Darstellung der Zentralregion mit anisotroper echoplanarer Diffusionswichtung (EPI-DWI)

Im Rahmen dieser Studie sollte untersucht werden, ob sich eine diffusionsgewichtete Sequenz eignet, unter Ausnutzung der anisotropen Diffusionsverhaltnisse entlang der Markfasern die Zentralregion (ZR) bei Probanden und Patienten verlasslich darzustellen. Funf Patienten mit Hirntumoren und 20 gesunde Probanden wurden an einem klinischen 1,5-TMR-Tomographen untersucht. Bei den Probanden dienten die „klassischen“ anatomischen Zeichen zur Lokalisation der Zentralregion an einem 3-D-T1-Datensatz als Goldstandard zur Lokalisation, bei den Patienten zusatzlich noch ein funktionelles Magnet-resonanztomogramm (fMRT) mit einem Finger-Tapping-Paradigma im Blockdesign und der intraoperative Befund. Be…

Revised Definition of Neuropathic Pain and Its Grading System: An Open Case Series Illustrating Its Use in Clinical Practice

The definition of neuropathic pain has recently been revised by an expert committee of the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain (NeuPSIG) as "pain arising as direct consequence of a lesion or disease affecting the somatosensory system," and a grading system of "definite," "probable," and "possible" neuropathic pain has been introduced. This open case series of 5 outpatients (3 men, 2 women; mean age 48 +/- 12 years) demonstrates how the grading system can be applied, in combination with appropriate confirmatory testing, to diagnosis neuropathic conditions in clinical practice. The proposed grading system includes a dynamic algorithm …

Broad disruption of brain white matter microstructure and relationship with neuropsychological performance in male patients with severe alcohol dependence.

Aims In the last years, refined magnetic resonance diffusion tensor imaging (DTI) methods have become available to study microstructural alterations in the human brain. We investigated to what extent white matter tissue abnormalities are present in male patients after chronic, excessive alcohol consumption and if these alterations are correlated with measures of alcohol consumption and neuropsychological performance. Methods Twenty-four detoxified adult male patients with severe alcohol dependence and 23 healthy male control subjects were included in the study. Neuropsychological tests were assessed for executive function, attention, memory and visuospatial function. DTI was acquired and pr…

Electrophysiological brainstem testing in the diagnosis of reversible brainstem ischemia.

The aim of this study was to evaluate the sensitivity of multimodal electrophysiological brainstem testing in the diagnosis of clinically suspected reversible ischemic deficits of the brainstem compared with diffusion weighted MR imaging. We investigated 158 consecutive patients presenting with signs of acute brainstem dysfunction. Serial electrophysiological brainstem tests including masseter reflex, blink reflex, masseter inhibitory reflex, AEP, MEP, EOG and the oculoauricular phenomenon were applied. In 14 of the 158 patients neurological deficits resolved in less than 24 hours, which was suggestive of a transitory ischemic attack (TIA), 19 patients had brainstem signs for more than 24 h…

Voxel-based morphometry depicts central compensation after vestibular neuritis.

Objective Patients who have had vestibular neuritis (VN) show a remarkable clinical improvement especially in gait and posture >6 months after disease onset. Methods Voxel-based morphometry was used to detect the VN-induced changes in gray and white matter by means of structural magnetic resonance imaging. Twenty-two patients were compared an average 2.5 years after onset of VN to a healthy sex-and age-matched control group. Results Our analysis revealed that all patients had signal intensity increases for gray matter in the medial vestibular nuclei and the right gracile nucleus and for white matter in the area of the pontine commissural vestibular fibers. A relative atrophy was observed in…

Multiple Somatotopic Representations of Heat and Mechanical Pain in the Operculo-Insular Cortex: A High-Resolution fMRI Study

Whereas studies of somatotopic representation of touch have been useful to distinguish multiple somatosensory areas within primary (SI) and secondary (SII) somatosensory cortex regions, no such analysis exists for the representation of pain across nociceptive modalities. Here we investigated somatotopy in the operculo-insular cortex with noxious heat and pinprick stimuli in 11 healthy subjects using high-resolution (2 × 2 × 4 mm) 3T functional magnetic resonance imaging (fMRI). Heat stimuli (delivered using a laser) and pinprick stimuli (delivered using a punctate probe) were directed to the dorsum of the right hand and foot in a balanced design. Locations of the peak fMRI responses were c…

Neural correlates of hemispheric dominance and ipsilaterality within the vestibularsystem

Earlier functional imaging studies on the processing of vestibular information mainly focused on cortical activations due to stimulation of the horizontal semicircular canals in right-handers. Two factors were found to determine its processing in the temporo-parietal cortex: a dominance of the non-dominant hemisphere and an ipsilaterality of the neural pathways. In an investigation of the role of these factors in the vestibular otoliths, we used vestibular evoked myogenic potentials (VEMPs) in a fMRI study of monaural saccular-otolith stimulation. Our aim was to (1) analyze the hemispheric dominance for saccular-otolith information in healthy left-handers, (2) determine if there is a predom…

Brainstem reflex circuits revisited

Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical-functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. These studies nevertheless had the disadvantage of deriving from post-mortem findings in only a few patients. We developed a voxel-based model of the human brainstem designed to import and normalize MRIs, select groups of patients with or without a given dysfunction, compare their MRIs statistically, and construct three-plane maps showing the statistical probability of lesion. Using this method, we studied 180 patients with…

Virtual endoscopy of the inner ear and the auditory canal.

