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Biomedical subjects

D Sander

Publications and source records attributed to D Sander.

At least 19 recordsLinked to original sources
PubMed2006

[Significant reduction of vascular risk factors within the framework of the population-based intervention project INVADE--a 2-year follow-up study].

BACKGROUND: The INVADE project (Intervention project of cerebrovascular diseases and dementia in the district of Ebersberg) analyzes the effect of risk factor evaluation and modification on the incidence of stroke and dementia. Here we evaluated the changes of risk factors after two years in the INVADE population, particularly in participants with diabetes mellitus and coronary heart disease (CHD). PATIENTS AND METHODS: Baseline data of 3909 participants were available. In addition to common risk factors and new risk indicators, various social demographic data and life style parameters were analyzed. A guideline-based therapy was proposed for each participant based on an individual risk profile. The differences between baseline and the 2-year follow-up data were analyzed using the paired t-test and the McNemar test. RESULTS: Complete follow-up data were available in 3185 participants (1288 men; mean age 69.5 years). For the overall project population the reduction of traditional risk factors was effective, particularly in subjects with hypertension or diabetes. The prevalence of hypertension was 76 %, including 19 % newly diagnosed subjects. In this subgroup, the systolic blood pressure could be reduced by 4.7 mmHg. 20.3 % of the participants showed a diabetes mellitus, blood glucose level decreased about 8 %. Additionally an improvement in hypertension therapy and lipid levels was seen. Comparable results were achieved in the CHD subgroup. Additionally, in the overall study population treatment with antihypertensives and statins increased significantly. DISCUSSION: Even after two years, the INVADE project was able to reduce vascular risk factors particularly in high risk patients with diabetes and CHD. Based on these findings, the primary aim of the project, the reduction of stroke and dementia incidence, can be achieved.

Aged↗
PubMed2006

Bilateral grey-matter increase in the putamen in primary blepharospasm.

BACKGROUND: Primary blepharospasm is a focal dystonia characterised by excessive involuntary closure of the eyelids. The pathophysiology of primary blepharospasm is unresolved. AIM: To pinpoint grey-matter changes that are associated with primary blepharospasm. METHODS: 16 right-handed patients with primary blepharospasm (mean age 67.4 (SD 4.3) years; 12 women) were compared with 16 healthy volunteers matched for sex and age. High-resolution T1-weighted magnetic resonance imaging of each participant was obtained and analysed by voxel-based morphometry, a method to detect regionally specific differences in grey matter between patients and control group. To evaluate whether the identified grey-matter changes were correlated with the duration of primary blepharospasm or botulinum neurotoxin treatment (BoNT), separate regression analyses were carried out. RESULTS: In patients with primary blepharospasm, grey-matter increase in the putamina was observed, whereas regression analyses did not indicate a correlation between grey-matter increases and the duration of primary blepharospasm or BoNT. Grey-matter decrease was detected in the left inferior parietal lobule; here regression analyses of grey-matter decrease showed a significant (p = 0.013) correlation of grey-matter decrease with the duration of BoNT. CONCLUSIONS: The data suggest structural changes in primary blepharospasm and point to a crucial role of the putamen for the pathophysiology of this focal dystonia.

Aged↗
PubMed2006

MRI lesions after invasive therapy of carotid artery stenosis: a risk-modeling analysis.

BACKGROUND: Diffusion-weighted imaging (DWI) abnormalities can frequently be detected after carotid endarterectomy (CEA) and carotid angioplasty with stent placement (CAS) of the carotid arteries. We looked for possible predictors for the development of DWI lesions during the intervention. METHODS: We investigated 41 patients who underwent CAS without protection devices and 93 patients who underwent CEA. DWI studies were performed 1 day before and after the intervention. RESULTS: Ischemic complications consisted of two strokes (2.2%) in the CEA group and one stroke (2.4%) in the CAS group. DWI lesions were detected in 28.0% of all patients after intervention. Using a multivariate regression analysis, diabetes mellitus (DM), hyperlipidemia, symptomatic stenosis, age and CAS were found to be significant predictors for the occurrence of DWI lesions. CONCLUSIONS: DWI is an objective and highly sensitive method for monitoring interventions of the carotid arteries. Our results point to an increased risk of patients with diabetes and hyperlipidemia to develop DWI lesions during invasive therapy of the ICA.

