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Biomedical subjects

S Kunze

Publications and source records attributed to S Kunze.

At least 19 recordsLinked to original sources
PubMed1996

Knowledge retrieval as one type of knowledge-based decision support in medicine: results of an evaluation study.

We report on a prospective, prolective observational study, supplying information on how physicians and other health care professionals retrieve medical knowledge on-line within the Heidelberg University Hospital information system. Within this hospital information system, on-line access to medical knowledge has been realised by installing a medical knowledge server in the range of about 24 GB and by providing access to it by health care professional workstations in wards, physicians' rooms, etc. During the study, we observed about 96 accesses per working day. The main group of health care professionals retrieving medical knowledge were physicians and medical students. Primary reasons for its utilisation were identified as support for the users' scientific work (50%), own clinical cases (19%), general medical problems (14%) and current clinical problems (13%). Health care professionals had accesses to medical knowledge bases such as MEDLINE (79%), drug bases ('Rote Liste', 6%), and to electronic text books and knowledge base systems as well. Sixty-five percent of accesses to medical knowledge were judged to be successful. In our opinion, medical knowledge retrieval can serve as a first step towards knowledge processing in medicine. We point out the consequences for the management of hospital information systems in order to provide the prerequisites for such a type of knowledge retrieval.

Computer Systems↗
PubMed1996

Intraoperative computer-assisted neuronavigation in functional neurosurgery.

The clinical experience with a frameless computer-assisted neuronavigational system (ISG. Canada) used in functional neurosurgery is described. The advantage of image-guided surgery is stressed for functional procedures of the cortex with delineation of the gyral pattern, e.g. motor cortex stimulation and procedures at the base of the skull with triplanar and three-dimensional reconstruction of the bony landmarks. A general use of the device for aiming at subcortical targets cannot be recommended. Limitations are the accuracy (< or = 2.2 mm) and software deficiencies and the lack of a reliable fixation of the position sensing arm (wand).

Cerebral Cortex↗
PubMed1996

Coil placement after clipping: endovascular treatment of incompletely clipped cerebral aneurysms. Report of two cases.

In up to 4% of patients whose aneurysms are microsurgically clipped, there is an expected or unexpected aneurysm residuum. The authors describe two patients in whom surgical clipping did not result in complete obliteration of the aneurysm sac and in whom a second operation was not believed to be the solution to the problem. In both patients complete occlusion of the aneurysm residuum was achieved via an endovascular approach. Using the Guglielmi detachable coil system, it was possible to place two platinum coils selectively into the aneurysms. The endovascular approach may be a good treatment option for all patients in whom surgical clipping does not result in complete obliteration of the aneurysm sac and reoperation is contraindicated or unacceptable to the patient.

Adult↗
PubMed1995

Overdrainage and shunt technology. A critical comparison of programmable, hydrostatic and variable-resistance valves and flow-reducing devices.

When vertical body position is simulated, conventional differential pressure valves show an absolutely unphysiological flow, which is 2-170 times the normal liquor production rate. Although this is compensated in part by the resistance of the silicon tubes, which may produce up to 94% of the resistance of the complete shunt system, a negative intracranial pressure (ICP) of up to 30-44 cmH2O is an unavoidable consequence, which can be followed by subdural hematomas, slit ventricles, and other well-known complications. Modern shunt technology offers programmable, hydrostatic, and "flow-controlled" valves and anti-siphon devices; we have tested 13 different designs from 7 manufacturers (56 specimens), using the "Heidelberg Valve Test Inventory" with 16 subtests. "Programmable" valves reduce, but cannot exclude, unphysiological flow rates: even in the highest position and in combination with a standard catheter typical programmable Medos-Hakim valves allow a flow of 93-232 ml/h, Sophy SU-8-valves 86-168 ml/h with 30 cmH2O. The effect of hydrostatic valves (Hakim-Lumbar, Chhabra) can be inactivated by movements of daily life. The weight of the metal balls in most valves was too low for adequate flow reduction. Antisiphon devices are highly dependent on external, i.e. subcutaneous, pressure which has unpredictable influences on shunt function, and clinically is sometimes followed by shunt insufficiency. Two new Orbis-Sigma valves showed relatively physiological flow rates even when the vertical position (30 cmH2O) was simulated. One showed an insufficient flow (5.7 ml/h), and one was primarily obstructed. These have by far the smallest outlet of all valves. Additionally, the ruby pin tends to stick. Therefore, a high susceptibility to obliterations and blockade is unavoidable. Encouraging results obtained in pediatric patients contrast with disappointing experiences in some German and Swedish hospitals, which suggests that our laboratory findings are confirmed by clinical results. The concept of strict flow limitation seems to be inadaequate for adult patients, who need a relatively high flow during (nocturnal) ICP crises. The problem of shunt overdrainage remains unsolved.

Adult↗
PubMed1995

[Description of selected aspects of health services for elderly citizens by social services in Saxony].

