DISEASE OF THE EAR AND ESPECIALLY OF THE INTERNAL EAR AND AUDITORY NERVE.
Tinnitus aurium, a noise in the ear, variously described as a ringing, a buzzing, a roaring, a singing or a grinding noise, is now considered to be often of nervous origin. The observations of many recent observers indicate that from diseased and disordered conditions of the internal ear, and of the auditory nerve which springs from it, certain important general symptoms of disease are induced, such as " ear vertigo," convulsive starts and movements, nausea, and various affections of the alimentary canal. Bearing on this point, Dr. Bucke, of London, Ontario, Canada, seems to me to have made one of the most important of modern sugges tions, by showing that the auditory nerve possesses the character istics of an organic nerve, and of being, as it were, a direct inter communicating line between the outer world and the ganglionic nervous centres. Thus the nervous mechanism at the origin of the auditory nerve, or of the nerve itself, from being subjected to an inflammatory condition or sequel of inflammation, to direct shock or irritability from shock, or to paralysis from disease or injury, may become the seat of symptoms affecting the whole of the body through the nervous organizations, directly through the organic, and indirectly, from the organic, through the cerebro spinal system.
Whether Dr. Bucke's observation should turn out to be cor rect or not, it is now certain that many symptoms of disease, hitherto believed to be of a general nervous character, have their seat or centre in the organ of hearing; and again, that the organ of hearing, in its turn, is subject to nervous derangements, and thereby, ultimately, to organic changes which are of the most serious import. Thus from pressure on the internal ear, and from congestion, inflammation, or exudation, within the labyrinth, there is produced a variety of vertigo or giddiness, "labyrinthine vertigo," to which the name of " Mesnier's disease," after the dis coverer of it, has been applied. Lately, Dr. Woakes, with much facility of exposition, has indicated that earache in infants, and most important nervous disorders arising from acute disease in the ear, may, by sympathetic connection, be induced from the irrita tion from teething and from the exanthematous diseases; that some forms of cough may, by reflex direction, be dependent on disease within the ear; and that vertigo, having its primary seat in the stomach and digestive system, is frequently developed through the inter-nervous relationships of the organic nervous chain and the auditory nervous apparatus.
The recent application of the electric balance by Professor Hughes, and the introduction of his most skilful instrument, the audiometer, have enabled the physician to make various new and important observations relative to disturbances in the internal au ditory apparatus. Thus I have myself found that in instances of labyrinthine vertigo the degree of vibration that may bring on the particular symptoms connected with the affection can be ac curately gauged, and the extent of the disease that is present estimated. In extreme examples the vibrations within a few de grees of zero, or point of absolute silence, are sufficient to excite the remote phenomena indicative of the local derangement.