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Biomedical subjects

A G Osborn

Publications and source records attributed to A G Osborn.

At least 19 recordsLinked to original sources
PubMed1995

Thrombosis of the deep venous drainage of the brain in adults. Analysis of seven cases with review of the literature.

OBJECTIVES: To characterize the clinical, radiographic, and pathologic findings in thrombosis of the deep venous drainage of the brain. To highlight clinical and radiographic findings that may lead to the diagnosis of disease and distinguish it from dural sinus thrombosis. To review the published literature on this disorder. DESIGN: Retrospective review of the medical and radiographic records of seven patients from three institutions over the past 10 years. Review of the English language literature from 1971 to the present. RESULTS: All seven patients had risk factors for cerebral venous thrombosis. Five patients presented with a short, rapidly progressing course characterized by headache, nausea and vomiting, and decline in level of consciousness. All five patients died or were rendered severely disabled. Computed tomographic scans, magnetic resonance imaging, and magnetic resonance angiography showed findings associated with deep cerebral vein thrombosis in three of four, in five of five, and in three of three patients, respectively. Transfemoral catheter angiography was diagnostic in two of two patients. Twenty-one reported cases of deep cerebral venous thrombosis were identified in the literature. CONCLUSIONS: When the two populations are combined and compared with large series of patients with dural sinus thrombosis, patients with deep venous system thrombosis are more commonly women, tend to present with a more rapidly declining time course, altered consciousness, and long tract signs. Death or long-term sequelae are far more likely to occur in internal cerebral vein thrombosis than with dural sinus thrombosis. Unenhanced computed tomography can demonstrate findings that are strongly suggestive of the diagnosis. Magnetic resonance imaging and magnetic resonance angiography are confirmatory. Angiography may still be necessary when the diagnosis is not clear.

Adolescent↗
PubMed1995

The cerebral ventricles: a computer-based interactive tutorial.

The computer-based tutorial, "The Cerebral Ventricles," enables the user to review the anatomy, imaging, and common pathologic conditions of the human cerebral ventricular system. The program runs on a workstation that includes a laser videodisk player and a videodisk with 21,000 still images plus motion sequences. By using a mouse to select specific portions of the anatomic diagram depicting the ventricles, the user can review different planes of normal gross anatomy, corresponding computed tomographic and magnetic resonance images of normal anatomy, images of gross specimens of different pathologic entities, and corresponding radiologic images. The motion sequences portion of the program shows reconstructed three-dimensional images of ventricular anatomy and helps the user gain a greater understanding of the complex anatomy as seen from all angles. Subprograms provide more detailed information about anatomic relationships, disease entities, and bibliographic references. "The Cerebral Ventricles" assists radiologists in gaining a greater understanding of the ventricles so that an appropriate differential diagnosis of an intraventricular lesion can be offered when such masses are encountered in clinical practice.

Cerebral Ventricles↗
PubMed1994

Safety and efficacy of iopromide in cerebral arteriography.

RATIONALE AND OBJECTIVES: Iopromide is a new nonionic monomeric contrast medium for cerebral arteriography. This agent has been approved for sale in over 45 countries; however, it is still undergoing clinical review in the United States. This study evaluated the safety and efficacy of iopromide in comparison with two other nonionic contrast media. METHODS: A total of 173 patients participated in the study, which was prospective, double-blind, and randomized. In two centers, patients received iopromide or iohexol; in the other three centers, patients received iopromide or iopamidol. Adverse events were monitored by investigators, and efficacy was evaluated by grading the radiographic images. RESULTS: Most adverse events were mild or moderate in severity; all resolved completely. Twenty-one percent of patients given iopromide were reported to have a drug-related adverse event, versus 44% of patients given a comparator. No statistically significant difference emerged between iopromide and the comparators with regard to efficacy. CONCLUSIONS: These study results indicate that iopromide is a safe and effective contrast medium for cerebral angiography.

Cerebral Angiography↗
PubMed1994

Bithalamic hyperintensity on T2-weighted MR: vascular causes and evaluation with MR angiography.