To assess the role of virtual endoscopy (VE) in the examination of intracisternal structures and of the inner ear, we studied the anatomy of the labyrinth and internal auditory canal using the original CT slices and VE on the unaffected side in three female and three male patients, age range 3–46 years, with contralateral retrocochlear hearing loss. We also examined seven patients with different pathological findings. VE was performed using an advanced postprocessing program with high- resolution 3D data sets of CT (1–1.5 mm thickness, pitch 1.25) and MRI-CISS-3D (constructive interference in steady state) images of the basal cisterns (1.5 T, slice thickness 0.7–1 mm). VE provides an endosc…

Cerebral activation in patients with somatoform pain disorder exposed to pain and stress: an fMRI study.

Patients with somatoform pain disorders are supposed to suffer from an early acquired defect in stress regulation. In order to look for common alterations of the pain- and stress-responsive cortical areas, we prospectively recorded cerebral activations induced by pin-prick pain, by cognitive stress and emotional stress using functional magnetic resonance imaging (fMRI) in a group of 17 patients and an age-matched control group. In addition, the hippocampal volumes of both groups were measured. Patients showed increased activations of the known pain-processing areas (thalamus, basal ganglia, operculo-insular cortex), but also of some prefrontal, temporal and parietal regions during first pai…

Corrigendum to ‘State dependent posterior hippocampal volume increases in patients with major depressive disorder’ [J. Affect. Disord. 135 (1–3) (2011) 405–409]

Cortical representation of saccular vestibular stimulation: VEMPs in fMRI

Short tone bursts trigger a vestibular evoked myogenic potential (VEMP), an inhibitory potential which reflects a component of the vestibulocollic reflex (VCR). These potentials arise as a result of activation of the sacculus and are expressed through the vestibulo-collic reflex (VCR). Up to now, the ascending projections of the sacculus are unknown in humans, only the representation of the semicircular canals or the entire vestibular nerve has been demonstrated. The aim of this study was to determine whether a sacculus stimulus that evoked VEMPs could activate vestibular cortical areas in fMRI. To determine this, we studied the differential effects of unilateral VEMP stimulation in 21 heal…

Anatomical correlates of ocular motor deficits in cerebellar lesions

Humans are able to stabilize the images of moving targets on the retina by means of smooth pursuit eye movements. After the pontine level, all smooth pursuit pathways pass through the cerebellum. Previous animal studies gave evidence that two specific lesion sites within the cerebellum cause smooth pursuit disorders: those of the flocculus/paraflocculus and the vermis including lobule VI, VII, the uvula and the deep cerebellar nuclei. To date, there have been only a few lesion studies in patients with smooth pursuit disorders that do not allow direct comparison with a control group. In the present study, new lesion mapping techniques determined which cerebellar structures were involved in p…

P25. Sensitivity of imaging and electrophysiological brainstem testing in the diagnosis of acute vertebrobasilar ischemia

The course of corticofacial projections in the human brainstem.

Transcranial magnetic stimulation was used to investigate the corticofacial projections in 53 patients with (n = 28) and without (n = 25) central facial paresis due to unifocal ischaemic lesions at different brainstem levels. Lesion topography documented by MRI studies was correlated with the electrophysiological findings. In the majority of patients the corticofacial fibres travel within the ventromedial base of the pons and cross the midline at the level of the facial nucleus. In some individuals, however, we found evidence that corticolingual fibres form an 'aberrant bundle' in a paralemniscal position at the dorsal edge of the pontine base. In other patients the corticofacial fibres loo…

The striatal and extrastriatal D2/D3 receptor-binding profile of clozapine in patients with schizophrenia.

Positron emission tomography (PET) studies reveal that clozapine at clinically used doses occupies less than 60% of D2/D3 dopamine receptors in human striatum. Here, the occupancy of D2/D3 dopamine receptors by clozapine in patients with schizophrenia was determined to test the hypothesis that clozapine binds preferentially to extrastriatal dopamine receptors. A total of 15 clozapine-treated inpatients with schizophrenia underwent a [18F]fallypride PET scan. Receptor occupancy was calculated as percent reduction in binding potential relative to unblocked values measured in seven normal volunteers. Mean D2/D3 receptor occupancy was statistically significantly higher in cortical (inferior tem…

Asymmetry in the human primary somatosensory cortex and handedness.

Brain asymmetry is a phenomenon well known for handedness and language specialization and has also been studied in motor cortex. Less is known about hemispheric asymmetries in the somatosensory cortex. In the present study, we systematically investigated the representation of somatosensory function analyzing early subcortical and cortical somatosensory-evoked potentials (SEP) after electrical stimulation of the right and left median nerve. In 16 subjects, we compared thresholds, the peripheral neurogram at Erb point, and, using MRI-based EEG source analysis, the P14 brainstem component as well as N20 and P22, the earliest cortical responses from the primary sensorimotor cortex. Handedness w…

Amygdala-hippocampal atrophy and memory performance in dementia of Alzheimer type.

The aim of the present study was to examine the involvement of brain structures, especially the amygdala-hippocampal complex, in dementia of Alzheimer type (DAT), and to assess the relation of amygdala-hippocampal atrophy with memory dysfunction. 14 patients with DAT and 10 healthy age-matched controls were examined with different neuropsychologic tests including the UCLA-Auditory Verbal Learning Test. MRI was performed with a conventional 1.5-tesla scanner. Atrophy was found in many brain structures of demented subjects in comparison with healthy age-matched controls. The volumes of amygdala-hippocampal complexes and of the temporal lobes of demented subjects were more reduced than the tot…

1.6. Dysarthria due to ischemic brainstem lesions

Emergency MRI in Clinical Peracute Brain Stem and Hemispheric Stroke

We show the capability and results of MRI examinations of peracute brainstem and hemispheric stroke patients in clinical emergency situations. The hypothesis that CT scan is faster and more accurate under this conditions is to be disproved.

