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Biomedical subjects

R Scheck

Publications and source records attributed to R Scheck.

At least 19 recordsLinked to original sources
PubMed2006

Reversible cerebral hyperperfusion syndrome after stenting of the carotid artery - two case reports.

Hyperperfusion syndrome can complicate carotid revascularization, be it endarterectomy or carotid artery stenting (CAS). Although extensive effort has been devoted to reducing the incidence of ischemic stroke complicating CAS, little is known about the incidence, etiology, and prevention strategies for hyperperfusion following CAS. We report two cases (female patients 72 and 81 years) presenting severe internal carotid stenosis (> 90%), who underwent presurgical and therapeutic intervention with CAS. Both patients developed hyperperfusion symptoms at 2 hours and at 30 minutes, respectively, following stenting, in both cases unilateral hyperperfusion was CCT confirmed. Case 1 was presenting with acute edema of the right hemisphere, case 2 with distended focal edema (left fronto-temporoparietally). Hyperperfusion syndrome and neurological symptoms retroceded in both cases (conservative therapy) and both patients returned to full activity (case 2 within 48 hours).

Aged↗
PubMed1999

Biomechanical analysis of stress distribution in the human temporomandibular-joint.

The positions of the head of the mandible, of the articular disc and the outline of the temporal surface are digitized from sagittal MRI-scans of the temporomandibular joint of a 32-year-old subject in 5 different positions of occlusion. The stress distribution in the joint is calculated on the basis of these data. For each position of the condyle, the momentary center of rotation in the head of the mandible and the tangent attached to the temporal surface are determined. The line connecting these two points indicates the direction of the resulting compressive force. Furthermore, the extension of the area available to the force transmission is estimated. By means of these parameters the stress distribution is calculated independently from the position. The analyses show that the temporomandibular joint is slightly eccentrically loaded in all positions. The increase of the stresses is in all cases oriented caudo-ventrally. The results are verified in an anatomical specimen of the articular tuberculum. The trabecular structures as well as the subchondral bone-lamella of the articular tuberculum are functionally adapted to the analyzed stress situations.

Adult↗
PubMed1999

Dose and image quality of electron-beam CT compared with spiral CT.

RATIONALE AND OBJECTIVES: To examine dose and image quality of electron-beam CT (EBCT) with continuous volume scan versus spiral CT. METHODS: An EBCT scanner was compared with a spiral CT (SCT) scanner. Three phantoms were used to measure low-contrast resolution, high-contrast resolution, slice width, and dose. RESULTS: The EBCT scans showed 30% lower high-contrast resolution for most settings. The dose was comparable to that of spiral CT with 3 mm collimation and 76%/106% higher with EBCT for 1.5 mm/6 mm collimation. Low-contrast resolution was comparable to that of spiral CT using 3 mm collimation, slightly worse for 1.5 mm, and bad for 6 mm EBCT collimation (four times higher dose to reach comparable contrast-to-noise ratio). CONCLUSIONS: Significant restrictions were found using EBCT with continuous volume scan. The authors found that 3 mm collimation can yield acceptable high-contrast resolution and good low-contrast resolution compared with spiral CT. The use of 6 mm or 1.5 mm collimation needs to be restricted to selected cases.

Evaluation Studies as Topic↗
PubMed1999

Normative volumetric data of the developing hippocampus in children based on magnetic resonance imaging.

PURPOSE: To acquire normative data of the hippocampus and its postnatal growth in 50 children (age, 1 month to 15 years) without epilepsy. METHODS: Morphometry of the hippocampus was carried out by using a spoiled FLASH 3D sequence (sagittal orientation), whereas the volume of the brain was assessed with a T2-weighted spin-echo sequence (transverse orientation). The volume of the hippocampus and the brain was determined by following Cavalieri's principle. Growth curves of the brain and hippocampus were fitted to a nonlinear Boltzmann sigmoidal equation. RESULTS: Intra-/interobserver coefficient of variation was 2.0/4.9% for hippocampal volume measurements and 2.0/2.1% for brain volumetry. A significant difference in volume was noted between the right and left hippocampus (p < 0.001), with the right side being larger on average by 0.10 cc. Correlation coefficients of growth curves ranged between 0.71 and 0.94. Growth curves demonstrated a faster development of the hippocampus in girls. A steeper slope of hippocampal growth as compared with brain growth was found in girls, whereas in boys, the slope of brain growth was steeper. CONCLUSIONS: Our findings will be of help in evaluating vulnerable phases of the hippocampal formation with accelerated growth, thereby leading to a better understanding of the development of hippocampal sclerosis in early childhood.

