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Wolfgang Reith

Publications and source records attributed to Wolfgang Reith.

At least 19 recordsLinked to original sources
PubMed2007

Reversal of flow during carotid artery stenting: use of the Parodi antiembolism system.

INTRODUCTION: To evaluate the flow reversal efficacy of the Parodi antiembolism system (PAES) in the prevention of distal emboli during carotid stenting. METHODS: A total of 90 patients were treated for internal carotid artery (ICA) stenosis with a stent device. A PAES device was used in 31 symptomatic and 5 asymptomatic patients (total 36 patients) with ICA stenosis, and 54 patients were stented without any protection device. Diffusion-weighted (DW) imaging was performed before and after stenting. RESULTS: In the group without PAES protection, 23 out of 54 patients showed new lesions on DW images after stenting. Of the lesions seen, 147 (2.72 lesions/patient) were in the vessel-dependent area. In the group with protection, 19 out of 36 patients had new lesions, and only 34 (0.94 lesions/patient) were noted in the vessel-dependent area. The number of new lesions in the nondependent vessel area did not differ if a protection system was used (P = 0.671). The use of PAES led to a significant reduction (P = 0.024) in the incidence of the most frequently seen lesions (size <2 mm). The stroke death rate was 3.3% overall, 3.7% in the group without protection device, and 2.7% in the PAES group. There were no permanent neurological deficits after 3 months. CONCLUSION: The PAES is a safe and effective tool to reduce the incidence of embolic complications during carotid stenting. Older patients and patients with higher grade stenosis seem to profit more.

Aged↗
PubMed2006

Recanalization after endovascular treatment of intracerebral aneurysms.

INTRODUCTION: The aim of this study was to evaluate the risks of endovascular therapy, aneurysm regrowth, recanalization and the need for reembolization. METHOD: A prospective analysis was performed on 211 aneurysms treated endovascularly from February 2000 to December 2003. Of these 211 aneurysms, 81 were asymptomatic and 130 were ruptured. The risks of endovascular therapy, aneurysm regrowth, recanalization and the need for reembolization were evaluated. RESULTS: The mean observation time was 10 months (ranging from 178 to 830 days). Complete occlusion (100%) in the initial intervention was achieved in 171 of 201 aneurysms (85%), 80-95% occlusion in 24 aneurysms (12%), and <80% occlusion in 6 aneurysms (3%). Recanalization had occurred at the first follow-up in 34 of all 153 aneurysms reassessed (22.2%). Of 133 aneurysms with initial 100% occlusion, 107 (80.4%) remained completely occluded, 17 (12.7%) showed recanalization, and 9 (6.7%) showed neck regrowth. Among those with 80-95% occlusion, 20 were reassessed, and of these 2 showed spontaneous occlusion, 10 (50%) still showed the initial neck, and 8 (40%) showed increased recanalization. One aneurysm which initially showed <80% occlusion remained unchanged, and another showed showed recanalization. Of the 153 aneurysms, 12 (7.8%) were recoiled, 2 initially <80% occluded, 7 initially 80-95% occluded and 3 initially totally occluded. CONCLUSION: In spite of low morbidity and mortality, one in four aneurysms will show recurrence. The initial degree of occlusion seems to have an influence on the likelihood of recanalization.

Aneurysm, Ruptured↗
PubMed2006

Differential hippocampal and prefrontal-striatal contributions to instance-based and rule-based learning.

It is a topic of current interest whether learning in humans relies on the acquisition of abstract rule knowledge (rule-based learning) or whether it depends on superficial item-specific information (instance-based learning). Here, we identified brain regions that mediate either of the two learning mechanisms by combining fMRI with an experimental protocol shown to be able to dissociate both learning mechanisms. Subjects had to learn object-position conjunctions in several trials and blocks. In a learning condition, either objects (Experiment 1) or positions (Experiment 2) were held constant within-blocks. In contrast to a control condition in which object-position conjunctions were trial-unique, a performance increase within and across-blocks was observed in the learning condition of both experiments. We hypothesized that within-block learning mainly relies on instance-based processes, whereas across-block learning might depend on rule-based mechanisms. A within-block parametric fMRI analysis revealed a learning-related increase of lateral prefrontal and striatal activity and a learning-related decrease of hippocampal activity in both experiments. By contrast, across-block learning was associated with an activation modulation in distinct prefrontal-striatal brain regions, but not in the hippocampus. These data indicate that hippocampal and prefrontal-striatal brain regions differentially contribute to instance-based and rule-based learning.