Topodiagnostic implications of hemiataxia: An MRI-based brainstem mapping analysis

The topodiagnostic implications of hemiataxia following lesions of the human brainstem are only incompletely understood. We performed a voxel-based statistical analysis of lesions documented on standardised MRI in 49 prospectively recruited patients with acute hemiataxia due to isolated unilateral brainstem infarction. For statistical analysis individual MRI lesions were normalised and imported in a three-dimensional voxel-based anatomical model of the human brainstem. Statistical analysis revealed hemiataxia to be associated with lesions of three distinct brainstem areas. The strongest correlation referred to ipsilateral rostral and dorsolateral medullary infarcts affecting the inferior ce…

Functional relevance and diagnostic utility of ROI-based and voxel-based diffusion-tensor imaging analyses in mild cognitive impairment

Cerebellar speech representation: lesion topography in dysarthria as derived from cerebellar ischemia and functional magnetic resonance imaging.

Background Lesion topography and the pathophysiological background of dysarthria due to focal cerebellar lesions have not yet been fully clarified. Objectives To investigate the lesion topography of dysarthria due to cerebellar ischemia and evaluate brainstem functions. Design Case studies. Patients Eighteen right-handed patients with sudden-onset dysarthria and cerebellar ischemia with and without brainstem involvement and 19 healthy, right-handed, monolingual, German-speaking volunteers. Methods In patients, we used multimodal electrophysiologic techniques to investigate brainstem functions. Functional magnetic resonance imaging (MRI) was performed in the 19 healthy volunteers. Activation…

Dysarthria in acute ischemic stroke: lesion topography, clinicoradiologic correlation, and etiology.

Background and purpose: Although dysarthria is a frequent symptom in cerebral ischemia, there is little information on its anatomic specificity, spectrum of associated clinical characteristics, and etiologic mechanisms. Methods: An investigation of 68 consecutive patients with sudden onset of dysarthria due to a single infarction confirmed by MRI or CT was conducted. Results: Dysarthria was associated with a classic lacunar stroke syndrome in 52.9% of patients. Isolated dysarthria and dysarthria–central facial and lingual paresis occurred in 2.9% (n = 2) and 10.3% (n = 7), respectively. Dysarthria–clumsy hand syndrome was observed in 11.7% (n = 8) of patients and associated with pure motor …

Association of 5′ end neuregulin-1 ( NRG1 ) gene variation with subcortical medial frontal microstructure in humans

Animal data suggest that the gene neuregulin-1 (NRG1) is involved in neuronal myelination. A haplotype (deCODE) in the 5' end region of the gene was described to double the risk for schizophrenia in an Icelandic population (Stefansson, H., Sigurdsson, E., Steinthorsdottir, V., Bjornsdottir, S., Sigmundsson, T., Ghosh, S., Brynjolfsson, J., Gunnarsdottir, S., Ivarsson, O., Chou, T.T., Hjaltason, O., Birgisdottir, B., Jonsson, H., Gudnadottir, V.G., Gudmundsdottir, E., Bjornsson, A., Ingvarsson, B., Ingason, A., Sigfusson, S., Hardardottir, H., Harvey, R.P., Lai, D., Zhou, M., Brunner, D., Mutel, V., Gonzalo, A., Lemke, G., Sainz, J., Johannesson, G., Andresson, T., Gudbjartsson, D., Manolesc…

Functional implications of hippocampal volume and diffusivity in mild cognitive impairment.

Abstract Hippocampal atrophy has been related to mild cognitive impairment (MCI) and early Alzheimer disease (AD), but the diagnostic significance of cross-sectionally determined hippocampal volumes is still ambiguous. Diffusion-Tensor-Imaging (DTI) in MCI patients revealed an association of microstructural changes in hippocampal areas with verbal memory decline. MRI volumetry and DTI were combined to investigate 18 MCI patients attending a memory clinic, and 18 carefully age- and gender-matched healthy controls. Neuropsychological testing, high resolution T1-weighted volume MRI scans, and DTI scans with regions-of-interest in hippocampal areas were applied. Left hippocampal volume was sign…

229 – ERBB4 genotype effects on human brain structure

Background:Disturbed functional and structural brain connectivity in schizophrenia has been shown in a large number of studies. There is evidence from several neuroimaging and post mortem studies that altered neuronal myelination may in part account for this deficit. Recent investigations have suggested that variations of the genes that encode the Neuregulin 1 (NRG1) ErbB4 receptor complex might be associated with schizophrenia illness. As NRG1 and ErbB4 have been implicated in myelination and neuronal proliferation. We investigated whether cerebral micro and macrostructure is predicted by two risk haplotypes of the ErbB4 gene. Methods: The effects of two single-nucleotide polymorphisms (SN…

PROTON MAGNETIC RESONANCE SPECTROSCOPY IN DEMENTIA OF ALZHEIMER TYPE

Reduced N-acetyl aspartate (NAA) and increased myo-inositol (MI) levels have been reported in patients with dementia of Alzheimer type (DAT) in comparison with controls. We wished to assess the validity of these findings and to evaluate possible correlations of metabolite proportions with cognitive dysfunction in DAT. Twelve patients with DAT and 10 healthy age-matched controls were included. The severity of dementia was assessed using different scales including the Mini-Mental State Examination. MRS was performed with a conventional 1.5 Tesla scanner in a single voxel in the centrum semi-ovale (TE = 30 ms or TE = 136 ms; TR = 1500 ms). The evaluation of MRS results was limited by low inter…

L�sionsverteilung von Hirnstamminfarkten im MRT

Seit langer Zeit sind typische Hirnstammsyndrome bekannt. Eines der haufigsten ist das Wallenberg- Syndrom bei dorsolateralem Medulla-oblongata-Infarkt. Ursache ist hier meist ein Verschluss der ipsilateralen PICA. Die Vielzahl der Syndrome auf der einen Seite sowie die Klassifikation der Hirnstamminfarkte in Gruppen andererseits konnen als Hinweis darauf angesehen werden, dass die Hirnstamminfarkte regelmasig bestimmte Territorien und Gebiete bevorzugen. Inwieweit diese Hypothese zutrifft, sollte an einem Patientenklientel mit akuten Hirnstamminfarkten untersucht werden. Ziel unserer Arbeit war die Darstellung typischer Lasionsverteilungen bei Patienten mit akutem Hirnstamminfarkt. Bei 117…

