The most common obstruction is an accumulation of the wax secreted by a small ring of glands near the orifice. The object of this cerumen or wax is to catch the particles of dust floating in the atmosphere; but sometimes it is harder than usual, and is no longer gradually expelled by the movements of the jaw in speaking and eating. At last, it fills the passage in the form of a hard plug, and sounds can neither pass through it nor by its side; if left, it gradually causes serious changes in the shape of tire passage, and even symptoms resembling diseases of the brain. Sometimes foreign bodies find their way into this passage, or tumors grow in it, and no unprofessional attempts should be made to remove them, lest the membrane of the drum be injured. It is but seldom that any instruments are necessary in addition to a stream of water thrown briskly in by means of a syringe, with a nozzle smaller than the circumference of the passage. Should the wax be very firm and hard, is is well to soften it by drop ping in some oil or au alkaline solution. But even a stream of water, unless great care be taken, may inure or burst the delicate membrana tympani, and the proceeding leave the patient suffering from a more serious condition than before.
A membrane, to be resonant, must have air on both sides of it, and the membrana tympani obtains this essential by means of the Eustachian tube, the lower orifice of which, on each side of the gullet, opens for a brief period at each act of swallowing, and admits a small quantity of air, which ascends into the tympanic cavity, if the tube is in a healthy condition; but frequently in persons suffering from relaxed mucous mem brane, the Eustachian passage becomes swollen and impassable, or blocked up by some thickened mucous secretion. During a common cold, persons often suffer from this cause of deafness. It has been supposed by some, that enlarged tonsils may interfere with the pharyngeal opening of the tube, and with that view they cut portions off them occasionally with great benefit to the condition of throat in which these glands are enlarged; but the latter are situated below and in front of the Eustachian tubes, and cannot be the immediate causes of the obstruction. • In some cases, the membrane of the drum may be perforated; and though the mere perforation is not sufficient to cause more than a slight degree of deafness, if the mucous membrane lining the tympanic cavity be thickened at the same time, the person is usually able to hear only the loudest sounds. If the perforation be stopped up, how
ever, the air confined in the tympanic. cavity vibrates sufficiently to stimulate the auditory nerve, through the round window of the labyrinth, and a useful degree of hearing is restored. In 1848, Mr. Yearsley of London showed that a small pellet of cotton-wool might be used for this purpose. It should be moistened with fine oil, and inserted on the end of a probe. Patients generally learn how to stick it neatly into the aperture themselves. It should be removed every three or four days, or oftener, should cleanliness require it.
Mr. Toynbee has invented an artificial membrana tympani of vulcanized india-rubber, attached to the end of a fine silver wire, by which it can be inserted or withdrawn. These beautiful little instruments may now be obtained of every surgical instrument maker, and are at least worth trying in cases of perforated membrana tympani, as they often do good, can do no harm, and are very cheap. The india-riffiber having been pared to the size likely to fit the individual's ear. it is moistened with warm water, and gently passed down the auditory passage; the sensations of the patient will easily decide when it has gone far enough, and he gladly discovers, by the sound of his own voice or that of the surgeon, that his hearing has been suddenly improved.
The deafness of aged persons has been shown, by Mr. Toynbee, to be generally caused by the effects. of previous inflammatory attacks, and may Irequently be much relieved by counter-irritation behind the car, alterative medicines, and washes which restore the healthy condition of the throat and the external auditory passage.
There are numerous "cures for deafness" advertised from time to time; some are harmless if useless, others are useless, but very dangerous, owing to the readiness with which inflammation may be set up, and the liability of the latter to extend to the brain or its membranes. The diseases which affect the ear are the same as affect other organs, and require to be treated upon the same principles. It is advisable, as soon as the first symptoms of approaching deafness are felt, to apply to one of the regularly qualified practitioners who devote themselves entirely to the subject, and to have nothing to do with these so-called cures, which benefit only the vendors.
The best English works on the subject are Practical Observations on Aural Surgery, by William R. Wilde of Dublin, and The Diseases of the Ear, by Joseph Toynbee,of London.