Audiologic evaluation of deaf children

This paper describes an audiologic test battery for hearing-impaired children which includes otoscopic examination, tympanometry, pure-tone audiometry, speech perception testing, and hearing aid evaluation. Several of the procedures and modifications to apparatus have been developed specifically for use with deaf children. Clinical data are presented from 160 hearing-impaired children (age range three-16 years). Eighteen percent of their ears were found to contain excessive cerumen and to require ear canal irrigation. The incidence of abnormal tympanograms was high for young children but decreased with increasing age. A simple auditory speech perception test designed for use with both severely and profoundly deaf children is described, which provides for evaluation of a child's ability to recognize words, categorize them into stress patterns, or both. The children's word recognition and word categorization scores were found to relate to their audiometric averages. The overall test battery is easy to administer and also is efficient, in that considerable audiologic information can be obtained quickly.

[The significance of tympanometry in pediatric audiometry (author's transl)]

Audiological findings through tympanometry and audiometry were correlated with pathological findings involving the tympanic membranes and the nasopharynx in 232 patients (406 ears) with various hearing disorders in order to determine the probability of a conductive hearing deficit when only tympanogram and clinical findings are known. These measures hold special import to patients in whom exact evaluations of pure tone hearing thresholds are not possible (ie, in small infants and in patients with severe hearing losses in low frequency ranges).

Correlation of tubal function and volume of mastoid and middle ear space as related to otitis media

In 69 ears with chronic otitis media and nine ears with traumatic perforations tubal function the size of the mastoid air cell system measured planimetrically on roentgenograms and the functional volume of the air filled ear spaces were studied for any correlations. The roentgenographic area and the functional volume were also studied for any variation in the duration of the disease. A correlation was found between abnormally small volumes and impaired tubal function, probably due to mucosal damage of the whole system, i.e. Eustachian tube, middle ear and mastoid air cells. No such association was found between area and tubal function. The volume, but not the area, decrease with the duration of the disease.

Eustachian tube ventilatory function in children

In order to establish a simple stimulus-response characteristic of Eustachian tube physiology in children, the tubal ventilatory function was studied. The parameters of active and passive opening of the tube were measured for three groups of patients with nonintact tympanic membranes. The group with traumatic perforations of the tympanic membrane without any history of middle ear disease had better active equilibration function than the group with chronic otitis media and perforations of the tympanic membrane and the group with tympanostomy tubes in the tympanic membrane. Quantitatively, this could be expressed in terms of residual positive pressures. In the study of repeated inflation of the middle ear, all groups had lower second opening pressures which are attributed to the effect of surface forces.

Tympanometry revealing middle ear pathology

In order to evaluate the usefulness of impedance audiometry as a screening method for school children, two different pilot studies were performed. The results indicated that impedance audiometry (tympanometry and stapedius reflex test) was more efficient than otoscopy and pure tone screening in the detection of ears with secretory otitis media (SOM). In order to gain some more experience, an extended study of 800 7-year-olds was performed. The results from this investigation showed 6.5% pathological values with pure tone screening, 13.5% pathological values with tympanometry and 32% elevated or nonelicitable stapedius reflexes. Analysis of our observations indicates that the stapedius reflex may be too sensitive a test to be used as a screening method. Tympanometry, however, is recommended as a complement to pure tone screening in screening of children. A 6-12 months follow-up was also performed on 357 ears in which an initial study had shown a middle ear pressure of less than or equal to -100 mm H2O. At the repeated test 20% had pathological pure tone screening, 40% had a middle ear pressure of less than or equal to -100 mm H2O, 57% had elevated or nonelicitable stapedius reflexes, and 14% had middle ear effusion. The high frequency of persisting abnormal middle ear pressure and effusion in these 357 ears suggests that a middle ear pressure of less than or equal to -100 mm H2O can be a predisposing factor for SOM. In an experimental study on human temporal bones it was demonstrated that the tympanogram preserves its original appearance when the water level is low in the middle ear, while a higher level gives rise to a pathological tympanogram. It is also demonstrated that there is a discrepancy between the tympanometrically, indirectly recorded middle ear pressure and the middle ear pressure as measured manometrically, directly from the middle ear.

Tympanometry: application and interpretation

The poor relationship between hearing loss and ear disease minimizes the effectiveness of audiometry as a technique for the identification of middle ear disorders. Tympanometry has been shown to be a highly sensitive technique for the identification of and differentiation between middle ear disorders. It is particularly useful in a pediatric population where ear disease is so frequently encountered. The interpretation of tympanometry on the basis of a descriptive analysis of tympanograms is proposed as opposed to a coded typing system. Descriptive analysis views the pathological effects of middle ear diseases on pressure peaks, amplitude and shape of tympanograms.

Two-component versus admittance tympanometry

The probe tone frequency of electro-acoustic bridges has a direct effect on the shape of the tympanograms obtained. At higher frequencies (800 Hz) typical patterns are generated for eardrum abnormalities and ossicular discontinuities. The 625- and 660-Hz frequencies sometimes prove to be not quite high enough to obtain the expected 'W' or undulating admittance tympanograms. Our investigation proves that much more certainty is given even at 660-Hz probe tone when components B and G are both recorded. The same information for ossicular disruption is found in an admittance (Y) together with a new kind of tympanogram, namely the phase tympanogram.