Adult↗
PubMed2006

Intraindividual comparison of gadobenate dimeglumine and gadobutrol for cerebral magnetic resonance perfusion imaging at 1.5 T.

RATIONALE AND OBJECTIVE: The objective of this study was to compare 0.1 and 0.2 mmol/kg body weight (bw) doses gadobenate dimeglumine (Gd-BOPTA; MultiHance) and gadobutrol (Gd-BT-DO3A; Gadovist) for cerebral perfusion magnetic resonance (MR) imaging at 1.5 T. METHODS: Twelve healthy male volunteers enrolled into a randomized intraindividual comparative study underwent 4 perfusion MR imaging examinations with 0.1 and 0.2 mmol/kg bw doses of each contrast agent. The imaging parameters, slice positioning, and contrast agent application were highly standardized. Quantitative determinations based on signal intensity/time (SI/T) curves at regions of interest (ROI) on the gray and white matter were made of the regional cerebral blood volume and flow (rCBV and rCBF, respectively), the percentage signal drop, and the full width half maximum (FWHM) of the SI/T curve. Qualitative evaluation of the quality of the rCBV and rCBF maps was assessed by an independent offsite blinded reader. RESULTS: A single dose of both agents was sufficient to achieve high-quality, diagnostically valid perfusion maps at 1.5 T, and no significant benefit for one agent over the other was noted for quantitative or qualitative determinations. The susceptibility effect, described by percentage of signal loss (gadobutrol: 29.4% vs gadobenate dimeglumine: 28.3%) and the FWHM (gadobutrol: 6.4 seconds vs gadobenate dimeglumine: 7.0 seconds) were similar for 0.1 mmol/kg bw doses of the 2 agents. Double doses of the 2 agents produced better overall image quality but no clinical benefit over the single-dose examinations. CONCLUSION: Both the 1 molar MR contrast agent gadobutrol and the weak protein-interacting agent gadobenate dimeglumine permit the acquisition of high-quality perfusion maps at doses of 0.1 mmol/kg bw. The susceptibility effect is comparable for both agents and stronger than for conventional MR contrast agents.

Adult↗
PubMed2006

Endovascular treatment of unruptured intracranial aneurysms: occurrence of thromboembolic events.

OBJECTIVE: The purpose of this study was to evaluate the frequency and causes of thromboembolic events associated with endovascular embolization of asymptomatic aneurysms. Correlations between radiological findings (aneurysm size, localization, embolization time, number of coils used, as well as patient age) were evaluated with the occurrence of thromboembolic events and clinical findings. METHODS: Sixty-eight patients treated for unruptured intracranial aneurysms (mean age, 49 yr) were evaluated. Hyperintense lesions on diffusion weighted imaging were analyzed in 50 patients. Aneurysm size was 3 to 15 mm. RESULTS: Complete occlusion of the aneurysms was achieved in 55 of 68 (82%). One patient had a transient paresis. There was one infarction and one aneurysm rupture during the procedure with no consecutive neurological symptoms. We found new hyperintense lesions in 21 of 50 (42%) diffusion weighted imaging studies. In 43% of these, there was only one lesion smaller than 2 mm. In 33%, there was more than one lesion less than 2 mm; in 19%, we found a lesion of 2 to 10 mm in size. In one case, a lesion greater than 10 mm occurred. There was no correlation between aneurysm location and the occurrence of lesions or among the number of coils used, the size of the aneurysm, patient age, or embolization time. Mortality rate was 0%, morbidity 4.0%. If the 18 aneurysms where no diffusion weighted imaging was obtained are included, morbidity is 2.9%. CONCLUSION: The high rate of thromboembolic events suggests that heparin is not sufficient to prevent ischemic lesions. An antiplatelet therapy, started before or during intervention, might diminish thrombus formation.

Adult↗
PubMed2006

A device for fast mechanical clot retrieval from intracranial arteries (Phenox clot retriever).

INTRODUCTION: To describe a new device meant for rapid endovascular thrombectomy of intracranial arteries of various sizes and its first clinical use. METHODS: A device with oriented microfilaments was constructed that consists of a core wires compound surrounded by a dense palisade of perpendicular-oriented stiff polyamid microfilaments (phenox clot retriever). The device is introduced into the target vessel through a 0.021- or 0.027-inch microcatheter, deployed distally to the thrombus, and slowly pulled back under continuous aspiration via the guiding catheter. RESULTS: The clinical use of the phenox clot retriever in two successive patients is described. Case 1: In a 78-year-old patient with acute posterior circulation ischemia not eligible for intravenous or intraarterial thrombolysis, endovascular recanalization of the occluded left V4 segment was possible using the phenox clot retriever within a few minutes. Case 2: A 70-year-old patient presented after the sudden onset of a left upper extremity paresis 1 day after abdominal surgery. Angiography revealed a thromboembolic occlusion of two cortical branches of the right middle cerebral artery. The rolandic artery was recanalized by a single passage of the phenox clot retriever, with complete neurological recovery. CONCLUSION: The phenox clot retriever, a flexible microfilament pattern, might be a useful supplement to the repertoire of currently available devices for endovascular intracranial thrombectomy.

