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Biomedical subjects

J Rudolf

Publications and source records attributed to J Rudolf.

At least 55 records · Page 3Linked to original sources
PubMed1998

Quantitative neuroimaging for the evaluation of the effect of stroke treatment.

A prerequisite for the successful treatment of acute ischaemic stroke is the existence of viable tissue that is morphologically intact but functionally impaired due to a flow decrease below a certain threshold. At this stage, tissue at risk of infarction can be identified only by functional imaging. This penumbral tissue can be classified as having a critical flow decrease with preservation of oxygen consumption and therefore increased oxygen extraction. Such 'misery-perfused' tissue has been observed consistently in the first few hours following ischaemic stroke but usually develops into necrosed tissue at follow-up observations. Several studies have indicated that penumbral tissue can be identified up to 17 h or even 48 h after stroke in the border zones of ischaemic tissue and that this condition is occasionally reversible without resulting in permanent infarction. Positron emission tomography studies of cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2) and cerebral metabolic rate of glucose (CMRglc) can be used to demonstrate the effect of treatment on functional variables within tissue showing perfusional disturbances. Such studies have shown the value of these markers of ischaemia, which also correlate with clinical efficacy. However, when therapeutic strategies, such as thrombolysis, do not permit arterial blood sampling, quantitative determinations of CBF and CMRO2 are not feasible. In such cases relative indices, such as those for CBF, must be applied. Such qualitative assessments of perfusion, which were calibrated in an independent cohort of patients with acute stroke, were used to demonstrate the effect of early systemic treatment of acute ischaemia with recombinant tissue plasminogen activator. By applying operationally defined thresholds for tissue viability and the penumbra, and co-registering these tissue compartments to infarcted and non-infarcted tissue on late magnetic resonance imaging, the proportions of at-risk tissue salvaged from infarction could be revealed in individual patients. In the future, functional imaging modalities that could eventually include tracers for neuronal integrity could be used to select patients for thrombolytic therapy. In some instances such techniques may permit the extension of the critical time period for inclusion of patients to aggressive stroke management strategies.

Animals↗
PubMed1998

Permanent cortical damage detected by flumazenil positron emission tomography in acute stroke.

BACKGROUND AND PURPOSE: Therapy of acute ischemic stroke can only be effective as long as neurons are viable and tissue is not infarcted. Since gamma-aminobutyric acid receptors are abundant in the cortex and sensitive to ischemic damage, specific radioligands to their subunits, the central benzodiazepine receptors (BZR), may be useful as indicators of neuronal integrity and as markers of irreversible damage. To test this hypothesis we studied the binding of the BZR ligand [11C]flumazenil (FMZ) early after ischemic stroke in comparison to the extent of final infarcts and hypometabolic cortical areas. METHODS: In 10 patients cerebral blood flow, cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and FMZ binding were studied by positron emission tomography 3.5 to 16 hours after onset of their first hemispheric stroke. Early changes in flow, oxygen metabolism, and FMZ binding were compared with permanent disturbances in glucose metabolism, and the size of the final infarcts was determined on MRI or CT 12 to 22 days after the stroke. RESULTS: In all patients except one cerebral blood flow was disturbed, with marked decreases in eight and a hyperperfusion in one patient corresponding to the location of neurological deficits. In these areas CMRO2 was also reduced but to a variable degree, inducing highly variable OEF. Areas with markedly decreased CMRO2 (<60 micromol/100 g per minute) corresponded to regions with decreased FMZ binding (<4.0 times the mean value in the white matter). In all patients the final cortical infarcts were visible on the early FMZ images. Infarcts could be discriminated from noninfarcted cortex by decreased FMZ binding despite a wide range of OEF. In finally hypometabolic cortex FMZ binding was initially decreased or normal, with OEF covering a wide range; this suggested neuronal loss and/or deactivation as the cause of metabolic disturbance. Additionally, a highly significant correlation was found between FMZ distribution within the first 2 minutes after injection and regional cerebral blood flow. CONCLUSIONS: These results demonstrate that permanently and irreversibly damaged cortex can be detected by reduced FMZ binding early after stroke. Since FMZ distribution additionally images regional cerebral perfusion, BZR radioligands have a potential as clinically useful tracers in patients with acute ischemic stroke. The evidence of tissue damage furnished by these tracers might be of relevance for the selection of individual therapeutic strategies.