The following analysis describes selected aspects of Saxonian social and medical care for people in need of help and elderly, via "community social service units". Almost 16% of people are older than 65 years in Saxonia, whereas the number of women is twice the number of men. To secure the social and medical care "community social service units" were founded partly from former municipal nursing stations of the former GDR and partly from newly founded institutions. Basic and medical care is an essential part of the supply in "community social service units". To approximate an all-embracing social and medical care, so-called "other tasks" complete the general service from a qualitative point of view.

Aged↗
PubMed1994

Mood changes after surgery for tumors of the cerebral cortex.

OBJECTIVE: To identify cortical lesion sites associated with particular mood states. DESIGN: A prospective study of patients with tumors affecting the cerebral cortex. The patients were examined neuropsychologically 1 to 5 days preoperatively and 2 to 10 days, several months, and several years postoperatively. Only data from the preoperative and the first postoperative examination were considered in this report. SETTING: Neurosurgical department of the University of Heidelberg (Germany). PATIENTS AND SUBJECTS: A consecutive sample of 141 patients with brain tumors (84 female and 57 male) with cortical lesions caused by microsurgical tumor resection; 29 clinical control patients (having undergone surgery for slipped disks); and 18 normal control subjects. MAIN OUTCOME MEASURE: Preoperative and postoperative mood state as measured with an adjective checklist. RESULTS: (1) Patients with lesions of the ventral frontal cortex or lesions of the temporoparietal cortex reported postoperatively significantly (P < .01) worse mood states (anxiety/depression, irritability/anger, fatigue) than did patients in the other lesion and control groups. (2) A more detailed lesion analysis revealed that lesions of heteromodal frontal or parietal association cortexes, combined with paralimbic lesions, were responsible for the negative mood states. Lesions of the sensorimotor cortexes ameliorated the negative effects of heteromodal and paralimbic lesions. (3) Lesion laterality did not influence the mood states. CONCLUSIONS: Heteromodal cortexes may be especially concerned with emotionally relevant operations. A loss of these functions deprives limbic structures of one of their main sources of input and is therefore likely also to produce changes in feelings, that is, emotional states.

Adult↗
PubMed1994

Risks of using siphon-reducing devices.

Reducing the cerebrospinal flow is the task of siphon-reducing devices (SRD). This paper shows test results with SRD, with special reference to the aspect of dysfunction of shunt valves in combination with anti-siphon. The local influences acting on the anti-siphon at the place of implantation and the dependence of the pressure range were examined as possible causes of dysfunction.

Cerebral Ventricles↗
PubMed1994

Early postoperative magnetic resonance imaging after resection of malignant glioma: objective evaluation of residual tumor and its influence on regrowth and prognosis.

In the vast majority of studies that address the role of surgery in the management of high-grade gliomas, the degree of tumor removal accomplished is solely based on the intraoperative perception of the neurosurgeon. Despite its fundamental importance for a comparison of different treatment modalities, little systematic effort has been made to evaluate the residual gross tumor by neuroimaging methods immediately after surgery. We report the results of a prospective study using contrast-enhanced computed tomography and magnetic resonance imaging (MRI) to monitor 60 patients after the resection of a high-grade glioma. In each case, the first scans were obtained between Days 1 and 5 after surgery, followed by serial imaging every 2 to 3 months, usually until the condition of the patient deteriorated severely or the patient died. Gadolinium-enhanced MRI proved to be extremely valuable for assessing gross residual tumor when performed during Days 1 to 3 after the resection of a preoperatively enhancing high-grade glioma. This timing avoided surgically induced contrast enhancement and minimized interpretative difficulties. In delineating residual tumor, MRI was vastly superior to computed tomography. About 80% of tumor "recurrences" emerged from definitely enhancing remnants, as revealed by early postoperative MRI. The neurosurgeon's estimation of gross tumor burden reduction could be shown to be much less accurate (by a factor of 3) than the postoperative assessment by modern neuroimaging. In our series, residual tumor enhancement was the most predictive prognostic factor of survival in patients with glioblastoma, followed by radiotherapy. Patients with a residual tumor postoperatively had a 6.595-times higher risk of death in comparison to patients without a residual tumor. Patients undergoing radiotherapy had a 0.258-times lower risk of death in comparison to patients who were not treated with radiation. Concerning survival, the prognostic significance of both variables surpassed age and performance.

Brain Neoplasms↗
PubMed1994

[Acute subarachnoid hemorrhage after aneurysm rupture: results of early surgery].

The introduction of early aneurysm surgery in subarachnoid hemorrhage in the beginning of the eighties diminished the frequency of rebleeding. However, there are some objectives against early surgery due to its supposed higher morbidity. The present retrospective data elucidates the advantage of early aneurysmal surgery. In 1990 and 1991 we treated 175 patients with subarachnoid hemorrhage, of which 9 had no vascular malformation. In 166 patients a total of 190 aneurysmal malformations could be found. Of 60 patients with preoperative good clinical grades I and II (according to Hunt and Hess) 59 patients (99%) showed good or very good results classified by the Glasgow Outcome scale (GOS). Only one patient did not survive. Even in 61% of patients with poor grade aneurysms (III to V by Hunt and Hess) the outcome was good to very good; 15 patients (14%) survived with a distinct neurological deficit (grade 3 by GOS). Only one patient remained in a vegetative state. The total mortality of these 106 patients with grades III to V (Hunt and Hess) was 24%, among them 15 patients with preoperative grade V (Hunt and Hess). Overall it can be established, that there are no definite disadvantages of early aneurysmal surgery. The benefits of early surgery are a minimized risk of rebleeding, some effects of ameliorated conditions for intensive care treatment still have to be proven. Not only patients in good clinical condition (I and II by Hunt and Hess) show a good prognosis, even for patients with poor grade aneurysms (III to V by Hunt and Hess) a very good or at least good result can be achieved in 61%.

