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A case of pseudoepitheliomatous hyperplasia involving the external, middle ear, and mastoid air cells and labyrinth resulting from long standing irrigations with alcohol is described for the first time.
Middle ears (515) from 26 species of the rodent family Heteromyidae - genera Dipodomys, Microdipodops, Perognathus, and Liomys - were studied both grossly and histologically, for qualitative and quantitative comparisons. Middle ear modifications characteristic of each genus are qualitatively described. Quantitative comparisons are made among the 26 species in the study. Some correlations between middle ear size and other measurements are discussed. The middle ear is an acoustical transformer that for best efficiency must match the impedance of the cochlea to the impedance of the air in the external auditory meatus. It accomplishes this by a pressure increase and a velocity decrease through the combined effects of the lever and areal ratios; however, because the important consideration is a matching of two impedances rather than an absolute pressure increase, the pressure transformer ratio is a less informative measure of the middle ear's efficiency than is the impedance transform ratio. The impedance transformer mechanism is explained (from a morphological point of view), and equations are presented. Dipodomys, Microdipodops, and Perognathus have a theoretical transmission (at the resonant frequency) of 94-100% of the incident acoustical energy; Liomys, 78-80%. The areal ratio of stapes footplate to 2/3 tympanic membrane is remarkably constant among the species, varying only from 0.04 to 0.07: in Dipodomys and Microdipodops this small ratio is due to the very large tympanic membrane; in Perognathus and Liomys it is due to the extremely small stapes footplate. The lever ratio of incus to malleus varies from 0.28 to 0.33 in Dipodpmys and Microdipodops, from 0.37 to 0.46 in Perognathus, and from 0.55 to 0.60 in Liomys. In addition, the middle ear volumes and the morphology of tympanic membrane, ossicles, ligaments, and muscles, all combine to minimize both mass and stiffness. All these data suggest middle ear mechanisms which are very efficient over a broad frequency range. The middle ear modifications found in heteromyids are adaptive in predator avoidance, especially in areas of little natural cover; nevertheless, contrary to expectations, there is no firm relationship between habitat and the extent of these modifications in the 26 species. However, environment did apparently plan an important role in the evolution of the family, and this is discussed.
Twenty-six children presenting bilateral secretory otitis media (SOM) had ventilating tubes inserted into both middle ears. Mucus was, however, aspirated only from one ear, the right side. The vast majority of ears right and left were seen to have cleared their effusion equally well regardless of whether they were aspirated on not. This experiment points toward the essential intactness of the mucociliary system and the patency of the lumen of the Eustachian tube in SOM. Promotion of middle ear clearance through ventilation, which reminds one of the second opening in a beer can, does obviously suggest the relief of some negative pressure. Direct manometric measurements of SOM middle pressure were performed in 41 ears showing negative pressure averaging --1.7 mm H2O, this range being two orders of magnitude less than tympanometric measurements. Normal ears did not have even such a small negative pressure. The validity of these direct manometric measurements was checked against a model of the middle ear. Tympanometry, which is a valid diagnostic tool, does indicate in all probability the presence of middle ear effusion due to its rheologic effects on the drum and ossicles rather than the measure of actual middle ear pressures. This is determined by the fact that direct needling of the middle ear, or even the insertion of a ventilating tube, did not change tympanometric values but aspiration of part of the effusion did: indeed the latter tended to bring manometry to normal values.
Ear canal, middle ear, temporal bone, and CPA angle masses (except for cholesteatomas) are rare in the pediatric population. The physician needs to have a high degree of suspicion for such lesions if a child presents with ear pain unrelated to infection or otorrhea that fails to improve after treatment. A precise diagnosis needs to be made in these children and also in those with hearing loss, vertigo, and facial paralysis. The most useful imaging procedures for ear, temporal bone, and CPA masses are CT and MR imaging. With a suspected vascular lesion, a definitive diagnosis usually can be made by an imaging procedure or angiography. In all cases of mass lesions, except for some aneurysms and infections, a tissue diagnosis must be secured.
335 ears from 210 childred in which tympanometry initially indicated middle ear pressure less than or equal to -100 mm H2O or a flat tympanogram have been reinvestigated 3 years later. When the inital investigation was performed all children were 7 years old. The present study reveals that 25% of these ears still have middle ear pressure less than or equal to -100 mm H2O and 16% middle ear pressure less than or equal to -150 mm H2O. In normal material of the same age group 9% have middle ear pressure less than or equal to -100 mm H2O and 4% middle ear pressure less than or equal to -150 mm H2O. The study also reveals effusion in 10% of ears with normal screening audiograms. In ears with normal screening audiograms and middle ear pressure greater than or equal to -145 mm H2O effusion was found in 5% and in ears with abnormal screening audiograms and middle ear pressure less than or equal to -150 mm H2O effusion was found in 81%. As tympanometric criterion for otologist referral, middle ear pressure less than or equal to -150 mm H2O or a flat tympanogram is suggested. The inclusion of tympanometry in routine screening for middle ear pathology in children is recommended.
