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G Schroth

Publications and source records attributed to G Schroth.

At least 73 records · Page 4Linked to original sources
PubMed2000

Silent cerebral ischemia detected by diffusion-weighted MRI after carotid endarterectomy.

BACKGROUND AND PURPOSE: Small emboli arising from a friable plaque during carotid endarterectomy (CEA) constitute an important risk of perioperative ischemic complications. To evaluate the incidence and significance of silent cerebral ischemic lesions of embolic origin after CEA, we prospectively examined a series of surgical patients with high-grade carotid stenosis by using diffusion-weighted MRI (DWI). We also tried to correlate postoperative ischemic lesions with the occurrence of sonographic cerebral embolic signals, the presence of plaque ulcerations, and the use of intraoperative shunting. METHODS: Of a consecutive series of 53 patients undergoing elective CEA for high-grade carotid stenosis, 48 patients with unchanged postoperative neurological status were prospectively studied with DWI of the brain the day before and the day after the operation. The magnetic resonance images were analyzed by 2 neuroradiologists blinded to the clinical result of the operation. Any new hyperintense signal was interpreted as a postoperative ischemic lesion. RESULTS: Forty-six (95.8%) of 48 patients had unchanged postoperative brain DWI. In 2 patients (4.2%), a new single asymptomatic hyperintense signal was observed on the side of the operation. Both lesions were small and presumably of embolic origin. They were not related to sonographic embolic signals, plaque ulcerations, or intraoperative shunting. CONCLUSIONS: These results suggest that the incidence of silent ischemic brain lesions of embolic origin after CEA is low and does not correlate with the occurrence of intraoperative sonographic microemboli. They confirm that CEA is a safe procedure that carries a low risk of postoperative cerebral events.

Aged↗
PubMed2000

Timing of coronary stent thrombosis in patients treated with prophylactic tirofiban.

BACKGROUND: Acute and subacute stent thromboses (ASST) are the major thrombotic complications of coronary stenting. The time course of ASST seems to be related to the type of antithrombotic therapy (four days in patients treated with aspirin and coumadin compared to 12 hours with the use of aspirin and ticlopidine). In this report, we compared the timing of ASST in patients treated with aspirin, ticlopidine/clopidogrel, heparin and tirofiban with that in patients treated with the same drugs but without tirofiban. METHODS: Retrospective analysis of the Hermann intervention database between January 1997 and October 1999 was performed. We identified 13 patients who required reintervention in the first week after a successful coronary stenting ( 1 stent). Four patients were treated with tirofiban (Group 1) and 9 were not (Group 2). RESULTS: The median time from stent deployment to ASST was 7 hours (interquartile range, 2.5Eth 33 hours) in group 2 compared to 84.5 hours (interquartile range, 56Eth 124.5 hours) in group 1. The mean time from stent deployment to ASST was 90.3 +/- 43.1 hours in group 1 versus 12.8 +/- 15.3 hours in group 2 (p = 0.0005). All episodes of ASST occurred 3 days in patients treated with tirofiban, whereas they occurred in the first 2 days in all patients not treated with tirofiban. CONCLUSION: Prophylactic tirofiban treatment delays the time to stent thrombosis after successful coronary artery stent implantation for more than two days. Patients at high risk for stent thrombosis treated with short-acting glycoprotein IIb/IIIa platelet receptor inhibitors may warrant close follow-up during the first week after stenting.

Angioplasty, Balloon, Coronary↗
PubMed1999

Determination of language dominance: Wada test confirms functional transcranial Doppler sonography.