Age Factors↗
PubMed2005

Structural brain changes in tinnitus.

Tinnitus is a common but poorly understood disorder characterized by ringing or buzzing in the ear. Central mechanisms must play a crucial role in generating this auditory phantom sensation as it persists in most cases after severing the auditory nerve. One hypothesis states that tinnitus is caused by a reorganization of tonotopic maps in the auditory cortex, which leads to an overrepresentation of tinnitus frequencies. Moreover, the participation of the limbic system in generating tinnitus has been postulated. Here we aimed at identifying brain areas that display structural change in tinnitus. We compared tinnitus sufferers with healthy controls by using high-resolution magnetic resonance imaging and voxel-based morphometry. Within the auditory pathways, we found gray-matter increases only at the thalamic level. Outside the auditory system, gray-matter decrease was found in the subcallosal region including the nucleus accumbens. Our results suggest that reciprocal involvement of both sensory and emotional areas are essential in the generation of tinnitus.

Adult↗
PubMed2005

[Doppler sonography suggesting fulminant aortic dissection in initial middle cerebral artery infarction].

Acute aortic dissection is a cardiovascular emergency with a wide spectrum of clinical symptoms making the diagnosis difficult if the leading symptom of thoracic pain is not present. In up to 10% of cases an ischemic stroke may be the first clinical sign. We report a patient with a middle cerebral artery infarction in whom an abnormal signal in the extracranial Doppler sonography revealed the first hint of an aortic dissection. Before the diagnosis could be verified, the patient died due to electromechanical decoupling; autopsy showed an extensive aortic dissection with cardiac tamponade. Based on this case report, we review special problems of diagnosis and therapy in aortic dissection with primary cerebrovascular manifestation.

Aged↗
PubMed2005

DWI in transient global amnesia and TIA: proposal for an ischaemic origin of TGA.

There are conflicting reports concerning signal intensity changes in transient global amnesia (TGA) using diffusion weighted imaging (DWI). We prospectively analysed DWI signal intensity changes in TIA and TGA patients, and compared the clinical characteristics and risk factors of both groups. Using DWI and conventional T1 and T2 weighted turbo spin echo sequences, 28 patients with acute TGA (13 men, mean age 61.5 years) and 74 TIA patients (47 men, mean age 62.4 years) were studied within 48 hours after symptom onset. Every patient underwent an intensive diagnostic investigation. In 10/28 (36%) of the TGA patients and 21/74 (28%) of the TIA patients, DWI signal intensity changes occurred. The time to DWI and the duration of symptoms were comparable in TIA and TGA patients. Overall, TIA patients showed an increased prevalence of vascular risk factors compared with TGA patients. In the TGA group, patients with abnormal DWI showed carotid atherosclerosis significantly more frequently. Based on our data, we suggest that the aetiology of TGA could be explained by an ischaemic event; due to arterial thrombembolic ischaemia in one subgroup, particularly in those patients with increased vascular risk factors, and due to venous ischaemia in another subgroup with valsalva-like activities before symptom onset.

Amnesia↗
PubMed2005

Improved cerebral vasoreactivity after statin administration in healthy adults.