Adolescent↗
PubMed1993

Accelerated methaemoglobin formation: potential pitfall in early postoperative MRI.

Postoperative magnetic resonance imaging (MRI) of glioblastomas to assess residual tumour should be performed within the first 4 days following surgery. Early methaemoglobin formation near the resection site may mimic residual tumour if only gadolinium-DTPA-enhanced images are obtained. In a prospective study 24 of 54 patients (44%) showed well-defined areas of increased signal intensity on unenhanced T1-weighted images performed soon after surgery. By in vitro experiments we showed that hydrogen peroxide used in neurosurgery as a styptic agent accelerates formation of methaemoglobin when added to whole blood samples.

Brain↗
PubMed1993

Clipping of proximal paraclinoid aneurysms with support of the balloon-catheter "trapping-evacuation" technique. Technical note.

A method is described in which we use a combined endovascular balloon-catheter technique and open microneurosurgical approach for clipping aneurysms of the proximal paraclinoidal intracranial segment of the internal carotid artery. By temporary occlusion of the cervical carotid artery and continuously retrograde sucking of blood from the distal vessel via a double-lumen balloon-catheter, clip application to large and critically located aneurysms is facilitated applying evacuation-decompression to the trapped arterial segment under intra-operative SEP-monitoring.

Adult↗
PubMed1992

Memory disturbances following anterior communicating artery rupture.

Thirty patients with lesions due to the rupture and repair of an aneurysm of the anterior communicating artery were compared neuropsychologically with 27 patients with ruptures but no lesions and 30 normal control subjects. Patients with combined lesions in the basal forebrain and striatum (n = 5), or basal forebrain, striatum, and ventral frontal cortex (n = 7), had severe memory deficits, whereas patients with lesions in the basal forebrain (n = 7) or the striatum (n = 5) alone showed virtually no deficits. Patients with lesions of the basal forebrain and ventral frontal cortex together (n = 6) showed mild memory deficits. In contrast to the memory effects, emotional changes were most pronounced in patients with striate lesions alone. Basal forebrain or ventral frontal lesions ameliorated rather than aggravated the emotional effects of striate lesions. It is suggested that the basal forebrain and the striatum form links of different pathways related to mnemonic information processing. Both systems may be able to compensate for a dysfunction of the other, but lesions of both systems together may lead to strong and unrecoverable memory deficits.

Affect↗
PubMed1992

[Stereotactic convergent-beam irradiation: its current prospects based on clinical results].

"Radiosurgery" is the term for a special concept in radiotherapy. It describes a percutaneous, stereotactically guided irradiation delivering a single high dose with collimated narrow beams. The precise stereotactic localization of the target point and a steep dose gradient outside the target volume allow the administration of high doses to a lesion without damage to adjacent normal tissue. Risk of necrosis, due to a dose volume relationship represents the limits of radiosurgery. Units for radiosurgery were designed at Stockholm using multiple external cobalt-60-gamma sources, at Boston operating with protons of a cyclotron, at Berkeley operating with helium ions accelerated by a synchrocyclotron. An attractive alternative to these complicated and expensive facilities is the use of a modified linear accelerator. At the German Cancer Research Center in Heidelberg such a system was developed and has been available for the treatment of patients since 1984. Though, data of over 100,000 patients with vascular malformations and cancer disease are available worldwide, the indication for this therapy is validated only for a minority of entities. In cases of inoperable arteriovenous malformations favourable results in achieving obliteration range between 60% and 100% were obtained. Median survival for solitary brain metastases with controlled, extracerebral tumor diseases were between nine and twelve months. Up to now, advantages of stereotactic irradiation for benign tumor masses could not be proven. Therefore, randomized trials should be initiated in this field, considering decisive improvements in local tumor control with techniques of microsurgery and fractionated, postoperative radiotherapy during the last few years.

Brain↗
PubMed1991

Commercial external ventricular drainage sets: unsolved safety and handling problems.

Twelve commercially available sets for drainage of cerebrospinal fluid were tested for handling, design, features for fixation of the ventricular catheter, reliability of the anti-reflux valve, obstruction, efficiency of the air ventilation filter caps, accuracy of flow measurement and adjustment of flow, quality of material, adjustment, and cost. All systems showed considerable deficiencies in their reliability and handling. None of them can be recommended without certain restrictions and they should all be revised.

Brain Diseases↗