Adolescent↗
PubMed1999

MR angiography versus color Doppler sonography in the evaluation of renal vessels and the inferior vena cava in abdominal masses of pediatric patients.

OBJECTIVE: Involvement of renal vessels and the inferior vena cava (IVC) plays a decisive role during operative planning for removal of abdominal masses in pediatric patients. Advantages and limitations of MR angiography and color Doppler sonography for determining these factors were evaluated. MATERIALS AND METHODS: MR angiography and color Doppler sonography were performed preoperatively in 42 neonates, infants, and children with abdominal masses and were compared with spin-echo MR imaging and with surgical findings. Variables evaluated were anatomic variants, vessel displacement, patency of vessels, collateral circulation, and intravascular tumor extension. Quality of vessel visualization was assessed in vessels not affected by tumor. RESULTS: In 88% of unaffected renal vessels, the entire vessel course could be visualized on MR angiography compared with 58% on color Doppler sonography and 43% on spin-echo MR imaging. In four of nine cases, color Doppler sonography revealed an accessory renal artery, whereas MR angiography revealed these variants in seven of nine cases. MR angiography showed 79% and color Doppler sonography 66% of displaced vessels. Unlike MR angiography, color Doppler sonography did not reveal five stenotic renal veins because they could not be completely imaged. In two cases, however, MR angiography falsely indicated an occlusion of the IVC, whereas color Doppler sonography showed residual flow. CONCLUSION: Anatomic variants, vessel displacement, collateral circulation, and neoplastic vessel infiltration were revealed more accurately by MR angiography than by color Doppler sonography. In cases in which patency of the IVC is unclear on MR angiography, color Doppler sonography should also be performed.

Abdominal Neoplasms↗
PubMed1998

[Performance of electron-beam CT: continuous-volume-scan compared to spiral CT].

To compare patient dose and image quality of electron-beam-CT vs. spiral-CT by means of phantom measurements. An EBCT scanner (C-150 XP) and a spiral-CT scanner (GE HiSpeed Advantage) were used to scan three different phantoms. Administered dose, high contrast (HC) resolution, low contrast (LC) lesion detectability and the width of the radiation beams were measured. EBCT showed 25-35% lower HC resolution in comparison to spiral-CT. LC lesion detectability showed equivalent results for S/N vs. patient dose using 3 mm collimation with EBCT and spiral-CT, whereas spiral-CT was superior for 1.5 and 6 mm collimation. Dose measurements revealed a 2 fold higher patient dose using EBCT with 1.5 mm or 6 mm collimation compared to spiral-CT using equivalent scan parameters. No differences were seen using 3 mm collimation. Differences were due to insufficient beamside collimation of the EBCT. The use of EBCT with 6 mm collimation should be avoided, because of impaired performance. Using 3 mm collimation, EBCT showed comparable performance like state of the art spiral-CT despite lower HC resolution.

Algorithms↗
PubMed1998

Marinesco Sjögren syndrome with rhabdomyolysis. A new subtype of the disease.

Four children from two families with characteristics of Marinesco-Sjögren syndrome (congenital cataract, ataxia) are presented. All children had clinical and neurophysiological signs of a demyelinating polyneuropathy. Three of them developed acute rhabdomyolysis with marked weakness and CK levels of up to 40,000 U/I following a viral infection. In all children CK levels returned to normal within two weeks. Symptoms were recurrent in one of the children and resulted in a severe disability. In two other children recovery of motor function took about a month following the first attack. Metabolic disorders of the muscle were excluded by pathobiochemical examination of a muscle biopsy in one of the children. In conclusion, acute rhabdomyolysis can occur as a neuromuscular complication of Marinesco-Sjögren syndrome.

