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Kerstin Sander

Publications and source records attributed to Kerstin Sander.

10 recordsLinked to original sources
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

In vivo quantification of spinal and bulbar motor neuron degeneration in the G93A-SOD1 transgenic mouse model of ALS by T2 relaxation time and apparent diffusion coefficient.

Magnetic resonance imaging (MRI) has provided important information in characterizing amyotrophic lateral sclerosis (ALS) in humans and in animal models. A frequently used animal model to study mechanisms of pathogenesis and the efficacy of drugs in ALS is a transgenic mouse over-expressing the human mutated G93A-superoxide dismutase 1 (G93A-SOD1). In our study, we applied MRI to find suitable progression markers, which can be used to monitor the development of ALS and to evaluate therapeutic approaches at early stages of the disease. Therefore, we generated parameter maps of the spin-spin relaxation time (T2) and the apparent diffusion coefficient (ADC) starting at day 70 after birth, i.e., before motor scores decline around day 90. Depending on the progression of the disease, G93A-SOD1 mice showed significantly increased values of T2 in the brain stem motor nuclei Nc. V (trigeminal nucleus), VII (facial nucleus), and XII (hypoglossal nucleus), and spinal cord compared to non-transgenic wild-type mice and transgenic mice over-expressing the non-mutated wild-type human SOD1 (tg-SOD1). Similar effects in these motor nuclei were revealed by ADC mapping. Furthermore, in the upper spinal cord, a dorsal-ventral difference with significantly higher T2 values in the ventral part was demonstrated by T2 mapping. While both T2 and ADC might prove useful as progression markers and enable the longitudinal non-invasive evaluation of ALS in G93A-SOD1 mice, the potential is limited by age-dependent effects in case of ADC mapping.

Amyotrophic Lateral Sclerosis↗
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↗
PubMed2005

Left auditory cortex and amygdala, but right insula dominance for human laughing and crying.

Evidence suggests that in animals their own species-specific communication sounds are processed predominantly in the left hemisphere. In contrast, processing linguistic aspects of human speech involves the left hemisphere, whereas processing some prosodic aspects of speech as well as other not yet well-defined attributes of human voices predominantly involves the right hemisphere. This leaves open the question of hemispheric processing of universal (species-specific) human vocalizations that are more directly comparable to animal vocalizations. The present functional magnetic resonance imaging study addresses this question. Twenty subjects listened to human laughing and crying presented either in an original or time-reversed version while performing a pitch-shift detection task to control attention. Time-reversed presentation of these sounds is a suitable auditory control because it does not change the overall spectral content. The auditory cortex, amygdala, and insula in the left hemisphere were more strongly activated by original than by time-reversed laughing and crying. Thus, similar to speech, these nonspeech vocalizations involve predominantly left-hemisphere auditory processing. Functional data suggest that this lateralization effect is more likely based on acoustical similarities between speech and laughing or crying than on similarities with respect to communicative functions. Both the original and time-reversed laughing and crying activated more strongly the right insula, which may be compatible with its assumed function in emotional self-awareness.

Acoustic Stimulation↗
PubMed2005

Left auditory cortex specialization for vertical harmonic structure of chords.

The representation of consonant and dissonant chords in the auditory cortex was investigated using low-noise functional magnetic resonance imaging and different experimental paradigms to separate the effects of vertical harmony from those of other musical features. The results revealed higher activation by consonant compared with dissonant chords in the left posterior auditory cortex, suggesting contributions of mechanisms of encoding the acoustical chord structure rather than mechanisms based on sequential integration of chords.

Acoustic Stimulation↗
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↗
PubMed2003

Left-lateralized fMRI activation in the temporal lobe of high repressive women during the identification of sad prosodies.

We investigated with fMRI whether different lateralization types of cortical activation in prosodic tasks are caused by individually different stress-related coping strategies. After healthy women had been classified as high or low repressive they performed four different identification tasks with acoustically presented speech material while being in the MR scanner. The two materials presented in blocks were emotionally irrelevant CV syllables and adjectives with a mix of different prosodic intonations. Sad and happy intonations had to be targeted by two affective identification tasks in the same adjective mixtures. For testing stimulus-material effects the phoneme /a/ had to be identified both in the syllables and the adjectives. This design allowed us to test influences of coping strategies and affective tasks on cortical activation in both hemispheres. Results showed no differences in global cortical lateralization as a function of high or low repressiveness and no global support for either the valence hypothesis or the right-hemisphere hypothesis of emotional processing. However, we observed differences in auditory and speech cortex. In accordance to the construct of repression/sensitization, high repressive women showed larger left, low repressive women larger right hemisphere activation during the identification of sad intonations. Thus, differences in stress-related coping strategies may not lead to general differences in cortical lateralization, but may depend on specific elicitors and task-relevant brain areas. In contrast, the identification of happy intonations led to strong and right-lateralized global cortical activation independent of coping strategies which complies with the right-hemisphere hypothesis of emotional processing. In addition, this may reflect general cognitive and arousal effects of task difficulty as well as auditory cue-specific attentional effects.

Adaptation, Psychological↗
PubMed2003

Audition of laughing and crying leads to right amygdala activation in a low-noise fMRI setting.

Adequate behavioral responses to socially relevant stimuli are often impaired after lesions of the amygdala. These impaired behavioral responses in particular concern the recognition of facial, and sometimes vocal, expressions of fear. Using low-noise functional magnetic resonance imaging (fMRI) in combination with controlled sound delivery, we investigated how the amygdala, insula and auditory cortex are involved in the processing of affective non-verbal vocalizations (laughing, crying) in healthy humans. The same samples of male and female laughing and crying were presented in two different experimental conditions: self-induction of the corresponding emotions while listening, and detection of artificial pitch shifts in the same stimuli. Both conditions led to bilateral activation of the amygdala, insula and auditory cortex with a right-hemisphere advantage in the amygdala, and larger activation during laughing than crying in the auditory cortex with a slight right-hemisphere advantage for laughing, both likely due to acoustic stimulus features. The results show that amygdala activation by emotionally meaningful sounds like laughing and crying is independent of the emotional involvement, suggesting the pattern recognition aspect of these sounds is crucial for this activation. This aspect was revealed by a low-noise fMRI protocol which presumably minimized confounding effects of stressful high-noise fMRI.

Acoustic Stimulation↗