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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
PubMed2001

Fibrous dysplasia involving the skull base and temporal bone.

OBJECTIVE: To gain a broader appreciation of the clinical presentation, operative treatment, and outcome of patients with fibrous dysplasia involving the skull base. DESIGN: Retrospective review of a clinical case series. SETTING: A single tertiary academic medical center. PATIENTS: Twenty-one patients with histopathologically confirmed fibrous dysplasia involving the skull base cared for over a 15-year-period (1983-1998). MAIN OUTCOME MEASURES: Clinical and radiographic location of the fibrous dysplasia lesions within the skull base, clinical presentation, surgical intervention, and clinical outcome were tabulated for each patient. RESULTS: The ethmoids were most commonly involved (71%), followed by the sphenoid (43%), frontal (33%), maxilla (29%), temporal (24%), parietal (14%), and occipital (5%) bones. The most common presenting features included atypical facial pain and headache, complaints referable to the sinuses, proptosis and diplopia, hearing loss, and facial numbness. Surgical treatment, guided by clinical presentation, ranged from simple biopsy with conservative follow-up to craniofacial resection. CONCLUSIONS: Fibrous dysplasia can present in myriad ways within the skull base. Modern imaging modalities and histopathologic analysis have made diagnosis relatively straightforward. Surgery, particularly in such a challenging region as the skull base, should be reserved for patients with functional impairment or a cosmetic deformity. Because of the benign nature of the condition, the surgery itself should be relatively conservative, with the primary goal being preservation of existing function.

Adolescent↗
PubMed2000

Dehiscence or thinning of bone overlying the superior semicircular canal in a temporal bone survey.

OBJECTIVE: To determine the incidence and etiology of dehiscences of bone overlying the superior semicircular canal in a temporal bone archive. DESIGN: A microscopic study was performed of 1000 temporal bones from 596 adults in a university hospital registry. Specimens were sectioned vertically in the plane of the superior semicircular canal. Measurements of minimum bone thickness over the superior canal were made in a subset of 108 randomly chosen specimens. All bones were examined for thinning or dehiscence relative to these norms. Clinical histories, when available, were reviewed. RESULTS: Complete dehiscence of the superior canal was identified in 5 specimens (0.5%), at the middle fossa floor (n = 1) and where the superior petrosal sinus was in contact with the canal (n = 4). In 14 other specimens (1.4%), the bone at the middle fossa floor (n = 8) or superior petrosal sinus (n = 6) was no thicker than 0.1 mm, significantly less than values measured in the control specimens (P<.001). Abnormalities were typically bilateral. Specimens from infants demonstrated uniformly thin bone over the superior canal in the middle fossa at birth, with gradual thickening until 3 years of age. CONCLUSIONS: Dehiscence of bone overlying the superior canal occurred in approximately 0.5% of temporal bone specimens (0.7% of individuals). In an additional 1.4% of specimens (1.3% of individuals), the bone was markedly thin (< or =0.1 mm), such that it might appear dehiscent even on ultra-high-resolution computed tomography of the temporal bone. Sites affected were in the middle fossa floor or a deep groove for the superior petrosal sinus, often bilaterally. These abnormalities may arise from failure of postnatal bone development. Thin areas of bone over the superior canal may be predisposed to disruption by trauma.

Adult↗
PubMed1999

Relationship of the utriculus and sacculus to the stapes footplate: anatomic implications for sound-and/or pressure-induced otolith activation.

One hundred thirty human temporal bones that were sectioned in the vertical plane were examined to evaluate the relationship between the stapes footplate and the otolith organs. The shortest distance between the footplate and the utriculus was 0.58+/-0.10 mm in the posterior third of the oval window, 1.04+/-0.20 mm in the middle third, and 1.51+/-0.20 mm in the anterior third. The distance from the sacculus to the footplate was 1.33+/-0.20 mm in the middle third of the oval window and 1.31+/-0.18 mm in the anterior third. Membranous connections extending between the utriculus and the footplate were found in 26% of temporal bones. These membranous connections in coexistence with additional anatomic factors such as stapes hypermobility and/or dehiscence of bone within labyrinthine structures may predispose patients to sound- and/or pressure-induced otolith activation. The findings may have implications for different causes of the Tullio phenomenon.

Acoustic Stimulation↗
PubMed1995

Association of heterotopic neuroglial tissue with an arachnoid cyst in the internal auditory canal.

An arachnoid cyst arising within the internal auditory canal, or within the cerebellopontine angle and subsequently extending into the internal meatus and enlarging it, is a rare occurrence. Nevertheless, the neurootologist and the neurosurgeon have an interest in its existence because its clinical manifestations are identical with the ones produced by a schwannoma, involving overwhelmingly the cochleovestibular nerve in that region. An equally rare observation in that location is the presence of ectopic neuroglial tissue. The two can occur independently or in combination. Examples of such lesions are presented, and their possible pathogenesis is discussed.

Journal Article↗
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↗
PubMed1982

A new, treatable source of recurrent meningitis: basioccipital meningocele.

A 19-month-old boy suffered eight episodes of bacterial meningitis. During the ninth episode a meningocele of the basioccipital clivus communicating with the nasopharynx was discovered. Identification of the organism causing the episodes of meningitis was not helpful in pointing to the site of this congenital anatomic defect. Surgical closure of the defect has prevented further recurrences.

Humans↗
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↗