Biomedical subjects

V Vladyka

Publications and source records attributed to V Vladyka.

At least 37 records · Page 2Linked to original sources

PubMed1995

[The Leksell gamma knife--a radiosurgery instrument].

Radiosurgery means delivery of a single dose of precisely directed ionizing radiation to a small volume of intracranial tissue without opening of the skull after the stereotactic localisation of the preselected target. Leksell gamma knife is a device enabling to deliver focused radiation toward the intracranial volume with the gamma rays emitted by the 201 sources of the isotope Co 60. Suitable indications for radiosurgery are cerebral arteriovenous malformations, benign and malignant intracranial tumors and functional diseases of the brain.

Brain↗

PubMed1995

[Radiosurgical treatment of meningioma with the Leksell gamma knife].

BACKGROUND: Up to the present time radical microsurgery of the tumour was considered the most satisfactory treatment. Now an ever more important part in the treatment of these tumours is played by radiosurgery. It involves minimal surgical stress, a minimal rate of complications and minimal change of lifestyle during the postoperative period. The objective of the submitted work was to evaluate the authors' results with the use of Leksell's gamma knife. METHODS AND RESULTS: In 1992-1994 48 patients with meningiomas were indicated for treatment with a gamma knife. The group comprised 12 men (25%) and 36 women (75%) aged 18-73 years (mean age 52.8 years which did not differ significantly in the two groups). In 19 patients (39.6%) one or more neurosurgical operations were carried out previously, in 4 patients (8.3%) fractionated radiotherapy. Karnofski's score, as an indicator of the general condition, varied between 30-90%, the mean value for the whole group being 71%. The calculated volume of the meningioma was between 0.7 and 25.8 cm3, the average being 7.4 cm3. Collateral oedema in the adjacent area of the tumour was found in 6 patients (12.5%). In 19 patients (39.6%) the tumour was at the base of the skull, in 29 patients (60.4%) at other sites. The radiosurgically administered dose was within the range of 6.5-24 Gy, on average 14,2 Gy, on the isodose on average 50.7% (range 40-75%). The dose below the maximum was within the range of 13-45 Gy), on average 28.3 Gy. Only in two patients fractionated administration of the dose was used. After a 6-month interval following operation 30 patients were examined. In 7 patients (23.3%) partial wrinkling of the meningioma occurred (range 6-18 months), Karnofski's score improved by 10% in 8 (26.6%) and deteriorated in 3 patients (10%). The neurodeficit improved in 7 (23.3%) and deteriorated in 4 patients (13.3%). Collateral oedema developed in 5 patients (16.6%) 5-7 months after operation, in about half the patients it was symptom free. During the follow up period 2 patients died (8 and 5 months following surgery): in one the cause of death was not associated with the basic disease, in the second patient (where radiotherapy was the third neurosurgical operation) the radiosurgical operation could not reverse tha fatal course of the disease. CONCLUSIONS: Radiosurgery of meningiomas is a safe therapeutic method with zero mortality, minimal surgical stress, a minimal rate of complications and a minimal morbidity. It is indicated in meningiomas and possibly their residues after subtotal neurosurgery up to a maximal volume of 30 cm3. It is primary treatment suitable in particular in old.patients, patients with a high per- and postoperative risk and in patients refusing open neurosurgery.

Adolescent↗

PubMed1995

[Use of the radiosurgery knife in the treatment of hypophyseal adenomas].

