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Dirk Sander

Publications and source records attributed to Dirk Sander.

At least 19 recordsLinked to original sources
PubMed2006

Development and implementation of evidence-based indicators for measuring quality of acute stroke care: the Quality Indicator Board of the German Stroke Registers Study Group (ADSR).

BACKGROUND AND PURPOSE: There is no consensus about indicators for measuring quality of acute stroke care in Germany. Therefore, a standardized process was initiated recently to develop and implement evidence-based indicators for the measurement of quality of acute hospital stroke care. METHODS: Quality indicators were developed by a multidisciplinary board between November 2003 and December 2005. The process was initiated by the German Stroke Registers Study Group in cooperation with the German Stroke Society, the German Society of Neurology, the German Stroke Foundation, Regional Offices for Quality Assurance and other experts proven in the field. National and international recommendations were considered during the development process. The process was based on a systematic literature review, an independent external evaluation of the process and its results, and a prospective pilot study to evaluate the defined indicators in clinical practice. RESULTS: Overall a set of 24 indicators was developed to measure performance of acute care hospitals in the 3 health care dimensions structure, process and outcome as well as in 3 treatment phases prehospital, in-hospital/acute and postacute. Practicability of the derived indicators was tested in a prospective pilot study. During a 2-month period, 1006 patients in 13 hospitals were documented. Application of the new indicator set was found to be feasible by participating physicians and hospitals. Median time to document the required information for 1 patient was 5 minutes. Nationwide implementation of the new indicator set within regional registers in Germany started since April 2006. CONCLUSIONS: The development of indicators to measure hospital performance in stroke care is an important step toward improving stroke care on a national level. The chosen standardized evidence-based approach ensures maximal transparency, acceptance and sustainability of the developed indicators in Germany.

Acute Disease↗
PubMed2006

Embolic signals in unselected stroke patients: prevalence and diagnostic benefit.

BACKGROUND AND PURPOSE: The present study investigated the prevalence of cerebral microemboli detected by transcranial Doppler sonography in unselected stroke and transient ischemic attack (TIA) patients under standard clinical conditions. We aimed to evaluate the feasibility and the value of the method for clinical use. METHODS: The records of 937 consecutive patients who were investigated between October 1995 and August 2004 at our institution were reviewed. Stroke or TIA were subtyped using the TOAST classification criteria. RESULTS: Two hundred and eighty-four subjects were excluded because there was an interval of >14 days between onset of symptoms and examination, no definite diagnosis of stroke or TIA at discharge, or an artificial heart valve. Embolic signals (ES) were detected in 37 (5.7%) of the remaining 653 patients. In subjects with positive ES detection the mean interval between symptom onset and ES detection was 4.9 (SD 4.0) days compared with 5.4 (SD 3.5) days in the remaining patients (P=0.01). ES were more common in patients with large-artery atherosclerosis compared with other subtype groups (P<0.001). The proportion of detected signals was influenced by the antihemostatic treatment: ES were found more often in anticoagulated patients than in patients receiving antiplatelet medication (P<0.001). CONCLUSIONS: The study shows a high clinical significance of ES in patients with recent stroke attributable to arterio-arterial embolism or of cardiac embolic origin and the high specificity of the technique. Given the low sensitivity shown, ES detection cannot generally be recommended for routine diagnostics in stroke patients.

Adult↗
PubMed2006

Elevated inflammatory laboratory parameters in spontaneous cervical artery dissection as compared to traumatic dissection: a retrospective case-control study.

Several studies have reported infection as a possible risk factor for cervical artery dissection (CAD). We retrospectively analyzed several inflammatory parameters of CAD patients with the aim of detecting differences between spontaneous (n = 25) and traumatic (n = 18) CAD. In this case-control study, we observed significantly higher absolute leucocyte values (10.3 versus 8.1 G/L; p = 0.02) as well as an elevated frequency of leucocytosis (64% versus 28%; p = 0.02) and elevated CRP (60% versus 28%; p = 0.04) in patients without a history of trauma ("spontaneous" CAD) compared with patients with trauma-related CAD. As the elevated inflammatory laboratory parameters were not associated with an elevated infection rate, these findings imply a role of an acute inflammation as a pathogenetic factor in spontaneous CAD. The cause and mechanism of the inflammatory process remain unknown.

