Amplification of mitochondrial DNA from archival temporal bone specimens

Archival temporal bone collections are an invaluable resource for studying the molecular genetics of many types of otopathology. The irreplaceable nature of temporal bone sections makes efficiency of DNA extraction of paramount importance. Several protocols are available for extracting DNA from fresh and preserved tissue. To establish the best protocol for reliably extracting DNA from celloidin-embedded temporal bone sections, a variety of DNA extraction techniques were tested. Using the optimum protocol, mitochondrial DNA fragments ranging in size from less than 100 base pairs to more than 400 base pairs were amplified, and the authenticity of polymerase chain reaction (PCR) products was confirmed through comparative sequence analysis.     

Anatomy of the guinea pig temporal bone.

The middle ear of guinea pigs has long been used for experimental studies, but no detailed information about its temporal bone anatomy is available. In 18 adult guinea pigs, the temporal bone, eustachian tube, and inner ear anatomy, in addition to the anatomy of the middle ear, were investigated under the dissection microscope. In addition to properties of the eardrum, ossicles, air cell system, and cochlea previously described, the appearance of Huschke's foramen and the crista stapedis in an adult guinea pig ear, the structure of the eustachian tube, the architecture of the internal auditory canal, and the communication of the mastoid cells with the tympanic bulla are described. Differences and similarities among guinea pigs, other experimental animals, and humans are discussed to show the advantages and disadvantages of the guinea pig ear for experimentation.     

Application of unbiased stereology on archival human temporal bone

OBJECTIVE: The current report presents unbiased stereological sampling and counting strategies for estimating the total number of neurons in the spiral and vestibular ganglia of the archival human temporal bone. STUDY DESIGN: Application of unbiased stereology using archival human temporal specimens. Observational study. METHODS: The practical sampling and counting strategies for estimating the number of neurons are presented. To illustrate the method described, the total number of neurons in spiral and vestibular ganglia from archival human temporal bone was estimated. RESULTS: The study found, on average, 41,643 (coefficient of variation = 0.12) spiral ganglion neurons in the subjects with an average age of 35.6 years (age range, 22-60 y) and, on average, 27,635 (coefficient of variation = 0.10) vestibular ganglion neurons in the subjects with an average age of 28.6 years (age range, 2-58 y). CONCLUSIONS: The total number of primary auditory and vestibular ganglion neurons from the current study differs significantly from the previously published data using assumption-based methods. The unbiased stereological technique presented in the current report thus would be invaluable for future studies on such specimens, including the study of the changes of neurons during aging and various pathological conditions.     

Cloning and sequencing of genomic DNA extracted from archival human temporal bone sections

Cloning techniques allow the engineering and production of highly purified DNA. Further advances in molecular biology have provided the means to identify DNA sequences in a rapid fashion. Sequencing methods can identify mutations, deletions, polymorphisms, or confirm a known genetic sequence. The use of these techniques in clinical medicine has made it possible to accurately diagnose infectious diseases and determine the molecular etiology of many genetic disorders and malignancies. In this study, DNA extracted from archival, celloidin-embedded temporal bone sections has been cloned and sequenced using these techniques. We amplified, cloned, and sequenced varicella-zoster viral DNA extracted from archival temporal bone sections from patients who had herpes zoster oticus. The application of cloning and sequencing techniques to DNA extracted from archival temporal bones provides the methodology to study temporal bone pathology at the molecular level.     

Flat-panel volume computed tomography for cochlear implant electrode array examination in isolated temporal bone specimens.

HYPOTHESIS: Flat-panel based volume computed tomography could improve cochlear implant electrode evaluation in comparison with multislice computed tomography. BACKGROUND: Flat-panel based volume computed tomography offers higher spatial resolution and less metal artifacts than multislice computed tomography. Both characteristics could improve the evaluation of challenging but important questions in cochlear implantation assessment, such as an exact imaging of cochlea, osseous spiral lamina, electrode array position, and single electrode contacts. These questions are not currently fully answered by multislice computed tomography. METHODS: Four isolated temporal bone specimens were scanned in a current multislice computed tomography scanner and in two experimental flat-panel based volume computed tomography scanners before and after cochlea implantation. To compare flat-panel based volume computed tomography and multislice computed tomography, four features were rated according to the following criteria: 1) visibility of the cochlea; 2) visibility of the osseous spiral lamina; 3) discernibility of individual electrode contacts; and 4) the ability to determine the electrode array position relative to scala tympani and scala vestibuli. Layer-by-layer microgrinding pictures were used as the ground truth for verification of imaging findings. RESULTS: Flat-panel based volume computed tomography was superior to multislice computed tomography in all four features rated. The cochlea and facial nerve canal were much better delineated in flat-panel based volume computed tomography. The osseous spiral lamina and single electrode contacts were only visible in flat-panel based volume computed tomography. Assessment of implant position with regard to the cochlear spaces was considerably improved by flat-panel based volume computed tomography. CONCLUSION: Cochlear implantation assessment could be improved by flat-panel based volume computed tomography and, therefore, would be highly beneficial for cochlea implantation research and for clinical evaluation. However, these first results were shown by scanning isolated temporal bone specimens; scanning whole human skull bases might be more challenging.     

Distant metastases from ear and temporal bone cancer.

Cancers of the temporal bone are rare. Cervical metastases occur in approximately 10% of cases and are much more likely once disease extends beyond the confines of the temporal bone. Nonlymphatic spread of squamous cell carcinoma is usually a late event resulting in metastatic deposits in the lung, bone, liver and brain. This chapter discusses detection of distant metastases and provides a recommended schedule for interval patient evaluation.     

