Volume 4 — MEDICAL OTOLOGY. (continued 2)

Vessels of the Labyrinth.—The labyrinth obtains its blood partly from the arteria auditiva interna, a branch from the basilar artery which comes from the vertebral, and partly through vessels communicating with the middle ear viâ the round and oval windows, and through others passing through the long walls themselves. The arteria auditiva interna divides in the internal meatus into a vestibular and cochlear branch. The former is distributed to the soft structures of the vestibule and semicircular canals. The cochlear branch is distributed to the modiolus and layers of the lamina spiralis. The venæ auditivæ internæ empty into the inferior petrosal sinus or the lateral sinus; other branches empty into the superior petrosal sinus.

The auditory nerve or portio mollis of the seventh nerve arises by two roots in the medulla oblongata. One ganglionic nucleus of origin is in the floor of the fourth ventricle, the other is in the crus cerebelli ad medullam (Stieda). The nerve winds around the restiform body, and passes into the meatus auditorius internus, and finally divides into a vestibular and cochlear branch. The vestibular branch divides into three branches: the superior is distributed to the utricle and ampullæ of the superior vertical and horizontal semicircular canals; the middle to the sacculis, and the inferior to the ampulla of the inferior vertical semicircular canal. The cochlear branch enters the modiolus and breaks up into smaller branches, which radiate fan-shaped into the lamina spiralis, and are then distributed between the two plates of the lamina spiralis through all its turns.

TINNITUS AURIUM.—It may be assumed that the normal ear is filled with continuous sound. The blood flowing through the large arteries and veins in close proximity to it (such as the carotid arteries and jugular vein), as well as the blood flowing through the vessels of the internal ear, will give rise to sound by throwing into vibration the soft tissues surrounding them, including also the walls of the vessels themselves. This motion is sufficient to excite the auditory nerve-elements by causing vibrations of the intra-labyrinthine fluids, and so produce sound; which, being a normal condition, and one to which the ear is accustomed, will remain unnoticed.¹¹

¹¹ To Theobald we are indebted for the vascular theory of sound.

The arterial system of the body throws the neighboring tissue into vibration, but this is not recognized unless our attention is particularly directed to it; or, in other words, the entire body is filled with movement as a normal condition, and therefore attracts no attention. But let this movement be increased—for instance, by violent muscular exertion, increasing the arterial action—or lessened, as in syncope, and at once an abnormal condition draws our attention to it.

In the same way the ear is filled with continuous sound as a normal condition, and therefore it is not perceived, these sound-vibrations escaping out through the middle ear and external canal. This can be readily proved. Let the external auditory canal be obstructed artificially, either by the finger or by a cork. At once a tidal tinnitus, so called, is produced, this being caused by the normal sound-vibrations being impeded in their outward passage and being thrown back again to impress the nerve-elements for a second time. This, being an abnormal condition, is at once recognized.

Different Varieties of Tinnitus Aurium.—I. Tinnitus caused by obstruction of the normal sound-vibrations in their outward passage through the middle ear and external canal; tidal tinnitus, so called from a resemblance to the noise of the ocean. Such obstructions may exist in the middle-ear cavity, as thickening of the soft tissues of the middle ear, exudations and adhesions, as found in chronic catarrh, or in the external canal, as impacted cerumen, a swollen canal, etc. The effect of such obstruction would be to interrupt the normal sound-vibrations and cause them to be reflected back again to impress for a second time the auditory nerve-elements, causing an abnormal and therefore recognized condition. This is the most frequent variety of tinnitus, and for the reason that it is produced by the more ordinary ear diseases.

II. Tinnitus caused by abnormal sound-vibrations produced either by increase or by decrease of intra-labyrinthine pressure. In a normal condition the auditory nerve-elements are subjected to a given intra-labyrinthine pressure; now, if this pressure be altered (either by being increased or diminished) an abnormal condition ensues, and is noted as such.

a. Tinnitus produced by increased intra-labyrinthine pressure may be caused by increase of the intra-labyrinthine fluids (by effusions, hemorrhages, etc., as in Menière's disease), or can be caused by increase in the amount of blood flowing through the arteries and veins of the internal ear. In either case there will result an increase of pressure that is exerted on the auditory nerve-elements. Also, another result of such increase of pressure on the arteries of the labyrinth would be to throw them into more active pulsation, and so cause greater movement on the intra-labyrinthine fluids. These abnormal vibrations impinging on the auditory nerve-endings would be noticed as such, and give rise to tinnitus of a pulsating character corresponding to the movements of the pulsating vessels. Such a condition is noticed in an eyeball afflicted by glaucoma, or can be artificially produced by finger-pressure on a normal eye. The veins of the retina will be first thrown into movement, and as the pressure increases the arteries will show marked pulsation. Why should not a similar set of conditions in the internal ear produce similar results?

b. Tinnitus produced by a lessened intra-labyrinthine pressure may be caused either by loss of intra-labyrinthine fluid or by a lessened blood-supply to the internal ear. The latter cause being the most frequent, a familiar example of this would be the tinnitus experienced by a fainting person, a common sensation being a swimming head accompanied with strange whizzing noises in the ears. The tinnitus of anæmia is of this class, and frequently of the pulsating variety. Another explanation might be given: an anæmic heart murmur might be conveyed along the blood-vessels as through a speaking-tube, and in that way impress the auditory nerve. In this variety of tinnitus it is supposed that the sound-conducting apparatus of the middle and external ear is normal; if any obstruction exists, it would cause increase of tinnitus of this variety.

