Disease of the nervous apparatus of the internal ear is met in hardly 10 per cent of ear patients. Some of these are due to injury and fracture at the base of the skull, others to cerebrospinal meningitis or other severe fevers, more still to the extension inward of the catarrhal or the suppurative middle-ear inflam mations. Mumps, too, or diphtheria may be followed by sudden total deafness. Inherited syphilis is one of the insidious and slowly acting causes, generally also giving rise to clouding of the cornea of the eye and marked by typical malformation of the second teeth. In any of these conditions the main hope of relief is through the absorption by mercury and iodine of the exuded material, which in the meningitis cases may be in the brain itself and not in the labyrinth. Of notable interest are the cases of "boiler-makers' deafness," as we sometimes call a group of occupation-disorders, usually lo cated in the internal ear, and affecting those subject to persistent clangor —a condition which may compel change of work, if freeing the Eustachian tubes and good plugging of the external canals fails to relieve the advance of deafness. Important too are the cases of ver tigo, due to ear-disease. Meniere called atten tion to some of these as caused by labyrinthine apoplexy and they are often called by his 41e; but the recognizable disease may be of rent nature and often is located in the m-cavity, indirectly . affecting the organ of c c librium in the semi-circular canals. Influ enza has caused a number of these cases in which the hearing for more or less of the scale has been suddenly lost and the patient made incapable for days or weeks of lifting the head from the pillow. Absorption is here also the best hope; but in some extreme cases advantage has been taken of the damaging effect upon the ear of large doses of quinia, and the irritative condition has been by it changed to a destruction with cessation of the vertigo.
The systematic development by Barany and others of tests of the equilibrium-apparatus has given us a most valuable power to stimulate chosen portions of the labyrinth and thus to investigate not only the end-organ, but the brain-centres and the paths which convey im pressions to them. Revolving the patient in a pivoted chair or using a cold or hot douche in the ear can elicit marked and definite oscillation of the eyes, technically known as "nystagmus"; and this, which may be varied at will in the normal, is modified or prevented by diseased conditions. Vertigo is usually produced by such
stimulation and the perverted equilibrium-sense causes the patient to point astray, to fall in known direction or to be made "sea-sick." Interruption of transmission along this path or that may clearly point to the exact site of disease and furnish information of far-reaching value to the brain-specialist and the surgeon for life-saving intervention.
Finally we may mention the brain-affections in which the hearing-centres, especially that for speech, are involved, when we may have "word deafness," which prevents recognition of the spoken word, although the hearing is perfect for tones of every pitch; for while the ear itself is uninvolved, it is only through ear-examination that one can by exclusion reach a correct diag nosis and perhaps point the way for the surgical removal of a brain-tumor.
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