Pediatric temporal bone fractures.

Twenty-seven temporal bone fractures in 25 pediatric patients were evaluated over a 6-year period. The diagnosis was confirmed with otoscopy and high-resolution computed tomography scans (HRCT). Three-dimensional reconstruction of high-resolution computed tomography scans were used to aid in the diagnosis. The most common fracture was an oblique fracture which is oriented in an axial or horizontal plane with the temporal bone. Facial nerve paralysis was found in 6 of our patients, which is less than the expected incidence when compared to adults. Hearing loss was found in 24 patients, the most common of which was conductive hearing loss, which had a higher incidence than expected when compared with adults.     

Osteoradionecrosis of the temporal bone.

Six cases of osteoradionecrosis of the temporal bone are described. Persistent symptoms of otitis externa refractory to local treatment measures should alert the physician to the possibility of underlying osteoradionecrosis. Treatment of superficial parotidectomy and partial temporal bone resection with preservation of the facial nerve is indicated if local aggressive conservative measures fail to control the disease. Benign mixed tumors of the parotid gland should be treated surgically with avoidance of radiotherapy.     

Inflammatory response to chronic otitis media in DiGeorge syndrome: a case study using immunohistochemistry on archival temporal bone sections.

Immunohistochemical analyses were conducted on archival celloidin-embedded human temporal bone sections from an 8-month-old boy with chronic otitis media and DiGeorge syndrome. We employed antigen retrieval methods with saturated sodium hydroxide-methanol solution, microwave incubation, and proteolytic treatment to demonstrate the distribution of T-lymphocytes, B-lymphocytes, macrophages, and intercellular adhesion molecule 1 (ICAM-1) expression in the middle ear. B-lymphocytes and macrophages were observed predominantly within the middle ear mucosa. T-lymphocytes were rare. Further, ICAM-1 was expressed in the vascular endothelium of the lamina propria, as well as infiltrating mononuclear cells. This suggests that the expression of ICAM-1 can be induced in the middle ear with otitis media, even if T-lymphocytes are depressed in a cell-mediated immunodeficiency disorder such as DiGeorge syndrome.     

Neoplasms of the temporal bone.

A series of 209 patients with chemodectomas and malignant neoplasms of the external auditory canal and middle ear seen during a 20-year period at the Mayo Clinic was reviewed. Ninety-nine patients had chemodectomas, and 110 had malignant lesions; 57 of the 110 patients with malignancies had squamous cell carcinoma. The study revealed that patients with chemodectomas had a normal expected length of survival, whereas patients with malignant lesions (especially those with squamous cell carcinomas and embryonal rhabdomyosarcomas) did poorly.     

Management of complication from temporal bone fractures

The objective of the study is to review clinical findings and outcomes in patients with temporal bone fractures, and to show an incidence and management of complications. It is the retrospective clinical study and the study took place at tertiary referral center. Fifty-two patients with temporal bone fractures. Data were collected from patients’ charts and clinical review. Patients were classified into five groups according to the CT scan. The primary endpoint of study was to show management of possible complication from temporal bone fractures and to analyze association with intracranial injuries. The second endpoint was to show incompleteness of traditionally classification of fracture type. Of the 52 patients with 54 fractures, 27 (50%) had longitudinal fractures, 4 (7.4%) had transverse fractures, 17 (31.5%) had temporal squama-mastoid fractures, 4 (7.4%) had mixed fractures and 2 (3.7%) had isolated meatal fracture. Fifty-eight percent of patients had at least one intracranial pathologic finding, of which 11% had two or more. Persistent conductive hearing loss was noted in 8 of 16 affected patients. The facial paralysis occurred in seven patients. One patient had benign paroxysmal positional vertigo developed 3 weeks after injury. In conclusion, rarely temporal bone fractures are isolated injures. The squama-mastoid fracture in most cases associated with intracranial injuries. Coordination between the neurosurgeon and otologist is essential in the care of such patients. Further large studies will be done to give a more complete classification of temporal bone fractures which will include all fracture patterns and predict clinical outcome.     

Primary lymphoma of the temporal bone.

Involvement of the temporal bone by lymphoreticular neoplasm is rare; all reported cases have been of secondary involvement. This article presents what we believe to be the first two reported cases of primary temporal bone lymphoma. The patients, an elderly man and a boy, both presented with infection of the ear, hearing loss, and facial nerve paresis. In both cases, facial paresis resolved after appropriate chemotherapeutic treatment. Patient presentation and clinical course are discussed in light of published work on temporal bone malignancy. Further investigation, including computed tomography and biopsy, should be considered for patients who present with an apparent middle ear infection unresponsive to medical therapy. The development of facial paralysis in such a patient warrants heightened suspicion of malignancy.     

Fibrous dysplasia of the temporal bone.

Fibrous dysplasia is characterized by a progressive replacement of normal bone elements by fibrous tissue. It is seen in the two first decades of life and is equally distributed in relation to the sex of patients. The temporal bone is involved in 18% of the cases. Fibrous dysplasia of the temporal bone is more commonly manifested in the external auditory canal (80%) and the inner and medium ear can also be involved. Sarcomatous alterations are rare. Diagnosis is based on radiological images. Treatment is conservative and surgery is reserved for preserving function and preventing complications. The case of a male patient, 16 years old, who presented with progressive hearing loss over a 1-year period is reported.