BACKGROUND. Surgery of pituitary adenomas did not produce quite satisfactory results. Therefore radiosurgery using Leksell's gamma knife has become the most widely used method which-with the contribution of MRI-meets the most important demands of aimed irradiation: a sufficiently high dose of radiation of the tumour and minimal radiation load of functionally important surrounding structures. The objective of the investigation was to assemble experience with this therapeutic method. METHODS AND RESULTS. During the period between October 1992 and September 1994 a total of 41 patients were treated: 16 men, 12-66 years old, mean age 40.8 years; 25 women age 16-76 years, mean age 50.2 years. Female:male ratio 1.5 : 1. In 30 patients (73.2%) a microsurgical operation had preceded, in 5 (12.2%) conventional fractionated radiotherapy and in 11 patients (26.9%) primary radiosurgery. As far as the type of pituitary adenoma is concerned, it conditioned acromegaly in 30, Cushing's syndrome in 3 or Nelson's syndrome in 1, or a prolactinoma was involved (in 2 patients). In five instances the adenoma was hormonally inactive. Its localization was most frequently intrasellar (36), less frequently parasellar (5). The range of administered doses varied as regards the maximum between 12.5 and 80 Gy, the average being 46.8 Gy, to the periphery of the adenoma a dose of 10-49 Gy was administered, on average 24.7 Gy using a 50-80% isodose. The time interval after treatment is relatively short for detailed analysis or evaluation. During current evaluation the authors did not observe in any of the patients progression of the disease, and in several patients diminution of the tumour was found. Karnofski's score seemed to improve. CONCLUSIONS. Radiosurgery, using Leksell's gamma knife, is after failure of conservative and microsurgical therapeutic possibilities suitable further treatment of pituitary adenoma. In indicated cases it may be the first choice. Postirradiation follow up indicates promising effects, for more detailed evaluation a several years' interval is necessary.

Adenoma↗

PubMed1995

[Fractionated stereotaxic radiotherapy with the Leksell gamma knife].

BACKGROUND: Stereotactic radiotherapy is treatment of a small or medium-sized intracranial focus, using a fractionated regime and the stereotactic method. It is carried out usually on linear accelerators. The objective of the present investigation was to test the possibility of stereotactic radiotherapy using Leksell's gamma knife and Leksell's stereotactic frame. METHODS AND RESULTS: During the period between April 1993 and November 1994 38 patients (16 women and 22 men aged 15-72 years) were indicated for stereotactic radiotherapy. The patients had the following diagnoses: adenoma of the epipharynx (1), low-grade gliomas (10), ependymoma (1), germinoma (1), meningioma (2), solitary metastases into the CNS (19), pinealomas (3) and chordoma (1). The volume of the tumour varied from 740 mm3 to 37,000 mm3. Stereotactic fractionated radiotherapy was carried out using a Leksell Gamma Knife, Electa Instrument AB, Sweden. For assessment of the total fractionated dose a linear quadratic model was used. Thus assessed value was further modified in relation to the volume and radiobiology of the tumour, critical structures surrounding the treated lesion and other factors. The total fractionated dose to the maximum varied from 20 Gy to 60 Gy and the total fractionated dose on the periphery of the tumour from 12 Gy to 30 Gy. With regard to the short time interval which has elapsed since treatment it is not yet possible to evaluate completely the achieved results; it will be possible to do so after a time interval of 1-5 years following the operation. The patients tolerated the 2-5 day fixation with a stereotactic Leksell frame very well and none of the patients developed complications. CONCLUSIONS: Fractionated stereotactic radiotherapy with Leksell's gamma knife, using Leksell's stereotactic frame, is a very accurate therapeutic method with a minimal radiation load of surrounding brain tissue. It requires a short hospitalization period and is associated with no or only minimal complications and improves the quality of patient's lives.

Adolescent↗

PubMed1995

Fractionated stereotactic radiotherapy with the Leksell Gamma Knife: feasibility study.

The main aim of this study was to check feasibility of stereotactic radiotherapy, which is routinely practised on linear accelerators, using a fixed Leksell stereotactic frame and a Leksell Gamma Knife. The study refers to the first experiences with 48 patients treated by a fractionated regimen (in 2-6 days). Isoeffect relationships calculations based on the linear-quadratic model and the levels of applied radiation doses, taking into account radiobiology of the tumour, tumour volume, critical structures surrounding the treated lesion and other factors are discussed. The procedure for quality control during the whole fractionated regimen is described. The study has shown that stereotactic radiotherapy with the Leksell Gamma Knife is feasible. However, only early effects can be discussed and there are still questions remaining which should be carefully studied: tolerance doses for critical structures at fractionation, definition of an 'ideal' fractionation regimen, and justification of the linear-quadratic model in the case of stereotactic radiotherapy.