III. Tinnitus caused by a diseased condition of the auditory nerve, either in the part lying between the internal ear and brain or in the brain-centre itself—pure subjective tinnitus. Here we enter upon a subject obscure from the fact that so little pathological research has been made in this direction; but, reasoning from analogy, why cannot the auditory nerve be subject to as many diseased conditions as the optic nerve, where the ophthalmoscope has clearly shown the existence of neuritis, atrophy, and many other pathological changes, caused, it may be, by disease of the retina, or it may exist as an inflammation of the nerve itself exterior to the eyeball, or it may be due to a brain tumor pressing on the optic nerve or optic tracts, also basilar meningitis? Gummata, osseous growths, etc. have in turn caused optic neuritis; finally, lesions at the optic nerve-endings in the brain itself have caused well-defined pathological changes in the optic nerve, which by the aid of the ophthalmoscope are recognized. Now, if these changes exist in the optic nerve, why may not the same conditions be present in connection with the auditory nerve, although from its anatomical location they are not capable of demonstration, as in the case of the optic nerve? And, as in the latter phosphene symptoms are common, due to nerve-irritation, so in irritation of the auditory nerve tinnitus would be developed, but of a subjective character. (In this connection it is not out of place to remark that in obscure internal ear disease examination of the optic nerve will often give valuable information toward clearing up the ear complication.) This variety of tinnitus may in some cases be due to a reflex nerve-irritation.

Finally, tinnitus may be noticed in cases of inflammation of the middle ear where fluid has collected, and is caused by the bursting of air-bubbles in their passage through this fluid, the air gaining access to the middle ear by way of the Eustachian tube. Tinnitus so produced resembles a bubbling or crackling sound. Hinton draws attention to certain cases where the tympanic membrane has lost its normal elasticity and become stiff, any movement of such a membrane causing a crackling sound. Also, there are some cases of tinnitus produced by foreign bodies being deposited on the tympanic membrane, such as cerumen, pieces of hair, etc., making a rustling or rasping noise.

Tinnitus produced by abnormal contractions of the tensor tympani or stapedius muscles has been thought to exist. Tinnitus may be intermittent or continuous. It also has an endless variety of sound, from one almost unrecognizable to a roar so loud as to render the patient nearly distracted.

Location of the Tinnitus.—Those varieties due to a diseased external or middle ear locate the sound, as a rule, in the ear itself. Subjective tinnitus is often located in the frontal and occipital regions; often also in the ear itself. It is also to be noted that marked tinnitus may be associated with a low degree of deafness, and the converse is true: slight tinnitus may be associated with a high degree of deafness.

PROGNOSIS.—The removal of tinnitus depends entirely upon the cause of it and the possibility of its removal. Continuous tinnitus is always to be regarded as a more pronounced symptom than the intermittent form.

The TREATMENT will be directed to the removal of the cause. If the disease is located in the external canal or middle ear, or in a diseased condition of the naso-pharynx, these irritating causes should be removed by treatment already laid down in previous pages. The treatment of subjective tinnitus will be guided by the same principles. Determine the cause and seek for its removal. As to whether any particular drugs exist peculiarly adapted to the removal of tinnitus, I would say that in tinnitus of a subjective character or due to nerve-irritation the bromides are indicated in appropriate doses. Inflation of the middle ear with air impregnated with ether (a few drops of ether dropped into a Politzer air-bag and the inflation made by the Politzer method), at intervals of three or four days, in some cases proves of benefit.

Deafness after Cerebro-Spinal Meningitis, Scarlet Fever, Mumps, etc.

This opens up a chapter in which our knowledge derived from post-mortem examination is very limited. In a given number of such cases the inflammation probably extends from the brain to the labyrinth; in others the changes that are found exist chiefly in the middle ear, so that it must be supposed that the inflammation in such cases has originated in the middle ear, and has secondarily invaded the labyrinth. In some cases, such as deafness after mumps, Toynbee is of the opinion that the peculiar poison of that disease affects the nervous apparatus of the ear, as the deafness comes on suddenly, and is usually complete, without evidence of disease in any other part of the ear. In this class of cases the prominent symptoms are deafness—which is total—and staggering gait, with vertigo. This symptom may last many weeks, and then cease. As a rule, examination of the tympanic membrane is negative, and the seat of disease is to be sought for in the labyrinth, whether it may be an inflammation of the soft structures or an effusion, causing increased intra-labyrinthine pressure. In many cases the suddenness of the attack would point to an effusion as the more probable cause.

