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Biomedical subjects

A Valavanis

Publications and source records attributed to A Valavanis.

At least 91 records · Page 5Linked to original sources
PubMed1988

Pelizaeus-Merzbacher disease: identification of heterozygotes with magnetic resonance imaging?

We report magnetic resonance imaging (MRI) findings in two obligate and four facultative carriers for the "classical" X-linked form of Pelizaeus-Merzbacher disease (PMD). In T2-weighted images MR revealed bilateral multiple areas with signal hyperintensity in the periventricular and subcortical white matter in five women. Until suitable and closely linked DNA probes are found for heterozygote determination, MRI may represent a suitable means for carrier detection in individuals at risk in PMD families.

Brain↗
PubMed1988

[NMR tomographic diagnosis of microadenomas of the hypophysis: a comparison of MRT, CT and operation].

The MR and CT findings of 24 surgically verified cases with clinical and neuroradiological evidence for pituitary microadenomas were compared. In 18 patients the preoperative diagnosis was surgically confirmed. In 6 cases the preoperative diagnosis proved to be wrong at operation. In 18 cases with confirmed diagnosis MR proved more sensitive than CT, whereas in the 6 cases with wrong diagnosis both methods proved to be of equal sensitivity. It is concluded that MR is superior to CT for the evaluation of pituitary microadenomas, provided that high-field and special examination techniques including thin, overlapping sections and enhancement with GD-DTPA are used.

Adenoma↗
PubMed1988

[Vascular cause of hemianopsia].

Hemianopsia of vascular origin can be caused by diseases in the carotid circulation (optic tract, proximal third of the optic radiation), as well as in the vertebrobasilar arterial system (middle and distal thirds of the optic tract, striate area/calcarina). Hemianopsia of ischemic origin must be differentiated from hemianopia in the presence of an enlarging aneurysm, a space-occupying intracranial lesion (hemorrhage, neoplasia), and inflammatory disease, occasionally in metabolic disorders. To detect the exact cause of a hemianopia in a given patient, recording of the patient's precise history and clinical-neurological, clinical-ophthalmological, and clinical-internal examinations are mandatory, as well as additional diagnostic procedures. Of these, the most important are neurovascular ultrasound examinations (extracranial, transcranial and B-mode/duplex Doppler examination), CT and MRI scans, and cardiological examination with echocardiography. The choice of these additional and costly examinations and their sequence in the diagnostic work-up in a given patient has to be adapted to the patient.

Aged↗
PubMed1988

Superselective embolization for intractable epistaxis: experiences with 19 patients.

Twenty-eight patients with intractable nose-bleeds were treated with either superselective embolization and/or surgery between 1983 and 1986. The follow-up time ranged between 6 months and 3 years. The results for the 2 groups were similar. The success rate for embolization was 74% and that for surgery 65%. Complications however, were more frequent after embolization, (i.e. facial nerve paralysis, soft tissue necrosis). Surgery is recommended as the treatment of choice in intractable nose-bleeds, until therapeutic embolization techniques have been further refined and the complication rate reduced.

Adult↗
PubMed1988

Lower cranial nerve palsies due to internal carotid dissection.

A 41-year-old man experienced intense headache and neck pain, bruits, and a complete unilateral cranial nerve palsy IX-XII (Collet-Sicard syndrome) after a trivial back trauma. Magnetic resonance imaging and angiography demonstrated features of bilateral internal carotid artery dissection with aneurysm formation at the base of the skull compressing the nerves at the level of the jugular foramen. Severe dysphagia persisted for 1 month but rapidly improved after occlusion of the carotid aneurysm with a detachable balloon.

Adult↗
PubMed1988

Brain tumors in children with von Recklinghausen neurofibromatosis.

We determined the frequency of brain tumors in a series of 133 children (18 years of age or younger) with von Recklinghausen neurofibromatosis who were patients at the Children's Hospital of Zurich from 1971 to 1987. Twenty-four patients (18%) were found to have intraorbital or intracranial tumors. Twenty patients (15%) had an optic-pathway glioma (OPG), including 15 (11%) with only an OPG and 5 (4%) with both an OPG and a tumor in the posterior fossa or brainstem. Another 4 patients (3%) had a tumor outside of the optic pathways. In most cases, magnetic resonance imaging was superior to computerized tomography in demonstrating these lesions. The results of this survey are comparable to those of other published reports.

Adolescent↗
PubMed1987

[Use of high performance nuclear magnetic resonance tomography in neuroradiology. Experience with 2,000 studies].