PURPOSE: To determine whether MR angiography can be used to differentiate between the two vascular causes of bithalamic hyperintensity on T2-weighted MR images: "top of the basilar" artery occlusion and deep cerebral vein thrombosis. METHODS: A retrospective review identified six patients with bithalamic T2 hyperintensity of vascular causes. MR angiography was performed in four patients, MR angiography and conventional angiography in one patient, and conventional angiography in one patient. Data pertaining to clinical presentation and hospital course were collected. MR angiographic techniques were multislab overlapping three-dimensional time-of-flight, 2-D time-of-flight, and 2-D phase-contrast. RESULTS: Three cases of top of the basilar artery occlusion and three cases of deep cerebral vein thrombosis were recognized. In all cases, T2 hyperintensity in a vascular distribution suggested cerebral occlusive disease. Infarction involving the thalami and basal ganglia was present in two cases of deep cerebral vein thrombosis. Infarction of the thalami, mesodiencephalic region, and cerebellar hemispheres was present in two cases of basilar artery occlusion. Bithalamic infarction alone was seen in one case of deep cerebral vein thrombosis and one case of basilar artery occlusion. In the five cases in which MR angiography was used, this technique accurately distinguished the vessels involved (arterial or venous). CONCLUSION: MR angiography is a useful adjunct to MR imaging in the evaluation of bithalamic T2 hyperintensity. It does help distinguish between the two vascular causes: top of basilar artery occlusion and deep cerebral vein thrombosis.

Adult↗
PubMed1990

Multiple sclerosis in adolescents: CT and MR findings.

The MR and CT findings in 12 adolescents with multiple sclerosis were compared with reported findings in adults. The adolescent group showed a more striking female predominance, more severe disease characteristics, and more frequent infratentorial involvement. Cortical atrophy and abnormal iron accumulation in the basal ganglia were uncommon in the adolescents. Neither group demonstrated a correlation between symptom severity and either extent or location of disease as delineated by MR imaging. MR was more sensitive than CT in detecting demyelinating plaques.

Adolescent↗
PubMed1990

Multiple sclerosis in adolescents: CT and MR findings.

The MR and CT findings in 12 adolescents with multiple sclerosis were compared with reported findings in adults. The adolescent group showed a more striking female predominance, more severe disease characteristics, and more frequent infratentorial involvement. Cortical atrophy and abnormal iron accumulation in the basal ganglia were uncommon in the adolescents. Neither group demonstrated a correlation between symptom severity and either extent or location of disease as delineated by MR imaging. MR was more sensitive than CT in detecting demyelinating plaques.

Adolescent↗
PubMed1989

Computed tomographic features of nonthyroid extraocular muscle enlargement.

While Graves' disease is the most common cause of enlarged extraocular muscles, other disorders may masquerade as dysthyroid orbitopathy. The authors conducted a retrospective analysis of the computed tomographic (CT) scans of 60 patients with nonthyroid enlarged extraocular muscles to establish the differential radiographic features of these disorders. The diseases were classified as primary or local invasion of neoplasm (26%), inflammatory (25%), metastatic tumor (20%), vascular (13%), infection (12%), and acromegaly (3%). The inflammatory cases demonstrated more bilateral involvement (40%) and less involvement of the tendons (47%) than previously appreciated. The relatively high incidence of these features in the inflammatory group is important because both features have been considered pathognomonic for Graves' disease. Primary and metastatic tumors produced a nodular muscle enlargement with sharp borders and frequent bone changes. Certain tumors showed a predilection for certain muscle groups. Vascular cases involved multiple unilateral muscles and usually enlarged the superior ophthalmic vein. Infectious cases usually demonstrated fusiform muscle enlargement with blurred margins, whereas acromegaly caused moderate enlargement of all recti. Although certain diagnosis-specific radiographic patterns are described, no feature is pathognomonic for any disorder.

Diagnosis, Differential↗
PubMed1989

Efficacy, safety, and tolerability of ioversol in intra-arterial digital subtraction angiography.

