Abstract Otology 2000 C19-1

Nikolaos Marangos MD, Antje Aschendorff MD

HNO-Klinik Albert-Ludwigs-Universität Freiburg D-Freiburg

Since children with congenital deafness have been considered Cochlear Implant candidates, high resolution computed tomography (CT) of their temporal bones has been performed routinely to evaluate cochlear abnormalities prior to Cochlear Implant (CI) surgery. Thus, several types of malformations of the bony cochlea and labyrinth are revealed by CT scans which were unknown previously, as CT was not performed on every congenital deafness. Many malformations were wrongly referred to as Mondini-dysplasia. Jackler proposed a radiologic classification of inner ear deformities based on the embryogenesis: those with abnormal or absent cochlea representing an interruption of embryogenesis in various stages and those with normal cochlea that are inde-pendent from embryonic development. Since 1986 more that 700 children with con-genital deafness, considered for CI, have been evaluated by high resolution CT. As many deformities observed cannot be assigned to this classification but they are of interest regarding cochlear implantation, they will be presented in this paper.

Abstract Otology 2000 C19-2

Bernhard Schick MD (1), Dominik Brors MD (1), Andreas Prescher MD, PhD (2)

(1) Department of ENT-Diseases, Head, Neck and Facial Plastic Surgery Academic Teaching Hospital D-Fulda
(2) Institute of Anatomy University Aachen D-Aachen

Objectives: Conductive hearing loss caused by congenital ear abnormalities is a rather rare finding. Beside stapes ankylosis fixation of the malleus can cause congenital conductive hearing loss. This study highlights on the embryological aspects of congenital malleus fixation. Methods: Embryological and comparative anatomical study. Results: The malleus derives from the posterior part of Meckel's cartilage. A part of this cartilage remains attached to the malleus to form the processus anterior mallei. The major part of this process usually recedes to form the ligamentum mallei anterius. The processus anterior mallei, which can be up to 10mm in neonates, remains in the adult malleus only as a small prominence. A lack of bony involution can keep the malleus fixed at the fissura petrotympanica. In comparative studies of animals (marsupials, carnivores) this theory of congenital anterior fixation of the malleus in the epitympanon was proved. Conclusion: As the malleus development is related to the Meckel's cartilage congenital malleus fixation represents a second branchial arch anomaly. Anterior bony fixation of the malleus in the epitympanon can be understood as atavism of the processus anterior mallei.

Abstract Otology 2000 C19-3

Bernard Fraysse MD (1), Young Shin MD (1), Didier Soulié MD (1), Bernard Escude MD (2), Corinne Berges MD (1), Oliver Deguine MD (1)

(1) Service ORL CHU Purpan F-Toulouse Cedex
(2) Radiology Department Clinique Pasteur F-Toulouse Cedex

The authors report their CT Scan experience in otosclerosis. On the one hand, in the positive diagnosis concerning a range of 485 CT scan asked in a context of transmission deafness with a normal ear-drum, 431 (89%) present a positive focus and 54 (11 %) had a negative CT Scan. In these last cases, 3 diagnosis have been found : - infra radiological form of otosclerosis (4 %) - minor malformation of the ossicular chain (4,5 %) - inner ear transmission deafness (2,5 %) On the other hand, the authors discuss of a CT Scan interest in the lesions topographic localisation (round window, cavitation, inner ear auditory canal, ossicular chain). At last, the authors describe the CT Scan interest before revision surgery concerning 31 cases and discuss the problem of intra vestibular penetration.