Adult↗
PubMed2005

Combined effects of hemoglobin A1c and C-reactive protein on the progression of subclinical carotid atherosclerosis: the INVADE study.

BACKGROUND AND PURPOSE: Glycohemoglobin (hemoglobin A1c [HbA1c]) and high-sensitivity C-reactive protein (hsCRP) are risk indicators for atherosclerosis. Limited information exists regarding the combined effects of inflammation and hyperglycemia. We investigated the joint effects of both parameters on early carotid atherosclerosis progression and major vascular events in diabetic and nondiabetic subjects. METHODS: We analyzed the data of INVADE (Intervention Project on Cerebrovascular Diseases and Dementia in the Community of Ebersberg, Bavaria), a prospective, population-based study conducted in 3534 subjects (mean age, 69 years). In addition to common risk factors, measurements of carotid intima-media thickness (IMT), hsCRP, and HbA1c were performed at baseline and after 2 years of follow-up. RESULTS: For the entire population, IMT progression was significantly related to HbA1c (P=0.003) but not to hsCRP (P=0.06) after risk factor adjustment. The interaction hsCRPxHbA1c was highly significant (P=0.001), and the most pronounced IMT progression was seen in subjects with both parameters in the fourth quartiles compared with subjects with both parameters in the first quartiles (0.028 [0.025, 0.031] versus 0.012 mm/year [0.007, 0.019]; P=0.0013). We observed a significant joint effect of HbA1c and hsCRP on IMT progression in the diabetic (n=882) as well as the nondiabetic subgroup (n=2652). Subjects with HbA1c and hsCRP in the upper 2 quartiles had an increased risk for new vascular events (adjusted hazard ratio in diabetics: 4.3 [1.8, 7.3]; P=0.001; nondiabetics: 2.9 [1.6, 4.7]; P=0.001). CONCLUSIONS: The combination of hyperglycemia and inflammation is associated with an advanced early carotid atherosclerosis progression and an increased risk of new vascular events in diabetic as well as nondiabetic subjects.

Aged↗
PubMed2005

Evaluation of C-reactive protein measurement for assessing the risk and prognosis in ischemic stroke: a statement for health care professionals from the CRP Pooling Project members.

BACKGROUND AND PURPOSE: Several studies have shown, in different populations, that modest elevation of plasma C-reactive protein (CRP) in the range seen in apparently healthy individuals is a strong predictor of future vascular events. Elevated plasma CRP concentrations are also associated with an increased risk of cerebrovascular events and an increased risk of fatal and nonfatal cardiovascular events in ischemic stroke patients. These epidemiological and clinical observations suggest that determination of plasma CRP concentrations could be used as an adjunct for risk assessment in primary and secondary prevention of cerebrovascular disease and be of prognostic value. The aim of this review is to summarize the evidence for CRP as an independent predictor of cerebrovascular events in at-risk individuals and ischemic stroke patients and to consider its usefulness in evaluating prognosis after stroke. SUMMARY OF REVIEW: CRP fulfils most of the requirements of a new risk and prognostic predictor, but several issues await further confirmation and clarification before this marker can be included in the routine evaluation of stroke patients and subjects at risk for cerebrovascular disease. Potentially important associations have been established between elevated plasma CRP concentrations and increased efficacy of established therapies, particularly lipid-lowering therapy with statins. CONCLUSIONS: At present, there is not sufficient evidence to recommend measurement of CRP in the routine evaluation of cerebrovascular disease risk in primary prevention, because there is insufficient evidence as to whether early detection, or intervention based on detection, improves health outcomes, although shared risk of cardiovascular disease indicates this may be of value. In secondary prevention of stroke, elevated CRP adds to existing prognostic markers, but it remains to be established whether specific therapeutic options can be derived from this.