Aged↗
PubMed1998

Alterations of neuropsychological function and cerebral glucose metabolism after cardiac surgery are not related only to intraoperative microembolic events.

BACKGROUND AND PURPOSE: High-intensity transient signals (HITS) during cardiac surgery are capable of causing encephalopathy and cognitive deficits. This study was undertaken to determine whether intraoperative HITS cause alterations of neuropsychological function (NPF) and/or cerebral glucose metabolism (CMRGlc), even in a low-risk patient group, and whether induced changes are interrelated. METHODS: Eighteen patients without signs of cerebrovascular disease underwent elective coronary artery bypass grafting (CABG), and two of these additionally underwent valve replacement in normothermia. Intraoperatively, HITS were recorded by means of transcranial Doppler ultrasonography (TCD). Perioperatively, NPF and CMRGlc were assessed using a standardized complex test battery and positron emission tomography with 18F-2-fluoro-2-deoxy-D-glucose (FDG-PET), respectively. RESULTS: Intraoperatively, the number of HITS ranged from 90 to 1710 per patient and hemisphere, more on the right side than on the left (P<.05). HITS occurred primarily during cardiopulmonary bypass (71.3%) and, to a lesser extent, during aortic manipulation (22.2%). Changes in global and regional CMRGlc between first (one day preoperatively) and second (8 to 12 days postoperatively) FDG-PET scans were mild. No correlations were found between the number of HITS, age of patient, duration of cardiac ischemia or cardiopulmonary bypass and the changes in CMRGlc. In patients with recorded HITS and a postoperative decrease of regional CMRGlc (n=11), the maximal decrease of rCMR Glc in each hemisphere below the individual global change of CMRGlc correlated with the number of HITS (r= -0.46, P<.05). Limitations in NPF occurred 8 to 12 days postoperatively, resolved within 3 months, and were not found to be correlated to the absolute number of HITS or changes in CMRGlc. CONCLUSIONS: HITS during cardiac surgery can cause alterations of both NPF and CMRGlc, even in a low-risk patient group. However, the number of HITS and changes in NPF and CMRGlc are not necessarily interrelated, which indicates that (1) the location of brain damage related to HITS is more important for the development of NPF than is the absolute number of HITS, and (2) factors in addition to HITS might contribute to surgery-related brain damage.

Adult↗
PubMed1998

Early intravenous thrombolysis for acute ischemic stroke in a community-based approach.

BACKGROUND AND PURPOSE: Controlled multicenter studies have demonstrated the efficacy of systemic recombinant tissue-type plasminogen activator (rtPA) treatment in selected cases of acute ischemic stroke. The feasibility of this therapeutic option in clinical practice was assessed in a community-based approach. METHODS: We offered rtPA treatment to stroke patients in a prospective open-label monocenter study applying inclusion criteria similar to those of the National Institute of Neurological Disorders, and Stroke study. In order to treat patients within 3 hours of symptom onset, a referral system was used by which eligible patients from all over the city of Cologne, Federal Republic of Germany, were rushed to the Department of Neurology of the University Hospital. We present data on the effectiveness of the referral system and the outcome results of the first 100 consecutive patients treated within an 18-month period. RESULTS: Of 453 consecutive patients with a presumed diagnosis of acute stroke referred to our department between March 1996 and August 1997, 100 patients (22%) were treated with intravenous thrombolysis, 26% of them within 90 minutes of symptom onset. The average time from stroke onset to arrival at our department was 78 minutes, and from arrival to treatment 48 minutes. After 3 months, 53 patients recovered to fully independent function. The rates of total, symptomatic, and fatal intracerebral hemorrhage were 11%, 5%, and 1%, respectively. Overall mortality was 12%. CONCLUSIONS: Thrombolysis with rtPA was effectively applied in routine management of stroke patients in a community-based approach with acceptable efforts and without additional costs. Under these circumstances, outcome and complication rates were comparable to those of multicenter trials.

Academic Medical Centers↗
PubMed1997

Surgical indications and prognosis in spinal metastases.

Based on the catamnestic evaluation of our own case material and the compilation of recent series from the literature, the indication for surgical intervention in spinal metastases is considered in the light of factors influencing the prognosis of the underlying malignant disease.