Aged↗
PubMed2005

Event-related potentials in people at risk for vascular dementia.

This study examined the relationship between the integrity of cerebrovascular microcirculation, neuropsychological testing and event-related potential indices of cognitive functioning in a nonclinical group of participants being at risk for vascular dementia. Sonographic measures, magnetic resonance (MR) scans and ERPs were recorded in 30 participants treated for arterial hypertension, with no report of neurological or psychiatric disorders. As a sonographic measure of cerebral microcirculation, the arteriorvenous cerebral transit time (cTT) was recorded. While neuropsychological measures of memory functions and general mental ability functions did not show systematic correlations with the cTT and other measures of vascular pathology, a pronounced correlation was obtained between P3a latency and cTT. Participants with long cTT showed a delayed P3a. These findings suggest that the P3a is a sensitive measure for reduced cognitive functions even at early stages of cerebrovascular pathology and by this may be a valuable tool for the early identification of cognitive deficits in individuals being at risk for vascular dementia.

Acoustic Stimulation↗
PubMed2005

Anticoagulation regimes and their influence on the occlusion rate of aneurysms: an experimental study in rabbits.

OBJECTIVE: Our purpose was to determine whether anticoagulation has an influence on the occlusion rate and thromboembolic occurrence in saccular aneurysms treated with Guglielmi detachable coils. METHODS: Aneurysms in the right CCA were created in rabbits. Group 1 served as a control group (n = 6) without embolization or anticoagulation. In Groups 2 to 5, aneurysms were embolized. In Group 2, no anticoagulation was given (n = 5). Group 3 received heparin before the placement of the first coil, then low molecular weight heparin (LMWH) for the next 2 days (n = 7). In Group 4, additional aspirin was administered after 2 days until sacrifice (n = 10). Group 5 received heparin before the placement of the first coil, then a LMHW was administered daily until sacrifice (n = 5). Angiography was performed 3 months after coiling, followed by a histological examination. RESULTS: Histopathological evaluation showed thrombus formation with neovascularization, regardless of the anticoagulation regime used. Only in the group with LMWH over 3 months was the thrombus not focally, properly organized, especially in the dome. The coils in the neck showed, however, the same fibrous scar tissue as in the other groups. CONCLUSION: Anticoagulation with heparin during the first days, followed by aspirin, appears unlikely to affect the occlusion rate in aneurysms. LMWH over a long period, however, could impair thrombus organization. Therefore, in regard to thrombus organization, an anticoagulation regime with aspirin seems to be superior to LMWH. This could play an important role in the prevention of thromboembolic events in humans treated with Guglielmi detachable coils.

Animals↗
PubMed2005

Intraosseous hemangioma of the skull with dural tail sign: radiologic features with pathologic correlation.

Osseous hemangiomas of the calvaria account for about 0.2% of bone neoplasms. We report a case of an extensive intraosseous cavernous hemangioma in a 46-year-old woman. MR imaging showed a mass in the right frontal bone with intra- and extracranial extension and a dural tail sign after gadopentetate dimeglumine administration, mimicking a meningioma in which the dural tail sign was due to a direct noninvasive superficial growth of the lesion.

Carotid Arteries↗
PubMed2004

Paravertebral glomus tumors.

We report on a 50-year-old man who suffered from chronic lumbago. CT and MRI revealed a paravertebral tumor mass growing through the neural foramen of lumbar vertebrae 1/2. Signal features on MRI and contrast medium enhancement characteristics were not diagnostically specific. After biopsy a glomus tumor of uncertain malignant potential was diagnosed. We also describe the features of glomus tumors and the possible differential diagnoses.

Biopsy↗
PubMed2004

Prefrontal-hippocampal dynamics involved in learning regularities across episodes.