Aged↗
PubMed2005

New insights into transient global amnesia: recent imaging and clinical findings.

Transient global amnesia (TGA) is one of the most striking syndromes in clinical neurology. Despite several new hypotheses concerning TGA pathogenesis-including psychological disturbances, personality traits, and hypoxic-ischaemic origin associated with venous congestion in memory relevant structures or small vessel changes-there is no consensus about the cause. New imaging techniques, particularly diffusion-weighted imaging, open up new insights into the location of TGA pathology. Studies with dynamic venous duplex sonography confirmed the importance of jugular-vein-valve insufficiency. We review these new findings and their implications for a better understanding of this remarkable syndrome. Although we still do not have all the answers, the use of new imaging modalities, neuropsychological findings, and epidemiological data may in future help to unravel the origin of TGA.

Amnesia, Transient Global↗
PubMed2004

Cardiac troponins and N-terminal pro-brain natriuretic peptide in acute ischemic stroke do not relate to clinical prognosis.

BACKGROUND AND PURPOSE: The prognostic value of cardiac troponins and natriuretic peptide in acute ischemic stroke is uncertain. We measured cardiac troponin T (cTnT), cardiac troponin I (cTnI), and N-terminal pro-brain natriuretic peptide (NT-proBNP) at admission in acute ischemic stroke patients without evident myocardial damage. METHODS: In 174 consecutive patients with MRI-confirmed ischemic stroke, serial measurements of cTnT, cTnI, and NT-proBNP were performed at 3 different time points in the hyperacute phase (at admission, on days 1 and 2). Relation of laboratory values to risk factors, stroke subtype classification, and clinical outcome after 3 months was analyzed. RESULTS: The highest proportion of raised parameters was found at day 2 for cTnI in 8 of 103 (7.8%), at day 3 for cTnT in 8 of 174 (4.6%), and NT-proBNP in 114 of 174 (65.5%) patients. Proportion of patients with good outcome was significantly reduced in the group with highest NT-proBNP quartile. However, using multivariate regression analysis, no significant relation to morbidity and mortality was found for cTnT, cTnI, or NT-proBNP. Significant impact on the outcome was detected for lesion size, insular involvement, sex, age, and stroke severity. CONCLUSIONS: NT-proBNP is raised in nearly two thirds of acute stroke patients, whereas elevated cardiac troponins are found only in a small number of acute ischemic stroke patients. Neither NT-proBNP nor cardiac troponins influence clinical outcome if other risk factors are considered.

Age Factors↗
PubMed2004

Bilateral thalamic gray matter changes in patients with restless legs syndrome.

Restless legs syndrome (RLS) is a common neurological disorder of a primary unpleasant sensation with an urge to move the legs occurring at rest. The etiology of idiopathic RLS is unknown and structural cerebral abnormalities have so far not been detected. We studied 51 right-handed patients with an idiopathic restless legs syndrome in two independent samples (Regensburg RLS-group: n = 28, Munich RLS-group: n = 23) and compared them to 51 sex- and age-matched healthy volunteers. High-resolution T1-weighted magnetic resonance imaging (MRI) of each subject was obtained and analyzed using voxel-based morphometry (VBM) to detect regionally specific differences in gray matter between patients and controls. Conjunction analysis was used to combine results from both centers. In patients with idiopathic RLS, both study centers observed independently a bilateral gray matter increase in the pulvinar. In the conjunction analysis including all patients and controls from both study centers, a significant gray matter increase in the pulvinar bilaterally (right: x = 16, y = -21, z = 12, Z = 4.57; left: x = -16, y = -24, z = 12, Z = 4.10) was present. This is the first demonstration of structural changes in the brain of patients with idiopathic RLS. These changes in thalamic structures are either involved in the pathogenesis of RLS or may reflect a consequence of chronic increase in afferent input of behaviorally relevant information.

Adult↗
PubMed2004

Detection of acute brainstem infarction by using DWI/MRI.