High opiate receptor binding potential in the human lateral pain system

To determine how opiate receptor distribution is co-localized with the distribution of nociceptive areas in the human brain, eleven male healthy volunteers underwent one PET scan with the subtype-nonselective opioidergic radioligand [(18)F]fluoroethyl-diprenorphine under resting conditions. The binding potential (BP), a parameter for the regional cerebral opioid receptor availability, was computed using the occipital cortex as reference region. The following regions of interest (ROIs) were defined on individual MR images: thalamus, sensory motor strip (SI/MI area), frontal operculum, parietal operculum, anterior insular cortex, posterior insular cortex, anterior cingulate cortex (ACC; peri-…

Disturbed structural connectivity is related to inattention and impulsivity in adult attention deficit hyperactivity disorder

Inattention and impulsivity are the most prominent clinical features of attention deficit hyperactivity disorder (ADHD) in adulthood. Structural and functional neuroimaging studies of subjects with ADHD have demonstrated abnormalities in several brain areas, including fronto-striatal and fronto-cerebellar networks. Mostly, these studies were based on volumetric measurements and have been conducted in children. We investigated white matter (WM) integrity and correlation with measures of attention and impulsivity in adult patients with ADHD adopting diffusion tensor imaging (DTI). N = 37 (21 males) never-medicated adult patients with ADHD combined subtype and N = 34 (16 males) healthy control…

Topodiagnostic significance of hemiataxia: An MRI based mapping analysis

Diffusion-tensor MR imaging at 1.5 and 3.0 T: initial observations.

Diffusion-tensor MR imaging was compared at 1.5 and 3.0 T. With sufficient signal-to-noise ratio, we found no differences in fractional anisotropy. With a 40% higher signal-to-noise ratio at 3.0 T, higher resolution could be obtained without introduction of noise-related errors, albeit at the cost of increased geometric distortions caused by 3.0-T magnetic field inhomogeneities.

Characterization of BOLD-fMRI signal during a verbal fluency paradigm in patients with intracerebral tumors affecting the frontal lobe.

Previous studies have indicated that the BOLD-fMRI signal can be modified by tumor processes in close vicinity to functional brain areas. This effect has been investigated primarily for the perirolandic area but there is only a limited number of studies concerning frontal cortical regions. Therefore, the aim of the current study was to characterize BOLD-fMRI signal and activation patterns in patients with frontal brain tumors while performing a verbal fluency task. Six patients (ages 31-56 years) suffering from frontal (5 left sided and 1 right sided) intracerebral tumors were examined with fMRI while performing a verbal fluency task in a blocked paradigm design. Eight healthy volunteers se…

Distribution and course of cortico-respiratory projections for voluntary activation in man

The function and course of the cortico-respiratory projections in man are not yet well established. In 30 normal volunteers respiratory muscles were activated by magnetic stimulation of the motor cortex and the cervical and thoracic spinal roots with bilateral recordings from the respiratory muscles. Following cortical stimulation contralateral responses were obtained in all subjects during voluntary inspiration showing a mean latency and amplitude of 13.4±1.4ms/1.6±1.2 mV (stimulation of the left hemisphere) and 13.2±1.3ms/2.5±2.5 mV (stimulation of the right hemisphere). Ipsilateral responses were obtained in only 18 (right side) and 21 (left side) subjects and had a significantly (p < 0.…

Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural equation modeling

The present study aimed to explore altered effective connectivity in schizophrenic patients while performing a 2-back working memory task. Twelve right-handed, schizophrenic patients treated with typical or atypical antipsychotics and 6 healthy control subjects were studied with fMRI while performing a "2-back" working memory task. Effective connectivity within a cortical-subcortical-cerebellar network for mnemonic information processing was assessed and compared between both groups. The path model included cortico-cortical connections comprising the parietal association cortex, ventrolateral prefrontal cortex (VLPFC), and the dorsolateral prefrontal cortex (DLPFC) as well as a cortico-cere…

Ultrastructural Hippocampal and White Matter Alterations in Mild Cognitive Impairment: A Diffusion Tensor Imaging Study

Mild cognitive impairment (MCI) is considered to be a transitional stage between normal aging and dementia. In Alzheimer’s disease (AD), white matter structural pathology is due to Wallerian degeneration and central angiopathy. However, in MCI patients, the presence and extent of white matter alterations as a possible correlate of impaired memory function and as predictor of subsequent progression to AD is not clarified yet. Diffusion tensor imaging (DTI) reveals the ultrastructural integrity of cerebral white matter tracts. Therefore, it could detect pathological processes that modify tissue integrity in patients with MCI. In our prospective study, conventional and diffusion tensor MR scan…

Predicting conversion to dementia in mild cognitive impairment by volumetric and diffusivity measurements of the hippocampus.

In our prospective study of diffusion tensor imaging (DTI), we measured hippocampal mean diffusivity (MD) and volumes in amnestic mild cognitive impairment (MCI). Thirteen MCI patients were followed-up by clinical assessment over a mean 112-year period. MCI patients who converted to dementia (6 of 13) during the observation period had slightly elevated left hippocampal mean diffusivity at baseline compared with MCI patients who remained clinically stable. Hippocampal volumes as well as baseline verbal memory and MMSE did not differ significantly between stable MCI patients and converters. Hippocampal diffusivity was superior to hippocampal volumes for prediction of conversion to dementia in…

Altered benzodiazepine receptor sensitivity in alcoholism: a study with fMRI and acute lorazepam challenge.