Brunner in a comparison of five cases of deafness after mumps¹² gives the following symptoms and course of the disease: 1. The nervous deafness after mumps can be one-sided or double-sided, the former being more frequent. 2. It is complete, and, according to past experience, incurable. 3. It develops rapidly, with vertigo and subjective noises, the later symptom lasting a long time. 4. There is little or no fever. 5. Pain is never or very seldom present. 6. Consciousness is not lost; excessive vertigo a prominent symptom. 7. It happens both in children and adults.

¹² Archiv Otology, vol. xi., No. 2, p. 103.

Menière's Disease.

A. Guye of Amsterdam has published a very full summary of the history of this disease.¹³ The following is extracted from it: Under the head of Menière's disease is included those cases of inflammatory processes in the semicircular canals or in the middle ear producing vertigo, which is either continuous, or caused by normal movements of the head, or appearing only at intervals of weeks or months; also, that this disease is of a secondary nature, and is due to inflammatory processes in the tympanum or antrum. In typical cases the vertigo is accompanied by sensations of rotation: first a sense of rotation about a vertical axis and toward the affected side; this is followed by a sensation of rotation about a transverse axis forward and backward. The vertigo then becomes complete, and is followed by fainting, with or without loss of consciousness and vomiting. The attack in some cases may last for a few minutes to a half hour; in others every movement will tend to produce vertigo for several days. In chronic cases the feeling of vertigo to a slight degree persists between the attacks. Guye considers the causes of middle-ear catarrh as the factors most likely to cause Menière's disease. Syphilis is also noted in some cases.

¹³ Ibid., vol. ix., No. 3.

TREATMENT.—In some cases an alterative treatment is most serviceable, such as iodide of potassium, also the bromide of potassium; quinine is also by some recommended. The use of alcohol and tobacco is to be forbidden.

The disease known as boiler-makers' deafness, because generally found among men laboring in machine-shops, where they are subjected to loud noises connected with the work they are engaged on, is thought to be due to a paralysis of the terminal endings of the auditory nerve due to concussion. The middle ear sometimes shows some thickening of the tympanic membrane. Treatment is without avail.

In internal-ear diseases a few common symptoms can be noted. All cases show deafness, and in most of them of an absolute degree. And here is where the tuning-fork proves a valuable aid in diagnosis of deafness due to middle-ear disease, in which cases the tuning-fork is heard best on the deaf side, and to deafness due to internal-ear disease, where the tuning-fork is heard the least on the deaf side. Vertigo and a staggering gait are quite common symptoms, probably due to irritation of the semicircular canals. Prognosis as a rule is bad, as far as recovery is concerned, and an alterative treatment is often indicated. Electricity, I would state, in my experience has not proved to be of any avail.

Deaf-Mutism

may be either congenital or acquired. Two-thirds of all cases will come under the first class, and often depend upon a mal-development of some part of the central nervous system or the ear itself, or may be due to intra-uterine disease of the ear. There is a strong tendency for this disease to be inherited, and particularly in children where there exists a blood-relationship between the parents. The acquired cases may arise from defects in the central nervous system or in the internal ear, or may be due to diseases affecting the middle ear, such as purulent inflammation; and this latter cause is to be noted, as no doubt proper treatment of the middle-ear disease in many cases would have prevented such a result.

All deaf cases become mute, unless the disease has occurred in adult life, when the patient has already acquired the power of language. A deaf-mute does not speak, because he cannot hear, and therefore speech is an unknown quantity.

The TREATMENT would consist in treating any middle-ear disease that might exist, such as the sequelæ of purulent inflammation, and the instruction of the patient in acquiring the power of intercommunication either by the methods long employed of finger-reading, or, much better, by the lip method, so called, where the power of speech is given to the patient. Such cases should attend schools where such instruction is given, commencing at five years of age, and many cases now attest the value of the latter method of instruction.

DIFFERENT METHODS OF DETECTING FEIGNED DEAFNESS.—The Moos Method.—Stop the external canal of the sound ear with a cork; place a vibrating tuning-fork on the head. If the person under examination declares that he does not hear the fork with either ear, he is feigning deafness, as it would be heard well by the sound ear.

The Urbantschitsch method makes use of the human voice. First determine that good hearing power exists in the sound ear; then shut the external canal of this ear with a cork and address the individual with a few loudly-spoken words. If he denies hearing at all, he is feigning, as a good hearing ear, by simple closure of the external canal, will be still able to hear loudly-spoken words.

Another method is to determine the distance at which the person can hear certain words and repeat them correctly. Then have the patient close the eyes and let the examiner try by lengthening and shortening the distance, and note the result. Often he will hear and repeat words spoken at long distances, and apparently not be able to repeat words spoken at short distances.

Müller's Method.—Speak into the sound ear through a tube or paper roll different words as softly and quickly as the examined person can repeat; then let a second examiner repeat the same in the deaf ear. Of course nothing will be heard by the person feigning. Then let the first examiner repeat his performance; the feigner will quickly repeat after him. Suddenly begins the second examiner to softly and quickly speak in the deaf ear, but choosing different words from the first examiner. A really one-sided deaf person will repeat the words spoken into the sound ear only, while the feigner will be in doubt, and will not be able to separate the words heard by both ears, so as only to repeat the words heard by the sound ear.