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Spiral CT of the temporal bone: value of image reconstruction at submillimetric table increments.

Axial spiral CT of the temporal bones with a nominal slice thickness of 1 mm and 180 degrees linear interpolation was performed in 13 patients. In 18 temporal bones, the spiral data set was used to reconstruct overlapping axial images with a table increment of 0.1 mm. These images gave additional information in four cases: in two by examining the heavily overlapping axial images themselves, and in two by obtaining supplementary information from secondary image reconstructions. In two cases less information was obtained than by using the conventional incremental images. This study shows that reconstructing overlapping slices can be useful, even if the temporal bone is scanned at 1 mm nominal slice thickness.

Humans↗

Manipulation of CT data for temporal-bone imaging.

The usefulness of CT in studying the temporal bone is limited by spatial resolution and by the range of absorption coefficients which can be displayed. The authors evaluated the effect of four types of data manipulation: (a) reconstruction of data with different convolution filters (target reconstruction), (b) extension of the range of CT numbers, (c) mathematical filtration to enhance edges, and (d) correction for beam hardening. Target reconstruction and extension of the CT range significantly improved visualization of small structures in the temporal bone.

Humans↗

[Potentialities of temporal bone computed tomography in the study of the facial nerve and in the diagnosis of peripheral pareses of thr 7th pair of cranial nerves].

Computed tomography (CT) was used to examine 200 patients (400 temporal bones) aged 3 to 74 years who had no signs of facial nerve lesion and 28 patients who had clinical manifestations of peripheral paresis of the facial nerve of varying genesis. Multipositional CT of the temporal bone is the most informative mode of visualization of the fallopian canal which is embodied on tomographic scans in 100% of cases irrespective of the age of a patient. CT data indicate that the formation of the facial nerve canal brings to completion by the age of 6 years. The following causes of n. facialis paresis were identified: facial neuroma; sarcoma of the temporal bone sarcoma; dehiscence of the canal wall in otitis media acuta; destruction of the tympanic wall of the canal in otitis nedia chronica, fractures of the temporal bone, anomalies of the fallopian canal in temporal bone malformations; stenosis of the canal in fibrous dysplasia. The detected alterations of the n. facialis canal permits further policy of management of a patient to be defined.

Adolescent↗

Ultrastructural evaluation of the microslicing method for the study of temporal bone pathology.

Microslices 3 mm thick from undecalcified human temporal bones were prepared with a special cutting machine and then processed for SEM and TEM in order to evaluate advantages and disadvantages of the microslicing technique for the study of the temporal bone pathology. In the examined microslices there was some mechanical distortion of the membranous labyrinth, detachment of soft tissues from bone and a considerable amount of contamination by bone dust and debris which are circulated during sectioning. For SEM the method therefore has limited value. For TEM a relatively contamination free area can be found some distance from the cutting surface of each microslice.

Cochlea↗

Detection of human papillomavirus in temporal bone inverted papilloma by polymerase chain reaction.

There is debate about the role of human papillomavirus in the induction of rare inverted papillomas involving the temporal bone and in the higher recurrence rates and association with squamous cell carcinoma of temporal bone inverted papillomas compared with sinonasal inverted papillomas. An exhaustive review of the literature revealed that eight cases of temporal bone inverted papilloma have been analysed for human papillomavirus. None of the cases studied with in situ hybridization proved positive. Only one case was found to be positive using the more sensitive polymerase chain reaction assay. We present the first two cases of Schneiderian-type papilloma involving the temporal bone to be analysed by type-specific polymerase chain reaction methods for human papillomavirus.

Ear Neoplasms↗

Undecalcified temporal bone morphology: a methodology useful for gross to fine observation and three-dimensional reconstruction.

Using a novel method of cutting undecalcified temporal bone specimens, quantitative structural analysis in the human and the Japanese monkey was undertaken. One millimeter thick serial slices made from unembedded temporal bones retained fine structure. Therefore, gross to fine observation could be performed systematically at the macroscopic, light, scanning, and transmission electron microscopic levels. The entire temporal bone three-dimensional reconstruction was completed from embedded sections; consequently, the volume of the tubotympanum and air cell system could be calculated. Available methods by embedding, tungsten carbide sectioning, grinding, and microwave irradiation for decalcification were also examined. These morphologic studies suggest that these novel methods offer timesaving advantages over any presently available techniques, and allow for elucidation of temporal bone morphology with only a few specimens.

Animals↗

Polymerase chain reaction amplification of DNA from archival celloidin-embedded human temporal bone sections.

A method was developed for fast and efficient isolation of DNA from formalin-fixed, decalcified, celloidin-embedded human temporal bone sections for subsequent use in polymerase chain reaction (PCR) DNA amplification. The method relies on the use of an enzymatic digestion with proteinase K to release and solubilize the patient's DNA from an individual 20- to 25-microns temporal bone section. The method described should be of great value to those investigators extracting DNA from archival individual human temporal bone sections for polymerase chain reaction assays of specific genetic alterations associated with temporal bone pathologies. The molecular characterization of viral infections, oncogenes, or other etiological agents of disease using PCR could provide important information regarding the etiopathogenesis of many auditory, vestibular, and facial nerve disorders, such as autoimmune hearing loss, congenital hearing losses, Meniere's disease, otosclerosis, or Bell's palsy.