Twenty-two women and 18 men undergoing intra-arterial digital subtraction angiography were enrolled in an open-label, noncomparative study to assess the efficacy, safety, and patient tolerance of the contrast medium ioversol. The quality of radiographs generated was excellent in 60.0% of the studies, diagnostic in 37.5%, and nondiagnostic in 2.5%. There were no clinically significant drug-related changes in vital signs or laboratory tests among the patients, and no drug-related adverse effects were reported. Heat and pain related to injection of ioversol were graded on a four-point scale, with 0 indicating none and 3 indicating severe. The average scores were 1.3 for heat and 0.1 for pain. In this study, ioversol was a safe and effective contrast medium for angiography and was associated with a low incidence of patient discomfort.

Adult↗
PubMed1989

The radiologic assessment of trigeminal neuropathy.

The clinical and radiologic records of 76 patients with trigeminal neuropathy and an abnormal imaging study (CT and/or MR) were analyzed retrospectively. The trigeminal nerve (cranial nerve V) was divided into proximal (brainstem, preganglionic, gasserian ganglion, and cavernous sinus) and distal (extracranial V1, V2, and V3) segments. Lesions were organized according to segments and correlated with the type and distribution of clinical symptoms or signs. The purpose of the study was to (1) determine the efficacy of clinical localization of cranial nerve V lesions, (2) compare CT and MR for cranial nerve V imaging, (3) develop an MR protocol for effective cranial nerve V imaging, and (4) construct a differential diagnosis by anatomic segment for lesions of cranial nerve V. Clinical localization was found to be extremely inaccurate. CT was not as sensitive as MR for lesions involving the basal cisterns and skull base and will not detect the most common brainstem lesions (small infarcts and multiple sclerosis plaques). The MR protocol developed does not rely heavily on clinical localization. On the basis of lesions found in this series, a differential diagnosis by segment was developed. Patients with cranial nerve V symptoms should undergo MR imaging according to the protocol provided in this article. CT is not as effective as MR in imaging some cranial nerve V segments. Clinical localization is inaccurate.

Adolescent↗
PubMed1988

Normal and diseased acoustic pathway: evaluation with MR imaging.

To evaluate the use of magnetic resonance (MR) imaging in the assessment of the normal and diseased acoustic pathway, 176 patients with sensorineural hearing loss (SNHL) underwent MR imaging. In 65 patients an abnormality was detected at MR; in 50 of the 65, the abnormality was believed to be definitely or possibly responsible for the SNHL. In 47% of cases, the cochlea (3%) or vestibulocochlear nerve (44%) was involved by primary lesions. Computed tomography (CT) was performed, in addition to MR, in 25 patients in whom an abnormality was seen at MR; in 18 (72%), MR was believed to be superior to CT for lesion display. A review of 30 normal MR images of the cerebellopontine angle and brain disclosed that the cochlea was directly imaged in all cases with the use of short or long repetition times (TRs). The vestibulocochlear nerve was directly seen in 77% of cases with the use of short TR imaging. In conclusion, MR imaging delineates the acoustic pathway more clearly than does CT and is recommended for the examination of abnormalities in this region.

Adolescent↗
PubMed1988

Disorders of histogenesis: the neurocutaneous syndromes.

MRI is uniquely suited to demonstration of the wide array of brain abnormalities in the neurocutaneous syndromes, due to its ability to provide previously unattainable neuroanatomic information on T1-weighted images and its extreme sensitivity to changes in water content of brain structures on T2-weighted images. It therefore is assisting physicians in better understanding the full expression of these heritable disorders, such as the extent of optic pathway involvement in optic nerve glioma, the presence of hamartomas in TS, and abnormal myelination in Sturge-Weber syndrome. It may in the future have a role in genetic counseling in TS. CT provides complimentary information to MRI in the evaluation of intracranial pathology in the neurocutaneous syndromes. Bone abnormalities and abnormal states of calcification may at times still be better evaluated by CT. Additionally, CT is a less expensive means of following existent abnormalities over time.

Angiomatosis↗
PubMed1987

Ranulas and their mimics: CT evaluation.

