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Biomedical subjects

G T Nager

Publications and source records attributed to G T Nager.

At least 19 recordsLinked to original sources
PubMed1991

Anatomic variations and anomalies involving the facial canal.

Congenital bony dehiscences in the facial canal result from incomplete closure during development and are observed in approximately 55% of temporal bones. Anomalies involving the facial canal frequently are encountered in malformations of the temporal bone. These anomalies include aberrations of the course of one or all of the segments of the canal; abnormal relation to the oval and round window; bifurcations and trifurcations of the nerve; and associations with dysplasia of the stapes, oval window, external ear canal, and auricle. Rarely, the facial nerve may be hypoplastic or totally absent. Two abnormal vessels occasionally may accompany the facial nerve in the Fallopian canal: a persistent stapedial artery and a persistent lateral capital vein.

Chorda Tympani Nerve↗
PubMed1987

Cephaloceles.

The meningoceles and encephaloceles of the calvaria and base of the skull are reviewed with regard to origin and local behavior. An additional variant is added to the subgroup of nasopharyngeal cephaloceles, the basioccipital nasopharyngeal cephalocele, which only recently has become recognized. The clinical importance, techniques for its identification, and surgical management are discussed with the aid of a case report.

Encephalocele↗
PubMed1986

The jugular bulb in otologic surgery: anatomic, clinical, and surgical considerations.

The jugular bulb varies widely in position and dimensions. In certain pathologic conditions there is an increased incidence of jugular bulb enlargement, but such enlargement also occurs without an obvious underlying cause. Jugular bulb enlargment may lead to clinical symptoms for the patient and particular difficulties for the otologic surgeon, not only in the middle ear but also in neurotologic approaches. The different clinical aspects and problems associated with jugular bulb enlargement are discussed with illustrative cases and temporal bone histologic findings.

Adult↗
PubMed1986

Solitary (unicameral) cysts involving the temporal bone.

The primary unicameral cyst which involves the temporal bone is very rare. Only about 30 patients have been reported in the literature during the past ten decades. The lesion is most frequently encountered in the first and second decade of life. In contrast to the other locations in the skeleton, it usually remains asymptomatic for a long time until it causes a deformity or dysfunction. The etiology has so far remained obscure. Its occasional association with malformations of the ears and nasopharynx and other developmental anomalies, its incidental bilateral occurrence, and certain histological aspects may suggest a congenital origin or a localized defect in bone formation and remodeling.

Adult↗
PubMed1975

Epidermoids involving the temporal bone: clinical, radiological and pathological aspects.

Epidermoids or congenital cholesteatomas arise from aberrant epithelial remnants and are, therefore, considerd blastomatous malformations. Their predilective sites are the intracranial cavity, the diploe of the skull and the spinal canal. In the base of the skull the temporal bone is the most frequent site. Epidermoids account for about 0.2-1.5 percent of all intracranial tumors. The majority originate in the cerebello-pontine angle where they account for 6-7 percent of all tumors. Their age incidence reveals a great scatter from birth to 80 years. The majority are recognized during the third and fourth decades with the onset of clinical symptoms occurring much earlier. They affect males more frequently than females. Their delicate capsule with a whitish mother-of-pearl sheen lends them a typical appearance. Epidermoids are generally slow growing lesions which may remain asymptomatic for years. The irritative effect of their content, however, can produce symptoms of dysfunction and intense inflammation. Malignant changes occur infrequently. Diploic epidermoids are easily recognized, whereas, intradural epidermoids are more difficult to identify. Epidermoids may arise in the vicinity, on the outer aspect or within the temporal bone. Epidermoids originating in any of these locations have certain characteristic features which may arouse suspicion of their presence. Examples of an epidermoid with origin in the typical locations within the temporal bone and cerebello-pontine angle are discussed to portray their individual characteristics.

Adolescent↗
PubMed1971

Congenital aural atresia: anatomy and surgical management.

Malformations involving the ear may be part of a developmental anomaly of the first and second branchial arch or of a malformation syndrome involving other regions of the skeleton. The anatomy and pathogenesis are discussed, a classification is suggested, and the general management is outlined. A surgical technic for the treatment of Group II (moderately severe) aural atresia is described. Of 21 patients, treated surgically during the past 12 years, 15 patients (71%) gained serviceable hearing. In six patients hearing was not improved.

Abnormalities, Drug-Induced↗
PubMed1971

Hereditary bilateral acoustic neuroma (central neurofibromatosis).

Fifty-five members of a kindred have bilateral acoustic neuroma. The trait is autosomal dominant with high penetrance. Onset is about age 20; survival varies from two to 42 years. In screening members, vestibular abnormalities are most consistently observed, but complete audiometric studies and brain scan are important, because no single study is diagnostically sufficient in all cases. Peripheral signs suggesting neurofibromatosis are rare, but other CNS tumors, often asymptomatic, are common suggesting this trait may represent a "central" form of neurofibromatosis.

Adolescent↗
PubMedDate not supplied

Sclerosteosis involving the temporal bone: histopathologic aspects.

Sclerosteosis is a rare, potentially lethal, autosomal recessive, progressive craniotubular sclerosing bone dysplasia with characteristic facial and skeletal features. The temporal bone changes include a marked increase in overall size, extensive sclerosis, narrowing of the external auditory canal, and severe constriction of the internal auditory meatus, fallopian canal, eustachian tube, and middle ear cleft. Attenuation of the bony canals of the 9th, 10th, and 11th cranial nerves, reduction in size of the internal carotid artery, and severe obliteration of the sigmoid sinus and jugular bulb also occur. Loss of hearing, generally bilateral, is a frequent symptom. It often manifests in early childhood and initially is expressed as sound conduction impairment. Later, a sensorineural hearing loss and loss of vestibular nerve function often develop. Impairment of facial nerve function is another feature occasionally present at birth. In the beginning, a unilateral intermittent facial weakness may occur which eventually progresses to a bilateral permanent facial paresis. The histologic examination of the temporal bones from a patient with sclerosteosis explains the mechanisms involved in the progressive impairment of sound conduction and loss of cochlear, vestibular, and facial nerve function. There is a decrease of the arterial blood supply to the brain and an obstruction of the venous drainage from it. The histopathology reveals the obstacles to decompression of the middle ear cleft, ossicular chain, internal auditory and facial canals, and the risks, and in many instances the contraindications, to such procedures. On the other hand, decompression of the sigmoid sinus and jugular bulb should be considered as an additional life-saving procedure in conjunction with the prophylactic craniotomy recommended in all adult patients.

Adult↗