BACKGROUND AND PURPOSE: Significant improvements of cerebral vasomotor reactivity during statin treatment were found in patients with cerebral small-vessel disease. The authors analyzed the cerebrovascular CO(2) reactivity before and after statin administration in healthy adults using a case-control study design. METHODS: The mean cerebral blood flow velocity (CBFV) of both middle cerebral arteries and the vasomotor reserve capacity (VMRC) were measured by repeated and simultaneous bilateral transcranial Doppler sonography in 25 healthy adults (7 men, mean age 28.8 years [95% confidence interval (CI): 25.7; 31.9]) before, during (days 1, 3, 7, and 14), and after administration of 40 mg pravastatin for 14 days as compared to 10 healthy control persons (4 men, mean age 30.6 years [95% CI: 22.9; 38.3]). The VMRC was calculated off-line as the percentage change of CBFV per 1% increase in end-tidal CO2 by a blinded investigator. RESULTS: In the statin group, 5 persons were excluded from further analysis. In the remaining 20 volunteers, the authors observed a highly significant effect of statin administration on VMRC (P = .002). The VMRC was significantly increased after statin administration on day 7 as compared to the initial value (3.03 [95% CI: 2.67; 3.38] vs 2.64 [95% CI: 2.41; 2.86]; P = .04). The effect was most pronounced in patients with lower initial VMRC values. In the control group, the VMRC did not differ significantly from baseline at different time intervals. CONCLUSIONS: The findings indicate an improvement of cerebral vasoreactivity even after short-term statin administration in healthy adults. However, this effect was related to baseline vasoreactivity.

Adult↗
PubMed2004

Reversible H-induced switching of the magnetic easy axis in Ni/Cu(001) thin films.

A reversible switching of the easy axis of magnetization for Ni on Cu(001) from in plane to out of plane is found by changing the partial pressure of hydrogen in the gas phase around the sample, allowing even for oscillations of the magnetization direction. A quantitative low-energy electron diffraction study of the diffracted intensity versus electron energy [I(E)] shows that the hydrogen-induced spin reorientation transition is accompanied by changes of the tetragonal distortion of the topmost Ni layer upon hydrogen adsorption. Surprisingly, the orientation switch to perpendicular to the surface comes with a relaxation, i.e., reduction of the film's tetragonal distortion rather than its amplification.

Journal Article↗
PubMed2004

Spin reorientation and structural relaxation of atomic layers: pushing the limits of accuracy.

The correlation between an ad-layer-induced spin reorientation transition (SRT) and the ad-layer-induced structural relaxation is investigated by combined in situ surface x-ray diffraction and magneto-optical Kerr-effect experiments on Ni/Fe/Ni(111) layers on W(110). The Fe-induced SRT from in-plane to out-of-plane, and the SRT back to in-plane upon subsequent coverage by Ni, are each accompanied by a small lattice relaxation of at most 0.002 A. Such a small strain variation excludes a magnetoelasticity driven SRT, and we suggest the interface anisotropy as a possible driving force.

Journal Article↗
PubMed2004

Estimation of neural energy in microelectrode signals.

We considered the problem of determining the neural contribution to the signal recorded by an intracortical electrode. We developed a linear least-squares approach to determine the energy fraction of a signal attributable to an arbitrary number of autocorrelation-defined signals buried in noise. Application of the method requires estimation of autocorrelation functions R(ap)(tau) characterizing the action potential (AP) waveforms and R(n)(tau) characterizing background noise. This method was applied to the analysis of chronically implanted microelectrode signals from motor cortex of rat. We found that neural (AP) energy consisted of a large-signal component which grows linearly with the number of threshold-detected neural events and a small-signal component unrelated to the count of threshold-detected AP signals. The addition of pseudorandom noise to electrode signals demonstrated the algorithm's effectiveness for a wide range of noise-to-signal energy ratios (0.08 to 39). We suggest, therefore, that the method could be of use in providing a measure of neural response in situations where clearly identified spike waveforms cannot be isolated, or in providing an additional 'background' measure of microelectrode neural activity to supplement the traditional AP spike count.

Action Potentials↗
PubMed2004

Frequency, clinical significance and course of cerebral ischemic events after carotid endarterectomy evaluated by serial diffusion weighted imaging.

