Biomedical subjects

A Raabe

Publications and source records attributed to A Raabe.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Practice of perioperative thromboembolic prophylaxis in neurosurgery: results of a German survey].

Many neurosurgical patients are at high risk of developing thromboembolic disease. Although recent data support the benefit of pharmacological thromboembolic prophylaxis, the optimal starting point for the different neurosurgical procedures remains unclear because the potentially devastating consequences of intracranial or intraspinal haemorrhage could easily offset the reduction in thromboembolic morbidity and mortality resulting from pharmacological thromboembolic prophylaxis. The objective of our study was to assess the use of pharmacological methods of thromboembolic prophylaxis in contemporary German neurosurgery using a postal survey in 34 neurosurgical departments. Low-dose heparin or low molecular weight heparin (LMWH) were used in 88% to 97% of neurosurgical units participating in our survey. In craniotomies, in 2 units (6%) heparin or LMWH was routinely started before surgery, in 10 units (29%) < 8 hours after surgery, in 15 units (44%) < 24 hours after surgery, in one unit at the second day and in 5 units at the third day after surgery. Data for burr hole craniotomy or spinal surgery were similar. In our survey a high rate of perioperative use of pharmacological thromboembolic prophylaxis was found. However, given the data from the literature, the optimum protocol remains unclear.

Anticoagulants↗

PubMed2000

Low-cost, small-animal shelf for simultaneously assessing several small animals with a whole-body PET scanner.

OBJECTIVE: The purpose of this work was to establish a low-cost device for simple positioning of several small animals within a whole-body PET scanner. METHODS: The device was designed as a stackable shelf for 3 x 3 animals, similar to a stackable shelf for wine bottles. It was constructed from ordinary PVC drain pipe and acrylic panes. RESULTS: The shelf simplified accurate and reproducible positioning of the animals and, therefore, supported automatic data processing. Deterioration of image quality by attenuation of photons within the shelf itself was rather small. CONCLUSION: The small-animal shelf is a useful, low-cost device for simultaneously assessing up to 9 small animals with a whole-body PET scanner.

Acrylic Resins↗

PubMed1999

Monitoring of intracranial compliance: correction for a change in body position.

The objectives of our study were 1. to investigate whether the intracranial compliance changes with body position; 2. to test if the pressure-volume index (PVI) calculation is affected by different body positions; 3. to define the optimal parameter to correct PVI for changes in body position and 4. to investigate the physiological meaning of the constant term (P0) in the model of the intracranial volume-pressure relationship. Thirteen patients were included in this study. All patients were subjected to 2 to 3 different body positions. In each position, either classic bolus injection was performed for measurement of intracranial compliance and calculation of PVI or the new Spiegelberg compliance monitor was used to calculate PVI continuously. Four different models were used for calculating the constant pressure term P0 and the P0 corrected PVI values. Pressure volume index not corrected for the constant term P0 significantly decreased with elevating the patients head (r = 0.70, p < 0.0001). In contrast, volume-pressure response and ICP pulse amplitude did not change with position. Using the constant term P0 to correct the PVI we found no changes between the different body positions. Our results suggest that during the variation in body position there is no change in intracranial compliance but a change in hydrostatic offset pressure which causes a shifting of the volume-pressure curve along the pressure axis without its shape being affected. PVI measurements should either be performed only with the patient in the 0 degree recumbent position or that the PVI calculation should be corrected for the hydrostatic difference between the level of the ICP transducer and the hydrostatic indifference point of the craniospinal system close to the third thoracic vertebra.

Adult↗

PubMed1999

Open MRI-guided neurosurgery.

OBJECTIVES: A number of different image-guided surgical techniques have been developed during the past decade. None of these methods can provide the surgeon with information about the dynamic changes that occur intra-operatively. MATERIAL AND METHOD: The first vertical open 0.5T MRI-scanner for intra-operative MRI-guided neurosurgery in Germany was installed at the University of Leipzig during the summer 1996. Since autumn 1996 a number of surgical procedures including biopsies (n = 31), craniotomies (n = 32), transsphenoidal procedures (n = 8) and interstitial lasertherapies (n = 3) have been performed using intra-operative MR image guidance. RESULTS: The development of MR-compatible and MR-safe non-magnetic instruments and components had to be solved. Specific surgical instruments were developed to perform biopsies, craniotomies, microsurgical tumour resections and transsphenoidal procedures in the 0.5-T open MRI. Several components required adaptation including the head holder the stereotactic navigation device, the high speed drill, the suction unit, the ultrasonic aspirator, the bipolar coagulation, the laser probe and the surgical microscope. All these newly developed technical features enable the neurosurgeon to perform a large number of surgical procedures under direct control and guidance of intra-operative MR imaging. In contrast to frame-based for framless navigation systems, intra-operative MRI provides accurate and immediate information during the progress of surgery. These intra-operative images allow definitive localization and targeting of the lesions and accommodate anatomical changes that may occur during surgery. CONCLUSION: Intra-operative MRI is helpful for navigation as well as determining of tumour margins to achieve a complete and safe resection of intracranial lesions. Complications related to the surgical procedure are reduced and the risk of neurological deterioration due to tumour removal and postoperative complications is minimized. It can be concluded that the intra-operative application of interventional MRI technology may represent a major step forward in the field of neurosurgery.