Congenital anomalies of the middle ear have been considered rare. The tremendous volume of middle ear surgery performed during the last 15 years has brought attention to numerous anomalies of the facial nerve, ossicles, and middle ear cleft, suggesting that middle ear anomalies are not as rare as once believed. This paper discusses anomalies of the descending and horizontal facial nerve which have been previously reported. The literature of anomalies of the ossicles is reviewed. A very rare anomaly of the carotid artery presenting in the middle ear is described and its surgical treatment outlined. Two anomalies of the middle ear associated with other branchial arch anomalies are reported and their treatment results discussed.
In 512 ears with various middle ear diseases, the middle ear pressure was measured a minimum of 2 years and a maximum of 10 years after tympanoplasty. The findings were related to the length of the follow-up period and to retractions of the drum and/or in the epitympanum. The tympanometric findings were best in sequelae to otitis with dry perforations, poorest in cholesteatomas and adhesive otitis. Tubal function had not further deteriorated 4 years after the operation. There was a highly significant correlation between the middle ear pressure and the frequency of retractions, which also does not essentially increase--except in the cholesteatoma cases.
The reconstruction of the destroyed ossicular chain has the purpose to re-establish an unhindered sound reception and transmission. With respect to the hydraulic factor, the reconstructed chain should be attached to a large effective area of the drum membrane, ideally to the malleus handle. The sensitivity is furthermore diminished in a linear relationship with increasing mass and stiffness. Therefore, cartilage cannot represent an acoustically ideal material for a drum membrane replacement. The reconstructed chain must vibrate without restraint for an unhindered transmission. Furthermore, the interposed prosthesis must be secured firmly to the remnants of the ossicular chain; the reconstructed chain must vibrate like one solid body. A loose contact attenuates the transmission and might result in a dislocation of the prosthesis with excessive ambient air pressure induced displacements of the drum membrane. A solid anchoring might be created by glueing, bony adhesion, special design of the prosthesis or with a wire connection. With unfavorable middle-ear conditions, the piston-like vibrational mode of the footplate has to be met with a direct driving of the stapes by a T-like prosthesis in the extension of the stapedial's vertical (high) axis. Ineffective rocking movements of the footplate are thus reduced. The almost perfect hearing result of the stapesplasty demonstrates that the impedance-matching middle-ear function is determined by the area ratio between the drum membrane and the width of the cochlear scala. Both components are not altered by the operation.(ABSTRACT TRUNCATED AT 250 WORDS)
The revelation of a sophisticated micro-mechanism within the ossicular chain--the gliding of the joints results in a characteristic change of the ossicular movement--extended our conception of the function of the ossicular chain. Contrary to our former ideas of the transmission of sound during hearing, the ossicles do not rotate around an axis, which runs through the center of mass of the malleus and anvil. The imaginary rotational axis is located outside the ossicles, resulting in a more piston-like vibration of the complete chain. The ossicular joints are rigid. This acoustic function of the ossicular chain must rigorously be separated from its behaviour at changes of static, ambient air pressure. The middle ear, working as a sensitive pressure receptor also reacts to these pressure changes with comparatively huge displacements of the drum membrane (visible in pneumatic otoscopy). Only now the malleus rotates around its axial ligaments. These movements cause a gliding motion in the malleus-incus joint, which results in a predominant up- and downward movement of the anvil; the incudo-stapedial joint glides, too, and the stapes (and the inner ear) are decoupled. This micro-mechanism explains several anatomical features of the middle ear construction, as there are the vertical alignment of the incudo-stapedial joint, the suspension of the anvil, the design of the malleus joint, etc. It also accounts for the peculiar anatomical arrangement of the middle ear muscles. Their function can be interpreted as preserving the intact cartilage of the ossicular joints.(ABSTRACT TRUNCATED AT 250 WORDS)
Of all the abnormal situations that one encounters in performing a tympanotomy, probably the last one to be thought of is vascular anomalies, and yet, potentially, this is one of the most hazardous of anomalous problems with which we have to deal. Most of the anomalies which have been reported concern the persistent stapedial artery. This artery arises from the stump of the second aortic arch (stapedio-hyoid artery), it traverses the developing stapes bone, leaving behind a monument to its existence - the obturator foramen of the stapes. The artery exits from the middle ear along the horizontal portion of the facial nerve, traversing this area for a variable distance and then usually divides into an intra-cranial branch and a sphenoidal branch. The stapedial artery in its development before its regression, gives rise to the anlage of many important cranial arteries. These vessels are usually anastomosed with and distributed by the branches of the internal maxillary artery and the ophthalmic artery. The hyoid artery is represented in the adult by the carotico tympanic artery. Anomalies involving the internal carotid artery are much more rare. The anomalies that have thus far been reported are: 1. Absence of the internal carotids. 2. Aneurysms. 3. Unusual courses. Venous anomalies are generally uncommon and are usually represented by an abnormally placed jugular bulb which can simulate a glomus jugulari tumor.
