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Biomedical subjects

J M Talbot

Publications and source records attributed to J M Talbot.

At least 19 recordsLinked to original sources
PubMed1997

Congenital encephalocele of the medial skull base.

Meningoencephaloceles of the temporal bone are rare. Although most often seen following otologic surgery or trauma, congenital meningoencephaloceles can exist. The clinical presentation, diagnostic evaluation, and surgical management of three patients with congenital meningoencephalocele are presented. Two of the three patients presented to our institution with recurrent episodes of meningitis; one presented with partial complex seizures. Diagnostic evaluation included temporal bone computed tomography with magnetic resonance imaging. In two patients, defects were imaged following high-pressure subarachnoid cisternography with computed tomography. All three patients were found to have congenital defects in the area of Meckel's cave. Early recognition of congenital meningoencephalocele is important to avoid delay of definitive surgical management and neurologic sequelae.

Adult↗
PubMed1997

Fibrous dysplasia of the temporal bone: reversal of sensorineural hearing loss after decompression of the internal auditory canal.

When fibrous dysplasia affects the temporal bone, it most often presents with conductive hearing loss attributable to stenosis of the external auditory canal. Sensorineural hearing loss has usually been attributed to involvement of the otic capsule. We present a patient with bilateral fibrous dysplasia of the temporal bones who complained of unilateral hearing loss, facial tingling, and facial twitching. The audiogram showed severe sensorineural hearing loss. The hearing markedly improved and facial twitching and tingling ceased after decompression of the internal auditory canal via a middle fossa approach. This is the only case of which we are aware showing reversal of sensorineural hearing loss caused by fibrous dysplasia.

Adult↗
PubMed1997

Candida glabrata chorioamnionitis following in vitro fertilization and embryo transfer.

Candida glabrata is a yeast which is considered to be a commensal of the vagina with limited pathogenicity in the immunocompetent host. We report 2 cases of severe chorioamnionitis occurring in pregnancies achieved by in vitro fertilization techniques which resulted in preterm delivery and pregnancy loss. Candida glabrata as the causative agent was probably introduced into the uterus by the cannula at the time of embryo transfer. It is recommended that appropriate investigation of the microbial flora of the cervix be undertaken and treatment instituted prior to embryo transfer in order to prevent this complication.

Adult↗
PubMed1997

Ovarian hyperstimulation syndrome.

A case of severe ovarian hyperstimulation syndrome (OHSS) prompted us to review our experience of the condition, and to critically evaluate its clinical associations and treatment. Severe OHSS complicated 1.8% of gamete intra-Fallopian transfer (GIFT) cycles, but none of the ovulation induction and artificial insemination by husband (OI/AIH) cycles. It is difficult to establish whether the higher pregnancy rate observed with OHSS was attributable to pregnancy increasing the risk of OHSS, or if it was the development of OHSS which increased the likelihood of pregnancy. Monitoring serum oestradiol levels and ultrasonographic evaluation of growing follicles may be helpful in identifying women at risk. Strategies for reducing the risk of developing severe OHSS were considered.

Adult↗
PubMed1997

Papillary endolymphatic sac tumors: CT, MR imaging, and angiographic findings in 20 patients.

PURPOSE: To determine the computed tomographic (CT), magnetic resonance (MR) imaging, and angiographic findings of papillary endolymphatic sac tumors. MATERIALS AND METHODS: Clinical and imaging studies in 20 patients (aged 17-65 years) with histopathologically proved papillary endolymphatic sac tumors were retrospectively reviewed. Patients underwent CT (n = 18), MR imaging (n = 15), or angiography (n = 12). CT scans were evaluated for bone erosion and calcification; MR images, for signal intensity, enhancement patterns, and flow voids; and angiograms, for tumoral blood supply. RESULTS: All tumors were destructive and contained calcifications centered in the retrolabyrinthine region at CT. The MR imaging appearance varied with lesion size; 12 of 15 tumors showed increased signal intensity at T1-weighted imaging. The high-signal-intensity area was circumferential in lesions 3 cm or smaller and was scattered throughout the lesion in advanced tumors. Only tumors larger than 2 cm had flow voids. The blood supply arose predominantly from the external carotid artery. Large tumors had additional supply from the internal carotid and posterior circulation. CONCLUSION: Papillary endolymphatic sac tumors are destructive, hypervascular lesions that arise from the temporal bone retrolabyrinthine region. Increased signal intensity at unenhanced T1-weighted MR imaging is common and may help distinguish these lesions from more common, aggressive temporal bone tumors.

Adenocarcinoma↗
PubMed1997

Molecular analysis of the POU3F4 gene in patients with clinical and radiographic evidence of X-linked mixed deafness with perilymphatic gusher.

