Manual of diseases of the ear : including those of the nose and throat in relation to the ear, for the use of students and practitioners of medicine / by Thomas Barr, M.D.
- Barr, Thomas, 1846-1916
- Date:
- 1901
Licence: In copyright
Credit: Manual of diseases of the ear : including those of the nose and throat in relation to the ear, for the use of students and practitioners of medicine / by Thomas Barr, M.D. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![CHAP. XX.] cent, of deaf-mutes are the offspring of consanguineous marriages. Some authorities, on the other hand, deny this. Probably these marriages are liable to produce defects in the descendants, only when serious constitutional anomalies exist in the family from which both parents spring, in which they would both share. The probability is that, when the lineage of the two is healthy, the offspring does not suffer from the relationship of the parents. In the Acquired Form of Deaf-Mutism, that is, where the deaf- ness causing the mutism has originated after birth, the pathological conditions are very various. They are frequently in the labyrinth or nerve of hearing, and are the sequelae of cerebral diseases, of cerebro- spinal or ordinary meningitis, of inflammation of the labyrinth, syphilis, injuries, mumps, scarlet fever, typhus fever, measles, diphtheria, etc. Pathological changes are not unfrequent also in the middle ear, as the consequences of catarrhal or inflammatory diseases. The most common are thickening or rigidity of the fenestral membranes, extensive ad- hesions, anchylosis of the stapes, and other effects of adhesive catarrh. At other times we find, owing to purulent inflammation, destruction of the tympanic membrane and ossicular chain. In all these cases, both ears must be seriously affected before leading to such a degree of deaf- ness as to hinder the hearing of loud speaking. Hereditary influence probably also plays a part in the causation of the acquired form. It is useful to recognize two forms of acquired deaf-mutism. First, when the deafness arises so early in life (in the first year or two years), that the child has never spoken. It is evident that, if he does not hear words, he cannot learn to speak. Second, where the deafness affects the child after the power of speech has been partially or com- pletely acquired, depriving him of speech. This may happen up till the seventh or eighth year of life. Deafness less disastrous in the Adult than in the Child. A degree of deafness, which would rob the child of speech, or which would prevent him acquiring it, would probably in the adult interfere very little with his social intercourse. The adult, who becomes very deaf, retains his power of speech, because (1) it is so firmly implanted in his memory that he can never forget it; (2) his knowledge of language, and of the lip and facial movements made in speaking, enables him to guess, from the words which he does hear, the sense of those he fails to hear, and also to partially understand what is said from the visible movements of the lips; (3) he insists on hearing and understanding by asking the speaker to articulate loudly and distinctly; and (4) his ability to read maintains and even extends his knowledge of language. Serious Effects of Deafness in Childhood. It is very different with the young child, who has only recently acquired, and that very](https://iiif.wellcomecollection.org/image/b24932553_0417.jp2/full/800%2C/0/default.jpg)