OBJECTIVE: To determine the efficacy of the invasive Wada test in determining language dominance, and to validate the functional transcranial Doppler sonography (fTCD) examination in patients. BACKGROUND: Previous work shows that simultaneous bilateral fTDC may identify cognitive hemispheric dominance in healthy individuals. METHOD: fTDC and the Wada test were performed prospectively in 14 patients with various diseases (tumors, cerebrovascular events, head injury, intractable epilepsy). fTDC hemispheric dominance was determined based on the hemispheric blood flow velocity shift for language and visuospatial tasks. RESULTS: fTDC was performed easily in patients. One patient could not be examined by fTDC because of absent temporal bone window for ultrasonic transmission. Two Wada tests were inconclusive due to patient somnolence. One of these patients suffered from right frontal tumor and had aphasia remitted under steroids when examined. fTDC indicated a bilateral language dominance. In the remaining 11 patients the correlation between fTDC and Wada language lateralization indices was 0.75 (p = 0.008). If a post hoc cutoff score was taken for the fTDC language lateralization index, in eight patients, both fTDC and Wada testing determined the left hemisphere to be dominant for language; in the other three patients, language function was bilateral in both examinations. CONCLUSION: Although the current results are preliminary and require replication in a larger sample, fTDC seems to be able to assess hemispheric language dominance not only in healthy individuals, but also in patients. It might become an alternative noninvasive or complementary tool to the Wada test, particularly in patients in whom the Wada test is impractical or gives inconclusive results.

Adolescent↗
PubMed1999

The "Bernese" frameless optical computer aided surgery system.

OBJECTIVE: We report on two years of clinical experience with a frameless Computer Aided Surgery system developed in Bern, Switzerland. MATERIAL AND METHODS: Our navigation system is based on a preoperative computer-tomography (CT) scan (without markers) and an intraoperative optical tracking of head movements and of the surgical instruments. Using landmark and surface-based registration, the skull can be accurately correlated to the CT images. The three-dimensional positions of the surgical instruments, as well as the endoscopic images, are displayed in real time on a monitor. RESULTS: In the last two years, 109 computer-aided interventions have been successfully performed: 89 on the anterior skull base/paranasal sinuses, 15 on the lateral skull base, and 5 minimally invasive procedures on other locations in the skull. No complications occurred. The practical accuracy on the cadaver skull is between 0.5 mm and 1.2 mm, and the clinical accuracy is between 0. 5 mm and 2 mm. CONCLUSIONS: Our navigation system has proven its accuracy and usability. Surgeons feel very comfortable with the increased safety provided by the unequivocal identification of important anatomical structures.

Cadaver↗
PubMed1999

Striatal grafts in a rat model of Huntington's disease: time course comparison of MRI and histology.

Survival and integration into the host brain of grafted tissue are crucial factors in neurotransplantation approaches. The present study explored the feasibility of using a clinical MR scanner to study striatal graft development in a rat model of Huntington's disease. Rat fetal lateral ganglionic eminences grown as free-floating roller-tube cultures were grafted into the quinolinic acid-lesioned striatum, and T1- and T2-weighted sequences were acquired at 2, 7, 21, and 99 days posttransplantation. MR images were then compared with images of corresponding histological sections. The lesion-induced striatal degeneration caused a progressive ventricle enlargement, which was significantly different from controls at 21 days posttransplantation. Seven days posttransplantation, T1-weighted images revealed a defined liquid-isointense signal surrounded by a hyperintense rim at the site of graft placement, which was found unaltered for the first 21 days posttransplantation, whereas a hypointense graft signal was detected at 99 days posttransplantation. At 2 days posttransplantation, T2-weighted images showed the graft region as a hyperintense area surrounded by a rim of low signal intensity but at later time-points graft location could not be further verified. Measures for graft size and ventricle size obtained from MR images highly correlated with measures obtained from histologically processed sections (R = 0.8, P < 0.001). In conclusion, the present study shows that fetal rat lateral ganglionic eminences grown as free-floating roller-tube cultures can be successfully grafted in a rat Huntington model and that a clinical MR scanner offers a useful noninvasive tool for studying striatal graft development.

Animals↗
PubMed1999

The site of atheromatosis in the subclavian and vertebral arteries and its implication for angioplasty.

We analysed the site of plaques and stenoses in the subclavian and vertebral arteries, to improve the safety of percutaneous transluminal angioplasty (PTA) in high-risk patients. These lesions were assessed on arteriograms of 35 patients with stenoses and occlusions of the subclavian and vertebral arteries; the degree of stenoses was measured. Of 19 subclavian artery stenoses 17 (89%) were in the segment proximal to the vertebral artery; 30 (79%) of 38 vertebral artery stenoses were on the medial wall. With this knowledge, a double-balloon technique using a simultaneous transbrachial and transfemoral approach for angioplasty of high-risk subclavian or combined subclavian and vertebral artery stenoses and occlusions was used successfully in seven patients. This new technique may broaden the endovascular therapeutic possibilities in the rare but dangerous situation where plaque extends directly from the stenotic subclavian artery into the origin of the vertebral artery.

