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Diseases Of The Sound Perceiving Apparatus

Diseases Of The Sound Perceiving Apparatus

THE sound perceiving apparatus consists of all those portions of the acoustic nerve apparatus central to the peripheral nerve cells in the labyrinth, but is usually considered to include all of the labyrinthine structures. About 10 per cent., of all aural cases show evidences of pathological changes in some part of this apparatus, or of functional disturbances of the same; some authors Burkner, Randall) make this percentage rather less. Middle age is the period of life relatively most free from such alterations.

Morphology. Complete absence of the labyrinth (Michel, Schwartze) or of the auditory nerve (Michel) may exist congenitally, or there may be anosseous spiral lamina; P, pillars of Corti; D, Deiters's cells; H, hair cells.

arrest of development in these parts producing corresponding deformities. Arrested labyrinthine development rarely occurs; but when it does, the cochlea is the part most frequently affected (H. Mygind). Malformation of the osseous labyrinth has heretofore been found most frequently, but it is probably true that with further observations the membranous labyrinth (Figs. 510, 511) will be found to be the part most commonly malformed ; in fact, it is possible for the arrest in development to be confined to it (A. Scheibe). The malformations, when congenital, are usually the same on both sides (Michel and Claudius), and may or may not be associated with similar changes in the sound conducting apparatus. Should these defects be slight in character, the hearing ability may be very little, if at all, impaired, as in a case of Voltolini's ; but when the defects are more extensive, they are generally combined with great or total deafness (A. Politzer).

Pathology. Of the circulatory disturbances occurring in the labyrinth, oligemia or anemia, if of limited duration, produces very little, if any, alteration in the anatomy of the part. It is possible that prolonged oligemia or anemia may give rise to degenerative changes (A. Politzer). Hyperemia of moderate intensity and duration is not likely to induce anatomical alterations, but, if long continued, may lead to increased pigmentary deposits (a moderate quantity of which, however, may be considered as not abnormal), to deposit of calcareous salts, to hypertrophy of the membranous labyrinth, to dilatation of the vascular structures, to serous saturation. If of great intensity, hyperemia may cause rupture of the vascular walls with consecutive hemorrhage. Hemorrhages and ecchymoses (Fig. 512) may occur in any part of the labyrinth, and there may have been no pre existing hyperemia. Hemorrhagic extravasation may either be completely absorbed, become organized, undergo fibrous or calcareous degeneration, may cause atrophy and degeneration of the epithelium, connective tissue, and nerve elements, with an abundant formation of granular cells, hyaline corpuscles, and pigmentary deposits, or may induce inflammatory changes terminating in suppuration. Emboli may lodge in the labyrinth, as in Friedreich's case of embolus of the arteria auditiva interna, or infections thrombi may form.

In regard to the inflammatory changes taking place in the labyrinth, the writer is inclined to believe that a classification according to the ideas expressed by Gruber is most reasonable and scientific, and would do much to dissipate the confusion now existing in most textbooks on the subject of diseases of the internal ear. The inflammations affecting the labyrinth are, therefore, divided into: (1) hyperplasic (tabyrinthitis hyperplastica) and (2) exudative (labyrinthitis exudative). In the former we may have hypertrophy of the auditory nerve stem, due to infiltration and proliferation of the neurilemma, (Politzer); deposits of calcareous salts or of amyloid bodies it, and about the nerve; hyperostosis of the petrous bone narrowing the labyrinthine cavities, thickening of the periosteum; increased quantity of the perilymph and endolymph (Steinbrugge); infiltration with small cells and hyperplasia of the connective tissue between the membranous and osseous labyrinth (Moos); a similar condition affecting the membranous labyrinth (Moos); development of osseous tissue from chronic inflammation of the labyrinthine periosteum ; excessive epithelial growth on the inner side of the membranous labyrinth in chronic inflammation (Politzer); chronic endarteritis; depositions of concretions of phosphate of lime and of corpora amylacea, within the labyrinth. In the exudative form of inflammation we have intense hyperemia which may produce a serous saturation of the structures of the labyrinth; an infiltration with small lymphoid cells (Moos) or round cells (Schwabach); a hemorrhagic exudation, as from a pachymeningitis hemorrhagica (Moos); a purulent inflammation, due either to the direct propagation of pus from neighboring structures, or by way of the blood vessels or by the lymph spaces (Politzer), or by dehiseences in the bony wall between the superior semicircular canal and the cerebral cavity (J. Dunn), or to infection by the immigration of micro organisms (Steinbrfigge).