Brain Neoplasms↗

PubMed1994

[Radiosurgery with the gamma knife].

The conception of radiosurgery now more than 40 years old is realized in clinical practice during last 25 years. There were elaborated 3 main methods: focused irradiation by gamma knife, by accelerated heavy charged particles and by linear accelerator. The results led radiosurgery spread over the world. The main indications are vascular malformations (44%), benign intracranial tumours (33%), malignant tumours including metastasis (21%) and functional disorders (2%). The pathological lesions can be controlled or liquidated in 80-95%. The hospital story is minimal, 1-2 days, and there is no risk of mortality and morbidity is minimal. Only the time of healing is prolonged to some years with indispensable follow-up. Further technical improvement and growing number of patients treated by radiosurgery can be expected.

Central Nervous System↗

PubMed1993

Neurohumoral relations in neurological and psychiatric patients.

Sixteen patients-epileptics, alcoholics, psychotics and post-contusion cases-were subjected to neurological, psychiatric, psychological, morphological (X-ray, CT, NMR), physiological (EEG, polysomnography, evoked potentials), immunological and SPECT examination. Most had CT and SPECT signs of focal brain damage. The results were but exceptionally due to injury, most were of unknown etiology. This tallied with EEG focal abnormalities, mainly sleep disorders, sometimes subjective ones, but invariably detectable objectively. In each case there was REM, in some also NONREM sleep deficiency. Half of the cases were tested immunologically, each time with positive results: increased levels of acute-phase protein and stress-reaction proteins. As copious literature and our experience show, the above pathological condition, rather than being accidental, constitute regardless of etiology, an integrated entity which could be called "programme cerebropathy". The primary role is played there by the epileptic focus and its properties, in particular, the speed of discharge and localization and brain stem humoroergic systems, i.e., their performance and mutual balance. There is a program sequence of events, first, and epileptic focus acting on the neighborhood, the rise of secondary and tertiary foci, and influence over the thalamocortical system. Soon afterwards, epileptic activity begins to act on brain-stem structures. This results in changes in sleep, mood, psychic output, immunity, endosecretion, and in paroxysms.

Adult↗

PubMed1993

[Detection of cerebropathy in neurologic and psychiatric diseases].

The authors made a comprehensive examination of 16 patients--epileptics, alcoholics, psychotic subjects and patients after cerebral contusion. The patients were subjected to a neurological, psychiatric, psychological examination as well as to a morphological examination (X-ray, CT, NMR), physiological examination (EEG, polysomnography, evoked potentials), immunological examination and SPECT. The majority of patients had positive CT and SPECT findings suggesting focal brain damage. These results could be explained only in exceptional cases by injury, the majority was of unknown aetiology. With this corresponded focal EEG abnormalities and in particular sleep disorders, sometimes subjective but always detectable by objective methods. There was always a shortage of REM, sometimes also NONREM sleep. Half the patients were subjected to an immunological examination which was always positive and comprised elevated acute stage proteins and proteins associated with the stress reaction. Numerous data in the literature and the authors' experience indicate that the mentioned pathological findings are not incidental and form, independently on the aetiology, an integrated unit for which the term cerebropathy can be used. A primary role is played by the epileptic focus and its quality, i.e. above all the rate of discharge and site and humoroergic systems of the brain stem, in particular their efficiency and mutual balance. The events have a programmed sequence. At the beginning an epileptic focus develops which influences the surrounding area, secondary and tertiary foci are formed and the thalamo-cortical system is affected. Soon this is followed by an apparent influence of the epileptic activity on structures of the brain-stem. The consequence are changes affecting sleep, mood, mental performance, immunity, endosecretion and paroxysms. Subsequently individual symptoms are already prepared but have a different latency of manifestation and the latter depends also on external provoking influences. The thalamo-cortical reaction is characterized by the manifestation of epileptic paroxysms and sets in after a different interindividual incubation following injury. The same applies to the hippocampal reaction manifested by the organic psychosyndrome. Some symptoms such as changes of immunity, sleep or endosecretory function are not necessarily manifested if the influence of the focus on structures of the brain-stem is not sufficiently intense. Conversely if the effect on the brain-stem and limbic structures is greater and the effect on the thalamo-cortical system smaller, psychotiform behaviour develops. Then there are marked changes of phoria, dynamogeny, rate, affectivity, sleep and hormonal secretion and its equilibrium.