Aged↗
PubMed1999

Clinical single-shot diffusion-weighted MRI of the human brain on a short-bore medium-field imager.

Diffusion-weighted MRI (DWI) is becoming important for assessment of acute stroke. Until recently single-shot DWI required expensive technology such as echoplanar imaging (EPI) available only at some research sites. A new medium-field (1.0 T) short-bore MR imager has been developed with which DWI data sets can be acquired. We prospectively studied 169 patients on this 1.0 T commercial system. After conventional imaging, DWI was performed with a single-shot multi-slice sequence with b values 0 an 900 s/mm2, and with the gradients switched in three directions. The apparent diffusion coefficients were calculated with online calculation software. There were 50 patients with totally normal MRI, and 17 had strokes, these strokes were detected as areas of high signal on the images at a maximal b value. There was a drop in the ADC in ischaemic regions: in sub-acute infarcts, the values were between 0.41 and 0.531 x 10(-3) mm2/s. In old infarcts the ADC was 1.15 x 10(-3) mm2/s. Cerebrospinal fluid (CSF) gave low signal whereas areas in the brain had more intermediate intensities (CSF: 3.00; deep white matter: 0.75, cortical grey matter: 0.80, basal ganglia (thalamus): 0.70 and cerebellar white matter: 0.65 x 10(-3) mm2/s. Anisotropy was detected as areas of restricted diffusion along the tracts. These preliminary data show that DWI can be acquired successfully on a medium-field short-bore system. This should allow the technique to be implemented at more sites, therefore facilitating the diagnosis of acute stroke and rendering early intervention feasible.

Brain↗
PubMed1999

Interdisciplinary management results in 100 patients with ruptured and unruptured posterior circulation aneurysms.

The authors report on a series of 100 posterior circulation aneurysms managed by surgical and endovascular procedures. The series consisted of 41 elective admissions more than 14 days after SAH or for unruptured aneurysms and 59 acute admissions after subarachnoid haemorrhage (SAH). In this first interdisciplinary series after the introduction of electrolytically detachable coils, surgical clipping was maintained as treatment of choice in good grade patients while endovascular therapy was primarily offered for patients in poor clinical grade or if the aneurysm was judged difficult to be accessed surgically. A total of 70 patients underwent aneurysm elimination, 54 surgically and 16 by the endovascular route. In 30 patients the aneurysm was not treated, either because of persisting grade 5 WFNS after SAH or because the risk of treatment appeared excessive with some complex unruptured aneurysms. A complication leading to permanent morbidity or mortality occurred after 5 surgical and 1 endovascular procedure (8.6%). Regarding overall management results after acute SAH, 14 of the total of 59 patients admitted with acute SAH died, corresponding to a management mortality of 24%. Although the present series cannot provide statistically firm conclusions, the authors believe from the actual experience and the accumulating literature, that the principal complementary aspect of the two treatment modalities is aneurysm location. Size and shape do not appear to be a primary factor to favour one or the other modality. The hope that endovascular therapy improves the prognosis of poor grade patients with posterior circulation aneurysms probably has been overstated. The good results of endovascular treatment with small narrow-necked aneurysms on proximal arteries of the posterior circulation, as seen in the present series and as reported in the accumulating literature, suggest that in future surgical and endovascular treatment should be considered as alternatives in these special cases while in large and broad-necked aneurysms surgery should be considered first.

Aneurysm, Ruptured↗
PubMed1999

PTA of the subclavian and innominate arteries: long-term results.