Adult↗
PubMed1997

Clozapine-induced agranulocytosis and thrombopenia in a patient with dopaminergic psychosis.

In patients with Parkinson' disease and dopaminergic psychosis, clozapine treatment is recommended as the drug is free from extrapyramidal side effects and does not worsen motor symptoms of the underlying disease. The use of clozapine, however, is limited due to its hematotoxic side effects. For treatment of clozapine-induced agranulocytosis, granulocyte colony-stimulating factors (G-CSF) are recommended. We report the case of a 72-years-old male patient with clozapine-induced agranulocytosis and thrombopenia. Neutropenia was successfully treated with G-CSF, but thrombopenia persisted and resolved spontaneously after 14 days. Bone marrow toxicity of clozapine is not restricted to white cell maturation, but may also impair thrombocytopoesis.

Aged↗
PubMed1997

[Advantages of the unreamed tibial nail in comparison with external fixator in treatment of grade 3 B open tibial shaft fractures].

Between 1987 and 1993, 41 grade 3B open tibial shaft fractures were treated with the unreamed tibial nail (URTN n = 22) or an external fixator (FIX n = 19). The method of treatment was left to the choice of the operating surgeon. Three below the knee amputations were performed, three patients died, and three were lost to follow-up. In all, 32 patients were followed up to union or at least for 1 year. There were no significant statistical differences between the two groups (P < 0.2, chi-squared, t-test) with respect to fracture type, fracture location, age, gender or accompanying injuries. The URTN group showed significantly better results regarding time to full weight-bearing (URTN 11 +/- 4 weeks; FIX 20 +/- 11 weeks, P < 0.01 M-W) Mann-Whitney Test, number of reoperations (URTN 1.04; FIX 2.89; P < 0.01 M-W), isolated bone grafting (URTN 3/22; FIX 8/19; P < 0.05 chi-squared), and average Karlström and Olerud score (URTN 30 +/- 4; FIX 26 +/- 5; P < 0.05 M-W). In all, 15/17 URTN patients and only 6/15 FIX patients achieved unlimited walking distance (P < 0.01 M-W). Time to bony union, infection, and nonunion were not significantly different between groups.

Adult↗
PubMed1997

Superior results of tibial rodding versus external fixation in grade 3B fractures.

From 1987 to 1993, 41 Grade 3B open tibial shaft fractures were treated with the unreamed tibial nail or an external fixator. The method of treatment was left to the choice of the operating surgeon. Three below knee amputations were performed; three patients died; and three were lost to followup. Thirty-two patients were observed until union or for at least 1 year. There were no significant statistical differences between the two groups with respect to fracture type, fracture location, age, gender, or accompanying injuries. The unreamed tibial nail group showed significantly better results regarding time to full weightbearing, number of reoperations, isolated bone grafting, walking range, and average Karlström and Olerud score. Time to bony union, infection, and nonunion were not significantly different between the groups.

Adult↗
PubMed1996

Unreamed intramedullary nailing of femoral shaft fractures: operative technique and early clinical experience with the standard locking option.

Nailing techniques have changed in recent years in ways which are not just limited to omitting the reaming process. These changes concern positioning patients, techniques of reduction and selecting implants. Techniques of approach and exposure have been modified to new, less-invasive procedures to fulfill technical, functional and cosmetic requirements. In addition, techniques have been developed to avoid fragment diastasis, rotational and sagittal malalignment, and leg-length discrepancy. Finally, simple algorithms have been elaborated for the management of specific fracture patterns (bilateral shaft fractures, ipsilateral tibial fractures or associated femoral neck fractures) and to determine the number and location of locking bolts. We developed these algorithms, techniques and procedures in a series of 133 femoral shafts, which were stabilized with the AO unreamed femoral nail (URFN) in a prospective study between 1991 and 1994. Of these, the first 57 cases with a mean follow-up of 17.9 months (range, 5-44) after injury were reviewed. Fractures were classified according to Müller's 1990 system: 12 type A, 29 type B and 16 type C. Closed soft-tissue injuries were classified by our classification of 1982: 17 type C 0/I, 42 type C II. Of 15 open fractures, six were OI, six OII, two OIIIA and one was OIIIB by Gustilo's classification of 1984. The major complications were two broken locking bolts, one nail breaking after 9 weeks, one case of osteitis and one of intra-operative lung embolism.