These inflammatory processes produce various alterations of the anatomical elements of the labyrinth: the effect of the invasion by microorganisms is manifested by a mycotic fatty degeneration of the endothelium of the blood vessels, causing coagulation and thrombosis and colloid degeneration of the. labyrinthine tissues (Moos) ; injury of the acoustic nerve apparatus by hemorrhages or mycotic degeneration the axis cylinders resisting longest (Moos) ; stasis and thrombosis of the periosteal blood vessels (Steinbrfigge) ; rapid destruction of the connective tissue elements; destruction of the osseous tissue through entrance of the micro organisms into the periosteum, the bone corpuscles, and the blood vessels of the Haversian canals. In addition, the poisonous products of metabolism, the toxalbumins, probably play an important part (Moos). The micro organisms (streptococcus, staphylococcus and Frankel's diplococcus of pneumonia (Schwabach) gain entrance to the labyrinth through the aqueducts, the periosteal bloodvessels and, probably, also along the sheath of the auditory nerve, as does the pus. In the beginning, the perilymphatic cavity is almost exclusively the seat of the disease, which later extends to the endolymphatic cavity (Habermann). The micro organisms seem to collect and to develop their greatest working power in the most dependent part , of the labyrinth (Habermann). The inferior portions of the cochlea are, therefore, most affected (Politzer); Steinbrugge, however, thinks the proneness to location in this region is rather due to the propagation of the affection from the cranial cavity.

As a result of the inflammation of the labyrinth, the nerve fibers, cells, and ganglia (see Figs. 514, 519) are destroyed or atrophied from pressure, their place being taken by newly formed connective tissue, or left vacant, thus forming a system of lacuna corresponding in arrangement to the normal nerve distribution of the part (Moos, Scheibe, Steinbrugge); the membranous labyrinth may be totally destroyed, likewise the structures of the labyrinthine windows, with displacement of the stapes (Habermann); coagulation necrosis of the labyrinthine ligaments may be produced, with consequent collapse of the membranous semicircular canals (Moos); the osseous capsule may be more or less destroyed. If the quantity or virulence of the infection be great, there may be absence of all tendency to reactive inflammation and the production of new formations (MOOS).

Should reactive inflammation be established, it results in the production of newly formed granulation (Habermann) (Fig. 513), connective (Moos, Scheibe), fibrous (Gradenigo), or osseous (Toynbee) tissue; these new formations at times going so far as to produce complete obliteration (Fig. 514) of the labyrinthine cavities (Politzer), of the foramina cribrosa, of the aqueducts (Scheibe), and of the oval and round windows (Toynbee). Ossification proceeds from the remnants of periosteum (Fig. 515) and from the newly formed connective and fibrous tissues.

Acoustic Nerve. Among the pathological alterations of the acoustic nerve apparatus we will first take up changes in the stem of the auditory' nerve. Hyperemia and ecchymosis may exist (Politzer); deposition of corpora amylacea or concretions of phosphate of lime; fatty degeneration

(Politzer); gray degeneration (Warnecke); atrophy; leukemic small celled infiltration (Alt) ; purulent infiltration (Heller) ; embedding of the nerve in meningeal exudation (Schwartze). Tumors, principally sarcoma, fibroma, and so called neuroma, may invade the internal auditory canal (Fig. 516), exerting pressure with consecutive atrophy or even solution of continuity (Politzer). The auditory nerve is more frequently the seat of morbid growths then any other cerebral nerve (Virchow). The changes most likely to occur in the region of the acoustic nerve origin in the medulla are due to thickening and purulent inflammation of the ependyma of the fourth ventricle and softening of the floor (Knapp) ; effusion into the fourth ventricle, either serous (Stuart), aqueous (Jackson), sero purnlent Armstrong and Clarke), or purulent (Ames) ; tumors in or about the fourth ventricle. Disease of the first and second convolutions of the left, temporal lobe also interfere with audition (Wernicke), the cortical center for hearing probably being located in this region. Of course, any pathological condition along the course of the cerebral acoustic nerve fibers also induces disturbances of function. Increased intracranial pressure may cause secondarily increased labyrinthine pressure with depression of Reissner's membrane (Steinbrugge) and bulging outward of the membrane of the round window (Moos). Many cases, however, of increased intracranial. pressure, as in chronic hydrocephalus, show no such change in labyrinthine pressure nor any impairment of the function of hearing (Pomeroy).

Etiology. Anemia or oligemia of the labyrinth has been noted in connection with general anemia (Miot and Herck), with continued fevers (Roosa), with gestation and parturition (Pomeroy), with aneurism of the basilar and atheroma of the internal auditory artery (Miot and Herck), with changes in the middle ear exerting pressure upon the labyrinthine structures through the round and oval windows (Pomeroy).

