually preceded, for a time, by 

 troublesome noises in the ears. Disturbances of vision, even to com- 

 plete blindness, are very frequent in tumors of the brain, but they are 

 not, by any means, always due to direct lesions of the optic nerves, 

 chiasm, tractus opticus, or corpora quadrigemina. Not unfrequently, 

 the tumor is at a distance from these parts, as in the cerebrum or cere- 

 bellum. I consider it a mistake to suppose that, in such cases, the 

 pressure has extended, through the intervening substance, to the optio 

 nerve, and, by pressing this against the base of the skull, caused its 

 atrophy. The correctness of this view appears to be opposed, among 

 other things, by the fact that, in blindness from tumors in the cere- 

 brum or cerebellum, the motor nerves of the eye, which are under 

 abou+ the same conditions as the optic nerve, are rarely paralyzed. 

 Many of the cases of amblyopia and amaurosis, caused by cerebral 

 tumors, depend on venous congestions in the eye, and the consequent 

 structural changes in the retina and optic nerve, and are due to com 