Adolescent↗
PubMed1996

Accuracy of intramedullary templates in femoral and tibial radiographs.

The accuracy of templates used for the preoperative planning of the fixation of intramedullary fractures depends on radiological magnification. To study the accuracy of these templates, we randomly selected 100 femoral and 100 tibial radiographs taken after stabilisation by an intramedullary nail using a standard technique. We then compared the known nail length with the corresponding measurements on the radiographs. The mean magnification factor for the femur was 9% and for the tibia 7%; these differ considerably from the range of magnification of the manufacturers' templates (femur, 15% to 17%; tibia 10% to 15%). We conclude that templates are unreliable for the selection of implant length and that this should be done by intraoperative measurements.

Bone Nails↗
PubMed1995

Outcome of tibial shaft fractures with severe soft tissue injury treated by unreamed nailing versus external fixation.

MATERIALS: Between 1987 and 1991, 114 fresh tibial shaft fractures with severe soft tissue injury, which met the inclusion criteria, were treated and retrospectively reviewed. There were 48 cases in the unreamed nail (unreamed tibial nail (UTN)) group and 66 cases in the external fixation (EF) group. METHODS: Soft tissue injury was classified by the Gustilo and Tscherne methods. There were 18 AO type A, 56 type B, and 40 type C fractures. There were no significant difference in fracture type, soft tissue injury, age, and additional injury between the groups. Outcome was assessed using the Karlström score after 28 months. RESULTS: There were a significantly higher number of reoperations in the EF group. Mean time to bony healing was 25.8 weeks. In the EF group, there was a 26% rate of pin tract infection, whereas 19% of cases had bolt breakages in the UTN group. In the UTN group, 40% had good results, compared with 27% in the EF group. In the UTN group, there were significantly fewer ante- and recurvatum deformities of more than five degrees. CONCLUSIONS: Treatment of tibial fractures by UTN, compared with EF, gave a lower reoperation rate and better functional outcome.

External Fixators↗
PubMed1994

[Functional significance of calcinosis of the basal ganglia via positron emission tomography].

Four patients with symmetrical basal ganglia calcification of different etiologies detected by cranial computed tomography (CT) were clinically evaluated and underwent positron emission tomography (PET) with (18F)-2-fluoro-2-deoxy-D-glucose (FDG). All patients were subjected to extensive laboratory investigation and neuropsychological testing. In two patients we found typical laboratory signs of hypoparathyroidism, the other two patients had no endocrinological alterations. Changes of glucose metabolism were mainly detected only in calcified tissues. Particularly in two patients with test psychologically confirmed psychomotoric retardation we did not find any cortical dysfunction. In conclusion, basal ganglia calcification in contrast to primary degenerative diseases has no influence on metabolic function in tissue that is not calcified.

Adult↗
PubMed1994

[Osteosynthesis of femur shaft fractures with the unreamed AO-femur nail. Surgical technique and initial clinical results standard lock fixation].

Nailing technique has changed in recent years in some important aspects which are not limited to the omitted reaming procedure. These changes concern patient positioning, reduction technique and determination of implant length and diameter. Approach and exposure techniques have been modified to new, less invasive procedures, in order to fulfill technical, functional and aesthetic requirements. Techniques and tricks have been developed for avoidance of fragment diastasis, axial and torsional malalignment and leg length differences. Finally, simple algorithms have been elaborated for the management of bilateral femoral shaft or ipsilateral tibial shaft fractures and the number and location of locking bolts. These algorithms, techniques and procedures were developed in a series of 108 femoral shafts, which were stabilized wit the AO unreamed femoral nail (UFN) in a prospective study between 1991 and 1994. Of these, 39 cases with a mean follow-up of 19.3 (range 8-40) months after trauma were reviewed. Fractures were classified according to Müller (1990): 6 type A, 21 type B and 12 type C. Closed soft tissue damage was classified according to our classification: C0/I, n = 14; CII, n = 15 (Tscherne 1982). Among 10 open fractures 4 were OI, 4OII, 1OIIIA and 1OIIIB (Gustilo 1976). The major complications were breakage of locking bolts (n = 2), one nail breakage after 9 weeks and one case of osteitis.

Adolescent↗
PubMed1994

[Current status of surgical technique for unreamed nailing of tibial shaft fractures with the UTN (unreamed tibia nail)].

