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J Rademacher

Publications and source records attributed to J Rademacher.

34 records · Page 2Linked to original sources
PubMed1997

Cerebral microemboli in patients with antiphospholipid syndrome.

CNS involvement is one of the hallmarks underlying poor prognosis in SLE and for therapeutic strategies it is difficult to assess which patients are at risk. As detectability of cerebral microembolic signals (MES) using long-term transcranial Doppler ultrasonography (TCD) proved to be predictive of past and future thromboembolic events in patients with carotid artery stenosis, we investigated whether MES might be similarly useful in patients with antiphospholipid syndrome (APS). Our study population consisted of 46 SLE patients and five with primary APS (pAPS). Twelve of the 46 patients with SLE, 10 of them with secondary APS (sAPS), and four of five patients with pAPS had a history of cerebrovascular ischaemia (CVI). MES in the middle cerebral artery were detected in 14 of 16 patients with and in one of 35 without CVI (P < 0.001). Antiphospholipid antibodies (aPL) were positive in 12 of 15 patients with and 18 of 36 without MES, and the rate of MES correlated to the titre of aPL. MES from APS patients resembled in their energy distribution those from patients with symptomatic carotid disease and were significantly different from those associated with artificial heart valves. In conclusion, cerebral MES are detectable in APS patients and correlate with a history of CVI. Whether this innovative method may provide individual risk assessment in APS patients has to be addressed in prospective studies.

Adolescent↗
PubMed1996

Color-flow Doppler-assisted duplex imaging fails to detect ulceration in high-grade internal carotid artery stenosis.

PURPOSE: Pathoanatomic studies suggest that plaque surface disruption, particularly ulceration, plays a key role in the destabilization of internal carotid artery stenosis. Until now, the validity of color-flow Doppler-assisted duplex imaging in detecting such pathoanatomically defined plaque surface abnormalities is unclear. METHODS: We prospectively determined the interobserver reliability and validity of detecting plaque ulceration by means of preoperative color-flow Doppler-assisted duplex imaging in 43 consecutive patients with high-grade (> or = 70%) internal carotid artery stenosis, comparing these ultrasonographic findings with pathoanatomic evaluations of the corresponding endarterectomy specimens. RESULTS: Interobserver reliabilities for detecting carotid plaque ulceration were kappa= 0.57 for ultrasonography and kappa = 0.82 for the pathologic reference method. Color-flow Doppler-assisted duplex imaging (observer consensus) failed to detect pathoanatomically defined ulceration (chi square = 0.43; p = 0.51). Likewise, sensitivity, specificity, overall accuracy, and positive predictive value were poor (33%, 67%, 56%, and 46%, respectively). CONCLUSIONS: We conclude from our data that color-flow Doppler-assisted duplex imaging is not a reliable or valid means to identify plaque ulceration in high-grade carotid artery lesions.

Adult↗
PubMed1995

Cerebral microembolism in patients with Sneddon's syndrome.

BACKGROUND: The pathogenesis of Sneddon's syndrome is unclear. This study addresses the question whether cerebral thromboembolism may be involved in the pathogenesis of the neurologic complications of the disorder. The study consisted of 13 patients with Sneddon's syndrome defined by both generalized livedo reticularis and a history of one or more cerebrovascular ischemic events; none had clinical or Doppler ultrasonographic evidence of atherosclerosis. METHODS: Transcranial Doppler microembolic monitoring of the middle cerebral artery; blood screening for antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibodies). RESULTS: Five patients (38%) showed clinically silent microembolism at transcranial Doppler monitoring, with individual microembolic event rates of the middle cerebral artery between 2 per hour and 33 per hour. In this group, the time since the last ischemic symptom was significantly shorter than in the eight patients without microemboli. Antiphospholipid antibodies were detected in three patients (23%), all of whom belonged to the microemboli-positive group. CONCLUSIONS: These data suggest that the detectability of both clinically silent cerebral microembolism and antiphospholipid antibodies may provide paraclinical evidence of active disease in patients with Sneddon's syndrome. The results support the notion that an immune-mediated prothrombotic state facilitating the formation of arterial thrombi with subsequent cerebral embolization, and/or triggering in situ thrombosis of cerebral vessels, plays a pathogenetic role in the neurologic manifestations of this disorder.