Child↗
PubMed1998

Prospective evaluation of MR arthrography performed with high-volume intraarticular saline enhancement in patients with recurrent anterior dislocations of the shoulder.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of high-volume saline-enhanced MR arthrography in assessing the labrum, the ligaments, and the bony components of the glenohumeral joint. SUBJECTS AND METHODS: Forty-four patients with recurrent anterior dislocations of the shoulder underwent MR arthrography after intraarticular injection of 15-40 ml of saline solution. Two-dimensional fast low-angle shot and T1-weighted spin-echo sequences were prospectively evaluated by two observers. Anterior (Bankart) lesions, superior labral lesions extending from anterior to posterior, and Hill-Sachs lesions were diagnosed. Glenohumeral ligaments (GHLs) were identified and classified using a standard system. MR imaging results were compared with those of arthroscopy (n = 32) or open surgery (n = 12), either of which was the gold standard. RESULTS: Bankart lesions and superior labral lesions extending from anterior to posterior were revealed with a sensitivity of 93% and 89%, respectively, and a specificity of 80% and 89%, respectively. Diagnostic accuracy was 89% for both types of lesions. All six patients with bony Bankart lesions had high fat-marrow signal intensity within the fragment on T1-weighted MR images. For GHLs, MR imaging results and arthroscopy correlated in 25 of the 31 patients. In three patients all three GHLs were visible on MR imaging, but only two GHLs were detected with arthroscopy. In three patients two GHLs were detected on MR imaging but all three were visible on arthroscopy. Hill-Sachs lesions were revealed with a sensitivity of 95%, a specificity of 50%, and an accuracy of 81%. CONCLUSION: High-volume saline-enhanced MR arthrography is accurate in revealing the labrum, the ligaments, and the bony components of the glenohumeral joint Saline solution is inert and inexpensive, two advantages over gadopentetate dimeglumine.

Adult↗
PubMed1996

Local muscle flaps of the second and third interosseus space for the treatment of osteomyelitis in the central metacarpal region.

Both experimental and clinical studies showed that muscle flap transposition is a reliable tool in treating chronic infections of the bone. The major advantage of local muscle flaps is the treatment with well perfused autogenous tissue without using any implants. The primary closure of the operation site and the cure of infection within four weeks allow a short immobilisation time. Nevertheless, the loss of muscle function with a possible functional and aesthetic defect in the donor site has to be accepted. The first dorsal interosseus muscle and the abductor digiti minimi muscle have been used successfully for the treatment of metacarpal osteomyelitis. Osteomyelitis in the central metacarpal bones cannot be treated with these techniques, because of their limited range. We present the muscles of the second and third interosseus space for local pedicled muscle flap transfer. The arterial network in this interosseus spaces and the vascularisation of the dorsal and palmar interosseus muscles allow to harvest muscle flaps with either proximal or distal pedicle. The loss of interosseus muscles in the second and third interosseus space is tolerable from a functional and esthetic point of view. Operative techniques are shown for the elevation of dorsal and palmar interosseus muscle flaps. Two cases of osteomyelitis in the central metacarpal bones, which were treated successfully with the new local interosseus muscle flaps, are reported.

Adult↗
PubMed1979

Effect of hemoperfusion with coated and uncoated charcoal on human blood in vitro.

During 4 hours, in-vitro hemoperfusion of human blood was performed in 4 series of experiments: control, cellulose coated charcoal, polyacrylohydrogel coated charcoal and uncoated charcoal. In the control series little change on corpuscular elements and electrolytes was observed. In all hemoperfusion series there was little change of RBC and uniformly a marked fall of the granulocyte count. Platelet- and lymphocyte counts were significantly less affected by cellulose coated charcoal than by the other preparations. Coated and uncoated charcoal absorbed avidly calcium and glucose from the blood. By contrast the potassium level decreased moderately with polyacrylohydrogel coated and uncoated charcoal, whereas the opposite was observed with cellulose coated charcoal.

