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Biomedical subjects

A Valavanis

Publications and source records attributed to A Valavanis.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Neuroradiologic exploration of cerebral arteriovenous malformations].

MR and superselective neuroangiographic investigation of 223 patients with cerebral arteriovenous malformations (AVMs) were retrospectively analyzed with regard to topography, morphology, vascular architecture and signs of increased bleeding risk. MR proved highly efficient in defining the topography of the lesion and highly sensitive in detecting AVM-induced parenchymal changes. Superselective neuroangiography enables complete endovascular mapping of the AVM and provides relevant information on its intrinsic vascular composition. In addition, this method gives new insights into the venous drainage patterns and the unexpectedly high incidence of associated venous changes. MR-neuroangiographic correlation in each individual case forms the basis for any therapeutic decision and treatment planning. In concordance with previous statements in the literature this study disclosed that the presence of stenotic draining veins or related aneurysms on feeding arteries represents an increased risk for AVM rupture.

Adolescent↗
PubMed1991

[MRT morphology and classification of cerebral cavernomas].

An MRI review of 54 histologically verified cavernomas allowed the introduction of a system classifying this cavernous venous malformation into four types: type I (20%) corresponds to the classic morphology of a cavernoma without hemorrhage; type II (67%) is characterized by intralesional hemorrhage; type III (11%) is associated with an extra-lesional hemorrhage that compresses or displaces the cavernoma itself; and type IV (2%) corresponds to a totally calcified cavernoma. These variable cavernoma types represent different possible stages of the natural evolution of a cavernoma and limit the differential diagnosis, especially in the group of occult or cryptic cerebral vascular malformations.

Adolescent↗
PubMed1990

[Injuries of the large brain-feeding arteries].

Among 2923 severely injured patients in the period 1980-1988, 17 had injuries or large supraaortic arteries. The incidence was 0.58%, with an overall mortality of 53%. In 75% of survivors there was a persistent neurological deficit. We treated 5 penetrating (A. carotis 4, A. vertebralis 1) and 12 nonpenetrating (A. carotis 11, A. vertebralis 1) injuries. In all penetrating carotid injuries (4) repair was performed on admission and mortality was 50%; 1 of 2 survivors has postoperative hemiparesis. Localization of nonpenetrating carotid injuries (11) was intrathoracic (2), in the neck (7) and intracranial (2). Main complication of nonpenetrating extracranial carotid injuries is neurological deficit (7/9) due to thrombosis (3) or stenosis (4) with embolism (2). Surgery was performed in 3 cases comprising pseudoaneurysm in 2 and concomitant aortic rupture in 1. Mortality was 44%, and 80% of survivors had persistent neurological deficits. Extracranial carotid injuries (n = 13) carried a mortality rate of 83% in occluded and 29% in nonoccluded vessels (p less than 0.05). Location of carotid injury in the neck (n = 11) carried a mortality of 55%, and intracranial (n = 2) of 100% respectively. Duplex-Doppler scanning of carotid arteries is a safe, noninvasive method which is essential in blunt carotid artery trauma. Prognosis is dependent upon the size of cerebral infarction. Once neurologic deficit has been established for more than 24 hours, reconstruction of the artery should be postponed and performed only for complications (pseudoaneurysm or embolization). Clamping of arteries without hypothermic circulatory arrest or shunt should be avoided. The danger of rupture in dissection and pseudoaneurysm is slight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

MRI in Cockayne syndrome type I.

MRI findings are reported from two patients with Cockayne syndrome (CS) type I, aged 11 and 37 years. Changes were compatible with diffuse white matter hypomyelination. Basal ganglia calcification was present in both, marked cerebellar atrophy in the older patient. MRI may support the diagnosis of CS in the appropriate clinical context. The view that CS is a dysmyelinating disorder is further substantiated.

Adult↗
PubMed1989

Neurohypophyseal ectopy in growth hormone insufficiency.

Nuclear magnetic resonance imaging of the hypothalamohypophyseal tract allows the detection and identification of ectopic posterior pituitary lobe tissue by its characteristic high signal intensity. We found this anomaly in 2 boys with growth hormone insufficiency. Neurohypophyseal ectopy may be misdiagnosed as subhypothalamic tumor and such patients risk to be subjected to unnecessary neurosurgery.

Child↗
PubMed1989

The surgical management of extensive nasopharyngeal angiofibromas with the infratemporal fossa approach.

Large juvenile nasopharyngeal angiofibromas are a therapeutic challenge because of their relation to major vasculature and cranial nerves at the base of the skull, and their propensity for recurrence. A classification scheme based on the growth pattern of this tumor is proposed to help the surgeon choose a procedure to access this lesion. This report describes the results obtained with the surgical removal of large (class III and IV) nasopharyngeal angiofibromas through the infratemporal fossa approach. Fourteen patients were cured and one individual developed a recurrence which was totally removed at a second procedure. Surgical morbidity was minimal and there was no mortality. Radiation therapy was necessary in only one patient who had tumor infiltration of the cavernous sinus.

Adolescent↗
PubMed1989

Management of the internal carotid artery in surgery of the skull base.

Management of the internal carotid artery in skull-base surgery can be a difficult problem when disease involves this vessel or resection is anatomically limited by it. The recent radiologic development of the detachable balloon catheter has permitted occlusion of the internal carotid artery in a controlled setting prior to any surgical procedure. An obvious prerequisite to using this technique is the demonstration of adequate collateral blood flow to the brain. Patients are evaluated with arteriography and temporary arterial balloon occlusion while monitoring physical signs and electroencephalography (EEG). Although usually performed preoperatively, internal carotid artery occlusion is needed intraoperatively on occasion. This essential adjuvant technique for the skull-base surgeon will be detailed along with its indications and limitations in 24 patients.

Carotid Artery, Internal↗
PubMed1989

Intracranial abnormalities associated with facial plexiform neurofibromas in neurofibromatosis type 1.

From 1975 to 1988 seventeen patients with neurofibromatosis type 1 and a disfiguring facial plexiform neurofibroma (FPN) were investigated. The FPN was left-sided in 13 patients. It was orbital/periorbital in 4, lower facial in 7 and involved the whole face in 6 subjects. Neuroimaging (n = 13) revealed a tumor (of optic pathways or basal ganglia) in 8, an ipsilateral middle cranial fossa arachnoid cyst in 2, multiple areas of high signal intensity (in T2-weighted magnetic resonance imaging) in 1, and normal findings in 2 patients. In NF-1 patients with FPN there seems to be a high incidence of intracranial tumors and possibly of arachnoid cysts. Our observation has to be confirmed in a larger patient series.

Adolescent↗
PubMed1989

Neural tolerance of iotrolan 300 in ascending cervical myelography: results of a multicenter study.

This study examined the opacification, dose, and tolerance of iotrolan 300 on 231 patients in ascending cervical myelography. The contrast was rated good in 188 (81.4%) of the cases and satisfactory in 40 (17.3%) of the cases. The contrast was poor in only three (1.3%) cases. In 152 patients a dose of 10 ml or less of iotrolan 300 was administered. A good contrast quality was obtained in 84.2% of all examinations. From a total of 231 patients, 146 exhibited no concomitant effects. The intensity of the headache and neck ache was recorded by the patients themselves by means of an analog scale. The frequency and degree of the postmyelographic complaints did not increase with higher doses, i.e., they were not dose dependent. Neurologic irritation, in the form of radicular symptoms, appeared in only 2 of 231 examinations. These data demonstrate that iotrolan 300 is excellent for use in ascending cervical myelography.

Adult↗
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↗