Even using diffusion-weighted images (DWI) detection of acute brainstem infarction (BI) is still a challenge. To evaluate the clinical efficacy of a DWI protocol with improved spatial resolution all images of 44 patients with clinically possible BI on admission (24 patients with definite BI and 20 patients with other etiologies) and first DWI within 24 h after symptom onset were blindly reanalyzed for visibility and detection of BI on the first DWI by reviewers with different expertise levels. Neuroradiologists identified definite BI in 21 out of 24 patients (sensitivity 90%, specificity 100%); neurologists and junior house officers achieved similar results (sensitivity 86 and 83%, specificity 98 and 97%). The use of DWI allows a definite diagnosis of BI, even if raters have limited experience.

Adult↗
PubMed2004

Microembolic signals detected by transcranial Doppler sonography during carotid endarterectomy and correlation with serial diffusion-weighted imaging.

BACKGROUND AND PURPOSE: Embolic events are a major cause for procedure-related strokes after carotid endarterectomy (CEA). Transcranial Doppler sonography can reveal embolic events as microembolic signals (MES) during CEA. MES during declamping and shunting are frequently detected. MES during shunting are rare and known to be correlated with the neurological outcome of the patient. In the present study, we analyzed the occurrence of MES within different stages of CEA and whether MES within those stages were correlated with cerebral ischemia, as detected by diffusion-weighted imaging (DWI), and brain infarction, as detected by contrast-enhanced MRI. METHODS: Thirty-three patients were monitored intraoperatively for MES using transcranial Doppler sonography. DWI was performed within 24 hours before and after surgery. Positive postoperative DWI led to reexamination with contrast-enhanced T1-MRI 7 to 10 days after CEA for detection of cerebral infarction. RESULTS: MES were detected in 32 of 33 patients. The highest number of MES was found during shunting and declamping. A significant correlation was found between MES and DWI-lesions during dissection. A significant correlation was found between MES during dissection and shunting, and nonsignificant correlation was found between MES and the occurrence of cerebral infarction. CONCLUSIONS: MES could be regularly detected during CEA. Dissection and shunting seem to be the most vulnerable stages of the procedure.

Aged↗
PubMed2004

Transient ischemic attack and stroke can be differentiated by analyzing early diffusion-weighted imaging signal intensity changes.

BACKGROUND: Diffusion-weighted imaging (DWI) has been established to diagnose acute cerebral ischemia. Signal intensity changes occur not only in patients with definite stroke but also in up to 67% of transient ischemic attack (TIA) patients. We investigated the predictive value of DWI signal intensity changes to distinguish between TIA and stroke. METHODS: Clinical data, conventional magnetic resonance imaging (MRI), and DWI were collected in 60 consecutive patients with TIA and 37 consecutive patients with stroke. DWI was performed within 24 hours after symptom onset. Using an image analyzing system, we calculated the ratio of the lesion and corresponding contralateral normal tissue average signal intensity (rAI). RESULTS: Eighteen of 60 TIA patients (30%) revealed focal abnormalities on DWI. The mean duration of symptoms was 5.3 hours in TIA patients with DWI lesions and 5.2 hours in patients without lesions. The time to DWI was comparable in TIA and stroke patients. Even within 6 hours after symptom onset, the signal intensity was significantly higher (P=0.03) in stroke patients (n=13, rAI=1.26) as compared with TIA patients with DWI lesions (n=9, rAI=1.16). CONCLUSIONS: Our data indicate that already within 6 hours after symptom onset, TIA and stroke might be differentiated by analyzing the signal intensity of the lesions.

Aged↗
PubMed2004

Progression of early carotid atherosclerosis is only temporarily reduced after antibiotic treatment of Chlamydia pneumoniae seropositivity.