Collodion↗

The use of the temporoparietal fascial flap in temporal bone reconstruction.

After routine canal wall down mastoidectomy, local muscle flaps with and without bone paté, cartilage and fascia are the standard techniques available to otologists wishing to obliterate the mastoid and reconstruct the external auditory canal. Reconstructive options for temporal bone defects after extirpative surgery for cancer, osteoradionecrosis, and revision surgery for chronic granulomatous otitis media, however, are few. Although the neighboring temporoparietal fascia flap (TPFF), based on the superficial temporal vessels, has been frequently employed for auricular reconstruction, its versatility in temporal bone reconstruction has not been widely explored. The TPFF has recently been employed at our institution in 11 patients who presented with a variety of reconstructive problems, including defects after temporal bone resection, surgery for malignant otitis externa, and revision mastoid surgery. Follow-up in these patients ranged from 1 to 43 months (average 18.4 months) and surgical objectives of achieving a dry mastoid bowl, fully epithelialized canal, and/or reduction of mastoid cavity volume was attained in 100% of cases. The TPFF offers many advantages to the otologic surgeon when faced with reconstruction dilemmas that center around a poorly vascularized mastoid cavity and temporal bone. The TPFF is a reliable source of local well-vascularized tissue that is extremely pliable and facilitates both hearing and nonhearing preservation temporal bone reconstruction.

Adult↗

Rapidly prototyped temporal bone model for otological education.

The anatomy of the temporal bone is extremely complicated. If a three-dimensional model could be simulated, it would greatly contribute to the stereoscopic understanding of anatomy and surgery. A simulated three-dimensional model of a human temporal bone was prototyped using the selective laser sintering method. The model could be shaved using a surgical drill in the same way as in real surgery. A magnified model was particularly useful for the instruction of anatomy and surgery. When a translucent area was selected, a bony labyrinth could be created together with an internal auditory meatus and facial nerve, which also contributed to the easy understanding of the inner ear structure. The three-dimensional prototyped model using selective laser sintering serves as a good educational material for middle ear anatomy and surgery.

Humans↗

High-resolution magnetic resonance imaging of the human temporal bone.

A magnetic resonance imaging (MRI) system (Hitachi, Naka, Japan) with a superconductive magnet running at 2.11 T was used to obtain 2-mm-thick slices of fixed, decalcified and celloidin-embedded human temporal bone. The temporal bone was then sectioned and stained for routine histological evaluation. Both the MR images and the histological sections were in the mid-modiolar slice plane, and comparable images and sections were analyzed to confirm the identity of the inner-ear structures visualized on the MR images. The cochlear duct, scala tympani, scala vestibuli and basement membrane of all three cochlear turns were clearly imaged on MRI. In addition, the vestibule and three semicircular ducts were also clearly seen. This study raises the possibility of some day using MRI for the diagnosis of inner-ear diseases.

Basement Membrane↗

Quantifying temporal bone morphology of great apes and humans: an approach using geometric morphometrics.

The hominid temporal bone offers a complex array of morphology that is linked to several different functional systems. Its frequent preservation in the fossil record gives the temporal bone added significance in the study of human evolution, but its morphology has proven difficult to quantify. In this study we use techniques of 3D geometric morphometrics to quantify differences among humans and great apes and discuss the results in a phylogenetic context. Twenty-three landmarks on the ectocranial surface of the temporal bone provide a high level of anatomical detail. Generalized Procrustes analysis (GPA) is used to register (adjust for position, orientation and scale) landmark data from 405 adults representing Homo, Pan, Gorilla and Pongo. Principal components analysis of residuals from the GPA shows that the major source of variation is between humans and apes. Human characteristics such as a coronally orientated petrous axis, a deep mandibular fossa, a projecting mastoid process, and reduced lateral extension of the tympanic element strongly impact the analysis. In phenetic cluster analyses, gorillas and orangutans group together with respect to chimpanzees, and all apes group together with respect to humans. Thus, the analysis contradicts depictions of African apes as a single morphotype. Gorillas and orangutans lack the extensive preglenoid surface of chimpanzees, and their mastoid processes are less medially inflected. These and other characters shared by gorillas and orangutans are probably primitive for the African hominid clade.

Adult↗

Correlation between temporal bone pneumatization, location of lateral sinus and length of the mastoid process.