[Tympanometry in chronic otitis media]

We present an analysis of the otological and audiological findings in 63 patients (113 ears) in which a myringotomy for suspected serous otitis media has been performed. In 98 ears (87%) the impedance data correlated with otoscopy. Tympanograms did not give further information than otoscopy alone in 49 patients with reliable pure-tone audiometrical results, whereas tympanograms would have missed 6 out of 78 ears containing fluid and 6 out of 49 ears who improved in hearing following myringotomy and transtympanic tube therapy. We feel, however, that, in patients who are too young or too retarded to be tested audiometrically, tympanometry in combination with otoscopy could eventually be helpful in settling the indication for a myringotomy, since 3 out of 83 ears with middle ear fluid and hearing improvement following transtympanic tube therapy had pathological tympanograms in spite of normal-seeming ear drums.

Tympanometric curves and otosclerosis

Patients with clinical otosclerosis (28 ears) were examined audiometrically and with an electroacoustic impedance bridge. The results were compared to corresponding findings for normal ears. The tympanometric curves of surgically proven otosclerosis were found to differ characteristically from those of normal ears. A curve typical of footplate fixation shows a rapid increase in acoustic impedance as external auditory canal pressure is reduced from ambient air pressure.

Paradoxical compliances in otosclerosis

Results of impedancemetry have been compared with operative findings in 1 867 cases of otosclerosis, 1 583 of which were pure otosclerosis. This comparison indicated that: (1) with present techniques, the results of impedancemetry are only of a relative value in otosclerosis; it is thus necessary to asses the various connected anatomical elements in the middle ear with extreme rigor; (2) impedancemetry data have an absolute value in all disorders of the middle ear with closed eardrum associated with otosclerosis; (3) relative impedancemetry often gives informative results when it concurs with the other elements of clinical and audiometrical diagnosis; (4) impedancemetry data are a valuable element of early diagnosis of otosclerosis before the first audiometric expression, either by a lowering of compliance or, most of all, by appearance of an on-off effect (diphasic impedance change) or by disappearance of the stapedius reflex; (5) parallel or crossed paradoxical compliances are only apparently paradoxical and are usually the sign of either an early stapedo-vestibular fixation (before its audiometric expression) or an associated factor in the middle ear, both of which may have been unnoticed; (6) the problem of compliance value in otosclerosis will be solved only when the proper stapes frequency is found and when it is possible to test this frequency. This problem is the subject of our current research.

Otoadmittance measurements in cases of dual ossicular disorders

Audiologic evaluations, including otoadmittance measurements, were obtained on two patients, each of whom had dual, series-connected disorders of ossicular fixation and disarticulation. In one case, the disarticulation was the lateral-most disorder; in the other case the fixation was the lateral-most disorder. In both cases, it was the lateral-most disorder that had the dominant effect on the otoadmittance of the tympanic membrane, due to the fact that the sites of the two disorders were connected in series with the tympanic membrane.

Dimethyl sulfoxide therapy in subjective tinnitus of unknown origin

In fifteen patients affected by essential nonvibratory tinnitus, local applications in the external auditive canal of 2 ml medicated DMSO spray were made. The spray solution contained DMSO integrated with anti-inflammatory and vasodilatory substances. This application was repeated every four days for a month. At the same time each patient was administered a daily intramuscular injection of a preparation that contained DMSO and a vasodilatory component. The therapeutic effect was evaluated through the subjective modification of the symptom and functional tests of the auditory system. Of the fifteen patients treated, the tinnitus symptom completely disappeared in nine, and did not return during a one-year observation period. The patient's symptoms diminished in two cases, and in four cases the permanent tinnitus became occasional, triggered principally by environmental cold. It is important to note that among the concomitant signs, the five patients with vertigo noted improvement. Hypacusis diminished in three of the six patients affected. Insomnia disappeared in eight and diminished in seven cases. The rise in the average tympanic membrane temperature from 36.8 degrees C before to 37.9 degrees C after treatment was noteworthy. This could indicate an improvement of the blood flow in the inner ear.

Acoustic neuromas and the acoustic impedance of the ear

The acoustic impedance at the tympanic membrane was measured at frequencies in the range 100–1000 Hz and found to be abnormal on the affected side in four patients with acoustic neuroma. In all four the resistance was abnormally high at low frequencies on the affected side, and in three the reactance of the affected ear was raised relative to that of the contralateral ear, particularly at low frequencies. The abnormality is attributed to an increase in the input acoustic impedance of the cochlea produced by the increase in protein content of the cochlear fluids and dilatation of the cochlear duct known to occur in acoustic neuroma. This explanation is supported by theoretical calculations carried out on an electric analogue of the conductive system, and it is suggested that similar abnormalities in the acoustic impedance at the tympanic membrane might occur in other pathologies which produce abnormal mechanical conditions in the cochlea.