Nailing technique has changed in recent years in some important aspects which are not limited to the omitted reaming procedure. These changes concern patient positioning, reduction technique, the use of temporary stabilizers such as the 'Pinless', and determination of implant length and diameter. Approach and exposure techniques have been modified to new, less invasive procedures, in order to fulfill technical, functional and aesthetic requirements. Techniques and tricks have been developed for avoidance of fragment diastasis and axial and torsional malalignment. Finally, simple algorithms are described for the management of large bone defects, bilateral tibia shaft or ipsilateral femoral shaft fractures, number and location of locking bolts, the 'when and how' of patient mobilization and load bearing, and primary and secondary dynamization. These algorithms, techniques and procedures were developed in a series of 152 tibia shafts, which were stabilized with the AO unreamed tibia nail (UTN) in a prospective study between March 1989 and June 1994. Of these, 75 cases with a mean follow-up of 19.4 +/- 6.3 (range 11-37) months after trauma were reviewed. Fractures were classified according to Müller (1990): 14 type A, 37 type B and 24 type C. Closed soft tissue damage was categorized according to our classification: C0/1, n = 5; C2, n = 12; C3, n = 9 (Tscherne 1982). Among 49 open fractures 8 were OI, 18 OII, 10 OIIIA and 13 OIIIB (Gustilo 1976). The main minor intraoperative complication was drill bit breakage (n = 10), most frequently at the proximal locking holes. The main postoperative complication was breakage of locking bolts (n = 16), mainly between weeks 6 and 20. Minor secondary reinterventions were, in most cases, secondary dynamization under local anaesthesia. Major reintervention were: soft tissue reconstructions (n = 5), isolated cancellous bone graft (n = 6), and change of treatment (n = 12). There were nine changes to a reamed nail, two changes, in very proximal fractures, to plate osteosyntheses. There were three deep infections. Mean time to union was 23.9 weeks (range 10-48 weeks, n = 73); in two cases non-union was observed. The overall result was judged with the Karlström-Olerud score, which was applicable in 66 of 75 cases; excellent, n = 2; good, n = 22; satisfactory, n = 24; fair, n = 9; poor, n = 9. In the remaining nine cases no scoring was attempted because of severe injuries around the knee or ankle.

Adolescent↗
PubMed1992

FDG transport and phosphorylation in human gliomas measured with dynamic PET.

Twenty-six patients with gliomas of WHO-grades two to four were examined with dynamic positron emission tomography (PET) and 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG rate constants and derived glucose metabolic rates (MRdyn) were determined in solid tumor tissue and in tumor-free brain tissue. In addition, glucose metabolism was also calculated from single scans recorded 30 to 40 min after injection (MRstat). All three rate constants, K1, k2, and k3, were significantly correlated with MRdyn in tumor-free brain. In contrast, in gliomas only k3 was significantly correlated with MRdyn. The ratio of k3 in tumors to k3 in tumor-free brain was also significantly related to histological tumor grade. The results indicate that FDG uptake in brain tumors is governed by FDG phosphorylation and is rather independent from the variation of FDG transport. A comparison between glucose metabolic rates calculated by an autoradiographic approach (MRstat) with the calculation based on individually fitted rate constants (MRdyn) revealed a very close correlation in spite of a moderate systematic difference in absolute values.

Adult↗
PubMed1992

Positron emission tomography demonstrates frontal cortex and basal ganglia hypometabolism in dystonia.

We studied 15 dystonic patients with positron emission tomography (PET) and (18F)-2-fluoro-2-deoxy-D-glucose (FDG). The group comprised patients with focal (n = 5), multifocal (n = 1), and generalized (n = 4) dystonia as well as patients with hemidystonia (n = 5). The age at onset was during childhood in four, during adolescence in two, and during adulthood in nine of the subjects. In dystonic patients, global cerebral glucose metabolism was unaltered when compared with normal controls, whereas the pattern of regional cerebral metabolic rate for glucose (rCMR[Glu]) was significantly different (p = 0.0001). rCMR(Glu) was significantly decreased in the caudate and lentiform nucleus and in the frontal projection field of the mediodorsal thalamic nucleus. The study confirms the concept that dystonia is caused by impaired connections between the basal ganglia, the thalamus, and frontal association areas.

Adolescent↗