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Biomedical subjects

D Winkler

Publications and source records attributed to D Winkler.

At least 55 records · Page 3Linked to original sources
PubMed1995

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Contract Services↗
PubMed1992

Treatment of tumours of the pineal region and posterior part of the third ventricle.

The evaluation of tumours located in the posterior part of the third ventricle or pineal region is achieved best by magnet resonance imaging (MRI). It shows the exact localization and extent, the involvement of neighbouring structures like thalamus or quadrigeminal plate and the displacement of the large veins, the internal cerebral veins, the vein of Galen and the veins of Rosenthal. If only CT is available, angiography should be performed prior to operation to identify the course of the veins. In children with a pineal region tumour the "tumour markers" AFP and beta-HCG should be determined before operation. We approach the rare tumours entirely located within the posterior part of the third ventricle by the posterior interhemispheric transcallosal route with the patient in prone position with the head elevated. The same approach is used for pineal region tumours extending above the internal cerebral veins. Tumours arising from the posterior thalamus extending into the thalamus and ventricle as well, are better approached by the posterior transcortical transventricular route since the lateral view is rather limited by the midline approach. The most frequent tumours in the pineal region are approached if they are located below the internal veins by the infratentorial, supracerebellar route in the sitting position. A total of 60 cases are evaluated. If AFP and/or beta-HCG are positive a highly malignant nongerminomatous germ-cell tumour must be suspected. We recommend initial chemotherapy with a combination of Vinblastine, Ifosfamide and Cis-platin without biopsy to avoid tumour seeding. After the "markers" are normalized operative removal of the residual tumour and radiotherapy should be carried out. In a series of 13 children operated on for pineal region tumours a rigid neuropsychological and endocrine evaluation was performed with encouraging results. During the last 10 years we have performed 49 open operations and 11 stereotactic biopsies. 40% of the patients were children under the age of 18. 40% of the tumours in childhood and 60% in adults were benign. In childhood 24% were germinomas and 20% non-germinomatous germ cell tumours.

Adult↗
PubMed1992

Chronic vagus nerve stimulation increases the latency of the thalamocortical somatosensory evoked potential.

The Neurocybernetic Prosthesis (NCP) is a pacemaker-like device that has been designed to provide chronic intermittent vagus nerve stimulation. It is currently under study for the treatment of refractory partial onset epilepsy, and preliminary studies have indicated that partial onset seizures are improved by this therapy. The mechanisms by which it exerts its antiepileptic effect are not well understood. Although there are extensive pathways to the forebrain from the nuclei of the vagus nerve, the evidence that the NCP alters neural transmission outside the vagal system is limited. We prospectively examined somatosensory and brain stem auditory evoked potentials (BAEPs) in three patients receiving NCP implantation to determine if changes in these studies occur as a result of chronic vagus nerve stimulation. The results demonstrate a significant prolongation of the cervicomedullary to thalamocortical potential (N13-N20) interval on somatosensory evoked potential (SSEP) studies following activation of the device. No other significant changes were seen on SSEP or BAEP in the NCP implanted patients or normal controls. The findings suggest that chronic vagus nerve stimulation does alter neuronal networks outside of the brain stem vagus system, and may potentially provide a means to clinically monitor and titrate this therapy.

Adult↗
PubMed1991

Branching and confluence pattern of glomerular arterioles in the rat.

In addition to the usual division of the glomerular tuft into lobules, a subdivision into an afferent and an efferent capillary domain is made. Immediately after entering the glomerulus the afferent arteriole splits into superficially located branches which supply the lobules. The capillaries of each lobule first run towards the urinary pole; these parts of each lobule establish the afferent domain. The capillaries of each lobule running back towards the vascular pole establish the efferent domain. The afferent domain represents the major part of the tuft; it has the shape of an incomplete globe with a deep depression on one side within which the efferent domain is situated. The efferent arteriole is established inside the glomerular tuft within the efferent capillary domain. Generally tributaries from each lobule converge to form the intraglomerular segment of the efferent arteriole, which leaves the tuft by passing through the mesangium of the glomerular stalk. At this site the intraglomerular segment of the efferent arteriole is fully surrounded by the mesangium; consequently, it is exposed to the intramesangial pressure.