Using functional magnetic resonance imaging, the neural correlates of context-specific memories and invariant memories about regularities across episodes were investigated. Volunteers had to learn conjunctions between objects and positions. In an invariant learning condition, positions were held constant, enabling subjects to learn regularities across trials. By contrast, in a context-specific condition object-position conjunctions were trial unique. Performance increase in the invariant learning condition was paralleled by a learning-related increase of inferior frontal gyrus activation and ventral striatal activation and a decrease of hippocampus activation. Conversely, in the context-specific condition hippocampal activation was constant across trials. We argue that the learning-related hippocampal activation pattern might be due to reduced relational binding requirements once regularities are extracted. Furthermore, we propose that the learning-related prefrontal modulation reflects the requirement to extract and maintain regularities across trials and the adjustment of object-position conjunctions on the basis of the extracted knowledge. Finally, our data suggest that the ventral striatum encodes the increased predictability of spatial features as a function of learning. Taken together, these results indicate a transition of the relative roles of distinct brain regions during learning regularities across multiple episodes: regularity learning is characterized by a shift from a hippocampal to a prefrontal-striatal brain system.

Adult↗
PubMed2004

ADC mapping of normal human brain.

BACKGROUND: The quantification of diffusion conditions in normal human brain has been gaining more and more attention since diffusion weighted imaging (DWI) was proved to be an important tool in the evaluation of cerebral pathologies, especially regarding the diagnosis of hyperacute stroke. The purpose of this study was to investigate the apparent diffusion coefficient (ADC) and anisotropy index (AI) in normal human brain to evaluate physiological ADC values for an ADC mapping of different brain regions. MATERIAL/METHODS: 22 regions of interest (ROIs) in the ADC maps of 53 volunteers showing no cerebral pathologies were measured in the gray and white matter of the frontal, parietal and occipital lobes, the corpus callosum, and the lateral ventricles. RESULTS: Apparent diffusion is quite inhomogeneous for different brain regions. In both subcortical white matter (ADC: 525 x 10(-8) mm2/s, AI: 0.05) and in gray matter (ADC: 1486 x 10(-8) mm2/s, AI: 0.05) diffusion was isotropic, while in periventricular white matter (ADC: 408 x 10(-8) mm2/s, AI: 0.34) and the corpus callosum (ADC: 799 x 10(-8) mm2/s, AI: 0.77) anisotropic. CONCLUSIONS: With the exception of children and young adults, ADC seems to be intra- and interindividually constant, with no sex or age dependency for the patient sample we investigated (mean age: 62+/-9.4 years). Hence the measurement of ADC may provide an index of lesion severity.

Adult↗
PubMed2004

MRI of the brainstem in patients with major depression, bipolar affective disorder and normal controls.

Structural imaging studies of bipolar affective disorder or major depression have shown a spectrum of abnormal findings. However, a characteristic pattern of abnormality for either disease has not yet emerged. While the majority of studies focused on brain atrophy and the volumes of supratentorial cerebral structures, little attention has been paid to infratentorial structures. This MRI study focused on the pontomesencephalic area including the region of the raphe nuclei. The raphe nuclei are of special interest in affective disorders as they are the origin of the major serotonergic projections in this region. MRI scans of 10 bipolar I patients, 10 patients with major depression and 10 age-matched healthy control subjects were studied. The brain stem and the fourth ventricle areas as well as T2-relaxation times in the area of the raphe nuclei were evaluated. A difference between patients with major depression and control subjects for T(2)-relaxation times was found in a region of interest located along the midline of the pons. No difference was found between patients with bipolar disorder and control subjects. This finding needs to be replicated in a larger sample with more elaborated MRI techniques (multi-echo sequences) for the determination of T2-relaxation times.

Adult↗
PubMed2004

Impaired volitional closure of the left eyelid after right anterior cerebral artery infarction: apraxia due to interhemispheric disconnection?

BACKGROUND: The inability of volitional unilateral eyelid closure is an uncommon symptom of a central nervous system disorder. When it occurs as the result of a localized brain lesion, it is debated to be a form of supranuclear facial palsy or an apraxic phenomenon. OBJECTIVES: To report and discuss a unilateral (left-sided) higher-order movement disorder of the facial periocular musculature bearing apraxic features. SETTING: University neurology department. PATIENT: A 78-year-old right-handed man was admitted to the hospital with a left-sided brachiofacial hemiparesis of sudden onset. After thrombolysis with intravenous recombinant tissue-type plasminogen activator, the hemiparesis, including the left-sided facial weakness, disappeared. Serial computed tomographic scans showed that the patient was left with a stroke in the right anterior cerebral artery territory, affecting the frontal commissural fibers of the corpus callosum. There were no signs of upper motor neuron facial paresis on the left side when gesturing in a natural context. Eyelid closure was complete during sleep. However, left eyelid closure and elevation of the left eyebrow were not possible on verbal command. In contrast, voluntary innervation of the perioral facial musculature was performed properly. CONCLUSIONS: The voluntary-automatic dissociation of our patient's eyelid closure was suggestive of an apraxic disorder. Disconnection from a praxis center caused by callosal damage may be assumed to be the underlying cause. The unilaterality of the symptom might imply that in a bilaterally organized corticonuclear system such as upper face innervation, it is the crossing fibers that are primarily involved in praxis tasks.