Biopsy↗

PubMed1999

Migraine associated bilateral intracerebral haemorrhages.

The authors report a case of bilateral basal ganglionic haemorrhages which occurred during an attack of classical migraine. The patient had a history of migraine associated with aura of neurological deficit for 10 years and a history of arterial hypertension for 20 years, which was treated with propranolol. Intracerebral haemorrhage during an attack of migraine is very rare and up to now the existence of true migraine-induced intracerebral haemorrhage has been controversial. Our case of bilateral occurrence of the haemorrhages supports the theory of the existence of migraine-induced damage of the wall of intraparenchymal vessels during vasoconstriction and focal ischaemia at the beginning of a migraine attack. Subsequent vessel rupture may occur during the following period of increased cerebral blood flow especially with coexisting arterial hypertension. The terminology of the syndrome of migraine associated with intracerebral haemorrhage is reviewed.

Basal Ganglia Hemorrhage↗

PubMed1999

Serum markers of brain damage and outcome prediction in patients after severe head injury.

The objective of the study was to investigate the validity of outcome prediction after severe head injury using serum levels of S-100B protein and neuron specific enolase. Eighty-two patients with severe head injury were included in this prospective study. Venous blood samples were taken after admission and every 24 h for a maximum of 10 consecutive days. For values of S-100 from 0 to 2.5 micrograms/l, and for values of NSE from 0 to 100 micrograms/l the sensitivity and specificity of incremental values as a predictor of unfavourable outcome were calculated and Receiver Operator Characteristics curves were plotted. Serum S-100 protein was found to be clearly superior to neuron specific enolase in terms of predicting outcome with higher specificity, sensitivity, positive and negative predictive value. According to our experience, S-100B protein represents the most promising serum marker of brain cell damage currently under investigation.

Adolescent↗

PubMed1999

Serum S-100B protein in severe head injury.

OBJECTIVE: Despite the significant recent progress in cerebral monitoring, it is still difficult to quantify the extent of primary brain injury and ongoing secondary damage after head injury. The objective of our study was to investigate S-100B protein as a serum marker of brain damage after severe head injury. METHODS: Eighty-four patients with severe head injury (Glasgow Coma Scale score < or =8) were included in this prospective study. Venous blood samples for S-100B protein were obtained as soon as possible after admission and every 24 hours thereafter, for a maximum of 10 consecutive days. Serum levels of S-100B protein were compared with outcome after 6 months, clinical variables, and the category of the Marshall classification of initial computed tomographic findings. RESULTS: Patients who died had significantly higher serum S-100B values compared with those who survived (median, 2.7 microg/L versus 0.54 microg/L; P < 0.0001, Mann-Whitney U test). Nineteen (58%) of 33 patients who died had peak S-100B values of 2 microg/L or higher, compared with 4 (8%) of the 51 surviving patients (P < 0.0005, Fisher's exact test). There was also a strong correlation between S-100B values and computed tomographic findings. Logistic regression analysis in a model with age, Glasgow Coma Scale score, intracranial pressure, and computed tomographic findings revealed S-100B as an independent predictor of outcome. Persistent elevation of S-100B levels for 2 to 6 days, even in patients with favorable outcome, may reflect ongoing secondary damage after severe head injury. CONCLUSION: S-100B may be a promising serum marker for assessing the extent of primary injury and the time course of secondary damage after severe head injury.

Adolescent↗

PubMed1999

Fatal secondary increase in serum S-100B protein after severe head injury. Report of three cases.

The S-100B protein is a small cytosolic protein that is found in astroglial or Schwann cells. It is highly specific for brain tissue and is increasingly being investigated as a diagnostic tool to assess the neurological damage after head injury, stroke, subarachnoid hemorrhage, and cardiopulmonary bypass. The authors report on three patients with severe head injury with otherwise normal cerebral perfusion pressure, SaO2, PaCO2, and controlled intracranial pressure (ICP), in whom a secondary excessive increase in serum S-100B was observed. In all cases, the S-100B increase was followed by an increase in ICP. All three patients died within 72 hours after the excessive increase in S-100B. These findings indicate that major secondary brain damage may occur at a cellular level without being identified by current neuromonitoring techniques.

