Biomedical subjects

B Krischek

Publications and source records attributed to B Krischek.

9 recordsLinked to original sources

PubMed2003

The Doppler-guided transfalcine venous approach in selected cases of vein of Galen malformations.

OBJECTIVE: This investigation was performed to evaluate the specific procedural issues and indications of a surgically assisted Doppler-guided endovascular transfalcine venous approach for the treatment of vein of Galen aneurysmal malformations (VGAM) in critically ill neonates. PATIENTS AND METHODS: Two neonates out of a clinical series of 15 children (8 males and 7 females) with vein of Galen malformations were treated by our neurovascular team, using a combined surgically assisted endovascular transfalcine approach. In the biplanar angiography room a radiographically guided craniotomy (1.5 cm) was placed over the cranial projection of the falciforme sinus. After craniotomy the orthograd flow of the falciforme sinus was identified by Doppler ultrasonography. The sinus was punctured by an i. v. cannula with injection port and was sutured to the skin. A microcatheter was maneuvered over a guide into the malformation under fluoroscopic control. For embolization Guglielmi electrolytically detachable platinum coils were placed into the malformation as an embolic agent. Neurological examination records, available MR images, computed tomographic scans, pre- and postembolization angiograms and follow-up data were analyzed. RESULTS: In both individuals the malformation was classified as VGAM. The follow-up was 6 and 7 months, respectively. No technique associated morbidity or mortality occurred in the present series. At discharge both selected neonates were in stable condition and the flow in the VGAMs could be significantly reduced by a combination of approaches including the venous transfalcine approach. Meanwhile, 6 months after birth one neonate died due to a deterioration of the pulmonary hypertension. CONCLUSIONS: Endovascular treatment is presently the most efficient strategy to allow neonates and infants survive the early manifestation of vein of Galen malformations and probably render a normal neurological development. Consequently, a combination of approaches in selected cases including the Doppler guided venous transfalcine route should be regarded as a preferential treatment modality, especially in patients with arterial vasospasms and venous stenosis.

Cerebral Angiography↗

PubMed2001

Biodegradable implants in neurosurgery.

BACKGROUND: Biodegradable materials have been used for osteosynthesis by orthopedic surgeons and craniomaxillofacial surgeons for many years. However, such materials are not yet widely used by neurosurgeons despite potential applications. This prospective study was undertaken to evaluate potential applications of biodegradable materials in neurosurgical interventions. METHODS: A total of 104 4-hole plates and 228 screws consisting of copolymer of poly-70 L/30 D,L-lactide were inserted for fixation of bone flaps in 8 patients and for reinsertion of laminoplasties at 28 levels in 16. The craniotomies were performed for removal of a brain tumour in 4 cases, for surgical management of an aneurysm or cerebral AVM in 2, and for treatment of craniocerebral trauma in another 2. Laminoplasties were performed at 25 levels for intraspinal hemangioblastomas in 15 patients. One patient with an ependymoma underwent 3-level laminoplasty. FINDINGS: One patient with severe head injury in whom the bone flap was re-implanted several months following the craniectomy, developed an aseptic necrosis of the bone flap, which had to be removed. Implant rejection was not observed. One patient suffered from mild local pain in the area of a biodegradeable screw in the frontal region following removal of a sphenoid wing meningeoma. None of the patients with laminoplasty showed signs of functional instability or spinal cord compression. Implant rejection was not observed. No delayed healing or infection occurred. Healing was not delayed and no infections occurred. INTERPRETATION: The results encourage further use of biodegradable materials for the described applications. Additional studies will be performed to investigate the usefulness of biodegradable devices in neurosurgery and to obtain long-term results.

Absorbable Implants↗

PubMed2000

Heparin-induced thrombocytopenia: a critical risk/benefit analysis of patients in intensive care treated with R-hirudin.