BACKGROUND: To investigate the long-term clinical and duplex sonographic results of percutaneous transluminal angioplasty (PTA) of the subclavian and innominate arteries, and the potential of a new double balloon technique to avoid cerebrovascular thromboembolism. PATIENTS AND METHODS: Forty-three PTAs were performed on 38 subclavian, four innominate arteries and one subclavian-subclavian bypass in 37 patients. In three instances a protective double balloon technique was used. Indication for the intervention was: subclavian steal syndrome (n = 14 [38%]), upper extremity arterial insufficiency (n = 26 [70%]), peripheral thromboembolism (n = 8 [22%]) and PRIND/stroke (n = 3 [8%]). Analysis of long-term follow-up (median 15, range 2 to 100 months) was possible of 28 patients including duplex sonographic assessment in 23 patients. The cumulative patency rate was calculated by means of life-table analysis. RESULTS: Technical success was achieved in 36 endovascular procedures (84%). Minor peripheral catheter complications occurred in three interventions (7%), cerebrovascular thromboembolism in four (9%). No cerebrovascular complications were seen using the double balloon technique. On final check-up 4 patients (14%) suffered from subclavian steal syndrome, 3 (11%) from mild upper extremity arterial insufficiency and one (4%) from rest pain. Duplex sonography showed no stenosis in 12 of 23 patients (52%) and a stenosis of less than 50% in 8 (35%). The life-table analysis showed a secondary cumulative patency rate of 72% after 100 months with all restenoses occurring within 24 months. CONCLUSIONS: PTA of the subclavian and innominate arteries appears to be a useful alternative to surgery with a low complication rate. The long-term patency rate of 72% is comparable to results of other series. In high risk situations cerebrovascular complications may be reduced using the new double balloon technique.

Adult↗
PubMed1999

Circulating antineutrophil autoantibodies in a child with isolated central nervous system vasculitis.

An 8-year old girl with history of twisted neck and painful swelling on the left side of the neck was found to have malfunction of glossopharyngeal and hypoglossal nerves on the left side. Magnetic resonance angiography revealed a giant aneurysm of the internal carotid artery surrounded by a widespread inflammatory tumor. Cerebral angiography disclosed a large, false aneurysm with almost complete compression of the internal carotid artery. Circulating antineutrophil cytoplasmic autoantibodies (titer 1:2560) and high levels of antibodies against antiproteinase 3 were detectable. This observation indicates that these autoantibodies may be a diagnostic tool in children in whom an undiagnosed central nervous system inflammatory disease is present.

Angiography, Digital Subtraction↗
PubMed1999

Assessment of >/=50% and <50% intracranial stenoses by transcranial color-coded duplex sonography.

BACKGROUND AND PURPOSE: A favorable risk-benefit ratio for warfarin compared with aspirin has been reported for the prevention of major vascular events in symptomatic >/=50% intracranial stenoses. Transcranial color-coded duplex sonography (TCCS) criteria providing an accurate detection of >/=50% and <50% stenoses of the anterior, middle, and posterior cerebral arteries and basilar and vertebral arteries were evaluated retrospectively with angiography used as the standard of reference. METHODS: Prospectively collected TCCS, extracranial color-coded duplex sonography, and intra-arterial digital subtraction angiography data of 310 patients were reviewed. The patients had angiography for confirmation of symptomatic extracranial >/=70% carotid stenoses, symptomatic stenoses (peak systolic velocity higher than the corresponding mean value +2 SDs of 104 normal subjects), and occlusions of the middle cerebral or basilar artery previously assessed by ultrasound. The sonographer was not aware of angiographic findings. RESULTS: TCCS would have detected all 31 of >/=50% intracranial stenoses with 1 false-positive and 35 of 38 <50% stenoses with 3 false-positives. One of 69 stenoses (1%) and 280 of 2741 normal arteries (10%) were missed because of inadequate insonation windows. The corresponding peak systolic velocity cutoffs for >/=50%/<50% stenoses were >/=155/>/=120 cm/s (anterior cerebral artery), >/=220/>/=155 cm/s (middle cerebral artery), >/=145/>/=100 cm/s (posterior cerebral artery), >/=140/>/=100 cm/s (basilar artery), and >/=120/>/=90 cm/s (vertebral artery). CONCLUSIONS: TCCS may reliably assess >/=50% and <50% basal cerebral artery narrowing and prove useful for noninvasive management of patients with symptomatic intracranial stenoses.

Adult↗
PubMed1998

Estrogen replacement therapy and outcome of coronary balloon angioplasty in postmenopausal women.