BACKGROUND: Chlamydia pneumoniae (Cp) infection has been associated with atherosclerosis and cardiovascular events. There are controversial results regarding the beneficial effects of antibiotic therapy on future cardiovascular end points. METHODS AND RESULTS: We determined the long-term effect of a 30-day roxithromycin therapy on intima-to-media thickness (IMT) progression of the common carotid artery in 272 consecutive Cp-positive and Cp-negative patients with ischemic stroke in a prospective, double-blind, randomized trial with a follow-up of 4 years. Cp IgG (> or =1:64) or IgA (> or =1:16) antibodies were initially found in 125 (46%) patients. During the 3 years before antibiotic therapy, Cp-positive patients showed an enhanced IMT progression even after adjustment for other cardiovascular risk factors (0.12 [0.11 to 0.14] versus 0.07 [0.05 to 0.09] mm/year; P<0.005). The 62 Cp-positive patients given roxithromycin showed a reduced IMT progression during the first 2 years compared with the Cp-positive patients without therapy (0.07 [0.045 to 0.095] versus 0.11 [0.088 to 0.132] mm/year; P<0.01). However, IMT progression increased again during the third and fourth year to similar values as before treatment. No significant difference in the occurrence of future cardiovascular events was found between both groups during follow-up. CONCLUSIONS: The only limited positive impact of antibiotic therapy on early atherosclerosis progression in Cp-positive patients observed in our study may explain the negative results of most antibiotic trials on clinical end points.

Aged↗
PubMed2004

Differences in number, size and location of intracranial microembolic lesions after surgical versus endovascular treatment without protection device of carotid artery stenosis.

BACKGROUND AND PURPOSE: The benefit of carotid endarterectomy in symptomatic high-grade stenosis has long been proven. The role of angioplasty as an alternative is still a matter of debate. We compared the occurrence of intraprocedural microembolic signals and ischemic lesions between carotid endarterectomy (CEA) and carotid angioplasty with stent placement (CAS) without a protection device. METHODS: 88 patients who underwent a CEA and 41 patients who underwent CAS were prospectively investigated. One day before and after the intervention diffusion weighted MRI-studies were obtained. In 21 CEA and 18 CAS patients transcranial Doppler (TCD) monitoring was performed during the procedure to detect microembolic signals (MES). RESULTS: DWI-lesions could be detected after intervention in 17% of the CEA patients compared with 54% of the CAS patients (p<0.005). The median lesion volume was 0.08 cm(3) in the CEA group and 0.02 cm(3) in the CAS group (p<0.001). Ischemic complications consisted of 2 strokes (2.3%) with symptoms lasting more than seven days in the CEA group and 1 stroke (2.4 %) in the CAS group. The median number of MES in the CEA group was 17 versus 61 in the CAS group (p<0.001). No significant correlation was found between the total number of MES and ischemic lesions in either group. CONCLUSION: A larger number of emboligenic particles with smaller volume is detached during CAS. Additionally DWI lesions were observed in different territories after CAS but not after CEA. Conventional TCD emboli detection is not useful to compare interventional therapies of the carotid arteries.

Aged↗
PubMed2003

Hemiballism with insular infarction as first manifestation of Takayasu's arteritis in association with chronic hepatitis B.

BACKGROUND: Takayasu's arteritis is a chronic inflammatory idiopathic disease involving large arteries like the aorta and its primary branches. Cell-mediated autoimmunity leading to vascular injury has been suspected in its pathogenesis although the antigen inducing the process remains unknown. CASE REPORT: A 50-year-old male patient suffered from acute hemiballism. Neuroimaging showed an infarction of right temporal insular cortex. Neurosonology and MR-Angiography revealed bilateral long-distant subtotal stenosis of the common carotid artery and left-sided occlusion of the subclavian artery. Positive hepatitis B serology with active viral replication was found. In the absence of other vasculitis or inflammation markers, Takayasu's arteritis was diagnosed and steroid therapy was started. CONCLUSIONS: Unilateral insular lesions may lead to transient hemiballistic movements which could be the result of decreased inhibitory output of the insula to basal ganglia. The hepatitis B virus possibly contains a surface antigen inducing a specific cellular immune response leading to Takayasu's arteritis.

Anti-Inflammatory Agents↗
PubMed2003

Adaptive noninvasive assessment of intracranial pressure and cerebral autoregulation.