Hyperemia ofthe labyrinth occurs in all conditions producing congestion of the head (Hartmann) ; in conditions exerting pressure on the venous channels of the brain and consequent obstruction to the return flow of blood from the ear (Politzer), on the vessels of the internal auditory canal (Politzer), or exerting pressure on the large veins of the neck (Sehwartze) ; in disturbances of thecirculation originating in the heart, lungs (Schwartze), or kidneys; in prolonged exposure to sharp sounds (Roosa) ; in the gouty or rheumatic diathesis. Any hyperemia of the labyrinth occurring in connection with inflammation of the external or middle ear must certainly be considered, since Eichler's recent anatomical confirmation of Schwartze's clinical observations, as the result of a reflex action through the sympathetic upon the vaso motor nervous system of the labyrinth, rather than a direct influence through anastomoses. Eichler found that the vascular supply of the labyrinth was entirely distinct from that of the surrounding tissues, and that the connection between the vessels of the tympanum and those of the labyrinth, which Politzer maintains, does not exist. Schwartze had long ago held that even in the very highest degrees of inflammation of the tympanum it is only exceptionally that a simultaneous hyperemia is met with in the labyrinth. It is a matter of observation that in chronic middle ear suppuration with granulomata and polypi the functional tests show no impairment of function of any importance in the sound perceiving apparatus.

Hemorrhages and ecchymoses are prone to happen in all conditions producing hyperemia of the labyrinthine structures ; in the infectious diseases causing changes in the vascular walls ; in pachymeningitis hemorrhagica (Moos) in leukemia (Steinbragge); in typhoid fever (Barclay) ; in nephritis, gout, and rheumatism ; in fracture or concussion of the skull ; in diabetes sometimes in embolism of the arteria auditiva interna (Gruber).

Atrophy and degeneration of the acoustic nerve apparatus may be caused by syphilis ; by any labyrinthine inflammation of sufficient gravity to interfere with nutrition ; by changes in chronic otitis media exerting long continued pressure on the labyrinth and thus producing anemia, which, if continued for a sufficient time, will result in nutritive changes of the nature of atrophy (Porneroy) and these secondary nerve affections may remain although the tympanic disease disappears (Gruber) ; by acute hydrocephalus internus, leading to softening and shrivelling of the nuclei of the auditory nerve (Politzer) ; by fetal ependymitis (Meyer) doing the same ; in chronic hydrocephalus, tumors of the brain and the nerve from pressure (Politzer) ; gray degeneration and atrophy in tabes dorsalis (Pierrot, Wernicke, Habermann) ; in old age by calcareous deposits (BUtcher) and corpora arnylacea (Politzer); by hemorrhage ; by nephritis and influenza (Gradenigo) ; by contraction of the basilar artery (Politzer); by apoplectic and inflammatory processes involving the floor of the fourth ventricle (Politzer) ; by professional concussion of sound (Roosa); by purulent inflammation of the ependyma (Politzer); by purulent inflammation of the stem of the auditory nerve from a similar condition of the meninges (Politzer); by emboli and embolic softening along the acoustic nerve tracts (Politzer). Among the nerves of sense, the auditory is the most " impressionable " that is, its function is more frequently impaired by general diseases and by chemical changes in the blood in infectious diseases (Politzer). Affections of the auditory nerve attack, in the majority of cases, both organs of hearing. It is probable that degenerative processes involving one auditory nerve will in time pass over to the other. The view that atrophy of the auditory nerve can take place purely from inaction, as in ankylosis of the stapes, has not yet been corroborated by experience (Politzer); in fact, the results of post mortem examinations point the other way. The changes which occur in presbycusis and otitis media sclerosa seem to be due to a coincident trophic disturbance similar to that in the middle ear rather than to any atrophy from disuse (Alderton). Central atrophy depends almost without exception upon cerebral disease, whilst the peripheral is most often a consequence of disorders of the auditory organ itself (Gruber). The occurrence of the disturbances of hearing in these processes depends less upon the extent than upon the seat of the pathological accumulation (Politzer).

Hyperplastic inflammation (labyrintbitis hyperplastica) may occur in syphilis, which is causative in most of the forms of this affection; in the first stages of exudative inflammation of the labyrinth due to infectious diseases, and the inflammatory process may advance no further (Moos); in gout and rheumatism; in rachitis; in typhoid fever and leukemia and in old age.

Exudative inflammation (labyrinthitis exudativa) may be caused b y obstruction in the internal auditory meatus to the outflow of blood from the labyrinth (Politzer); by typhoid fever(Barclay); leukemia (see Fig. 517) (Politzer) ; epidemic cerebro spinal, hemorrhagic, pachy and simple meningitis (Heller, Moos, Politzer) ; syphilis, tuberculosis, measles, diphtheria, scarlatina, searlatinal diphtheria, mumps, variola ; by an extension from an otitis media stimulants of long standing (Bezold). This form of inflammation occurs more frequently in children than in adults, because of the more frequent occurrence in children of the acute exanthemata, etc. Further, the anastomotic connections between the middle ear and the labyrinth on the one hand, and between the labyrinth and the cranial cavity on the other, are more numerous in children than in adults; and further, because in the child's ear through the aqueducts there is a freer communication between the labyrinthine fluid and the cerebrospinal cavity than in the adult (Politzer).