Previous studies suggested altered sensitivity of the GABA/benzodiazepine receptor system in alcoholic patients. Expanding on these findings, the present functional magnetic resonance imaging (fMRI) study aimed to assess whether a differential modulation of cognitive brain activation by an acute GABAergic drug challenge could be detected in patients with alcoholism. Eight detoxified male patients meeting DSM-IV criteria for alcohol dependence and nine healthy male control subjects were studied with fMRI while performing a 2-back working memory task. The fMRI scans were performed 1 h after intravenous administration of saline and again 1 h after 0.03 mg/kg lorazepam I.V. After saline, a task…

Chapter 4 3D brainstem topodiagnosis – a voxel-based model analyzing MR imaging data

Publisher Summary This chapter presents a new method of statistically based three-dimensional (3D) brainstem mapping to identify brainstem structures responsible for specific clinical and electrophysiological abnormalities. To ensure reliable correlations, a large cohort of patients with magnetic resonance (MR)-documented brainstem infarctions were recruited in two European neurological institutions—namely, the Department of Neurology, Johannes Gutenberg University, Mainz, Germany, and the Department of Neurological Sciences, “La Sapienza” University of Rome, Italy. This method minimizes the risk of highlighting vascular territories rather than the structures specifically responsible for th…

Combined spike-related functional MRI and multiple source analysis in the non-invasive spike localization of benign rolandic epilepsy.

Abstract Objective To localize the irritative zone in children by combined spike-related fMRI and EEG multiple source analysis (MSA) in children with benign rolandic epilepsy. Methods Interictal spikes were averaged and localized using MSA, and source locations were displayed in the anatomical 3D-MRI in 11 patients (5–12 yrs, median 10). Interictal spikes were additionally recorded during the fMRI acquisition (EEG-fMRI), and the fMRI sequences were correlated off-line with the EEG spikes. Results MSA revealed an initial central dipole in all patients, including the face or hand area. A second dipolar source was mostly consistent with propagated activity. BOLD activations from EEG-fMRI, cons…

Color-coded diffusion-tensor-imaging of posterior cingulate fiber tracts in mild cognitive impairment.

Abstract Different processes like microvascular dysfunction, free radical toxicity, β-amyloid deposits, and Wallerian degeneration can cause functionally relevant disturbances of cerebral neuronal networks by myelin degeneration. Color-coded diffusion-tensor-imaging (ccDTI) allows the structural identification and quantification of myelinated fiber tracts. Particularly, posterior cingulate fiber tracts, which are regarded as important neuronal substrates of the network representing memory processing can be localized only imprecisely by conventional magnetic resonance imaging techniques. The posterior cingulate bundles were assessed by ccDTI in 17 patients with amnestic mild cognitive impair…

Scalp, basal epidural and intravascular far-field recordings after median nerve stimulation: evidence for a separate N18a potential

Far-field somatosensory evoked potentials (SSEPs) after median nerve stimulation were recorded from scalp- (Fz), epidural- (ED) and intravascular electrodes (basilar artery [Bas]) to study the nature of the controversial N18a component of the widespread N18 potential. In healthy volunteers frequently an N18a potential was recorded at Fz. Simultaneous Fz and ED recordings at the pontomesencephalic junction as well as Bas-recordings at the caudal basilar artery showed N18a components identical in latency and shape. With intravascular recordings the shapes differed between the top of the basilar artery and the caudal artery recordings. These findings support the existence of a separate N18a po…

Association between cingulum bundle structure and cognitive performance: an observational study in major depression.

AbstractBackgroundMajor depression can be regarded as a systemic neurobehavioral disorder resulting from dysfunction of the limbic-cortical networks. The cingulum bundle represents a major association fiber tract of those networks. The aim of our study was to determine the association of brain structural tissue markers of the cingulum bundle and cognitive function in patients with major depression.MethodsRegion-of-interest-based analyses of the middle-anterior and middle-posterior cingulum bundle fractional anisotropy (FA) and mean diffusivity (MD) using color-coded diffusion-tensor imaging and neuropsychological assessment in 14 patients with major depression.ResultsFA of the middle-anteri…

Effect of Intra-Arterial Infusion of Papaverine Hydrochloride on Brain Tissue Oxygen Pressure in the Management of Severe Vasospasm Following Aneurysmal Subarachnoid Hemorrhage

Despite considerable advances in diagnostic, surgical and interventional techniques, the overall outcome for patients with aneurysmal subarachnoid hemorrhage remains poor. Concerning perioperative course, cerebral ischaemia is one of the major factors causing secondary brain demage. The aim of all therapeutic interventions is the stabilization and maintance of cerebral blood flow and tissue oxygenation in order to prevent cerebral ischaemia and consecutively brain infarction [1].

A new method to investigate brain stem structural-functional correlations using digital post-processing MRI - reliability in ischemic internuclear ophthalmoplegia

We investigated the reliability of a new digital post-processing magnetic resonance imaging (MRI) technique in ischemic brain stem lesions to identify relations of the lesion to anatomical brain stem structures. The target was a medial longitudinal fasciculus (MLF) lesion, which was evident from ipsilateral internuclear ophthalmoplegia (INO). Sixteen patients with acute unilateral INO and an isolated acute brain stem lesion in T2- and EPI-diffusion weighted MRI within 2 days after the onset of symptoms were studied. The MRI slice direction was parallel and perpendicular to a slice selection of a stereotactic anatomical atlas. The individual slices were normalized and projected in the digita…

Missense PANK2 mutation without "eye of the tiger" sign: MR findings in a large group of patients with pantothenate kinase-associated neurodegeneration (PKAN).