The molecular defect in some patients with X-linked mixed deafness with perilymphatic gusher at stapes surgery (DFN3) was recently attributed to mutations in the POU3F4 gene. In this manuscript we describe the molecular analysis of the POU3F4 gene in 5 patients with clinical and radiographic evidence of DFN3. Novel mutations were found in 2 of the 5 patients analyzed, while 3 had an entirely normal protein coding sequence. The fact that 3 of the 5 patients with clinical histories and radiographic abnormalities characteristic of X-linked mixed deafness with perilymphatic gusher displayed normal POU3F4 gene sequences supports the possibility that not all patients with the characteristic phenotype have involvement of the POU3F4 gene.

Base Sequence↗
PubMed1997

Endolymphatic sac obliteration for large vestibular aqueduct syndrome.

The objective of this study was to investigate the effects of endolymphatic sac obliteration for stabilization of progressive hearing loss in patients with the large vestibular aqueduct syndrome. This was a retrospective case review conducted at a private neurootologic office in a metropolitan area. Seven ears in six patients were subjected to surgery for obliteration of the endolymphatic sac in an effort to stabilize progressive hearing loss associated with the large vestibular aqueduct syndrome. The study population was composed of four boys and two girls 4-17 years of age. The large vestibular aqueduct was unilateral in two patients and bilateral in four patients. All seven ears demonstrated progressive sensorineural hearing loss preoperatively. Surgical tissue obliteration was performed via a transmastoid approach in seven ears. The main outcome measure was comparison of pre- and postoperative hearing levels and stability. Magnetic resonance imaging also was performed in all cases at least 6 months postoperatively to determine patency of the endolymphatic sac and vestibular aqueduct. Six of seven ears maintained stable hearing during the follow-up period, which ranged from 6 months to 6 years (mean 3.2 years). One patient showed continued progression of hearing loss postoperatively. All seven ears demonstrated continued obliteration on postoperative imaging studies. Surgical obliteration of the endolymphatic sac may stabilize hearing in patients with the large vestibular aqueduct syndrome and progressive hearing loss. These results support the theory of pressure or fluid reflux into the labyrinth as a cause of progressive hearing loss in these patients.

Adolescent↗
PubMed1997

A critical appraisal of the role of auditory brain stem response and magnetic resonance imaging in acoustic neuroma diagnosis.

Auditory brain stem response (ABR) is the most sensitive and specific audiometric test for acoustic neuroma (AN) detection. The ABR sensitivity rate increases with tumor size; consequently, small tumors have notably low ABR sensitivity for detection. However, larger tumors also can fail recognition by ABR testing. The ABR must be viewed on its own merits compared to magnetic resonance imaging studies for the diagnosis of AN. Where does ABR fit into the screening process for detecting AN today?

Cochlea↗
PubMed1994

Magnetic resonance imaging-enhancing lesions of the labyrinth and facial nerve. Clinical correlation.

OBJECTIVE: Gadolinium-enhanced magnetic resonance imaging (MRI) is useful in assessing inflammatory and neoplastic lesions of the labyrinth and facial nerve. The following cases demonstrate the ability of MRI to differentiate neoplastic from inflammatory lesions within the labyrinth. PATIENTS OR OTHER PARTICIPANTS: Nine patients were selected with enhancing lesions of the labyrinth and the facial nerve identified on MRI. INTERVENTION: Acyclovir and prednisone were prescribed for herpes zoster oticus; surgical removal of neoplastic lesions was performed. MAIN OUTCOME MEASURE: The hypothesis was developed in the course of clinical practice. No planned outcome was emphasized, as this article is based on the differential diagnoses of the cases reported. RESULTS: Gadolinium-enhanced MRI is useful in differentiating neoplastic from inflammatory lesions within the labyrinth. Axial and coronal 3-mm sections with gadolinium enhancement were necessary for identifying these lesions and particularly for recognizing the sharp enhancement of the neoplastic margin in contrast to the dull cloudy margins of an inflammatory lesion. CONCLUSIONS: The MRI differentiation of these lesions is helpful in providing appropriate medical and surgical management of neoplastic and inflammatory lesions of the labyrinth.

Adult↗
PubMed1994

Computed tomographic diagnosis of X-linked congenital mixed deafness, fixation of the stapedial footplate, and perilymphatic gusher.

Stapes surgery for fixed footplate associated with X-linked congenital mixed hearing loss usually results in a "gusher" and severe worsening of hearing. Four patients with X-linked deafness were diagnosed by the characteristic temporal bone computed tomography (CT) findings of enlarged internal auditory canal, hypoplasia of the cochlear base, absent bony modiolus, abnormal vestibular aqueduct, and enlarged labyrinthine facial nerve canal. Three patients were scanned after stapes surgery resulted in a gusher and, in two patients, severe worsening of their hearing loss. Stapes fenestration in the other patient was avoided by CT recognition of the dysplasia. The authors believe that young males presenting with congenital mixed hearing loss should be studied with temporal bone CT prior to middle ear exploration.