Symptomatology. Functional Reactions in General. Before taking up the departures from the normal reactions to functional tests in diseases of the sound perceiving apparatus it is necessary to devote some attention to the normal decline in hearing evidenced in advancing age. Zwaardemaker has tabulated the average responses for the upper tone which is not lower than Galton 4.8 (Zwaardemaker). The lower tone limit is elevated to about the same extent in old age (N. J. Cuperus). In old age the B. C. (bone conrduction) does not alone experience a reduction, but sinks proportionately with the lessening of the hearing distance, the A. C. (airconduction), etc. (Bezold).

In diseases of the sound perceiving apparatus, the. upper tone limit, obtained by means of the Galton whistle, is lowered i. e. the highest notes elicited by the whistle being denoted by one or fractions of one, and the lower notes by multiples of one and their fractions; as the obturator is withdrawn the note deepens or lowers at the same time that the indicator or graduated scale shows higher and higher numbers, and, therefore, a higher number on the scale, as 4.8, indicates a much lower note than a lower number, as 1.22. The lower tone limit by A. C. (air conduction), as obtained by a clamped tuning fork vibrating from 26 to 64 double vibrations in the second, is impaired very little or )lot at all. The absolute duration of B. C. (bone conduction), Schwabach's test, is shortened, or abolished for all or for certain tones. A. C.>B. C. (air conduction is better than bone conduction), both in intensity and in duration throughout the musical scale, Rinne's test. If the disease is unilateral, the vibrating tuning fork C, placed in contact with the vertex, midway between the ears, should be heard in the unaffected ear, Weber's test; or in the better hearing ear if the disease is bilateral. This test is not so reliable as those previously described. In labyrinthine disease the patients hear the deeper tones of speech very well, while the higher tones are no longer perceived (0. Wolf). It is well in testing with the whisper or speech to remember 0. Wolf's division of the voice sounds into

1. The deep, like R and V;

2. The middle like the explosives B, K, and T;

3. The high and strong, like S, Sh, and G; and the high and weak, like F, L, N, and H (which are excluded as dependent on other tones tone borrowing).

Wolf devotes particular attention to the consonants. Bezold employs the names of numbers as test words, as these are familiar to both children and adults. Equal intensity of sound can be obtained by using the reserve air left after a forced inspiration followed by a normal expiration (J. E. Sheppard). To test the hearing for speech thoroughly, it, is quite sufficient in most cases, after testing a few words, to note the distance for those words perceived with the greatest difficulty (Lucae).

Disturbances of equilibrium are apt to be observed in any process producing irritation of the nerve endings in the vestibule, the semicircular canals, or in the stem and origin of the auditory nerve. In testing for disturbances of equilibrium, it is well first to determine the static (the body at rest) equilibrium and then the dynamic (the body in motion) equilibrium. The author tests the former by means of the apparatus shown in Plate 12, consisting essentially of a movable inclined plane, after the method of v. Stein. A person with normal powers of equilibrium should be able to maintain his erect position until the board reaches an inclination of 350 to 40' to the horizontal when facing toward the apex of the angle anterior inclination. Posterior inclination, with the back turned toward the apex, varies from 200 to 30' ; lateral inclination, with the side toward the apex, from 371 to 38'. In patients with labyrinthine. disease, giving rise to vertigo, etc., the angle measures 20' or less by anterior inclination, etc., and this is much decreased when the eyes are closed. The static equilibrium is also tested with the eyes open and shut, with the legs close together, while standing on the toes, and while standing on one leg. A healthy person can stand in these positions for some time, with slight balancing, while the eyes are closed; but a person with imperfect powers of equilibrium. immediately begins to show disturbances of these powers. The dynamic equilibrium is tested by walking forward and backward on a level, by turning on the vertical axis of the body to the right or left with legs together, and, finally, by turning about on one leg alone. The last movement is the most difficult, but a healthy person can go through these various motions with little if any trouble ; whereas aural patients with disturbance of the powers of equilibrium find it more or less difficult or impossible, and their movements are attended by great weariness.

Given these reactions, the inference is well founded that we have to do with an affection of the sound perceiving apparatus. Still other tests have been devised by Bing, Brenner, Gradenigo, Gelle, and others; but the above have been more universally tried, are sufficient for the purposes of diagnosis, and are more reliable.

The symptoms of affections of the sound perceiving apparatus' are more particularly described as follows:

Anemia. There is usually some dullness of hearing, which is manifested either as a slowness of perception only, or as a real impairment of the hearing power. The impairment in the hearing ability follows along the line of the test responses as given above, especially, however, being noticeable in the curtailment of the duration of B. C. Annoying tinnitus of a low pitch is commonly present. The patient may be subject to occasional attacks of vertigo, and usually is the victim of general anemia.