Purpose: To present some unusual MR findings in a group of patients from the south-west of the Dominican Republic suffering from Pantothenate Kinase Associated Neurodegeneration (PKAN). Materials and Methods: Twenty patients and one preclinical case homozygous for the PANK2 mutation, 13 heterozygous gene carriers and 14 healthy volunteers were scanned prospectively using a 3 Tesla system. Results: All patients showed the typical signal reduction within the globus pallidus and the substantia nigra. A surprising finding was the absence of the bright spot (“tiger's eye”) in the medial part of the pallidum in 6 patients, but not in the preclinical case. Both fractional anisotropy (FA) and mean …

ErbB4 genotype predicts left frontotemporal structural connectivity in human brain.

Diminished left frontotemporal connectivity is among the most frequently reported findings in schizophrenia and there is evidence that altered neuronal myelination may in part account for this deficit. Several investigations have suggested that variations of the genes that encode the Neuregulin 1 (NRG1)-ErbB4 receptor complex are associated with schizophrenia illness. As NRG1--ErbB4 has been implicated in neuronal myelination, we investigated with diffusion tensor imaging (DTI) whether fractional anisotropy (FA)--a putative measure of neuronal myelination--is predicted by a risk haplotype of the ErbB4 gene. The effects of the ErbB4 genotype were investigated in healthy subjects (N=59; mean …

[ 18 F]Fluoroethylflumazenil: a novel tracer for PET imaging of human benzodiazepine receptors

5-(2'-[18F]Fluoroethyl)flumazenil ([18F]FEF) is a fluorine-18 labelled positron emission tomography (PET) tracer for central benzodiazepine receptors. Compared with the established [11C]flumazenil, it has the advantage of the longer half-life of the fluorine-18 label. After optimisation of its synthesis and determination of its in vitro receptor affinities, we performed first PET studies in humans. PET studies in seven healthy human volunteers were performed on a Siemens ECAT EXACT whole-body scanner after injection of 100-280 MBq [L8F]FEF. In two subjects, a second PET scan was conducted after pretreatment with unlabelled flumazenil (1 mg or 2.5 mg i.v., 3 min before tracer injection). A t…

State dependent posterior hippocampal volume increases in patients with major depressive disorder.

Abstract Background The hippocampal formation has been implicated in etiology and therapy response in major depressive disorder (MDD). However, prospective longitudinal studies investigating volumes in hippocampal subregions and their association with clinical findings are still lacking. Methods Global and regional hippocampal volumes and neuropsychological performance were assessed longitudinally in 15 young patients with unipolar early onset MDD who responded to therapy and 13 matched healthy control subjects. Results Although volumes at baseline did not differ between groups, patients with MDD showed significant posterior hippocampal volume increases during the treatment course (mean obs…

Blink reflex R2 changes and localisation of lesions in the lower brainstem (Wallenberg's syndrome): an electrophysiological and MRI study

OBJECTIVES—Pathways of late blink reflexes are detected by high resolution MRI. Electronically matched stroke lesions superimposed to an anatomical atlas show the suspected course. METHODS—Fifteen patients with infarction of the lower brainstem, MRI lesions and electrically elicited blink reflexes were examined. The involved structures in patients with R2 and R2c blink reflex changes were identified by biplane high resolution MRI with individual slices matched to an anatomical atlas at 10 different levels using digital postprocessing methods. RESULTS—The blink reflexes were normal in five of 15 patients (33%) and showed loss or delay of R2 and R2c to stimulation ipsilaterally to lesion (R2-…

3.4. Functional brainstem infarction studies: Previous results and new ways of lesion coregistration

Diffusionsgewichtetes MRT bei vertebrobasil�ren Isch�mien

The aim of this study was to evaluate the applicability, sensitivity, and predictive power of diffusion-weighted MR imaging (DWI) in the diagnosis of vertebrobasilar infarction. From 1997 to 2002, we prospectively recruited 268 patients with acute signs and symptoms suspective of vertebrobasilar ischemia. The patients underwent biplanar EPI-T2 and EPI DWI within 24 h after onset of symptoms and high-resolution MRI as a control within 7 days. One hundred twenty-one patients had additional CT scanning. The DWI revealed acute vertebrobasilar infarction in 71.0%. The mean time exposure of DWI was 8 min and thus no more than that of CT imaging. It showed significantly more acute lesions than CT …

Disturbed brain activation during a working memory task in drug-naive adult patients with ADHD.

Neuroimaging studies in attention-deficit/hyperactivity disorder (ADHD) have shown abnormalities in several brain areas including the frontostriatal circuitry and were mostly conducted in children and adolescents. We investigated 30 never-medicated adult ADHD patients (16 males) and 30 matched healthy control individuals. Functional magnetic resonance imaging was acquired during a working memory paradigm (n-back). Group activation maps and group differences of activation were calculated using voxel-based analyses. The generic activation pattern was more extended in the control group. In ADHD patients, significantly decreased activation was found in the right inferior parietal cortex. Distur…

Evidence for cortical visual substitution of chronic bilateral vestibular failure (an fMRI study).

Bilateral vestibular failure (BVF) is a rare disorder of the labyrinth or the eighth cranial nerve which has various aetiologies. BVF patients suffer from unsteadiness of gait combined with blurred vision due to oscillopsia. Functional MRI (fMRI) in healthy subjects has shown that stimulation of the visual system induces an activation of the visual cortex and ocular motor areas bilaterally as well as simultaneous deactivations of multisensory vestibular cortex areas. Our question was whether the chronic absence of bilateral vestibular input (BVF) causes a plastic cortical reorganization of the above-described visual-vestibular interaction. We used fMRI to measure the differential effects of…

Topodiagnostik ischämisch bedingter Dysarthrophonien

In einer prospektiven Studie untersuchetn wir 106 konsekutiv eingeschlossene Patienten mit apoplektiform auftretender Dysarthrophonie aufgrund eines im MRT gesicherten singluaren, nicht raumfordernden Infarkts.