Aged↗
PubMed2004

Monocular visual activation patterns in albinism as revealed by functional magnetic resonance imaging.

Human albinism is characterized by a disturbance of the chiasmatic projection system leading to predominant representation of just one eye in the contralateral hemisphere. Patients show congenital nystagmus without perceiving oscillopsia. The purpose of the present study was to demonstrate the consequences of atypical chiasmatic crossing with monocular visual stimulation using functional magnetic resonance imaging (fMRI). Sixteen patients with albinism and fifteen normally pigmented controls were stimulated with a monocular visual activation paradigm using flickering checkerboards. In patients, we observed contralaterally dominated activation of visual cortices correlating to clinical albinism parameters. This confirms albinism as a continuous range of hypopigmentation disorders. Additionally, albinos showed activation of the superior colliculus and of visual motion areas although the stimulus was stationary. Activation of visual motion areas is due probably to congenital nystagmus without a conscious correlate like oscillopsia.

Adult↗
PubMed2004

Recovery of semantic word processing in global aphasia: a functional MRI study.

One important issue concerning the recovery of higher cognitive functions-such as word comprehension in aphasia-is to what extent impairments can be compensated for by intact parts of the network of areas normally involved in a closely related function ("redundancy recovery"). In a previous functional MRI investigation, we were able to show that left hemispheric redundancy recovery within a distributed system of related lexical-semantic functions was the most probable basis of recovery of comprehension from transcortical sensory aphasia. The question remained, however, whether redundancy recovery may play a more general role in the recovery of comprehension after large left hemispheric lesions and severe aphasia. We had the possibility, using the same fMRI paradigm, to study seven cases with left middle cerebral artery (MCA) infarction and partial recovery of comprehension > or =6 months after presentation with global aphasia on acute assessment. Lateralization of activation did not differ significantly between patients and controls. The most consistent regions of activation included the left extrasylvian posterior temporal and the right posterior parietal cortex. Recovery of language comprehension was associated predominantly with activations in regions, which were also activated in several normal subjects. We suggest that a redundancy recovery mechanism within multiple representations of closely related functions was more important than take-over of function by previously unrelated areas (vicariation) as the basis of recovery of word comprehension in our patients in spite of extensive left hemispheric damage. We conclude that redundancy within the lexical-semantic system seems to make an important contribution to recovery of comprehension even in severe aphasia.

Acoustic Stimulation↗
PubMed2003

Prefrontal cortex involvement in preattentive auditory deviance detection: neuroimaging and electrophysiological evidence.

Previous electrophysiological and neuroimaging studies suggest that the mismatch negativity (MMN) is generated by a temporofrontal network subserving preattentive auditory change detection. In two experiments we employed event-related brain potentials (ERP) and event-related functional magnetic resonance imaging (fMRI) to examine neural and hemodynamic activity related to deviance processing, using three types of deviant tones (small, medium, and large) in both a pitch and a space condition. In the pitch condition, hemodynamic activity in the right superior temporal gyrus (STG) increased as a function of deviance. Comparisons between small and medium and between small and large deviants revealed right prefrontal activation in the inferior frontal gyrus (IFG; BA 44/45) and middle frontal gyrus (MFG; BA 46), whereas large relative to medium deviants led to left and right IFG (BA 44/45) activation. In the ERP experiment the amplitude of the early MMN (90-120 ms) increased as a function of deviance, by this paralleling the right STG activation in the fMRI experiment. A U-shaped relationship between MMN amplitude and the degree of deviance was observed in a late time window (140-170 ms) resembling the right IFG activation pattern. In a subsequent source analysis constrained by fMRI activation foci, early and late MMN activity could be modeled by dipoles placed in the STG and IFG, respectively. In the spatial condition no reliable hemodynamic activation could be observed. The MMN amplitude was substantially smaller than in the pitch condition for all three spatial deviants in the ERP experiment. In contrast to the pitch condition it increased as a function of deviance in the early and in the late time window. We argue that the right IFG mediates auditory deviance detection in case of low discriminability between a sensory memory trace and auditory input. This prefrontal mechanism might be part of top-down modulation of the deviance detection system in the STG.

Acoustic Stimulation↗