Hyperemia. There is very little if any impairment of the hearing power, and there may be present hyperesthesia of the nerve to certain sounds. Often there is a feeling of fullness and distention in the ears or in the head, with dullness of intellect or even giddiness or vertigo at times. With this is usually associated a high pitched tinnitus. The functional tests show a limited involvement of the sound perceiving apparatus. Paresthesite are likely to be complained of.

Hemorrhage is usually immediately followed by marked vertigo, aggravated on closure of the eyes, with possible falling or unconsciousness (the latter is rather rare) unless the hemorrhage is confined to the cochlea, in which case vertigo is absent (Gradenigo). With or immediately following this occur nausea or vomiting, severe tinnitus (in some cases preceding the attack), occasionally profuse perspiration, and impairment of the hearing up to complete deafness. The symptoms thus given constitute what was formerly generally designated as Meniere's disease, and is the only condition to which that name should be given. Amelioration of these symptoms takes, place in a short time, the vertigo, hardness of hearing, and tinnitus continuing longest. The hardness of bearing rarely disappears entirely, and the tinnitus is likely to persist, although diminished in intensity. There is always danger of a repetition of the hemorrhage. The functional tests give varying responses according to the locality and the extent of the hemorrhage, but always confirm a diagnosis of involvement of the sound perceiving apparatus.

The symptoms of embolism and thrombosis are presumably similar to those of hemorrhage, and serous effusion can give the same more fleetingly (Gruber).

Labyrinthitis Hyperplastica. The most marked form of this inflammation is seen in connection with syphilis, usually as a late manifestation in the acquired, or around puberty in the hereditary, and gives rise to deafness, appearing gradually or suddenly, subject to periods of quiescence and exacerbation; also to loud aural tinnitus. Vertiginous attacks and disturbances of equilibrium are usually slight unless the exudative form of inflammation is induced. It is likely to be accompanied by very violent headache (Charazac), often nocturnal (Pomeroy) when due to syphilis. Both ears are usually affected. The sudden deafness coming on with serous saturation or lymphoid infiltration may disappear almost completely; but usually the hyperplastic formations are causative of a certain amount of permanent deafness. The functional tests leave no doubt as to the seat of tile trouble in the sound perceiving apparatus.

Labyrinthitis exudative in its most acute form comes on very suddenly. with perhaps a rigor; with fever, nausea, or vomiting very commonly; with profound deafness, marked derangement of co ordination ; at times, stupor or delirium (although usually the mind is clear) ; intense tinnitus and vertigo, and, in some cases, pain. This very acute form occurs with epidemic cerebrospinal meningitis (Voltolini described this form of inflammation as a primary inflammation, but there is not much doubt that it is an affection secondary to a more or less localized meningitis), with the acute infectious diseases (measles, scarlet fever, diphtheria, etc.) or epidemic parotitis, etc. Most of the symptoms abate or disappear in a few days to a few weeks, but the staggering gait and deafness are more persistent the latter rarely improving to any great extent. Functionally, the upper tone limit is greatly lowered; B. C. markedly reduced throughout or destroyed for part or ail of the musical scale; A. C.>B. C. ; the power of equilibrium much impaired. The less acute forms of exudative inflammation of the labyrinth give rise to vertigo (unless confined to the cochlea), to sudden loss of bearing power, intense tinnitus, lowering of the upper toile limit, with B. C. reduced or absent, A. C.>B. C., and to disturbances of equilibrium.

In affection of the nerve trunk the most prominent symptom is impairment of bearing. There are also present tinnitus, vertigo, staggering gait, and excessive functional exhaustibility (Gradenigo). Usually unilateral, it may be bilateral, as in tabes dorsalis. Hardness of hearing is usually most pronounced for the tuning forks of middle register (Gradenigo), perception for high and low notes being fairly well preserved. B. C. is very much impaired.

Word deafness (sensory aphasia) furnishes the most reliable sign of involvement of the cortical area.. usually of the left first temporal convolution. The function of both ears is usually impaired; tinnitus is more commonly absent ; B. C. is reduced in duration (see page 710).