Adolescent↗
PubMed1990

Otic capsule dysplasia: clinical and CT findings.

Many congenital dysplasias of the osseous labyrinth have been identified. Differentiation of these dysplasias is essential for patient management. High-resolution computed tomography (CT) was used to identify individual malformations in 32 patients. Thirty patients had six previously described forms, while two patients had a form that has not previously been reported to our knowledge. Review of patient histories revealed clinical characteristics that were specific for certain forms of otic capsule dysplasia. CT enabled detailed analysis of each lesion and helped direct proper treatment of each patient. The characteristic CT appearance and clinical presentation of each form of dysplasia are presented.

Congenital Abnormalities↗
PubMed1988

Potential hearing loss resulting from MR imaging.

To determine if the loud noise generated by magnetic resonance (MR) imaging equipment is capable of inducing hearing loss, the hearing of 24 patients was tested before and after MR imaging. Fourteen patients were imaged without ear protection, and six (43%) suffered a temporary, mild loss of hearing (less than or equal to 15 dB at at least one frequency). Ten patients were imaged with ear protection, and only one experienced any hearing loss. Therefore, the noise generated by MR imagers may cause temporary hearing loss, and earplugs can prevent this loss. All threshold changes had returned to within 10 dB of baseline by 15 minutes after completion of the second audiometric test.

Adult↗
PubMed1987

Nutrition and metabolism in spaceflight.

The United States Space Station being planned for the 1990s will accommodate six or more crew members on 90-d flights in low earth orbit. Adequate nutrition will be essential for maintaining crew health, effectiveness and morale. Although much is known from prior space experience about in-flight metabolism, nutrition and associated food technology, important gaps in knowledge exist that need additional research, development and analysis to meet Space Station requirements. This paper is a synopsis of a report prepared by the Life Sciences Research Office (LSRO), FASEB, from a study of the nutritional and metabolic aspects of spaceflight. It reviews available data on the metabolic responses to spaceflight including extravehicular activity, physiological responses to microgravity that influence metabolism and energy needs, in-flight nutritional experience, space menus, food packaging, in-flight food service methodology, water supply and disposal of food wastes. The LSRO ad hoc Working Group identified critical gaps in knowledge and suggested corresponding research approaches for acquiring essential new data. The 38 research suggestions detailed in the report address in-flight metabolic needs, nutrient requirements, food systems and nutritional countermeasures.

Diet↗
PubMed1986

A review of the psychological aspects of space flight.

Instances of overt, serious functional impairment of space crews caused by adverse psychologic responses have not been scientifically documented. However, transient disorientation, spatial illusions, and visual disturbances as well as anomalous myopias, sleep disturbances, and instances of substandard performance have been described. Moreover, anecdotal information describes significant psychologic aberrations in space flight. Adequate scientific data are lacking for optimal psychological and psychophysiological methods for crew selection, training, and performance evaluation, for identifying key psychosocial factors for crew compatibility, cohesiveness, and productivity, and for determining the effects of space flight on perceptual, intellectual, and motor skills. The ad hoc Working Group, convened to review psychological aspects of space flight, favored establishment of a comprehensive research and development program to address the deficiencies identified in the study.

Behavior↗
PubMed1986

Influence of space flight on red blood cells.

Losses of red blood cell mass (RCM) averaging 10-15% have been observed consistently in astronauts after space flight; postflight recovery of RCM requires 4-6 wk. Although apparently not harmful to the health and effectiveness of crews during uncomplicated flights, decreased RCM could compromise health and performance in the event of illness, injury, or partial malfunction of the life support system. Whether the loss of RCM would worsen or stabilize in missions longer than 7 months is unknown. As a biological response, it is a significant, predictable reaction whose etiology, biological mechanisms, and potential operational significance are inadequately defined. Weightlessness is probably the primary cause; however, contributory factors may include hypokinesia/hypodynamia, bone loss, muscle atrophy, altered hemodynamics, stress, and metabolic disturbances. Space medical specialists consider other possible influences such as hypoxia, hypobaria, radiation, toxic contaminants, and launch and reentry accelerations as less likely factors. Because the data base on loss of RCM is insufficient for the National Aeronautics and Space Administration's space medical responsibilities, the Life Sciences Research Office ad hoc Working Group on Space Anemia suggested research approaches ranging form fundamental topics such as utilization of erythropoietin and oxygen in target organs and cell-cell interactions, through possible splenic and vascular dysfunctions, metabolic disturbances, and inhibitors of erythropoiesis, to methodology and models.

Body Weight↗