Patients in intensive care may be at high risk of in vivo platelet activation because comorbid conditions, such as infections, septicemia, shock, disseminated intravascular coagulation, and cancer represent procoagulant states. Hyperreactivity of platelets with or without a decline of cell count may result in thromboembolic complications potentially associated with the phenomenon of heparin-induced thrombocytopenia. We analyzed the data of 10 patients highly suspected of having heparin-induced thrombocytopenia during their intensive care treatment of 29 plus or minus 22 days. In seven patients, thrombocytopenia coincided with thromboembolic complications. Six patients had additionally undergone fibrinolytic therapy before starting activated partial thromboplastin time-adapted alternative anticoagulation with r-hirudin. In three patients, the platelet count decreased without a clinical manifestation, of heparin-induced thrombocytopenia. R-Hirudin treatment monitored by activated partial thromboplastin time and prothrombin time (PT) was effective and safe. The target value for activated partial thromboplastin time was a twofold prolongation. In four of five patients with deep venous thrombosis, a partial recanalization of the lower extremity could be achieved. Three patients with pulmonary embolism associated with deep venous thrombosis in two cases and in one additional case with an acute myocardial infarction did clinically profit from fibrinolysis with recombinant tissue plasminogen activator (rtPA) and r-hirudin treatment. Two lethal events probably caused by the underlying multimorbidity could not be prevented. No recurrence of thrombosis occurred, and there were no severe bleeding complications attributed to r-hirudin treatment. Platelet counts were significantly reduced on day 9.4 plus or minus 6.4 of heparin administration in all cases (>50% decrease related to the initial values) from 224,000 plus or minus 126,000/microL to 96,000 plus or minus 61,000/microL, and increased during rhirudin treatment to mean values of 224,000 plus or minus 126,000/microL. The heparin-induced platelet activation assay (HIPAA) assay was positive in 8/10 cases, whereas the PF4 enzyme-linked immunosorbent assay showed a positive result in four of eight analyzed cases. In four cases, the assays were concordantly positive. The PF4 enzyme-linked immunosorbent assay was not performed in two cases.

Adult↗

PubMed1999

Improved therapeutic safety of oral anticoagulant therapy in Germany: the Saarland model.

In contrast to other European countries, in Germany more than 90% of oral anticoagulated patients are controlled by general practitioners. The International Normalized Ratio (INR) system in laboratory control is not in widespread use, often leading to misinterpretations of prothrombin time (PT) measurements. To improve the management of anticoagulated patients, a model was developed, consisting of different questionnaires and on the base of the INR system. Since 1993, 60 patients in our Department's outpatient anticoagulant clinic and since 1996 16 patients in the office of a general practitioner were followed for 146.32 patient years. There were no thromboembolic events and no major bleedings during follow-up. A total of 126 minor bleedings occurred in 30 patients. There were no significant differences in INR values and stable phases between the two centers; however, significantly shorter stable phases in patients with bleeding episodes were noted. Thus, this model seems to be useful also in general practitioners' hands.

Administration, Oral↗

PubMed1999

Phenprocoumon from a neurosurgical perspective.

A 9-year series of 45 intracranial and spinal hematomas in patients under oral anticoagulant treatment with phenprocoumon was analyzed and compared to data from the literature. In 42% of the patients, International Normalized Ratio (INR) values >4.5 were found on admission, 36% were older than 70 years and most patients (38%) were under long-term treatment after cardiac valve replacement. Patients who recovered did not report to have given informed consent at the start of anticoagulant therapy. Because an average of five serious hemorrhages are reported/year from German neurosurgical departments, it can be estimated that about 650 intracerebral or intraspinal hematomas, including about 250 fatalities/year occur in Germany under oral anticoagulant treatment. These complications reach the same incidence than spontaneous hematomas either from aneurysms or angiomas. Standards for indications, clinical control, quality INR testing and INR targets not exceeding 4.0, and collecting more data on incidences and causative factors of complications may be an important contribution to reduce these fatalities.

Anticoagulants↗

PubMed1999

The overdosed patient and bleedings with oral anticoagulation.