Concussion of the head may provoke symptoms indicating an involvement of the sound perceiving apparatus even up to complete deafness, and this latter may be induced without any recognizable changes being necessarily found in the labyrinth on postmortem examination (Gruber). The syrup toms usually present are diminution of hearing, tinnitus, vertigo, headache, unconsciousness, pain occasionally, occasionally acoustic hyperesthesia or alteration in pitch of certain tones, etc., one or all. These symptoms have been explained as due to shock to the acoustic nerve (Buck), basilar inflammation resulting from a blow (Buck), or hemorrhage at the point of origin of the acoustic nerve (Moos

Fractures of the petrous bone, involving the labyrinth, are accompanied by hemorrhage from the meatus, or if the tympanic membrane is not, rupt┬Čured, the blood ma y pass through the tympanum and the Eustachian tube into the throat (Buck); serous looking discharge in considerable quantity; very pronounced subjective noises ; disturbances of equilibrium and vertigi┬Čnous symptoms; facial paralysis in 55 per cent., of the cases (Schmidt). In both concussion and fracture the functional tests of involvement of the sound perceiving apparatus are present.

Neurotic disturbances of the sound perceiving apparatus, which may be unassociated with pathological anatomical alterations, are by no means uncommon, and are described below.

Acoustic neurasthenia has as symptoms impairment of bearing, varying from mere slowness (acoustic torpor or lassitude) to considerable deafness, especially marked under any prolonged strain or confusion of sound, mental anxiety, or extreme physical fatigue (Poll), and improving rapidly after rest. Tinnitus may or may not be present, and is increased by fatigue; paresthesie are common, with great fluctuation of the ability to bear; the upper tone limit is not apt to be impaired; but the duration of B. C. is lowered throughout the musical scale, and there is great functional exhaustibility of the acoustic nerve. Either one or both ears may be involved, though usually both. The patients are. generally neurasthenic, and any circumstance which aggravates this condition is the cause of marked decrease in the bearing (Gelle). This condition is frequently associated with that following.

Acoustic hysteria is usually associated with great deafness, which appears suddenly and is not subject to the fluctuations noticeable in neurasthenia; it is the same throughout the continuance of the attack. Vertigo is never present Rohrer and tinnitus is not frequent; one or both ears may be affected or the attack may pass from one ear to the other; paresthesie or anesthesia of the external auditory canal and the tympanic membrane may be present (Wurdemann) ; functional tests are apt to be contradictory, the most constant being lowering of the upper tone limit.

Hyperacusis is an overexcitable condition of the acoustic nerve, sometimes even painful, occurring generally periodically in connection with great nervous or mental excitement, with neuralgie, or after partaking of stimulants (Politzer). It also occurs in the incipiency of inflammatory affections of the ear.

Paracusis consists in the false perception of the pitch of a sound. Paracusis loci is the inability to tell the direction from which the sound comes, and depends upon the difference in the acuteness of perception of the two ears. As our judgment of the direction of sound depends upon binaural bearing, in unilateral deafness the apparent source of the sound will be projected in the direction of the normal hearing ear (Politzer).

Diplacusis is a form of' paracusis in which a single tone is heard double; either each ear perceives the tone differently and it seems doubled (D. binauricularis Knapp), or a double perception of a single tone is got by one ear (D. monauricularis): the two tones differ from each other in time (D. echoica) or in interval (D. harmonica or disharmonica H. Daae).

"Nervous tinnitus" ( Politzer) may exist as a pure neurosis without difficulty of hearing. It is observed as an irritable condition of the nerve in convalescence from severe febrile affections ; in connection with sexual excesses, intemperance, overfatigue of the auditory nerve, and extreme mental disturbance. It may continue indefinitely, the bearing remaining unimpaired.

Hallucinations of hearing may occur rarely in ear diseases without a changed condition in the brain (Politzer).

Color hearing is a term employed to define that phenomenon by which certain tones always excite in some people the sensation of color.

Deaf mutism. One of the most important results of labyrinthitis is the production of deaf mutism. In the United States there were about 38.2 deafmutes to every 100,000 inhabitants (v. Troltsch), but this proportion is apparently diminishing. They belong, to a great extent, by birth to those classes of society which are least favorably situated economically as well as socially (H. Mygind), In the majority,, the deaf mutism develops before the end of the third year (Robertson), but may develop as late as the eighth year (Lemcke). The pathological seat of the causative process is, almost without exception, in the labyrinth (H. Mygind). In connection with the labyrinth, the middle ear is surprisingly often found to be affected, only exceptionally as regards lack of formation, but almost regularly by violent inflammation, generally of a purulent nature (H. Mygind). Deaf mutism occurs more frequently in the male sex (v. Troltsch). More than half the cases are due to acquired deafness (H. Mygind), and epidemic diseases are probably most often the cause of the deafness (H. Mygind). Bezold is probably nearly right in his statement that about 43 per cent. are totally deaf, and it is the general opinion that among these the acquired are greater in number than the congenital (Hartmann). There is noticeably a very frequent occurrence of partial defects. in the musical scale, in which sometimes the upper and sometimes the lower limits of tone are absent; sometimes single or multiple gaps or islands are found which show no perception at all (Bezold). Only about 8.4 per cent. have hearing power sufficient for intercourse with other people (Lemcke). Disturbances of equilibrium (static or dynamic) are present in 50 per cent. (A. Bruck), and those showing normal equilibrium are also much more apt to have normal speech (L. W. Stern). Heredity exerts a great influence, especially in those families in which there are many cases of hardness of bearing, but direct transmission is absent, as Mygind found that not a. single child of deaf mute parents was itself deaf and dumb. Consanguineous marriages are only causative when joined to hereditary and other influences (as constitutional disease) (L. Blau). Deaf mutism is especially apt to occur in those families in which many children have been born in rapid succession (IT. Mygind). Gillespie has drawn attention to the frequency of goiter in deaf mutism; and Lemcke, of affections of the naso pharyngeal tract, especially adenoid vegetations. The bodily growth keeps pace with that of normal persons, but there is defective brain development (Lemcke) ; as a rule, however, they are endowed with organic, mental, and normal sensitiveness but little inferior to the normal (Ottolenghi). They do not exhibit a higher mortality than normal individuals living under the same circumstances (H. Mygind), but they are especially prone to lung diseases. Nearly half of all deaf mutes over 20 years of age are obliged to fall back on the help of others for their maintenance (H. Mygind). Marriages contracted by deafmutes exhibit a very small degree of fertility (H. Mygind).