Experience with 2000 MRI's in the field of neuroradiology is summarized. The advantages and limits of this new modality are discussed in diseases of the brain and the spinal cord. MRI is superior to CT in detecting small lesions. Spots of demyelinization can be readily shown and the extent of a tumor can be assessed by cuts in three directions. CT is complementary to MRI in differentiating the nature of lesions. Emergency cases should be investigated with CT.

Adolescent↗
PubMed1987

Growth-mechanism of giant intracranial aneurysms; demonstration by CT and MR imaging.

In four cases of giant intracranial aneurysm, CT demonstrated a hyperdense open-, or closed-ring structure at the periphery of the aneurysm. Surgery in two of the cases demonstrated that this peripheral hyperdensity represents fresh clot inside the wall of the thrombosed mass. An analogy is established between giant intracranial aneurysms, chronic subdural hematomas and growing encapsulated intracerebral hematomas. The common feature of the three entities is slow growth by recurrent hemorrhages into the lesion. It is proven that growth of chronic subdural hematomas and of growing encapsulated hematomas is related to recurrent hemorrhage from capillaries sprouting within the membrane of the lesion. The highly vascularized membranous wall of a giant intracranial aneurysm seems to behave like the membrane of a chronic subdural hematoma. It is suggested that the giant intracranial aneurysm grows by recurrent hemorrhage into its wall and behaves like growing encapsulated hematomas.

Adult↗
PubMed1986

Temporal bone fractures and their complications. Examination with high resolution CT.

A total of 84 patients with 89 fractures of the temporal bone were examined with high resolution CT (HRCT) a few hours to 21 months after the initial trauma. Axial HRCT disclosed 63 longitudinal, 13 transverse, 10 complex and 3 atypical fractures. The diagnosis of a temporal bone fracture was established by axial HRCT in almost every case. However, for the precise topographic analysis of the course of the fracture, additional coronal HRCT proved helpful. The most common, surgically treatable complication of temporal bone fracture is disruption of the ossicular chain. Twenty-three such lesions were demonstrated by combined axial and coronal HRCT; 22 lesions of the facial canal could be demonstrated in 27 patients presenting with facial nerve palsy. The most common site of injury to the facial canal was the region of the geniculate ganglion. The only life-threatening complication of a temporal fracture may be otorhinoliquorrhea. This was present in 9 cases. The most common site of leakage identified was the tegmen tympani. With Metrizamide-HRCT precise localisation of the dural laceration was possible in 7 of these 9 cases.

Adolescent↗
PubMed1986

Corticotrophin-releasing factor-test used with bilateral, simultaneous inferior petrosal sinus blood-sampling for the diagnosis of pituitary-dependent Cushing's disease.

Bilateral, simultaneous inferior petrosal sinus blood-sampling for determinations of ACTH levels has improved the ability to establish a differential diagnosis of Cushing's disease, particularly in patients whose endocrinological studies show equivocal results and whose computed tomography scans yield negative or inconclusive findings. Individual anatomical variations in the configuration of the sinus and insignificant differences between the ACTH levels obtained from its two sides may be a problem. Seven patients with clinically and biochemically typical Cushing's disease and one with atypical Cushing's disease were examined. An alternative approach for catheterization of the inferior petrosal sinus through the deep vertebral venous plexus was used in those patients who did not have direct connections between the sinus and the internal jugular vein. In two of the eight patients, only ACTH secretion stimulated with corticotrophin-releasing factor could unmask a significant difference between the ACTH levels on the two sides which was not obvious from the basal ACTH levels. Beta-lipotrophin values showed a behaviour similar to that of ACTH values, but because of a slower turn-over rate, the CRF-induced peaks were better visible. The aetiology of Cushing's disease was established from the results of this examination and corresponded with the surgical findings in this series, with the exception of one in which the patient had a highly atypical form of the disease. The abnormal ACTH source was found later to be a thymus carcinoid.

Adenoma↗
PubMed1986

Classification of brain arteriovenous malformation nidus by magnetic resonance imaging.

T1 and T2 weighted high field magnetic resonance imaging (MRI), computed tomography (CT) and intraarterial digital subtraction angiography (DSA) were performed in 30 patients with brain arteriovenous malformations. T2 weighted MR sequences proved superior to both CT and intraarterial DSA for displaying the configuration of the nidus, its intrinsic morphology and the state of the surrounding parenchyma. As was evidenced by histologic examination of the nidus in 18 cases, high-signal intensity of the intervening or surrounding parenchyma on T2 weighted images indicates gliosis. Preliminary experience with 5 cases suggests that gliosis of the intervening or surrounding brain parenchyma may make it safer to attempt embolization in these patients. Based on these parameters, we introduce a classification of brain AVM nidus.

Adolescent↗