Overdose or bleeding with oral anticoagulation requires gradual antagonization of the drugs. Minor bleedings are most commonly managed by temporarily discontinuing treatment and by giving vitamin K to antagonize the coumarin derivative effects. Major bleedings, in contrast, especially intracranial hemorrhages, require immediate antagonization of anticoagulation. This is also necessary in required major surgery of anticoagulated patients. Instant normalization of hemostasis in such cases is achieved by the administration of clotting factors, in particular prothrombin complex concentrates. The use of fresh frozen plasma, instead, is less useful. The treatment with prothrombin complex concentrates requires a strict risk-benefit estimation and laboratory monitoring is recommended to optimize dosage adjustment. A 2-year follow-up of 45 out-patients receiving phenprocoumon at our center revealed a total of 11 bleeding complications (11.6/100 treatment-years, 10 minor and 1 major bleeding). Discontinuing or reducing oral anticoagulation together with vitamin K were the methods most frequently used to efficiently manage hemorrhages, whereas prothrombin complex concentrates were only used in one case with major bleeding. Oral anticoagulation appeared to be an enhancing factor for an otherwise existing bleeding diathesis rather than a genuine cause for hemorrhages.

Administration, Oral↗

PubMed1999

Training of patients for self-management of oral anticoagulant therapy: standards, patient suitability, and clinical aspects.

Self-control and self-management of oral anticoagulant therapy have become more and more attractive for patients undergoing long-term treatment. In our training center, we examined 50 patients who took part in a standardized training course for self-management. Patients (36 men, 14 women) were preselected according to the guidelines of the German Association for Self-management of Oral Anticoagulation (ASA e.V.) and were all trained by the same physician. The complete course took an average of eight sessions. Patients older than 59 years needed significantly more training time in theoretical advising than younger patients; they did not need more training time in practical matters. The values between International Normalized Ratio (INR) measured in venous blood samples and by self-assessment were comparable for both groups. There was a good overall correlation between self-controlled INRs and laboratory assays, however, the self-assayed INRs were significantly lower than those from the venous blood samples.

Administration, Oral↗

PubMed1999

Dimensions of quality of life and self-monitoring therapy with oral anticoagulants--still research or everyday practice?

In correlation with increased life expectancy of patients, quality of life (QOL) has become a factor of increasing interest by the patient himself and also of importance in health-care planning and recruitment of financial resources. In this context, self-monitoring of long-term anticoagulant treatment might be a strategy that could mean a step forward in health-related as well as general life satisfaction for patients participating in self-monitoring programs. Also, the new strategy of increased home-control of anticoagulant treatment illustrates the complexity of multiple factors that can lead to changes in the subjective feeling and objective aspects of QOL. Our intention in a pilot study was to probe the feasibility of QOL research and relevant factors of influence by retrospectively evaluating data from two groups of outpatients seen in a large treatment center. The high frequency (n = 8 in sample 2) of disturbed sleep as a simple screening indicator stresses the probable importance of undetected depression, which might require treatment and could confound research as to QOL. Instruments to measure QOL in oral anticoagulation self-monitoring should therefore be adapted to the heterogeneous structure of factors in the target population, and include psychological parameters, especially in regard to health-related locus of control and mood.

Administration, Oral↗

PubMed1998

Diagnostic and microsurgical presentation of intracranial angiolipomas. Case report and review of the literature.

Angiolipomas (ALs) are hamartomas composed of abnormally differentiated vessels and mature adipose tissue. Although they are most commonly found in peripheral tissues, ALs sometimes grow in the spinal epidural space. Intracranial ALs (ICALs) are rare: only seven cases have been reported in the literature. The authors describe the case of a 70-year-old woman who presented with ocular symptoms from a clinically and radiologically progressing parasellar ICAL. The radiological as well as the microsurgical findings are illustrated and compared with the seven previously published cases. The most frequent location of ALs is the skull base, especially the parasellar region. Other ICALs were diagnosed as components of cerebral arteriovenous malformations and were not symptomatic by themselves. Neuroradiological studies of ICALs usually demonstrate the characteristics of both adipose and vascular tissues. However, a review of the literature shows that the diagnosis had not been suspected preoperatively in any of the cases. Operative descriptions emphasize that most neurosurgeons were caught off guard by the profuse bleeding and the unusual relationship of this unexpected lesion to the cavernous sinus, so that removal was rarely complete. The authors conclude that preoperative diagnosis of ICALs is achievable based on magnetic resonance analysis, which should help optimize the microsurgical management of these lesions.

Aged↗