Diagnosis. The diagnosis has been almost sufficiently indicated in the symptomatology, but there are a few points that it seems well to emphasize.

In any case of hardness of hearing the first thing to be determined is whether the lesion is located in the sound conducting or in the sound perceiving apparatus. The antagonistic reactions to the functional tests may be tabulated as follows:

In order to bring these differing reactions more graphically before the eye, the author has arranged them below in the schema originally devised by himself, first giving the normal reaction in the healthy ear for comparisonthe numerals representing the duration of perception in seconds, the Rinne showing whether the respective forks are heard louder by A. C. or B. C. at the initial point.

In marked disease of the sound conducting apparatus the reaction will be approximately as below:

It will be noticed that the upper tone limit is slightly impaired in the scheme; this is in keeping with the author's findings as described. in the article " The Upper tone Limit in the Normal and Diseased Ear."

In disease of the sound perceiving apparatus the following reactions will serve as a type:

In cases in which there is an affection of both the sound conducting and sound perceiving apparatus, both upper and lower tone limits are contracted, the duration of B. C. is impaired, B. C. is better than A. C. ( Rinne) for the lower forks, while A. C. is better than B. C. (+Rinne) for the higher forks, and both the higher and deeper tones of speech are imperfectly beard. The degree in which one or the other apparatus is responsible for the hardness of hearing is indicated by the closeness of the resemblance of the results of the functional tests to the reactions given by the one or the other type of disease.

In the matter of locating the lesion in any particular portion of the soundperceiving apparatus much has yet to be learned, but the following deductions seem to be well established as the result of postmortem examinations of cases clinically observed before death : word deafness points to involvement of the cortical areas ; lower and upper tone limits fairly well preserved with deafness for forks of middle register and greatly impaired B. C. indicate involvement of the nerve stem (Gradenigo) ; disturbances of equilibrium may occur in the course of any pathological process causing irritation of the terminal filaments in the vestibule or ampulla, of the nerve fibers in the auditory nerve stem (Kreidl), or of the central origin of the nerve (Hillairet) ; pathological processes involving the cochlea alone do not induce vertigo (Gradenigo); the cochlea is the only part specialized for the perception of sound, as the retina is for light, and its total destruction is followed by total deafness; it is probable that the lower notes are perceived at the cupola, and the higher notes at the base.

In attempting to make a diagnosis these deductions should be borne in mind while studying the results of the functional testing, remembering always, however, that it is often impossible to determine whether the disease is in the labyrinth, nerve trunk, or central course (Politzer).

In fracture of the petrous bone, the escape of cerebro spinal fluid is not essential (Gruber), and no certain conclusions with respect to the anatomical situation, gravity, or the subsequent behavior of the fracture can be drawn from the external appearances in the ear and from the functional disturbances (Schmidt). In most cases both the internal and middle ear are affected together (Schmidt). Fracture may occur without loss of hearing (J. E. Sheppard) if the labyrinth is not involved in the fracture line.

The diplacuses are, in the author's experience, usually due to affections of the middle ear, as in a case recently observed of diplacusis echoica coming on during the acme of an attack of otitis media subacute.

The neuroses are recognized by their symptoms and the peculiar constitutional condition of the patient.

Bearing in mind the above few remarks in connection with those on symptomatology, the diagnosis, according to our present knowledge, should not offer insuperable obstacles to the conscientious observer.

