Search PubMed⌕ Search

Biomedical subjects

A Valavanis

Publications and source records attributed to A Valavanis.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1986

[CT diagnosis of traumatic injuries of the temporal bone].

73 patients with 78 fractures of the temporal bone were examined by high-resolution computed tomography (CT). Analysis of the CT-findings disclosed 55 longitudinal, 12 transverse, 8 combined and 3 atypical fractures. For determination of the fracture type, axial sections usually proved sufficient. However, for precise topographic analysis of the course of the fracture additional coronal sections were necessary in most of the cases. In the radiologic evaluation of temporal bone fractures detection of associated complications is clinically important since these can be surgically corrected. In this series 20 lesions of the ossicular chain were demonstrated by the combined performance of axial and coronal sections and sagittal reformations. High resolution CT demonstrated a lesion of the facial nerve canal in 79% of a patient group with traumatic facial nerve palsy. The most frequent site of injury of the facial nerve canal was the region of the geniculate ganglion. With the use of metrizamide-CT-cisternography the site of cerebrospinal fluid leakage was demonstrated in 7 of 9 patients with liquorrhea. It is concluded that high-resolution CT is the radiologic method of choice for both topographic evaluation of temporal bone fractures and detection and precise localization of fracture-complications.

Adolescent↗
PubMed1984

[Cerebrovascular Doppler studies--a potent tool in neuroangiology].

Cerebrovascular disease is caused in about half of the patients by obstructions in the extracranial cerebral arteries. In the other half, stroke is due in roughly equal proportions to obstructive intracranial arterial lesions, emboli from the heart, or intracranial hemorrhage. Half of the patients with major ischemic stroke had previous warning signs in the form of transient ischemic attacks (TIA), reversible ischemic neurologic deficit (RIND) or infarction with only minor residual deficit not limiting daily activity, professional skills, and quality of life. Investigation of patients with warning signs of impending ischemic stroke is mandatory in order to prevent other events with possible major disability, but also, in patients with acute infarction, in order to choose the appropriate early therapy and rehabilitation. Routine cerebrovascular Doppler examination based on continuous-wave equipment has been successfully used to detect extracranial arterial obstructions. In the authors' experience of more than 12000 patients this noninvasive diagnostic tool makes it possible-in conjunction with the patient's history and the results of the clinical examination-to differentiate between obstructions needing surgery and lesions small enough to warrant medical treatment. Minor lesions which do not disturb blood flow locally, or accessible to available continuous-wave Doppler equipment, can be detected with real-time ultrasound imaging systems, i.e. B-mode or B-mode-Doppler-(duplex) systems in addition to routine Doppler examination. These complex systems also serve to follow-up patients with minor lesions which are not treated, or treated medically, in regard to deterioration, possible invariability, or even regression of a lesion.

Adult↗