Adolescent↗

PubMed1998

An avoidable methodological failure in intracranial pressure monitoring using fiberoptic or solid state devices.

Failure of intraventricular pressure (IVP) measurement in case of catheter blockage is believed to be eliminated by using intraventricular microtransducers. We report about an avoidable methodological error, which may affect the reliability of IVP measurement with these devices. Intraventricular fiberoptic or solid state devices were implanted in 43 patients considered to be at risk for catheter occlusion. Two different types were used: devices where the transducer is placed inside the ventriculostomy catheter (Type A), and devices where the transducer is integrated in the external surface of the catheter (Type B). Of the 15 patients treated with Type A devices, no reliable pressure recording could be obtained in three patients where ventricular puncture was not successful. In four cases of the remaining 12 patients, periods of erroneous pressure readings were revealed. After opening of CSF drainage, all Type A devices failed to reflect real IVP. In patients treated with Type B devices, no erroneous pressure recording could be identified, irrespective if CSF drainage was performed or not. Transducers, which are simply placed inside the ventriculostomy catheter require fluid coupling. They may fail, either during CSF drainage or when the catheter is blocked or placed within the parenchyma.

Catheters, Indwelling↗

PubMed1998

Correlation of computed tomography findings and serum brain damage markers following severe head injury.

The objective of our study was to investigate the association between the initial levels of serum S-100B protein and neuron specific enolase and the severity of radiologically visible brain damage and outcome after severe head injury. Admission computed tomography (CT) scans of forty-four patients with severe head injury were analysed. Initial levels of S-100B protein and neuron specific enolase were compared between the different outcome groups at 6 month, the different categories of the Marshall classification, the presence of traumatic subarachnoid haemorrhage, the type of haematoma and the volume of contusion. Serum S-100B was significantly higher in patients with unfavourable outcome (1.1 micrograms/l versus 0.3 microgram/l, p < 0.005, Mann-Whitney U test). In diffuse injury, unfavourable outcome significantly increased with higher Marshall grades (p < 0.05). There was a significant correlation between the four grades of diffuse injury and initial serum S-100B protein (r = 0.48, p < 0.001). Patients with focal mass lesions and a favourable outcome after 6 month had significantly lower S-100B values than those who had an unfavourable outcome (0.51 microgram/l versus 1.3 micrograms/l, p < 0.05). A significant correlation was demonstrated between the volume of contusion visible on CT scans and serum S-100B (r = 0.58, p < 0.001). In our study, initial serum S-100B protein was a powerful predictor of outcome even within the same category of radiologically visible brain damage. Serum S-100B protein may provide independent information about the severity of primary brain damage after head injury.

Adolescent↗

PubMed1998

Reliability of intraventricular pressure measurement with fiberoptic or solid-state transducers: avoidance of a methodological error.

OBJECTIVE: The failure of intraventricular pressure measurement in cases of catheter blockage or dislodgement is thought to be eliminated by using intraventricular microtransducers. We report on an avoidable methodological error that may affect the reliability of intraventricular pressure measurement with these devices. METHODS: Intraventricular fiberoptic or solid-state devices were implanted in 43 patients considered to be at risk for developing catheter occlusion. Two different types were used, i.e., devices in which the transducer is placed inside the ventriculostomy catheter (Type A) and devices in which the transducer is integrated in the external surface of the catheter (Type B). Type A devices were used in 15 patients and Type B devices in 28 patients. Pressure recordings were checked at bedside for the validity and reliability of the measurement. RESULTS: Of the 15 patients treated with Type A devices, no reliable pressure recordings were able to be obtained in three patients in whom ventricular punctures were not successful. In 4 of the remaining 12 patients, periods of erroneous pressure readings were detected. After opening of cerebrospinal fluid drainage, all Type A devices failed to reflect real intraventricular pressure. In patients treated with Type B devices, no erroneous pressure recordings were able to be identified, irrespective of whether cerebrospinal fluid drainage was performed. Even when ventricular puncture failed, pressure measurement was correct each time. CONCLUSION: Transducers that are simply placed inside the ventriculostomy catheter require fluid-coupling. They may fail, either during cerebrospinal fluid drainage or when the catheter is blocked or placed within the parenchyma.

Catheters, Indwelling↗

PubMed1998

Reliability of epidural pressure measurement in clinical practice: behavior of three modern sensors during simultaneous ipsilateral intraventricular or intraparenchymal pressure measurement.