Animals↗
PubMed1989

Clinical efficacy of perioperative antimicrobial prophylaxis in neurosurgery--a prospective randomized study involving 159 patients.

In a randomized study 87 patients received perioperative antibiotic prophylaxis with 2 x 2 g ceftriaxone (Rocephin) at the beginning of the operation and in the following morning. Seventy-two patients received no antibiotic prophylaxis. In patients receiving the prophylaxis, a lower incidence of infections was observed postoperatively in addition to a reduction in wound-healing disorders. Respiratory tract infections were more successfully prevented than urinary tract infections. The number of pathogenic bacteria detected in the group on receiving prophylaxis decreased. The positive effect of the perioperative administration of antibiotics was more evident in protracted operations, such as brain surgery, than in operations involving the spinal cord.

Bacteria↗
PubMed1989

Long-term analysis of sterility testing of immunobiological preparations.

The data for sterility testing for 16 years show a high stability from different points of view. The summarized and compared results after 10 and 16 years are similar, so we can assume a fixed methodological, technological and biological balance. The necessity of changes in these methods and the achieved balance is discussed.

Biological Products↗
PubMed1988

Intramedullary spinal cord tumors resected with CO2 laser microsurgical technique: recent experience in fifteen patients.

We have operated upon 15 intramedullary spinal cord tumors with the aid of a CO2 laser attached to the microscope. The operative technique is described. Most of the tumors were localized within the cervical spinal cord. Nine tumors were benign gliomas: 4 ependymomas, 1 subependymoma, 3 astrocytomas, and 1 ganglioglioma. Six were removed totally, and 3 were removed subtotally. The remaining 6 tumors consisted of 3 hemangioblastomas, 1 intramedullary neurofibroma, 1 lipoma, and 1 primary intramedullary melanoma. Neurological function postoperatively compared to the preoperative function of the upper extremities was unchanged in 13 patients (86.5%), improved in 1, and worse in 1 patient. In the lower extremities, the preoperative neurological status was unchanged in 11 patients (73.3%), improved in 1 patient, and worse in 3 patients (20%). Magnetic resonance imaging was superior to myelography and computed tomography in localizing these lesions. Enhancement with paramagnetic substances (e.g., gadolinium-DTPA) helps to localize solid tumor within cysts. Histological evaluation of small tissue biopsies or frozen section histology is unreliable. The entire lesion should be exposed in all cases, and an attempt should be made to remove the tumor totally or, if this is not possible, to resect as much of the center of the tumor as is possible until the cord is decompressed. The decision to administer further treatment is based on the histological features of the tumor.

Adolescent↗
PubMed1987

Does the timing of aneurysm surgery neglect the real problems of subarachnoid haemorrhage?

In 1984, in connection with the introduction of the calcium antagonist nimodipine, a new strategy for the treatment of subarachnoid haemorrhage (SAH) due to ruptured aneurysm was developed in our hospital. With no rigid regard to "timing" all patients undergo surgery as soon as possible. The only exception being those in Hunt and Hess grades IV and V without space-occupying intracranial haemorrhage and those bearing aneurysms of the vertebrobasilar circulation that are difficult of access. As soon as the risk of rebleeding has been eliminated surgically an active therapy against the possible consequences of SAH--cerebral vasospasm and simultaneous disturbances of autoregulation--is started. It consists in lowering the increased intracranial pressure, raising of mean arterial pressure and improving of rheological properties of the blood in order to prevent delayed build-up of neurological deficit due to ischaemia. It goes without saying that calcium antagonists are given from the very beginning of the patient's treatment even before operation. The advantages of this therapeutic concept are demonstrated by two series of non-selected consecutive patient material. The first series (A; n = 135) was treated between 1981 and 1984 before the change in treatment strategy, the second (B; n = 183) from 1984 to 1986 after that change. The overall mortality in series A was 27%, that in series B 20%. Operative mortality could be reduced from 22% to 16% in patients having undergone early operation and from 6% to 2% in patients with late surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