Adult↗
PubMed1995

Cerebral microembolism and the risk of ischemia in asymptomatic high-grade internal carotid artery stenosis.

BACKGROUND AND PURPOSE: Previous work has shown that cerebral microembolism detected with transcranial Doppler sonography distal to internal carotid artery stenosis occurs more frequently in recently symptomatic compared with asymptomatic patients. It has remained unclear whether cerebral microembolism also indicates a higher risk of future cerebral or retinal ischemia. SUMMARY OF REPORT: Sixty-four asymptomatic patients with unilateral 70% to 90% internal carotid artery stenosis were investigated prospectively (mean follow-up, 72 weeks). Five patients developed ischemic symptoms attributable to the stenosis (transient ischemic attack, 2 patients; stroke, 3 patients). A microembolic rate of > or = 2 per hour in the ipsilateral middle cerebral artery was associated with a substantially increased risk of developing ischemia of the corresponding carotid territory (odds ratio, 31; 95% confidence interval, 3 to 302; P = .005). CONCLUSIONS: This prospective pilot study suggests that cerebral microembolism detected with transcranial Doppler sonography may define a high-risk subgroup among patients with asymptomatic high-grade internal carotid artery stenosis.

Aged↗
PubMed1992

Abnormal intracellular calcium ion concentration in platelets and lymphocytes of bipolar patients.

The authors measured intracellular Ca2+ concentrations in four manic and five bipolar depressed patients and seven comparison subjects. Platelet and lymphocyte intracellular Ca2+ concentrations were comparable. The patients' mean intracellular Ca2+ concentrations were higher than those of the comparison subjects and demonstrated more interindividual variation. These findings suggest a diffuse abnormality in mechanisms affecting intracellular calcium homeostasis in bipolar disorder.

Adult↗
PubMed1990

Total surface of temporoparietal intrasylvian cortex: diverging left-right asymmetries.

Measurements of the total convoluted surface area of cortex buried in the temporoparietal transition of the Sylvian fissure were performed using "three-dimensional" magnetic resonance morphometry in 10 randomly selected human cadaver brains. The measurements comprised the planum temporale, which covers the superior temporal gyrus posterior to Heschl's first transverse gyrus, and the caudally adjacent walls of the descending and ascending rami of the Sylvian fissure. Also, the total convoluted surface of the planum temporale was compared with its superficially exposed surface as determined by photographical planimetry after brain section, so that the index of cortical folding of the planum temporale could be estimated. The following results were obtained: Cortical folding of the planum temporale did not differ significantly between left and right hemispheres (p greater than .6). The total and the superficially exposed surface of the planum temporale showed significant leftward asymmetry (p less than or equal to .0078). In contrast, the total surface of cortex buried in the caudal segments of the Sylvian fissure posterior to the planum exhibited significant rightward asymmetry (p less than or equal to .016). The combined cortical surface area buried in the whole posterior Sylvian fissure caudal to the first transverse gyrus did not show significant left-right asymmetry (p greater than 0.3). The data suggest divergent lateral asymmetries in the posterior intrasylvian region with excesses of superior temporal cortex in left hemispheres and of supramarginal cortex in right hemispheres.

Aged↗
PubMedDate not supplied

Topographical variation of the human primary cortices: implications for neuroimaging, brain mapping, and neurobiology.