OBJECTIVE: In recent years, new devices for epidural pressure (EDP) measurement have been developed, with claims of improved accuracy. However, there have been no new data from simultaneous pressure measurements to reverse the skepticism regarding this technique. METHODS: The reliability of EDP recording was investigated in 26 patients with severe head injuries, during simultaneous measurement of ipsilateral intraventricular pressure (IVP) or intraparenchymal pressure (IPP). RESULTS: Periods of simultaneous measurement ranged from 3.3 to 168 hours. Technical failure occurred in five cases. Clinically significant erroneous pressure values (defined as differences of >10 mm Hg between EDP and IVP or IPP, lasting for >10 min) occurred in 7 of 21 measurements (33%). In three of these seven cases (43%) the difference between the EDP and the IVP or IPP remained nearly stable throughout the period of observation, whereas in four cases (57%) significant drifting over time was observed. Analysis of the transfer function calculated for the first to sixth harmonics between the EDP and the IVP or IPP showed no significant differences between the pulse pressure waveforms, even when significant drifting of more than 20 mm Hg occurred. CONCLUSION: The reliability of EDP measurement has not improved, compared with 10 years ago. Using this technique, one must be aware of the possibility of overestimating intracranial pressure by more than 10 mm Hg and the possibility of significant drifting of EDP over time, which argues against the use of this method even for trend analysis.

Brain Edema↗

PubMed1998

Jugular venous and arterial concentrations of serum S-100B protein in patients with severe head injury: a pilot study.

The objective of this study was to analyse the temporal course of the jugular venous-arterial gradient of S-100B protein after severe head injury and the correlation between the absolute concentrations of serum S-100B protein and outcome, CT findings, and clinical variables. Fifteen patients were included in this pilot study. All patients were treated according to a standard therapy protocol targeted to maintain cerebral perfusion pressure. The serum concentration of S-100 protein was measured daily for five consecutive days after injury by a monoclonal two site immunoluminometric assay. Nine patients showed favourable and six unfavourable outcome after 6 months with a mortality rate of 33% (five patients). The mean gradient between jugular venous and arterial blood was 8.2% (p<0.05). Patients showing an unfavourable outcome had significantly higher jugular venous or arterial S-100 values compared with those with a favourable outcome (jugular venous S-100B 2.78 microg/l v 1.22 microg/l, p<0.05; arterial S-100B 2.48 microg/l v 1.19 microg/l, p<0.05). All patients with an initial or secondary increase in S-100B value of >2 microg/l were found to have an unfavourable outcome. S-100B was found to be an independent predictor of outcome after severe head injury. The persisting increase of S-100B for three to five days even in patients with favourable outcome and no signs of secondary insults might reflect continuing damage to the blood-brain barrier or ongoing glial cell death.

Adolescent↗

PubMed1998

Serum S-100 and neuron-specific enolase for prediction of regaining consciousness after global cerebral ischemia.

BACKGROUND AND PURPOSE: The aim of our study was to assess the use of S-100 protein (S-100) and neuron-specific enolase (NSE) in serum and cerebrospinal fluid (CSF) for the prediction of patients' regaining consciousness after acute global cerebral ischemia. METHODS: Sixty-four unconscious patients were followed until the return of consciousness or until death/vegetative state. Serum and CSF samples for measurement of S-100 and NSE using an immunoradiometric assay technique were obtained 24 hours (serum) and 48 hours (CSF) after the acute event and correlated with patient outcome. RESULTS: Values for serum S-100 protein, serum NSE, CSF S-100, and CSF NSE were significantly different in the 2 outcome groups. A serum S-100 value of >0.7 micrograms/L was found to be a predictor of not regaining consciousness, with a high positive predictive value (95%) and high specificity (96%). CONCLUSIONS: S-100 protein used as serum marker 24 hours after acute global cerebral ischemia gives reliable and independent information on the outcome of the patient that is comparable or superior to that obtained with CSF markers. Therefore, S-100 may be a serum marker of brain cell damage useful for clinical assessment of these patients.

Adult↗

PubMed1997

Combination of fractionated irradiation with nicotinamide and carbogen in R1H-tumours of the rat and its pulmonary metastases.