BACKGROUND AND PURPOSE: A mathematical model has previously been introduced to estimate noninvasively intracranial pressure (nICP). In the present multicenter study, we investigated the ability of model to adapt to the state of cerebral autoregulation (SCA). This modification was intended to improve the quality of nICP estimation and noninvasive assessment of pressure reactivity of the cerebrovascular system. METHODS: We studied 145 patients after severe head injuries or stroke. All patients had direct ICP, arterial blood pressure (ABP), and transcranial Doppler middle cerebral artery blood flow velocity (FV) monitored. The SCA was assessed by moving correlation (Mx index) of cerebral perfusion pressure (CPP=ABP-ICP) and cerebral blood flow velocity and correlation of ABP and ICP (PRx index). nICP was calculated from ABP and FV waveforms. When nICP was used instead of ICP, the SCA was continuously estimated, and the model was dynamically adapted to the SCA. RESULTS: High and moderate correlations between invasively (Mx, PRx) and noninvasively (nMx, nPRx) estimated autoregulation indexes were observed (Mx: R=0.90, P<0.001; PRx: R=0.62, P<0.001). Values of Mx and nMx indicated contradictory SCA in 4 of 167 evaluated recordings; values of PRx and nPRx were contradictory in 27 recordings. When the model was adapted to the SCA, the mean error of ICP estimation decreased significantly (P<0.005). CONCLUSIONS: Continuous adaptation of the model to SCA improves the accuracy of noninvasive estimation of ICP and ICP dynamics. The same model provides a noninvasive and continuous assessment of SCA.

Adolescent↗
PubMed2003

A truly simultaneous combination of functional transcranial Doppler sonography and H(2)(15)O PET adds fundamental new information on differences in cognitive activation between schizophrenics and healthy control subjects.

UNLABELLED: Working memory deficits are a cardinal feature of the pathophysiology of schizophrenia. Lesion studies and functional blood flow-dependent imaging methods with coarse temporal resolution, such as PET and functional MRI (fMRI), tend to paint a fairly static picture of the cortical regions involved. In contrast, functional transcranial Doppler sonography (fTCD) provides a high temporal resolution. Truly simultaneous fTCD-fMRI is not yet possible for technical reasons, but H(2)(15)O PET and fTCD can be used really simultaneously. However, this combination has not yet been used for cognitive activations in schizophrenia. We therefore investigated the extent to which there are both spatial (PET) and temporal changes (fTCD) in the activation patterns of schizophrenic patients. METHODS: Eleven clinically stable chronic schizophrenic, right-handed patients and 10 healthy, right-handed control subjects, matched for age, sex, education, and intelligence quotient, participated in the study. We selected stable chronic schizophrenic patients who could perform a working memory task (N-back task) as well as healthy volunteers to exclude the possibility of imaged artifacts due to poor performance. All subjects were examined with a truly simultaneous fTCD-H(2)(15)O PET combination under cognitive activation. RESULTS: Schizophrenic patients activate a significantly larger cortical volume for adequate task performance (P < 0.05), but with a significantly lower blood flow increase in this volume (P < 0.01), than do control subjects. Furthermore, they cannot significantly increase blood flow velocity during the time course of cognitive activation as control subjects do. There were only significant correlations between neuropsychologic performance and imaging parameters (fTCD changes, PET blood flow changes) in control subjects (all r >or= /0.65/; P < 0.05), but no significant correlations in schizophrenics (all r < /0.3/; P > 0.4). CONCLUSION: We demonstrated that schizophrenic patients exhibit qualitative differences in the spatial and temporal resolution of cognitive processing. All facts could be interpreted as a sign of alternative, less efficient problem-solving strategies in schizophrenia that lead to the working memory deficits observed during the further course of this disease. Truly simultaneous fTCD-PET can be used in neuroscience to add fundamental new information on spatial and temporal cognitive activation behavior to understand the true physiologic nature of the disease-specific differences of mental illnesses that are seen as disorders of the mind arising in the brain.

Adult↗