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Computer-stimulated test fitting of an implantable hearing aid using implantable hearing aid using three-dimensional CT scans of the temporal bone: preliminary study.

In preparation for future implantation of the implantable middle ear transducer in patients, a method was sought for preoperatively test fitting a model of the device, using computer generated three-dimensional (3-D) temporal bone images derived from spiral computed tomography (CT) data. A 3-D model of the implantable middle ear transducer was designed using NIH Image software on a Macintosh computer. High resolution human temporal bone CT scans were obtained using a spiral CT scanner (Siemens Somatom Plus S). The 3-D transducer model was superimposed onto 3-D reconstructions of the temporal bone using ANALYZE software on a computer graphics workstation (Sun SPARCstation 10), showing the transducer "implanted" in the temporal bone. Measurements were validated using a cadaver temporal bone. This process produced images demonstrating the "fit" of the current transducer design in the mastoid region of the adult temporal bone. It permitted assessment of the proximity of surrounding structures such as the external auditory meatus, dura, or sigmoid sinus. Preliminary cadaver validation measurements confirmed the accuracy of this method. Three-dimensional CT is a feasible method for preoperative planning of the surgical implantation of devices in the temporal bone. This method of 3-D test fitting will be used in the future to determine optimum orientation and size limitations for human implantable devices.

Cochlear Implants↗

Chondroblastoma of the temporal bone.

A chondroblastoma within the temporal bone in a 16-year-old boy is reported. The tumor recurred after intracapsular resection and curettage. After reoperation, radiotherapy was performed. The data from 137 cases of chondroblastoma are summarized.

Adolescent↗

Developmental temporal bone anatomy and its clinical significance: variations on themes by H. F. Schuknecht.

Fifty-eight fetal and neonatal temporal bones were studied to evaluate the mechanisms of development of the hiatus of the facial canal, hypotympanic fissures, periotic duct, tympanomeningeal fissures, and fetal inner ear vascularity. These were correlated with the clinical pathologic entities of temporal bone trauma, glomus jugulare tumor extension within the temporal bone, CNS-temporal septic conduits, and inner ear vascularity. Temporal bone developmental anatomy and histopathology provide rich sources of information on which to base the scientific and clinical study of otology.

Adult↗

Anatomy of the temporal bone.

High resolution computed tomography has proved to be invaluable in the evaluation of the temporal bone, and demonstrates its bony anatomy in exquisite detail. Furthermore, the role of magnetic resonance imaging, especially with improving high resolution techniques, has continued to expand in the past decade. A thorough understanding of normal temporal bone anatomy is a requisite for accurate radiologic evaluation. The ensuing discussion is an attempt to summarize the normal temporal bone anatomy with emphasis on clinically relevant structures, temporal bone pneumatization, and common anatomic variants.

Ear↗

Metastatic adenocarcinoma of the temporal bone.

Metastatic carcinoma involving the temporal bone is extremely rare. A case is reported with an unusual presentation--recurrent episodes of acute mastoiditis. Mastoid exploration and biopsy established the diagnosis. We believe this to be the first reported case to present in this manner.

Adenocarcinoma, Mucinous↗

Cochlear implant. Histopathological guide to indications and contraindications: a post mortem study on temporal bones.

We have studied the temporal bones of 4 deceased donors, individuals one with cochlear saccular degeneration, another with Mondini dysplasia, another with an ossification of the basal turn of the cochlea and the round window, post meningitis and the fourth who was implanted 10 years before. The indications and contraindications for cochlear implant placement are discussed.

Cochlea↗

Primary adenocarcinoma of the middle ear and temporal bone.

Primary adenocarcinoma of the temporal bone is a rare disorder. Fewer than 40 cases have been reported in the English literature, most of these being single case reports. Exclusion of metastatic adenocarcinoma is imperative. Adenocarcinomas must be differentiated from benign adenomas. Adenocarcinomas are best managed by aggressive surgical resection, with postoperative irradiation used in cases of incomplete resection or high-grade tumors.

Adenocarcinoma↗

Temporal bone findings in cases of salt water drowning.