Abstract Otology 2000 C19-4

Dominik Brors MD (1), Maria Schäfers MD (2), Bernhard Schick MD (1), Wolfgang Draf MD, PhD, FRCS (1)

(1) Department of ENT-Diseases, Head, Neck and Facial Plastic Surgery D-Fulda
(2) Department of Neurology University Hospital Würzburg D-Würzburg

Objectives: Langerhans cell histiocytosis is a rare and enigmatic proliferative disorder, which usually occurs in children. It is characterized by localized granulomas (Hand-Schueller-Christian disease, eosinopilic granuloma) or by an extensive involvement of multiple organs as in Letterer-Sive disease. The etiology of this disease is probably a dysfunction of the immune system. The lesions are localized in allmost all bones, but the mandible, the skull, the ribs and the femur are most frequently involved. In single cases temporal bone affection can cause the first symptoms. Surgery, radiotherapy and chemotherapy are the different therapeutic options. Case presentation: A 12year old boy presented in 1979 with recurrent painful tumors of the skull, multiple bone lesions (femur, tibia) and skin affections. Between 1983 and 1994 different therapies (local radiotherapy 5 times, chemotherapy 2 times and surgery 2 times) were performed to treat bone and skin lesions. Already in 1986 x-ray indicated temporal bone affection on the right side. Acute vestibular symptoms gave rise in 1996 to perform computertomography and MRI evaluation. Both temporal bones were affected by granulomatous lesions and erosion of the lateral semicircular canal on the left site was detected. Conclusion: Vestibular symptoms present a rare finding in Langerhans cell histiocytosis. As localized and multiple sites of manifestation as well as a wide range of acute fulminant to waxing, chronic courses with possible spontaneous regression, individual therapy based on precise radiological diagnosis and long term observation is demanded.

Abstract Otology 2000 C19-5

Viktor Chrobok MD, PhD, Eva Simakova MD

ENT Department General Hospital CZ-Pardubice

A total of 37 temporal bones were examined from 22 fetuses. Five fetuses had renal agenesis, six polycystosis, two nonserious kidney pathology and nine had no pathology in the renal/urinary tract. During the histological study of temporal bones we found abnormalities of the stapes in three temporal bones of two fetuses. There were missing crura of stapes. Dilatation of the eustachian tube was seen in one case with Potter's sequence. Mondini's dysplasia was seen in the inner ears in the same three temporal bones with pathology of the stapes. Second part of study, we measured the volume of mesenchymal tissue in the middle ear cavity. We used the method of picture analysis by PC computer [Lucia]. The group without any pathology of the renal/urinary tract demonstrated that mesenchyme had decreased during the life of fetus. But the fetus with renal agenesis or polycystosis had much more mesenchyme than normal group. We demonstrated these results in graphs and statistic analysis. Such mesenchymal remnants may play a role in the development of otitis media, hearing loss or cholesteatoma can arise from this tissue. This problem is discussed in the literature.

Abstract Otology 2000 C19-6

Andreas Prescher MD, PhD (1), Dominik Brors MD (2), Björn Loewenhardt MD (3), Bernhard Schick MD (1)

(1) Institute of Anatomy University Aachen D-Aachen
(2) Department of ENT-Diseases, Head, Neck and Facial Plastic Surgery D-Fulda
(3) Institute of Radiology Academic Teaching Hospita D-Fulda

Capybara, the largest of all living rodents, is native in the inaccessible forests, rivers and swamps of Venezuela and Brazil. As the subcutaneous fatty tissue of this animal is iodiferous, it is used to produce different drugs. The crown-rump-length of this animal measures 100-130cm, the bodyhigh lies about 50cm. The capybara shows a short-stubby snoout with cleft superior lip and small, rounded ears. The anatomical description of capybara is still fragmentary. The architecture of the temporal bone was investigated by Hyrtel (1845) and Denker (1899) by use of corrosion casts and sections. Both authors reported already interesting specific anatomical features (e.g. dehiscence in the anterio-inferior part of the bony external auditory meatus, very enlarged epitympanic recess communicating with the tympanic cavity by a special foramen, 4 2/3 or more turns of the cochlea, a thickwalled promontorium in contrast to other rodents and a special anatomy of the internal auditory meatus). Therefore it can be assumed that the temporal bone of the capybara has an exceptional position within the rodent. 3 adult and one juvenile capybara skulls were studied by means of conventional x-ray, computertomography including 3-D-reconstructions and anatomical dissections. Additionally to the studies of Hyrtel and Denker the presented findings give an overview about the temporal bone anatomy of this rare and conspicious animal.