Prognosis. The prognosis is always hopeful in those cases in which there has been no destruction of the anatomical elements, as in anemia, neurasthenia, etc. ; always unfavorable in those cases in which such destruction has taken place. The condition remaining after a trial of treatment of moderate duration is apt to be the condition that will remain permanently, except in the case of hemorrhage, where repeated attacks will tend to further impairment of bearing.

Amelioration may and usually does take place in the other symptoms, such as vertigo; but the hearing improves only so far as the anatomical elements develop recuperative power, and when that power is exhausted, improvement ceases.

Treatment. The treatment of anemia of the labyrinth is in most cases practically that of the treatment of' general anemia, as in the anemia and oligemia following gestation and parturition. In the local anemia due to aneurysm or atheroma very little can be done; when due to pressure brought on by changes in the middle ear, operative interference to relieve that pressure, if possible, should be undertaken.

Hyperemia, if acute, should be met by local blood letting, purgation, and rest at the same time that the diet is limited and stimulants interdicted. The causative agency should always be searched for and corrected as far as possible on general fines. Regulation of the diet and bowels, curtailment or denial of stimulants, and correct ordering of the care of' the body and method of life are always indicated and produce the best results.

Hemorrhages into the labyrinth should be treated, until the acute symptoms subside and absorption begins, by complete bodily rest, local bloodletting, purgation, hot foot baths, limitation of diet, and abstinence from the use of all stimulants, alcohol, tobacco, etc. Later, comparative rest and abstention from mental or physical work, with the regulation of the diet and bowels, will do more to favor absorption than the administration of drugs. Should this method of treatment be found impracticable, or conjointly with it, iodid of potassium in gradually increasing doses has given the best results in the author's hands. Pilocarpin has been strongly advocated by some authors, given either by the mouth or hypodermatically, beginning with one eighth of a grain two or three times daily and working up until the physiological effect is obtained, when the patient is held to that dosage for a shorter or longer time.

In the hyperplastic form of labyrinthitis, regulation of diet and digestion, of the bowels, and denial of stimulants, counter irritation over the mastoid, and attempts to provoke derivation and, most important, the attempted removal of the cause. Resolution may be encouraged by the administration of iodid of potassium or of pilocarpin, if these are not contra indicated by the condition causing the lesion or by the state of health of the patient.

During the acute stage of the exudative form of labyrinthitis as much should be done as possible to decrease the intensity of the attack and to limit the extension of the process. This in most cases amounts to very little. Rest in bed is imperative, limitation of the diet, cardiac sedatives, diaphoretics, regulation of the bowels, and derivative,; not contra indicated by the general condition. After the acute symptoms have subsided, resolution is to be encouraged by the continuance of rest, light but nourishing diet, the regulation of the excretory organs, and the administration of those remedies known to have an effect on the pathological deposits and new formations, such as the iodid of potash, mercury,, pilocarpin, etc.

The regeneration of the affected nerve elements may be encouraged by the administration of the various nerve stimulants and nerve foods, such as strychnia, phosphorus, etc.

The principal treatment for concussion and fracture is rest and the meeting of symptoms as they arise.

The treatment of' acoustic neurasthenia is, of course, that of the general neurasthenic condition. The general health should be improved by all the means at our command. The author has found that the feeling of well being produced by the administration of gelsemium. is a very important aid in inducing the patient to attempt and to adhere to those regulations necessary to the attainment of this much hoped for improvement ; it should be administered in the form of' the fluid extract. Strychnia has produced only a temporary improvement in the author's bands. The general health must be improved if any permanent betterment is to be attained, and gelsernium has the power of stimulating the ambition of the neurasthenic to the extent of accomplishing the tasks necessarily set for this purpose.

Hysteria requires the administration of those remedies pharmaceutical, psychical, and physical usually recommended for use in the general condition.

The various other neuroses reflex and otherwise, are to be treated from the standpoint of the cause.

It will be noticed that the subject of the treatment of affections of the sound perceiving apparatus by means of electricity, phono massage, and various other more or less imperfectly tried remedies has not been touched upon by the writer. The reason for this lies in the fact that the advantage to be derived from these remedies has been much doubted by very many competent otologists who have given them fair trial, and that certain disadvantages in their use have been discovered in some conditions. Further attention needs to be devoted to them as remedial agencies.

The treatment of deaf mutism consists in the removal of any curable pathological conditions found to exist in the sound conducting apparatus and the improvement of what hearing power still remains in the sound perceiving apparatus. Chronic suppuration of the middle ear is especially prevalent among those mute from acquired deafness, and should receive competent attention to prevent fatal results. Urbantschitsch has recommended systematic acoustic instruction by the pronunciation of vowels, consonants, single words, and sentences; the instruction to be given for a short time two or three times daily. Politzer is of the opinion that this may be the means of effecting a modulation in speech, but that the bearing cannot be affected thereby, because it has generally been lost through processes which have run their course and have left behind irreparable anatomical changes.

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