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At least 919 records · Page 51Linked to original sources
PubMed1986

The middle ear transformer mechanism: man versus mouse.

The anatomy and physiology of the middle ear transformer mechanism in man and a species of rodent, desmodillus auricularis, are compared. This rodent's middle ear mechanism has a transformer ratio of 147:1 as compared to 18,3:1 in man--some 8 times greater. The reasons for this difference are given and possible applications to middle ear surgery are suggested.

Animals↗
PubMed1999

Three-dimensional reconstruction of the incudostapedial joint with helical computed tomography.

Three-dimensional images of the incudostapedial joint (I-S joint) were reconstructed using helical computed tomography (CT). The images of the joint were most often reconstructed when threshold values were selected at -500 to -700 Hounsfield Units. These shapes were changed by choosing various threshold values. Histological examinations of the cadaver specimen indicate that these changes are due to structure of the I-S joints. We conclude that these 3-D images may be useful in assessing pathology of the I-S joint.

Ear, Middle↗
PubMed1984

Ossicular reconstruction--a new prosthesis.

We have used human teeth for ossicular reconstruction in 20 tympanoplasties, the longest follow-up being over 2 years. The take of the graft and the hearing improvement have been very satisfactory and long-lasting. This preliminary report discusses the merits of the tooth as a prosthetic material for ossicular reconstruction. Our experience to-date indicates that the material satisfies all the criteria of an ideal prosthesis.

Bioprosthesis↗
PubMed1982

Incudo-stapedial joint pathology: a tympanometric approach.

Two-component tympanometry with a high probe-tone frequency enables a better distinction to be made between mobile but normal middle-ear systems and middle-ear systems suffering from necrosis, luxation, or disruption. Susceptance and conductance tympanograms obtained from 14 patients with confirmed pathological middle-ear lesions and 8 postmortem temporal bones, experimentally manipulated either surgically or with a 1 N HCl solution, were compared to tympanograms obtained from 80 normal subjects of an earlier study. With a 660-Hz probe tone, normal middle ears generate bell-shaped or normal sharp W-shaped patterns, whereas the pathologies of the middle ear give rise to irregular multi-extrema tympanograms. The differences between the two types of multi-extrema curves are discussed in detail. The use of phase-angle tympanometry is recommended to enable a quick and accurate distinction between normal and abnormal types of multi-extrema tympanograms. This study also points out clearly that 220-Hz tympanograms do not allow clear differentiation between pathological and normal middle ears.

Acoustic Impedance Tests↗
PubMed2004

An analysis of the single-stage tympanoplasty with over-underlay grafting in tympanosclerosis.

OBJECTIVES: Our objective was to analyze the results of tympanosclerosis surgery using over-underlay tympanoplasty and to find out the effect of single-stage surgery on hearing results. MATERIALS AND METHODS: Forty-two patients who were operated on for tympanosclerosis between July 1998 and February 2002 were included in the study. These were one-stage tympanoplasties, because second-stage operations and revisions were not included. Operative records and audiograms of the patients were obtained. Of the patients, 48% had bilateral tympanosclerosis. In three (7.1%) of the patients, tympanosclerosis and cholesteatoma occurred concomitantly. The cog was present in eight (20%) of 40 mastoidectomies. Körner's septum was present in nine (22.5%) patients. The graft take rate was 95.2%. RESULTS: The pre- and postoperative air-bone gap values of the patients were not significantly different (p > 0.05). Thirty-three percent of the patients met the successful hearing criteria (air-bone gap <20 dB). However, 47% had an air-bone gap closure between 20 dB and 30 dB, whereas 20% had a gap of more than 30 dB. CONCLUSION: Single-stage surgery does not result in a satisfactory hearing improvement in most of the patients with tympanosclerosis. Only one third of the patients, most of whom had a mobile stapes, had satisfactory hearing results. Mobilization of a fixed stapes is not an effective option for hearing restoration in tympanosclerosis. Second-stage surgery for stapedectomy and placement of a prosthesis-like piston or total ossicular replacement prosthesis should be considered to obtain better hearing results in tympanosclerosis.

Audiometry, Pure-Tone↗
PubMed2005

The ponticulus: an anatomic study.

HYPOTHESIS: The purpose of this study was to resolve anatomic ambiguities of the ponticulus so the surgeon will be better able to remove disease from the posterior tympanum. BACKGROUND: The first step in refining an operative approach is to acquire a thorough understanding of the anatomy. A detailed study of one structure of the posterior tympanum, the ponticulus, has not yet been reported. METHODS: Fifty temporal bone plugs harvested from human cadavers were studied. The presence or absence of the ponticulus, its configuration, and its proximity to other middle ear structures were recorded for each temporal bone. RESULTS: There was complete formation of the ponticulus in 33 of the 50 specimens. In 7, only a remnant of the ponticulus formed, and it was completely absent in 10 of the 50 specimens. In the 33 specimens in which the ponticulus was present, it measured less than 1 mm in thickness in 22, it was larger than 1 mm in 7, and in 4 specimens it extended down to the floor of the middle ear as a sheet of bone. In 8 specimens, the ponticulus lay just adjacent to the stapes. CONCLUSION: The ponticulus is present in the majority of ears. It is best defined as a bridge of bone from the pyramidal eminence to the promontory and most commonly occurs as a thin, bony structure. This definitive study of the ponticulus will allow the otologic surgeon to better remove disease from the posterior tympanum.