Adult↗

PubMed1991

Grafting of fetal dopamine neurons in Parkinson's disease. The Czech experience with severe akinetic patients.

Preliminary results in three patients with Parkinson's disease, who had transplantation of human embryonic mesencephalic tissue into the caput nuclei caudati, are reported. Some improvement was achieved.

Brain Tissue Transplantation↗

PubMed1991

[Consciousness and the electroencephalogram].

In the course of 12 years the authors subjected to clinical EEG and stereo-EEG (SEEG) 72 patients (66 epileptics with the diagnosis of psychomotor epilepsy and grand mal) and six psychotic patients suffering from schizophrenia. With the exception of five epileptics and two psychotic patients all subjects had epileptic foci in the amygdalohippocampal complex (AHK). After coagulation of these foci marked improvement of the fits and the mental state occurred in half the patients. During EEG and SEEG recording the authors used different activation methods (hyperventilation through the nose and mouth, sleep, listening to music) and above all direct electric stimulation (ES) of one of the AHK. Secondary epileptic foci had, as a rule, more spikes and a lower threshold for ES than primary ones which contained more delta and slow theta waves. The ES led as a rule to an emotional response, such as anxiety and fear, more rarely to illusions, depersonalization and oneiroid hallucinations and twice to a hedonic response of non-sexual character. The purpose of ES was to assess the site from where it is possible to start the original aura or typical parox. The authors considered these foci, consistent with data in the literature, as the leading focus and it was subsequently coagulated. The authors investigated the reactivity and vigility by the patient's response to sound (the patient had to press a button) and by an interview with the patient. It was revealed that in isolated discharges of the spikes and waves in the scalp electrodes, i.e. in the neocortex, reactivity is lacking. In isolated discharges in the AHK the reactivity was satisfactory, but as a rule anxiety developed. It is thus possible to divide consciousness into emotional consciousness with its site in the AHK, i.e. in the limbic system, and rational consciousness which is a function of the neocrotical system. Congenital changes of consciousness such as vigility or sleep are described as "states" of consciousness. The rational or emotional aspect of behaviour is described as "type" of consciousness. Under normal conditions the states of consciousness alternate periodically and are sharply defined, the types of consciousness are closely linked and are difficult to separate. Under pathological conditions the "states" of consciousness differ less markedly and the "types" of consciousness are in dissociation. Thus obnubilation, depersonalization, illusions, pathic affects etc. develop, as a rule as part of the epileptiform or psychotiform syndrome.

Adolescent↗

PubMed1990

[Instruments used in various operations in the area of the gasserian ganglion].

The authors describe instruments which make it possible to perform retrogasserian thermolesions (RGT), glycerol radiculolysis (GRL) or trigeminal balloon compression (TBC) or possibly a combination of these methods from a single surgical approach. This makes it possible to adjust the selection of the type of lesion to unforeseen conditions any time during the operation. The surgical results are compared in 308 RGT, 50 GRL and 22 TBC. There are no substantial differences and therefore the selection of the type of lesion depends on technical circumstances during operation.

Humans↗

PubMed1989

The possibility of retrogasserian thermocoagulation, glycerol radiculolysis and balloon compression in Meckel's cavity with a single surgical instrumentarium.

483 patients were operated on one of the percutaneous method. The radiofrequency thermocoagulation, the application of glycerol to the trigeminal cistern and the balloon compression of the ganglion were used. There are no substantial differences in the results and number of recurrences obtained with any of the different lesions. The choice of the type of lesion is often appointed by technical circumstances. The kind of instrumentarium which permits to perform in a single approach one of the three types of trigeminal lesion or there combination was designed.

Catheterization↗

PubMed1988