The otologic literature contains no description of the histopathological features of temporal bones of persons who perished in drowning accidents. Three temporal bones from two fatal cases of drowning were studied in serial sections. Two temporal bones were from a man aged 31 years who collapsed after scuba diving and died three days later. One temporal bone was from a 32-year-old man, serving in the navy, who drove his car, probably accidentally, into the sea and drowned in it. Histopathological findings appeared to be similar in the two cases. Diffuse hemorrhage was evident throughout the middle ear and inner ear. The tympanic and round window membranes appeared to be intact although hemorrhage had occurred within the tissue layers of the membranes. This finding contrasts with observations of ruptured membranes by other investigators.

Adult↗

Glomus tumors of the temporal bone: contemporary evaluation and therapy.

Surgical management of glomus tumors of the temporal bone requires accurate preoperative assessment and a knowledge of temporal bone anatomy, contemporary microsurgical techniques, and appropriate postoperative management. Care should be exercised to minimize postoperative neurologic deficit and deformity resulting from surgery of this usually benign lesion. The primary preoperative goal is to determine the extent of the lesion; although the history and physical examination are helpful, radiologic delineation of the tumor is imperative. Recent advances in surgical approaches and techniques have allowed the removal of larger tumors with lessened mortality and morbidity. Our overall experience in this series of glomus tumors leads us to believe that surgical excision is the treatment of choice for the treatment of glomus tumors of the temporal bone.

Adult↗

Temporal bone cholesteatoma.

Clinical features of temporal bone cholesteatoma are miscellaneous, and sometimes misleading: signs of middle ear cholesteatoma, progressive or sudden facial palsy, sensorineural deafness as in acoustic neuroma, conductive deafness as in otosclerosis, secretory otitis media, or intracranial complications. Polytomography is the only way to pinpoint topography and extension. CT scanning is very useful in determining extension. Topography and severity of deafness are the guidelines for surgical approach. Among sixteen cases, total deafness was produced by the lesion itself in ten cases, and six had an intact inner ear; preservation of hearing was possible in only three. Supralabyrinthine cholesteatomas (five cases) are best managed by the middle fossa approach. Infralabyrinthine cholesteatomas (six cases) must be removed via the infratemporal approach with anterior displacement of the tympanic and mastoid segments of the facial nerve and permanent obliteration of the middle ear. Posterior perilabyrinthine cholesteatoma (five cases) may be removed by the otologic approach combined with the middle ear fossa approach if the inner ear is to be preserved. If hearing loss is total, the translabyrinthine approach can be used.

Adolescent↗

Temporal bone necrosis: diagnosis, classification, and management.

OBJECTIVE: The goal of this study was to analyze temporal bone necrosis and classify its diagnosis and treatment according to extent of necrosis and cause. METHODS AND MATERIAL: Twenty-six cases of temporal bone necrosis were retrospectively reviewed between 1988 and 1997 at the University of British Columbia. RESULTS: Patients were classified on the basis of disease extent restricted to the tympanic bone or extension beyond the tympanic bone, as well as on the basis of the cause of disease; treatment based on classification. Patients with localized disease of the tympanic bone had minimal symptoms. Those with radiation-induced localized necrosis were less likely to respond to conservative medical management. Patients with diffuse disease were more likely to require surgical intervention. CONCLUSIONS: Temporal bone necrosis comprises a spectrum of disease from idiopathic tympanic bone necrosis, which rarely requires surgery, to the more severe forms of radiation-induced diffuse temporal bone necrosis that may cause life-threatening complications requiring surgical intervention.

Adolescent↗

Extended temporal bone resection for squamous cell carcinoma.

