Deaf-mutism is the result of aural dis ease acquired in infancy consecutive to acute rhinitis. From neglect there fol lows atrophy of the acoustic nerves. These cases would be curable if the nerves could be stimulated to proper de velopment by vibrations carried through the cranial vault. Twelve deaf-mutes thus cured, but it required several years. The naso-pharynx received particular at tention; the drum was mobilized by means of Politzer's inflator and by the apparatus of Delstanche, the patients also receiving oral instructions. Acute rhinitis in children should be carefully watched and treated. Verdos (Annales des Mal. de l'Oreille du Larynx, No. 5, '97).
Unchermann found in 1885 about 1841 deaf-mutes in Norway, of whom 51 per cent. were hereditary, and the remain ing percentage were acquired, with the exception of 0.5 per cent., in whom it could not be determined. It is not al ways possible to determine, even by ex amination after death. Most cases of acquired deaf-mutism are caused by dis eases of the labyrinth, most of which have spread from the brain or middle ear. Mygind. in his work in 1894, re ported over 139 cases in which the mid dle ear only was diseased, but lie stated nothing about the labyrinth or the his tological examination of the labyrinth. Thus, Matte could completely deny the occurrence of deaf-mutism due solely to middle-ear disease. Two personal cases in which the middle ear only was de monstrable as a cause of the deaf mutism. J. llabermann (Archiv f. Ohrenh., Bd. liii, S. 52-67, 1901).
Morbid Changes of the Brain (Cere brum).—The defective development of the surface of the third convolution and of the insula Reilii of the left side may be mentioned as an mality several times discovered in deaf mutes, but which has no causal tion to deafness. Riidinger and Wald schmidt found this abnormality in eral deaf-mutes who presented no his tory of disease, and whose labyrinths were not examined, while other investi gators found it in two deaf-mutes who had both become deaf after birth, in the third year, after meningitis and scarlet fever, respectively, and who both exhib ited pronounced abnormalities in the ear. The flattening of the cerebral convolu tions is doubtless due to atrophy, caused by the inactivity of the parts of the brain which are known to be the motor centre of speech, on account of the inactivity of the muscles of speech. In the two latter cases, also, there was information proving that the deaf-mutes in question had never learned to speak.
Case of deaf-mutism, in an adult, found at the autopsy to have been due to symmetrical lesions in the two tem poral lobes. The entire cranial capacity was less than /tonna], the brain weigh ing 935 grammes (30 ounces), and the left hemisphere was almost one-fourth smaller by weight than the right. The first and second temporal convolutions were destroyed, normal being replaced by cicatricial tissue, while the third convo lutions—the supramarginal and the angular gyri—were atrophied and scle rosed. The convolutions of the island of
Reil were intact on the right, but largely destroyed on the left; acoustic nerves very thin. The patient presented notable deficiency of intellect, with absolute deafness and dumbness. She possessed a certain amount of intelligence, how ever, and could comprehend, to a certain degree, mimetic language. No motor paralysis of trunk or limbs existed, nor was there any defect present in vision or cutaneous sensibility. Seppilli (Alienist and Neurologist, Apr., '93).
If we cast a retrospective glance over the foregoing facts it will be seen, first, with regard to the nature of the morbid changes met with in the hearing organs of deaf-mutes, that they do not differ, so far as their quality is concerned, from those generally found in ear diseases, but that the difference must be rather sought in the intensity and extent of the morbid processes. The abnormalities found in deaf-mutes may, at least in a great number of cases, be most naturally inter preted as being the results of intense and wide-spread inflammatory processes. This is particularly evident in cases re ferring to deaf-mutes who had become deaf after birth. It will further be seen that the abnormalities found in cases of congenital and acquired deafness often present exactly the same appearance; so that in many cases it is impossible to decide, from the post-mortem examina tion alone, whether the changes are of fcetal or post-foetal origin. It is, thus, evident that the formerly accepted opin ion, that deaf-mutism arising from con genital deafness was due to congenital malformations of the auditory organs, has not been confirmed, since abnormali ties which are the indubitable expression of such malformations are but seldom met with. So far as the seat of the abnor malities was concerned, it was found that these were, as a rule, bilateral, but have often differed greatly on either side, both as to character a,nd localization, and es pecially as to intensity. The few cases in which the principal abnormalities were confined to the one side, while the other was normal or only the seat of unimportant anomalies, must, for the present at least, be looked -upon with sus picion. Finally, it has been proved that the middle ear has very frequently been the seat of changes, accompanied, as a rule, by important abnormalities in the inner ear. These were most frequently situated in the semicircular canals, least frequently in the vestibulum, and were to be considered as the principal cause of deafness. The auditory nerve in many cases exhibited signs of atrophy and de generation and a few other abnormali ties, while in a considerable number of cases no changes were visible. In some few cases the brain deviated somewhat from the normal.