The spectrum of computed tomographic (CT) findings in ten patients with pathologically proved simple and diving ranulas is reviewed. These retention cysts originate within the sublingual space from obstruction of the sublingual or minor salivary glands; when they enlarge, the cysts herniate to involve the submandibular and inferior parapharyngeal spaces (the so-called diving or plunging ranula). CT findings in 38 additional patients with a variety of cystic lesions in the floor of the mouth are contrasted with findings in cases of ranulas. The relevant anatomy is reviewed. This experience indicates that a unilocular, cystic mass emanating from the sublingual space and extending into the adjacent submandibular and/or inferior parapharyngeal spaces can be considered a diving ranula in virtually all cases. A unilocular, cystic mass entirely within the sublingual space can be considered a simple ranula in most instances, although absolute distinction between a simple ranula and an epidermoid cyst cannot be made radiographically.

Diagnosis, Differential↗
PubMed1987

Cochlear implant candidates: assessment with CT and MR imaging.

Eighty-seven patients with severe to profound hearing loss were evaluated for possible placement of a multichannel cochlear implant hearing device. After initial clinical screening, 42 patients underwent computed tomographic (CT) examination. Five of these patients were also examined with magnetic resonance (MR) imaging. Twenty-two patients received implants. CT of the middle and inner ear was normal in 24 patients (57.1%) and showed labyrinthine ossification in 12 (28.6%), cochlear or fenestral otosclerosis (or both) in four (9.5%), and congenital cochlear malformation in two (4.8%). The information provided by CT was used to (a) exclude patients in whom multichannel cochlear implantation would most likely be unsuccessful (owing to obliterative labyrinthine ossification, or congenital cochlear malformation, severe cochlear, or fenestral otosclerosis), (b) help select the best ear for implantation, and (c) provide a preoperative picture of normal variants and avoidable surgical pitfalls. MR experience is limited but assessment of the size of the cochlear nerve and the membranous labyrinth is possible with this modality and may provide additional information in the evaluation of these patients.

Adolescent↗
PubMed1987

Vagal neuropathy: evaluation with CT and MR imaging.

The vagus nerve, as a result of its protracted course from the brain stem to the abdomen, can present a difficult imaging problem when it is compromised by a clinically occult lesion. The clinical and radiologic records of 48 patients with suspected vagus nerve dysfunction were reviewed to derive an efficient and effective approach to imaging this patient population. An imaging algorithm is proposed in which vagal neuropathies are divided both clinically and radiologically into proximal and distal categories. Proximal vagal lesions are part of a cranial neuropathy complex and have associated oropharyngeal signs and symptoms (e.g., abnormal gag reflex, uvular deviation). Distal vagal lesions occur as an isolated paralysis of the vagus nerve with no symptoms or signs referable to the oropharynx. Either computed tomography (CT) or magnetic resonance imaging can be used to diagnose proximal or distal lesions. However, CT will be insensitive in the detection of the more cephalic proximal lesions, especially those in the brain stem, basal cisterns, and skull base.

Algorithms↗
PubMed1987

CT patterns of facet fracture dislocations in the thoracolumbar region.

Thoracolumbar facets are not as commonly dislocated as are those of the cervical spine. It is, however, crucial to make an early and accurate diagnosis of thoracolumbar facet dislocation since the injury may be unstable and require reduction and internal fixation. This paper presents three major CT patterns of thoracolumbar facet fracture dislocation. The first represents anterior subluxation of the vertebral body with anteriorly locked facets. The second is a lateral vertebral body subluxation with laterally locked facets. The third is an acute kyphosis with little vertebral body subluxation but superiorly dislocated facets. Since the vertebral body subluxation may be missed on axial CT images, these facet-dislocation patterns should be recognized by identifying the paired superior and inferior facets and establishing their congruency. Identification of the facets is accomplished by their orientation with respect to the vertebral body (superior facets are directed posteromedially and inferior facets are directed anterolaterally) as well as by the shape of the articular surface (superior facet articular surface is concave, inferior facet articular surface is flat or convex).

Fractures, Bone↗