The bacterial flora was examined in 108 Icelandic children treated for middle ear inflammations during the period, 1986-1989. Among children with acute otitis media, growth of H. influenzae was obtained in pure cultures in 54 per cent of cases. Where inflammation had caused tympanic membrane rupture, both H. influenzae and S. pneumoniae were cultured in 58 per cent of the samples. In the group with persistent seromucous secretion in the middle ear, 60.5 per cent of the samples were abacterial. S. aureus was the species most commonly isolated in samples from children with chronic discharge. The results suggest H. influenzae to be more common in acute otitis media in Iceland than elsewhere.
Middle ear pressure was recorded from 396 ears and aural symptoms inquired of 198 adult subjects with seasonal allergic rhinitis. Evidence of eustachian tube dysfunction was found in 24% of subjects. Increased duration of exposure to pollen over a further 2 weeks increased the incidence of eustachian tube dysfunction to 48%. The development of eustachian tube dysfunction did not correlate with the severity of nasal symptoms.
Over the past ten years, polyethylene tube, stainless steel wire and absorbable gelatin sponge have come to be used in middle ear surgery. A modified Williams' steel chamber with a transparent central area was embedded in a rabbit ear lobe surgically, and cross-sectioned polyethylene tube, stainless steel wire or absorbable gelatin sponge were inserted respectively. The in vivo tissue reaction to each of these installed materials was observed daily microscopically. Finally, in the case of both the cross-sectioned polyethylene tube and the stainless steel wire, the chambers were fixed with 10% formalin solution and the contents stained for histological study. The results were as follows: Absorbable gelatin sponge was absorbed completely by phagocytosis in 62 days. Polyethylene tube was encapsulated by a layer of fibroblasts by day 110 in one case and by day 140 in another case; these findings were confirmed histologically on day 110 and 281. Almost all the surface of the stainless steel wire was encapsulated by a layer consisting of giant cells, on which a dense fibrous layer was superimposed by day 82. It is concluded that polyethylene tube, stainless steel wire, and absorbable gelatin sponge should be well tolerated in middle ear surgery.
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Eustachian tube and middle ear function has been studied in the acute and chronically prepared Rhesus monkey preparation. Measures have included observations of tympanometry and input impedance of the middle ear, of transmission of energy through the middle ear, of static middle ear pressure and of threshold and suprathreshold hearing. Positive and negative long and short-term static middle ear pressures, the effects of middle ear fluids, and various aspects of Eustachian tube function in both normal and pathologic preparations have been studied. In general our observations indicate that the Old World monkey may provide a model permitting acquisition of quantitative data of a variety of middle ear functions under carefully controlled laboratory conditions, including those requiring measures simply not possible in man.
This study was designed to evaluate the diagnostic sensitivity of a prototype tympanometric screening instrument. Results from automatic tympanometry and complete electroacoustic impedance measurements (tympanometry, static compliance, and acoustic reflex thresholds) were compared to otologic diagnosis in 53 ears with middle ear pathology. Results suggested a high percentage of agreement between screening tympanometry, results from a complete impedance test battery and pneumatic otoscopy. These findings lend support for theuse of screening tympanometry in school hearing-screening programs and in pediatric practice.
Immunocompetence of the middle ear was studied in guinea pigs in two series of experiments. The first, afferent phase, consisted of grafting iso and allografts in the guinea pig's middle ear to sensitize the animals which were later to receive a skin graft on the back. The second, efferent phase, first sensitized the animals with a skin graft on their back and later in the middle ear. The results show a rather low capacity of the middle ear to elicit a second-set rejection of the skin grafts. This lack of sensitization is explained by the authors by the concept of tolerance.
Early detection of middle ear effusions is highly desirable not only from a medical standpoint, but also educationally, psychologically and socially. Present methods do not appear to be adequate and the proposal has been made that impedance measurement may be of greater effectiveness in detecting abnormalities of middle ear function. Eighty children have been studied over a period of six to seven years during which time the middle ear function has been monitored by means of an impedance meter. Approximately one-half of the children have not indicated any variation in middle ear function over the period of observation. About one-third of the children have had isolated episodes of effusion from which they have recovered spontaneously and without adverse effects. The remaining one-sixth have had repeated episodes of effusion or persistent middle ear malfunction for substantial periods of time. Observation of the middle ear muscle reflexes at suitably chosen time intervals appears to have promise as a method of early detection of effusion in the middle ear.