Estrogen replacement therapy (ERT) in women after menopause is associated with prevention of clinical coronary artery disease. However, few studies have investigated possible benefits from ERT in postmenopausal women undergoing treatment for established coronary disease. We therefore retrospectively reviewed the clinical outcomes of 428 postmenopausal women undergoing percutaneous transluminal coronary balloon angioplasty (PTCA) to test the hypothesis that ERT has a beneficial effect in this setting. The women were divided into 2 groups based on ERT status at the time of the procedure. Estrogen users were younger (60 +/- 10 vs 68 +/- 9 years, p <0.001), more commonly had family histories of coronary heart disease (54% vs 41%, p = 0.04), had less incidence of hypertension (63% vs 76%, p = 0.02), and had slightly fewer diseased vessels per patient (1.3 +/- 0.5 vs 1.5 +/- 0.7, p = 0.03) compared with nonusers. No in-hospital deaths occurred in estrogen users compared with 5% hospital mortality in nonusers (p = 0.01). The combined outcome of death or myocardial infarction (MI) also was lower in estrogen users (4% vs 12%, p = 0.04). Of 348 women discharged after successful PTCA, 336 (97%) were able to be contacted at an average follow-up interval of 22 +/- 17 months (range 5 to 82). Estrogen users had superior event-free survival both for death as well as for death or nonfatal MI. Repeat revascularizations were similar in both groups (32% vs 24%, p = 0.15). In a Cox proportional-hazards model, nonusers had 4 times the likelihood of death after angioplasty compared with estrogen users (OR = 4.025, 95% CI = 1.3 to 13.4, p = 0.02). We conclude that estrogen replacement may offer protection against clinical coronary events in postmenopausal women who already have established coronary disease and are undergoing balloon angioplasty. The benefit was independent of age, smoking, presence of diabetes mellitus, or the number of diseased coronary vessels. However, it did not include a reduction in repeat revascularization procedures, suggesting no reduction in restenosis.

Adult↗
PubMed1998

A novel capacitative calcium entry channel expressed in excitable cells.

In addition to voltage-gated calcium influx, capacitative calcium entry (CCE) represents a major pathway for calcium entry into the cell. Here we report the structure, expression and functional properties of a novel CCE channel, TRP5. This channel is a member of a new subfamily of mammalian homologues of the Drosophila transient receptor potential (TRP) protein, now comprising TRP5 (also CCE2) and the structurally related CCE1 (also TRP4). Like TRP4, TRP5 forms ion channels mainly permeable for Ca2+ which are not active under resting conditions but can be activated by manoeuvres known to deplete intracellular calcium stores. Accordingly, dialysis of TRP5-expressing cells with inositol-(1,4,5)-trisphosphate evokes inward rectifying currents which reversed polarity at potentials more positive than +30 mV. Ca2+ store depletion with thapsigargin induced TRP5-mediated calcium entry dependent on the concentration of extracellular calcium, as seen by dual wavelength fura-2 fluorescence ratio measurements. TRP5 transcripts are expressed almost exclusively in brain, where they are present in mitral cells of the olfactory bulb, in lateral cerebellar nuclei and, together with TRP4 transcripts, in CA1 pyramidal neurons of the hippocampus, indicating the presence of CCE channels in excitable cells and their participation in neuronal calcium homeostasis.

Amino Acid Sequence↗
PubMed1998

Structure and mRNA expression of a bovine trp homologue related to mammalian trp2 transcripts.

Mammalian homologues of the transient receptor potential (trp) gene product from Drosophila melanogaster function as Ca2+-selective or non-selective cation channels. Complementary DNA was isolated from a bovine testis cDNA library which encodes bovine trp2 (btrp2), a protein of 432 amino acid residues comprising four predicted transmembrane segments. Btrp2 mRNA is expressed in bovine testis, spleen and liver but not in brain, heart, adrenal gland or retina. In bovine testis expression of btrp2 mRNA is restricted to spermatocytes but is not present in spermatogonia, Leydig or Sertoli cells suggesting that btrp2 may contribute to the formation of ion channels in sperm cells.

Amino Acid Sequence↗