The relationships of the "primary" cytoarchitectonic neocortical fields, 17, 41, 3b, and 4 (Brodmann areas), to salient topographic landmarks have been reconstructed from serial histological sections in 20 human cerebral hemispheres (10 brains). Each of these architectonic fields is found to bear a characteristic relationship to a set of enframing anatomic landmarks, in particular, gyri, fissures, and sulci, that can be readily defined by MRI. Two classes of variability were found characteristic, at least to some extent, of each of the fields. Class 1 variability--variability that is not predictable from visible landmarks--was typical of the polar and for the cuneal and lingual extracalcarine distributions of field 17 and the distribution of field 4 upon the paracentral lobule. Class 2 variability--variability that is closely predictable from visible landmarks--is seen in the marked interindividual or interhemispheric variation in size or shape of a field and was found to be prominent for all four fields. Because of the prominence of class 2 variability, direct reference to the landmarks that frame these fields may be expected to be a more reliable basis for functional mapping than reference to a template or stereotactic coordinate-based system of reference to a standard or idealized brain.

Adolescent↗
PubMedDate not supplied

The human brain age 7-11 years: a volumetric analysis based on magnetic resonance images.

Volumetric magnetic resonance image (MRI)-based morphometry was performed on the brains of 30 normal children (15 males and 15 males) with a mean age of 9 years (range 7-11 years). This age range lies in a late but critical phase of brain growth where not volumetric increment will be small but when the details of brain circuity are being fine-tuned to support the operations of the adult brain. The brain at this age is 95% the volume of the adult brain. The brain of the female child is 93% the volume of the male child. For more than 95% of brain structures, the volumetric differences in male and female child brain are uniformly scaled to the volume difference of the total brain in the two sexes. Exceptions to this pattern of uniform scaling are the caudate, hippocampus and pallidum, which are disproportionately larger in female than male child brain, and the amygdala, which is disproportionately smaller in the female child brain. The patterns of uniform scaling are generally sustained during the final volumetric increment in overall brain size between age 7-11 and adulthood. There are exceptions to this uniform scaling of child to adult brain, and certain of these exceptions are sexually dimorphic. Thus, with respect to major brain regions, the cerebellum in the female but not the male child is already at adult volume while the brainstem in both sexes must enlarge more than the brain as a whole. The collective subcortical gray matter structures of the forebrain of the female child are already at their adult volumes. The volumes of these same structures in the male child, by contrast, are greater than their adult volumes and, by implication, must regress in volume before adulthood. The volume of the central white matter, on the other hand, is disproportionately smaller in female than male child brain with respect to the adult volumes of cerebral central white matter. By implication, relative volumetric increase of cerebral central white matter by adulthood must be greater in the female than male brain. The juxtaposed progressive and regressive patterns of growth of brain structures implied by these observations in the human brain have a soundly established precedent in the developing rhesus brain. There is emerging evidence that sexually dimorphic abnormal regulation of these terminal patterns of brain development are associated with gravely disabling human disorders of obscure etiology.

Adolescent↗
PubMedDate not supplied

Cerebral asymmetry: MR planimetry of the human planum temporale.

A method is described for the imaging and planimetric measurement of the planum temporale (PT) using computer reformations from three-dimensional fast low angle shot magnetic resonance (MR) data. The procedure allows the determination of size and left-right asymmetry of this area on the posterior supratemporal surface, which has been assumed by previous investigators to be a structural correlate of speech lateralization. To establish a consistent method for future studies, special effort was invested in the elaboration of reliable imaging criteria for the borders of the PT. The authors report MR planimetric measurements of the PT in 10 human cadaver brains performed independently and in a "blinded" fashion by two observers. A high degree of interobserver agreement was found, demonstrating the reliability of the MR criteria for PT delineation. The planimetric data correlated with those from subsequent anatomic measurements following section of the same specimens. The left-right ratios of PT size were almost the same with both methods (mean 1.9). Magnetic resonance planimetry of the PT is a noninvasive, reliable, and quantitative procedure to determine gross cerebral asymmetry in the posterior speech area.

Aged↗