Ear, Middle↗
PubMed1978

Can recurrent cholesteatoma be avoided?

After closed operation techniques recurrences of cholesteatoma are often caused by retraction of squamous epithelium under the bony annulus, under which it spreads into the attic or the mastoid cavity. Consequently, retractions under the bony annulus can be avoided, if the annulus is removed. An endaural operation technique is described in which the superior and posterior bony ear canal wall is completely removed and the posterior wall is reconstructed by means of a meatal skin flap. As the oval window is often partly hidden by the frame of the tympanic membrane it is more favourable for the restoration of the sound conducting mechanism if the frame and surface of the tympanic membrane are extended backwards. This can be done by repositioning the posterior cutaneous ear canal wall and grafting the tympanic membrane with fascia. By doing this, the attic is incorporated into the ear canal. Should the factors which originally induced the development of the cholesteatoma remain effective and cause a new retraction, the full breadth of the posterior ear canal skin will retract into the exenterated mastoid cavity. An easily accesible open cavity and not a recurrence will be the result. In a follow-up study of 112 patients it was found that 67 of them had developed such an open cavity, which caused no serious problems.

Cholesteatoma↗
PubMed1980

Homografts in tympanoplasty: will they be a disaster? an experimental study.

Experimentally transposed homograft ossicles in rats showed behaviour less stables than autografts, all being resorbed within 48 weeks. Using information derived from this and other experimental work in both animals and humans it is predicted that homografts will be unstable in humans in the long term.

Animals↗
PubMed1981

The tympanic cavity: tomographic anatomy.

This study was carried out on 100 tomograms of the petrous bone using Guillen's transorbital view of the anatomy of the middle ear. It provides basic data concerning the morphology, size and surface area of the tympanum, the epitympanum and the hypotympanum. It correlates the surface area of the epi-and hypotympanum, and suggests certain embryological interpretation. This study contributes to the diagnostic radiology of the middle ear in the following ways: I It provides basic data for the interpretation of tomograms in patients with ossicular dislocation. 2 It provides essential data for the radiology of congenital malformation and of tumors. 3 It puts in perspective certain criteria used for the diagnosis of cholesteatoma. Finally, this study justifies the use of preoperative radiological investigation.

Adult↗
PubMed1995

Three-dimensional CT-imaging of the ossicular chain.

In eight patients, with a known air-conduction hearing loss, three-dimensional images of the ossicular chain were constructed based on heavily overlapping high resolution CT-slices, obtained from a spiral CT data set. High quality three-dimensional images could be obtained in all eight patients. Supplementary information was derived from these three-dimensional images in three patients; in one, this supplementary information had therapeutic importance. The slight image quality loss in spiral-CT of the temporal bone, compared with conventional CT, is in some cases largely compensated by the possibility of rendering high quality secondary reconstructions.

Adult↗
PubMed1989

Acquired disruptions of the incudostapedial articulation: diagnosis with CT.

To determine the best technique for diagnosing incudostapedial joint disruption with computed tomography (CT), the authors reviewed 15 surgically proved cases. In each case, the articulation was depicted on axial but not coronal images. Disruption was due to inflammation in ten cases and trauma in five. Axial high-resolution CT is valuable in the diagnosis of traumatic and inflammatory disruption of the incudostapedial joint.

Adult↗
PubMed2002

Fetal development of the human tympanic ossicular chain articulations.

OBJECTIVES: To obtain further knowledge on the morphogenesis of the articulations in the tympanic ossicular chain in humans. MATERIAL AND METHODS: In 25 temporal bones of human fetuses the structural development of incudomallear, incudostapedial and stapediovestibular articulations was studied. The chronological ages were between the 7th week (21 mm) and the 29th week (270 mm). RESULTS AND DISCUSSION: Incudomallear articulation showed diarthrosis and sellar joint characteristics. It showed a homogenous interzone in the 7th week of development, a three-layered interzone in the 8th week, the first cavitation signs in the 9th week and the presence of an articular cavity in the 10th week. The presence of a hyaline cartilage covering articular surfaces was observed starting in the 20th week of development. Incudostapedial articulation showed typical characteristics of a diarthrosis and spheroidal joint with a homogenous interzone at the 7th week, showing similar characteristics for 12 weeks, and completed its cavitation at the 16th week. We observed hyaline cartilage on articular surfaces from 29 weeks. Stapediovestibular articulation showed typical characteristics of syndesmosis. The annular ligament primordium derived from cartilage differentiation, both from stapedial footplate and from the surrounding otic capsule, into mesenchyme and its subsequent transformation into fibrous tissue, reaching definitive characteristics from the 12th week.

Body Patterning↗