OBJECTIVES: Neurological deficit defines the outcome of Carotid Endarterectomy (CEA) that is mainly caused by cerebral ischemia. Diffusion-weighted imaging (DWI) is a sensitive method for demonstrating even small ischemic lesions. The aim of this study was to evaluate the frequency, clinical significance and course of ischemic lesions after CEA using serial DWI. METHODS: DWI was performed within 1 day before and after CEA in 88 patients. Postoperative lesions were analyzed by their quantity, volume and distribution. To differentiate temporary ischemia from definite cerebral infarction (blood brain barrier disruption) all patients with a positive postoperative DWI were reexamined with contrast-enhanced T1-MRI 7-10 days after the procedure. All patients were examined by a neurologist within 2 days before and after CEA. RESULTS: Two patients showed a postoperative neurological deficit. Postoperative DWI revealed ipsilateral ischemic lesions in 15 patients. In seven of these patients a brain infarction was diagnosed on the T1-MRI during follow-up. A significant correlation between the number of DWI lesions (p=0.031) as well as the volume of DWI lesions (p=0.023) and definite infarction was found. Symptomatic patients preoperatively showed significantly more DWI lesions (p=0.036) and cerebral infarcts (p=0.003). CONCLUSION: DWI is a sensitive method of demonstrating ischemic events after CEA. The number and volume of DWI lesions after CEA are highly predictive of brain infarction.

Aged↗
PubMed2004

Changes of cerebrovascular response to visual stimulation in migraineurs after repetitive sessions of somatosensory stimulation (acupuncture): a pilot study.

OBJECTIVES: To evaluate the effect of repetitive somatosensory stimulation (acupuncture) on cerebrovascular response in migraineurs by functional transcranial Doppler. METHODS: Changes of cerebral blood flow velocity in the right posterior and left middle cerebral arteries were measured by functional transcranial Doppler during visual stimulation (flickering light over 57 seconds) in 10 migraineurs before and after 10 acupuncture sessions. The same stimulation paradigm was performed in 10 control subjects. Cerebral blood flow velocity data were analyzed with a previously validated technique based on automated stimulus-related averaging. To evaluate the clinical effect of the treatment, a headache diary monitored the frequency and intensity of the migraine attacks. A positive treatment effect was defined as a reduction of at least 50% in the attack frequency or the mean headache intensity (or both). RESULTS: Before treatment, migraineurs showed overshooting cerebral blood flow velocity changes at the beginning and at the end of the stimulation and a delayed decline to baseline compared with control subjects. After treatment, this response pattern was significantly diminished (P</=.05) in those who benefited from treatment (n = 6). Those who did not benefit from treatment (n = 4) showed a significantly (P</=.05) more marked alteration of the cerebral blood flow velocity pattern. CONCLUSIONS: Data indicate that repetitive somatosensory stimulation (acupuncture) might positively influence the abnormal cerebrovascular response in migraineurs. In a subgroup of migraineurs, however, the dysfunction of the cerebrovascular system might deteriorate under the treatment.

Acupuncture Therapy↗
PubMed2003

Obstacles in the diagnosis and treatment of syphilitic amyotrophy.

The authors describe a case of syphilitic amyotrophy in a 37-year-old man presenting with subacute progressive painless weakness in the right arm. Syphilitic amyotrophy is still an existing differential diagnosis of painless and progressive weakness. The authors explore potential obstacles in the diagnostic workup and finding of adequate therapy.

Adult↗
PubMed2003

Multiple progressive intracerebral hemorrhages due to an angiosarcoma: a case report.

Identification of intracerebral hemorrhage (ICH) and the underlying cause is a common clinical problem. Rare causes of ICH can be particularly difficult to diagnose. We describe a man on oral anticoagulation with multiple progressive ICHs, who initially showed no signs of a malignant disease. After normalisation of all coagulation tests, the ICHs continued to spread. Autopsy examination revealed an angiosarcoma. Multiple progressive ICHs caused by an angiosarcoma that mainly affects the brain have not yet been described. In the presence of normal coagulation tests, further progression of ICH should raise questions about common causes of ICH such as oral anticoagulation in our case.