BACKGROUND AND PURPOSE: The combination of radiotherapy with nicotinamide and carbogen is a promising method to improve treatment outcome. The aim of the present study was to investigate its effect on rat lungs, the R1H-tumour and its pulmonary metastases. MATERIALS AND METHODS: Subcutaneous tumours and artificially induced pulmonary metastases of the rhabdomyosarcoma R1H of the rat were treated either with fractionated irradiation alone or in combination with nicotinamide and carbogen. Local metastatic control, net growth delay and lethal lung damage were used as endpoints. RESULTS: Radiosensitivity of the lungs of WAG/Rij rats increased by a factor of 1.13, while no positive effect of the combined treatment either on subcutaneous R1H-tumours or on pulmonary metastases could be detected. This resulted in a therapeutic loss of 18% (P = 0.003). CONCLUSION: The results indicate that deleterious effects of the combination of radiotherapy with nicotinamide and carbogen cannot be excluded under all circumstances.

Animals↗

PubMed1997

The transcallosal interforniceal approach to the third ventricle: anatomic and microsurgical aspects.

OBJECTIVE: The ability to visualize median-sagittal brain structures by magnetic resonance imaging improves planning for surgery to treat lesions of the third ventricle. The most appropriate path to the third ventricle is the transcallosal approach. The present study was undertaken to describe the surgical anatomy and landmarks encountered during this approach. METHODS: The transcallosal-interforniceal approach was undertaken in 30 formalin-fixed brains using an operating microscope. The surface landmarks for the approach pathway were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. Using these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures that are encountered during the surgical approach. Measurements that were made include the following: 1) the distance between P5 and the cingulate sulcus, 2) the distance between the cingulate sulcus and the corpus callosum, 3) the height of the corpus callosum, 4) the distance between the anterior commissure and the foramen of Monro, and 5) the distance between the lower margin of the corpus callosum and the fornix. RESULTS: Mean values for these key measurements were as follows: 1) 23.96 mm (range, 15.0-32.0 mm); 2) 13.50 mm (range, 8.0-20.0 mm) with reference to P5 and 12.73 mm (range, 16.0-18.0 mm) with reference to P7; 3) 6.12 mm (range, 4.0-8.0 mm) with reference to P5 and 6.60 mm (range, 4.0-9.0 mm) with reference to P7; 4) 4.96 mm (range, 2.5-10.0 mm), independent of P5 and P7; and 5) 8.46 mm (range, 3.0-16.0 mm) with reference to P5 and 11.04 mm (range, 6.0-22.0 mm) with reference to P7. CONCLUSION: The detailed quantitative information obtained in this study about the interforniceal approach permitted definition of surgical approach pathways that preserve important anatomic structures, such as the motor strip, genu of the corpus callosum, fornical commissure (hippocampal commissure), anterior commissure, and fornical columns. The approach through this surgical corridor can easily be planned and performed in individual cases using median-sagittal magnetic resonance imaging scans.

Adult↗

PubMed1996

The possible influence of breathing patterns on the measurements of breathing frequency.

The breathing frequency is a common parameter to assess the radiation response of the lungs of laboratory rodents. Rats of the strain WAG/Rij which were bred in Hamburg show different breathing patterns which consist of short regular and long irregular breaths. Depending on the breathing pattern, the breathing frequency of untreated animals varies by a factor of three. Although this phenomenon might be strain-specific, it seems noteworthy because it might influence the results obtained after irradiation significantly, especially if breathing frequency is automatically converted into a numerical value.

Animals↗

PubMed1994

Radiobiological determination of growth kinetics and radiosensitivity of pulmonary micrometastases of the R1H tumour.

The aim of the study was to determine the radiosensitivity and the growth kinetics of pulmonary micrometastases of the R1H tumour of the rat. Lung metastases were induced by intravenous injection of viable tumour cells. At different time intervals (3-32 days) after injection, lungs were locally irradiated with 200 kVp X-rays, using 1.5 Gy/fraction. Total doses of 6-33 Gy were administered within 11 days. Endpoints used were survival time, local control rate, and number of metastases in the lungs at autopsy. The data were evaluated using the multi-target model. Beginning in the fifth week after tumour cell inoculation the animals started to exhibit a pronounced dyspnoea and were sacrificed. Sections revealed an extensive metastatic infiltration of the lungs. With increasing total dose a prolongation of survival time as well as an increase in cure rate was observed. The number of metastases found in the lungs decreased with increasing total dose. It is concluded that metastatic growth does not start earlier than 3 days after tumour cell inoculation and accelerates continuously. The doubling time of the tumour cells in the micrometastases decreases continuously and from 5.2 to 1.2 days between day 3 and 40, whereas larger metastases containing more than 10(6) cells show gompertzian growth kinetics. The cell doubling time in this stage of metastatic growth is longer than 5 days. During the first 4 weeks of metastatic growth the radiosensitivity of metastatic R1H cells in the lungs is the same as in vitro.

Animals↗