OBJECTIVE: The aim of this study was to assess the surgical results of a series of patients from this unit who underwent extended temporal bone resection for recurrent squamous cell carcinoma as a salvage procedure. DESIGN: The surgical records of 15 patients were analyzed in detail. Each patient had salvage surgery in the form of an extended temporal bone resection with supraomohyoid block dissection, dural grafting, and free microvascular forearm or scalp rotation flap repair for recurrent squamous cell carcinoma in a radical mastoid cavity. RESULTS: Radical surgery yielded a 47% 5-year survival. Twenty-nine percent of the survivors had temporal lobe involvement that necessitated a partial excision of the temporal lobe of the brain. Histologic evidence of local lymph node involvement in the supraomohyoid neck dissection was present in 13% of cases. Those who died did so in the first postoperative year. All those with poorly differentiated tumors died. The survivors had well or moderately differentiated tumors. CONCLUSIONS: Radiotherapy alone or partial temporal bone resection, most commonly a radical mastoidectomy with or without preoperative or postoperative radiotherapy is used by the majority of otolaryngologists in treating squamous cell carcinoma of the temporal bone. The 5-year survival rate after this treatment remains depressingly low and the prognosis gloomy, particularly for advanced tumors. The findings in this series of extended temporal bone resections as salvage surgery in recurrent disease is encouraging, and radical surgery combined with radiotherapy from the outset may give much better 5-year survival figures in the future than the conventional partial temporal bone resection and radiotherapy.

Adult↗

Detection of labyrinthine fistulas in human temporal bone by virtual endoscopy and density threshold variation on computed tomographic scan.

OBJECTIVE: To assess the sensitivity of the routine computed tomographic (CT) scan of the temporal bone coupled to a virtual endoscopy, with density threshold variation, in detecting small fistulas in human temporal bone specimens. DESIGN: Single-blind, before-after trial. SETTING: This study was carried out in a research laboratory in collaboration with a radiology department. PATIENTS: Five human adult temporal bone specimens were included. INTERVENTIONS: The fistulas were created with calibrated burrs (0.3, 0.5, and 0.8 mm) in the 3 semicircular canals and in the promontory of 3 temporal bones. Two other temporal bones served as controls. All bones underwent CT scan (1-mm section thickness) before and after dissection. Three-dimensional images were obtained from CT scan native axial views at different density reconstruction thresholds. The virtual endoscope was placed in the middle ear cavity looking to the inner ear wall. The threshold at which a bony defect appeared on virtual endoscopic images (opening threshold in Hounsfield units [H]) was noted for each location. MAIN OUTCOME MEASURES: Opening thresholds before and after dissection. RESULTS: On standard axial views, fistulas smaller than 0.5 mm were not visualized. By virtual endoscopy, all fistulas could be visualized. The opening threshold decreased after fistula creation in the semicircular canals (1244 +/- 50.5 H [n = 36] vs 778 +/- 52.4 H [n = 34]; P<.001; 1-way analysis of variance and Dunnett multiple comparisons posttest) and in the promontory (1541 +/- 37.8 H [n = 12] vs 1334 +/- 35.1 H [n = 8]; P<.001). The opening thresholds in the control specimens remained unchanged after dissection. CONCLUSION: Virtual endoscopy with variation of reconstruction threshold allows the detection of small labyrinthine fistulas with diameters of 0.3 mm or smaller.

Adult↗

A technique for retrieving antigens in formalin-fixed, routinely acid-decalcified, celloidin-embedded human temporal bone sections for immunohistochemistry.

The application of immunohistochemistry to routinely decalcified, celloidin-embedded human temporal bone sections has been hampered because of antigen loss during processing of the specimens. To our knowledge, there has been no published report to date describing immunohistochemical staining of such tissues suitable for examination by light microscopy. Here we report a novel antigen retrieval technique which can be successfully used to stain a variety of antigens in routinely formalin-fixed, trichloroacetic acid-decalcified, celloidin-embedded human temporal bone sections. The new procedure reported here for decalcified human temporal bone tissues simply requires immersing slides for 30 min at room temperature in an antigen retrieval solution. A total of 60 decalcified, celloidin-embedded human temporal bone tissues were tested with monoclonal antibodies (MAb) to 15 different antigens. Of these, 12 MAb showed definite positive staining, while three were negative. This technique may prove very useful in studying the expression of various antigens by immunohistochemistry in formalin-fixed, acid-decalcified, celloidin-embedded tissues.

Antibodies, Monoclonal↗

Temporal bone findings in rhabdomyosarcoma with predominantly petrous involvement.