Aged↗
PubMed2002

[Circumscribed vasculitis with posterior infarct in Hashimoto encephalopathy].

The aetiology of Hashimoto's encephalopathy is still unknown. A 52-year-old woman with so far unspecific thyroid disorder presented with acute onset of right-sided sensory loss and visual disturbances. The neurological examination revealed a right upper quadrant anopsia and subtle right-sided sensory loss and weakness. The cranial MRI showed a left-sided cerebral infarction. MR angiography demonstrated a stenosis of the proximal segment of the left posterior cerebral artery, which was confirmed by conventional catheter angiography. The patient had no cardiovascular risk factors, no signs of systemic vasculitis, and no thromboembolic disorder. Thyroid function tests showed a subclinical hypothyroidism with plasma TSH level of 12.0 mU/ml, and thyroid antibodies were markedly elevated (hTG-AB 3390 U/ml, TPO-AB > 8000 U/ml). Typical features of Hashimoto's disease were demonstrated by ultrasound and scintigraphic examination of the thyroid gland. To the best of our knowledge, this is the first description of Hashimoto encephalopathy with localised vasculitis of the posterior cerebral arteries and left posterior infarction. It could be shown that the MR angiogram is a feasible tool to demonstrate regression of the vasculitis under glucocorticoid therapy.

Cerebral Angiography↗
PubMed2002

[Intervention project on cerebrovascular diseases and dementia in the Ebersberg district (INVADE): rationale and design].

The aim of INVADE (Intervention project on cerebrovascular diseases and dementia in the district of Ebersberg) is to analyse the effect of risk factor evaluation and modification (arterial hypertension, dyslipoproteinaemia, diabetes mellitus,hyperhomocysteinaemie, smoking, adipositas, alcohol abuse, lack of movement and depression) on the incidence of stroke and dementia in a population based sample. Stroke represents the third-common cause of death in the industrialized countries and is together with dementia one of the main causes for dependency in the activities of daily living. The project was performed in an area near to Munich, the district of Ebersberg. Risk factors were evaluated and if necessary modified by means of the primary care concept. INVADE was performed in cooperation with the health insurance company AOK and most of the general practitioners (n=65) of the district. All inhabitants of the district born 1946 and earlier who were also member of the AOK (10548 persons) are able to participate.

Aged↗
PubMed2001

Prognostic relevance of pathological sympathetic activation after acute thromboembolic stroke.

OBJECTIVE: To evaluate the prognostic impact of early pathologic sympathetic activation after stroke. METHODS: The authors examined 112 consecutive patients (mean age, 69 years; 60 men) with their first brain infarction. A pathologic sympathetic activation was presumed if the initial norepinephrine level exceeds 300 pg/mL. In addition, involvement of the insular cortex, nighttime blood pressure changes, and several cardiovascular risk factors were determined. One-year outcome measures were mortality rate, cardiovascular and cerebrovascular events, and activities of daily living (Barthel index and Rankin score). RESULTS: Norepinephrine levels greater than 300 pg/mL, nighttime blood pressure increases, and insular involvement were associated with a lower Barthel index (p < 0.005) at the 1-year follow-up. By stepwise logistic regression analysis, insular infarction, serum norepinephrine concentration, right-sided infarction, and nighttime blood pressure increase were significant and independent predictors of an unfavorable functional outcome. Cox regression analysis showed a higher rate of cardiovascular and cerebrovascular events (hazard ratio, 2.9; 95% CI, 1.07; 6.83; p < 0.04) in patients with initially increased norepinephrine concentrations. CONCLUSIONS: The involvement of the insular cortex, the occurrence of a pathologic nighttime blood pressure increase, and an initially increased serum norepinephrine concentration are independent predictors of poor long-term outcome.

Aged↗