A topodiagnostic investigation on body lateropulsion in medullary infarcts.

Body lateropulsion may occur without signs of vestibular dysfunction and vestibular nucleus involvement. The authors examined 10 such patients with three-dimensional brainstem mapping. Body lateropulsion without limb ataxia reflected an impairment of vestibulospinal postural control caused by a lesion of the descending lateral vestibulospinal tract, whereas body lateropulsion with limb ataxia was probably the consequence of impaired or absent proprioceptive information caused by a lesion of the ascending dorsal spino-cerebellar tract.

Bilateral Wallerian degeneration of the medial cerebellar peduncles after ponto-mesencephalic infarction

Three patients with acute large paramedian ponto-mesencephalic infarctions developed a bilateral retrograde degeneration of the medial cerebellar peduncles within 4 months after the insult. In an initial magnetic resonance imaging (MRI) within the first 2 weeks, the medial cerebellar peduncles showed normal intensities, but a control MRI after 4 months showed bright hyperintensities in the T2-TSE weighted images, and moderately increased signal intensities in echo planar imaging-diffusion weighted imaging were seen, possibly representing bilateral Wallerian degeneration of the cerebellar-pontine fibers.

Diagnostic utility of hippocampal size and mean diffusivity in amnestic MCI

Hippocampus atrophy is a frequent finding in mild cognitive impairment (MCI), whereas diffusion-tensor-imaging (DTI) has demonstrated its value to detect subtle brain tissue changes in several neuropsychiatric diseases including MCI. To compare the diagnostic accuracy of both methods, high resolution MRI scans for hippocampus volumetry, and co-registered DTI-scans for ROI-based mean diffusivity (MD) and fractional anisotropy (FA) were carried out in 18 patients with amnestic MCI (7 females, age 67.3+/-8.7 years, MMSE 25.2+/-2.2) and 18 controls (age 66.9+/-9.0 years, MMSE 28.7+/-1.0). Diagnostic properties of normalized hippocampus volume (HV) and DTI measures with regard to MCI status were…

Virtual reality system for planning minimally invasive neurosurgery

Object The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Methods Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. Results After a short period of acclimatization, the system proved easy to operate and is currently used routinely for pre…

Asymmetry in dopamine D2/3 receptors of caudate nucleus is lost with age

Molecular and functional imaging techniques reveal evidence for lateralization of human cerebral function. Based on animal data, we hypothesized that asymmetry in dopamine neurotransmission declines during normal aging. In order to test this hypothesis, we measured dopamine D2/3 receptor availability with [18F]desmethoxyfallypride-PET (DMFP) in putamen and caudate nucleus (NC) of 21 healthy, right-handed males (24-60 years; 35+/-10). For volumetric analysis, high-resolution T1-weighted MR-images were obtained in 18 of the PET-subjects in order to assess possible age-related decreases in NC and putamen volume. The calculated DMFP binding potentials (BP) showed a right-ward asymmetry in NC of…

Diffusion weighted magnetic resonance imaging in the diagnosis of reversible ischaemic deficits of the brainstem

Objectives: To evaluate the sensitivity of diffusion weighted magnetic resonance imaging (MRI) for the diagnosis of clinically suspected reversible ischaemic deficits of the brainstem. Methods: A total of 158 consecutive patients presenting with acute signs of brainstem dysfunction were investigated using EPI diffusion weighted MRI within 24 hours of the onset of symptoms. High resolution T1 and T2 weighted imaging was performed as a follow up after a median of six days Results: Fourteen of the 158 patients had a complete clinical recovery within 24 hours (transitory ischaemic attack (TIA)), and 19 patients recovered in less than one week (prolonged reversible neurological deficit (RIND)). …

Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation.

Abstract Objectives: Somatosensory evoked potential (SEP) studies suggested that some early cortical SEP components may be generated in the primary motor cortex (M1) rather than the primary somatosensory cortex (S1). Methods: We now used functional magnetic resonance imaging (fMRI) to study activation of S1 and M1 by electrical median nerve stimulation in healthy volunteers. Results: The hand areas of both S1 and M1 showed significant activation (correlation coefficients >0.45) in 7 of 9 subjects (activated volume S1>M1). For comparison, a sequential finger opposition task significantly activated S1 in 7 and M1 in all 9 subjects (activated volume M1>S1). Conclusions: These data show that th…

Neurocysticercosis with a single brain lesion in Germany: a case report

Neurocysticercosis is rare in Western Europe and a high degree of physician awareness is necessary for diagnosis. We describe a case of Neurocysticercosis with a single brain lesion acquired in Germany in which only surgical removal and subsequent histological examination allowed diagnosis whereas diagnostic investigation yielded no pathological findings.

Increased hippocampal head diffusivity predicts impaired episodic memory performance in early Alzheimer's disease

Recent neuroanatomical and functional neuroimaging studies indicate that the anterior part of the hippocampus, rather than the whole structure, may be specifically involved in episodic memory. In the present work, we examined whether anterior structural measurements are superior to other regional or global measurements in mapping functionally relevant degenerative alterations of the hippocampus in Alzheimer's disease (AD). Twenty patients with early AD (MMSE 25.7+/-1.7) and 18 healthy controls were studied using magnetic resonance and diffusion-tensor imaging. Using a regions-of-interest analysis, we obtained volumetric and diffusivity measures of the hippocampal head and body-tail-section …

Association of attentional network function with exon 5 variations of the CHRNA4 gene

Mutational analyses in xenopus oocyte and mice models indicate that the positive effect of nicotine on attention may be modulated by genetic variations within exon 5 of the alpha4 subunit of the nicotinergic acetylcholine receptor gene CHRNA4. The potential relevance of exon 5 is further emphasized by two recent family-based association studies of nicotine dependence because subgroups of nicotine-dependent subjects are thought to 'self-medicate' attentional deficits with nicotine. We investigated a synonymous single nucleotide polymorphisms (SNP): rs1044396, which has recently been associated with nicotine-dependence, plus two adjacent synonymous SNPs rs1044394 and rs1044393 in exon 5 of n …

Dysarthria and Pathological Laughter/Crying as Presenting Symptoms of Corticobasal- Ganglionic Degeneration Syndrome

Modulation of [18F]fluorodopa (FDOPA) kinetics in the brain of healthy volunteers after acute haloperidol challenge.