The relationship between temporal bone pneumatization and the location of the lateral sinus and length of the mastoid process was investigated in 60 fresh frozen adult temporal bones, by plain X-rays, computed tomography and surgical dissection including otomicroscopic findings. Temporal bone pneumatization was classified as small, moderate and large. After drilling, the shortest distances between the middle fossa dura and mastoid tip representing the mastoid length and between the sigmoid sinus and posterior border of external auditory canal were measured and compared to the degree of pneumatization. The distances in the specimens with pathological eardrum and adhesions in the middle ear were compared to the ones without gross pathology. The length of mastoid process was significantly shorter in specimens with small pneumatization than those with large (Mann Whitney P less than 0.001). The specimens with a pathological eardrum and middle ear adhesions had a significantly shorter mastoid length than those without gross pathology. There was no significant difference between degree of pneumatization and the shortest distance between sigmoid sinus and external auditory canal (Mann Whitney P greater than 0.05). It is demonstrated that the 'under-developed' mastoid process can be a consequence of hampered pneumatization.

Adult↗

Proximity of carotid canal wall to tympanic membrane: a human temporal bone study.

OBJECTIVE: The objective was to examine the possible risk of injury to the internal carotid artery during procedures in the middle ear, including myringotomy. STUDY DESIGN: Histopathological morphometric study of human temporal bones. METHODS: One hundred forty-two human temporal bone specimens obtained from 92 individuals without any known ear disease were prepared for light microscopic study. Using 83 bones that were available for measurement, the thickness of the carotid canal wall (CCW), which is the medial wall of the bony portion of the eustachian tube, was measured. Using 15 bones selected for three-dimensional measurement, the closest distance from CCW to the anterior tympanic annulus was measured. Using all 142 temporal bone specimens, the CCW was examined to detect the presence of partial dehiscence. In one case, the images of CCW dehiscence and its surrounding structures were reconstructed by a personal computer. RESULTS: The thickness of the CCW was 0.00 to 0.73 mm (average thickness, 0.24 mm [+/-0.12 mm]). The distance from the CCW to the anterior tympanic annulus was 1.8 to 8.1 mm (average distance, 4.9 [+/-1.7 mm]). Dehiscence of CCW was observed in 7 (4.9%) of 142 temporal bone specimens. The reconstructed image showed that the posterior half of the dehiscence of CCW could be seen from the external ear canal. CONCLUSIONS: The CCW was found to be extremely thin or even dehiscent in some cases, rendering the internal carotid artery vulnerable during transtympanic procedures. The study's findings emphasized the need for judicious care when operating in the anterior mesotympanum.

Adolescent↗

Aneurysms of the temporal bone.

Aneurysms of the internal carotid artery in the temporal bone are rare lesions which can present clinically as a growth in the middle ear cleft. Hemorrhage, occurring spontaneously or iatrogenically, is a primary concern. This study describes morphological and embryological characteristics of the internal carotid artery in relationship to the protympanum and temporal bone. Concepts of pathogenesis and pathology are discussed, with reference to the neurosurgical and otolaryngologic literature. Clinical characteristics, including methods of surgical repair, are presented using three illustrative case reports. Methods of surgical repair include: 1) reinforcement; 2) ligation; and 3) primary excision and reanastomosis.

Adolescent↗

Temporal bone histopathology of atresia auris congenita with chromosome aberration.

Temporal bone findings in two infants demonstrating congenital aural atresia with microtia were presented focusing mainly on the external and middle ears. These two cases were proved to have chromosome aberration that is, 13-15 trisomy and extra chromosome in group G individually. Temporal bones showed the multiple anomalies through the external, middle and internal ears. The external canals were filled with connective tissue in one case and with bony plate in the other to form aural atresia. There were no development of the tubotympanic recess in a case of 13-15 trisomy. The oval window area in both cases was poorly developed resulting in a connective tissue fissure in the lateral wall of the vestibule except for one ear, while the round windows were normally formed in all ears. The facial nerves showed an abnormal running course without forming the geniculate ganglion and the horizontal segment. These findings indicate that the structures derived from the second branchial arch might be more deeply involved than the first one in the congenital aural atresia.

Chromosome Aberrations↗

Pneumolabyrinth: an unusual finding in a temporal bone fracture.

Pneumolabyrinth or pneumocochlea are rarely found in temporal bone fractures. The presence of air in the inner ear is evidence of a pathological connection between the inner ear and the air-filled mastoid or middle ear cavities. A case of a pneumolabyrinth in a 2-years-old child is presented here. Diagnosis was made by means of a high resolution, thin sections computed tomography (CT) scan of the temporal bones, which is the imaging modality of choice in cases of otologic complaints after head trauma.

Air↗

[Atypical ossifying hemangioma of the temporal bone].

Over the last decade, the hemangioma of the temporal bone has become clinically recognized as the benign tumor most commonly involving the facial nerve in its intratemporal portion. Its locally aggressive nature affects the VIIth cranial nerve at a very early stage, usually before the tumor reaches a 10 mm diameter. We present a case of ossifying hemangioma of the temporal bone which, in spite of being located in the region of the geniculate ganglion and of measuring over 20 mm, only caused hearing conductive loss. The atypical clinical course of this case contrasts with those described in the literature.

Adult↗