Blood Cell Count↗
PubMed1979

[Obstetrical problems in patients with Glanzmann's thrombasthenia. A casuistic presentation (author's transl)].

Glanzmann's thrombasthenia is a rare, autosomal recessive disorder of bleeding arrest. The differential diagnosis of this platelet defect with respect to recently gained knowledge is presented in the case of a pregnant woman. Because of pelvic presentation a cesarean section was performed after adequate platelet substitution, which did not involve excessive blood loss. A severe puerperal infection necessitated an abdominal hysterectomy after appropriate platelet transfusion. The difficulties in testing platelet function in the newborn are discussed. The effectiveness of a commercially available homologous phospholipide complex (Fibraccel) was tested on the patient in a noncritical phase. The results appear important for general procedure when pregnancy and platelet dysfunction concur.

Adult↗
PubMed1977

[Emergency treatment of haemophilia A with factor VIII inhibitors using activated prothrombin complex concentrates (author's transl)].

Severe rectal bleeding in a 6-year-old boy with haemophilia A and factor VIII inhibitors could not be stopped with factor VIII concentrates. But a good effect was achieved with activated prothrombin complex concentrates (fraction FEIBA), given over eight days. Amaurosis occurred as a complication after injection of the first dose, but disappeared completely within several minutes. Tests revealed accelerated intravascular coagulation with increased fibrin monomers and fibrin/fibrinogen degradation products.

Blindness↗
PubMed1977

The effect of somatostatin on platelets: in vivo and in vitro studies.

The influence of somatostatin on platelets was studied in healthy volunteers. After a bolus injection of 250 microgram somatostatin followed by a three hour infusion at a rate of 250 microgram somatostatin/hr a statistically significant fall of platelet count and impairment of platelet aggregation was observed. The aggregation inhibiting effect of somatostatin at the end of the three hour infusion is clinically unimportant as compared to the effect of aspirin. In vitro concentrations up to 10.0 microgram somatostatin per ml do not show any effect on platelet aggregation and platelet stickiness. Endocrinologically active doses of somatostatin in short term infusions are very unlikely to cause bleeding disorders.

Adolescent↗
PubMed1976

Coagulation studies and platelet function after somatostatin infusion.

The effect of short- and long-term somatostatin (GIF) administration on haemostatic function in man was investigated. The dosage programme applied in this study was 250 mug GIF as a bolus injection and 250 mug GIF/h by way of infusion. In five healthy volunteers a short-term (3h) treatment resulted in a statistically significant drop of platelet count and impairment of platelet aggregation at the end of infusion. However, these changes were within the physiologically normal range and disappeared after two hours on all subjects. Other parameters such as bleeding time, thromboplastin and partial thromboplastin time, fibrinogen, fibrin/fibrinogen split products, plasma factor XIII, ethanol gelation test were not affected. In two patients with gastric haemorrhage and persistent amylasaemia a 67 or 120-h treatment induced no remarkable haemostatic defect. By contrast, peptic ulcer bleeding in one patient stopped 60 min after starting the GIF infusion. These studies indicated that somatostatin administration in man at the dosage programme used neither results in clinical evidence indicating bleeding tendency nor does it influence laboratory parameters in an apparent way.

Adult↗
PubMed1975

[Platelet dysfunction as a result of inhibition of ADP release (aspirin-like defect) in two identical twins(author's transl)].

An abnormal release of platelet adenosine diphosphate (ADP), as seen after intake of acetylsalicylic acid, was demonstrated to be the cause of a clotting disorder in two identical female twins. The signs of bleeding occurred at the age of 26 and consisted of an increased frequency of haematomas, hypermenorrhoea not explained on gynaecological grounds, and prolonged bleeding after minor injuries. Increased bleeding time, abnormal aggregation after stimulation with collagen and absence of the second aggregation phase after addition of ADP were the abnormal findings of this clearly hereditary form of platelet dysfunction. The platelets were slightly larger than normal ones and there were changes in ultrastructure.

Adenosine Diphosphate↗