Temporal bone rhabdomyosarcomas are rare tumors that occur almost exclusively in children. They arise most commonly in the middle ear, from which they extend through the mastoid and petrous portions of the temporal bone, eventually invading the cranium. We report the histopathologic findings of a rhabdomyosarcoma with anterior and medial displacement, predominantly involving the petrous bone. Recognition and separate study of this type of tumor is clinically important. Predominantly petrosal rhabdomyosarcomas are less prevalent than similar lesions with lateral expansion and tend to develop significant ear symptoms late in the course of the disease. When first diagnosed, these lesions usually exhibit signs of intracranial extension, and consequently are less amenable to treatment and are more rapidly fatal.

Child↗

Bone destruction resulting from rupture of a cholesteatoma sac: temporal bone pathology.

OBJECTIVE: The purpose of the current study was to research the pathogenesis of bony destruction of cholesteatoma. STUDY DESIGN: We conducted a case report. SETTING: The study was performed at Fukushima Medical University. PATIENTS: The first case involved a 21 trisomy, whereas the second case was cancer of the hypopharynx. Both cases showed cholesteatoma. RESULTS: The following histopathologic findings in the temporal bones of cholesteatoma were obtained. Bony destruction in cholesteatoma was detected in the lesion of the rupture of the cholesteatoma sac. Epithelial debris of cholesteatoma was scattered throughout the rupture of the cholesteatoma sac. Rupture of the matrix was the result of a small abscess. CONCLUSION: Rupture of the cholesteatoma sac was believed to have been a pathway of either endogenous substances from the matrix and/or epithelial debris of cholesteatoma.

Aged↗

Measurements of selected parameters of the guinea pig temporal bone.

On the basis of dissections of 32 temporal bones of the guinea pig, measurements were taken of selected size parameters of the temporal bone. The measurements performed included external and internal size parameters of the bone. Among these were the following: the length, width and height of the external and internal auditory meatus, the length of the incudomallear complex, the height of the attic, the full length and height of the tympanic cavity and the parameters characterising the localisation of the external orifice of the facial nerve. The semicircular canals are relatively large, the lateral canal being the largest and the posterior the smallest. The length of the spiral canal of the cochlea does not exceed 16 mm. It is worth noting that both the vertical and horizontal dimensions of the scala vestibuli and scala tympani only exceed 1 mm in the basal turn, decreasing significantly in the further turns to as little as decimal parts of a millimetre. This should be taken into account during all tests which require the introduction of examining instruments into the cochlear scala.

Animals↗

CT-MR image data fusion for computer assisted navigated neurosurgery of temporal bone tumors.

PURPOSE: To demonstrate the value of multi detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative work up of temporal bone tumors and to present, especially, CT and MR image fusion for surgical planning and performance in computer assisted navigated neurosurgery of temporal bone tumors. MATERIALS AND METHODS: Fifteen patients with temporal bone tumors underwent MDCT and MRI. MDCT was performed in high-resolution bone window level setting in axial plane. The reconstructed MDCT slice thickness was 0.8 mm. MRI was performed in axial and coronal plane with T2-weighted fast spin-echo (FSE) sequences, un-enhanced and contrast-enhanced T1-weighted spin-echo (SE) sequences, and coronal T1-weighted SE sequences with fat suppression and with 3D T1-weighted gradient-echo (GE) contrast-enhanced sequences in axial plane. The 3D T1-weighted GE sequence had a slice thickness of 1mm. Image data sets of CT and 3D T1-weighted GE sequences were merged utilizing a workstation to create CT-MR fusion images. MDCT and MR images were separately used to depict and characterize lesions. The fusion images were utilized for interventional planning and intraoperative image guidance. The intraoperative accuracy of the navigation unit was measured, defined as the deviation between the same landmark in the navigation image and the patient. RESULTS: Tumorous lesions of bone and soft tissue were well delineated and characterized by CT and MR images. The images played a crucial role in the differentiation of benign and malignant pathologies, which consisted of 13 benign and 2 malignant tumors. The CT-MR fusion images supported the surgeon in preoperative planning and improved surgical performance. The mean intraoperative accuracy of the navigation system was 1.25 mm. CONCLUSION: CT and MRI are essential in the preoperative work up of temporal bone tumors. CT-MR image data fusion presents an accurate tool for planning the correct surgical procedure and is a benefit for the operational results in computer assisted navigated neurosurgery of temporal bone tumors.

Adult↗