In animal studies, acute antipsychotic treatment was shown to enhance striatal DOPA-decarboxylase (DDC) activity. However, this phenomenon has not been demonstrated in humans by positron emission tomography (PET). Therefore, we investigated acute haloperidol effects on DDC activity in humans using [18F]fluorodopa (FDOPA) PET. Nine healthy volunteers were scanned with FDOPA in drug-free baseline conditions and after 3 days of haloperidol treatment (5 mg/day). A continuous performance test (CPT) was administered in both conditions. The net blood-brain clearance of FDOPA (K(in)app) in striatum, mesencephalon, and medial prefrontal cortex was calculated by volume-of-interest analysis. The macro…

Cerebral spinal fluid flow, venous drainage and spinal cord compression in achondroplastic children: impact of magnetic resonance findings for decompressive surgery at the cranio-cervical junction

In order to investigate the diagnostic properties of MRI of the brain and spine in achondroplastic children with regard to decompressive surgery, 25 patients were examined by conventional morphological and by "functional" imaging of CSF flow and magnetic resonance angiography (MRA) of the veins and sinuses at the cranial base following a special protocol. The results were compared to those from age-matched controls and were correlated with each other and retrospectively with the neurological findings. Measurements of distances and angulations at the cranio-cervical junction (CCJ) from MR scans showed similar values to those from conventional radiographs and CTs and thus can be used without …

Clinical and neuroradiological findings in classic infantile and late-onset globoid-cell leukodystrophy (Krabbe disease)

In the present study the clinical course and imaging of early and late-onset forms of Krabbe disease are analyzed. We report on 11 patients with a biochemical diagnosis of galactosyl ceramide β-galactoside deficiency. Two presented as the classic infantile form and died within the second year of life. In 9 children the first clinical signs, such as gait difficulties and visual failure, started after age 2 years. All these patients developed slow regression of motor and mental capacities, and most of them died within their first decade. In patients of both groups computed tomography (CT) and magnetic resonance imaging (MRI) were performed. In the late-onset form, hypodensities of the central…

Distributed BOLD-response in association cortex vector state space predicts reaction time during selective attention.

Human cortical information processing is thought to be dominated by distributed activity in vector state space (Churchland, P.S., Sejnowski, T.J., 1992. The Computational Brain. MIT Press, Cambridge.). In principle, it should be possible to quantify distributed brain activation with independent component analysis (ICA) through vector-based decomposition, i.e., through a separation of a mixture of sources. Using event-related functional magnetic resonance imaging (fMRI) during a selective attention-requiring task (visual oddball), we explored how the number of independent components within activated cortical areas is related to reaction time. Prior to ICA, the activated cortical areas were d…

93. Structural brain abnormalities in attention-deficit/hyperactivity disorder: A voxel-based MRI study in adult patients

High striatal occupancy of D2-like dopamine receptors by amisulpride in the brain of patients with schizophrenia.

The 'atypicality' of the antipsychotic drug, amisulpride, has been attributed to preferential extrastriatal binding. Previous investigations of striatal D2 receptor occupancy by amisulpride revealed conflicting results. The aim of this PET study was to measure the striatal occupancy by amisulpride and to correlate it with the corresponding drug plasma concentrations. Nine amisulpride-treated patients and 12 healthy volunteers serving as controls were studied with PET and [18F]desmethoxyfallypride. Occupancy values and plasma concentrations were nonlinearly fitted to an E max model. Results showed 43-85% (putamen) and 67-90% (caudate) D2-like receptor occupancy. Plasma amisulpride concentrat…

Functional relevant loss of long association fibre tracts integrity in early Alzheimer's disease.

Abstract The aim of our study was to quantify the structural integrity of the long association fibre tracts in early Alzheimer's disease (AD) and to correlate the findings with the cognitive performance of the patients. We conducted region-of-interest-based analyses of color-coded diffusion-tensor imaging in 12 patients with early AD (age 69.8 ± 8.0 years; MMSE 25.3 ± 1.8) and 16 age- and education-matched healthy controls. Early AD patients showed significantly decreased fractional anisotropy (FA) of the cingulate bundles and the inferior fronto-occipital fascicles bilaterally, whereas FA values of the superior longitudinal fascicles (second division) did not differ significantly between p…

Stentgraft-Implantation for Treatment of Internal Carotid Artery Injury during Endonasal Sinus Surgery

Background Damage of the internal carotid artery (ICA) is very rare but can be a dramatic complication of endonasal sinus surgery. In the literature only a few cases are reported, some of them with fatal results. Methods We present two cases with massive bleeding of the ICA caused by endonasal sinus surgery. Results In both cases bleeding could be stopped sufficiently by implanting a stentgraft. Conclusion The lumen of the artery could be preserved and no neurological deficits were observed.

Mechanisms and predictors of chronic facial pain in lateral medullary infarction

The purpose of this study was to identify clinical predictors and anatomical structures involved in patients with pain after dorsolateral medullary infarction. Eight out of 12 patients (67%) developed poststroke pain within 12 days to 24 months after infarction. The pain occurred in the ipsilateral face (6 patients) and/or the contralateral limbs and trunk (5 patients, 3 of whom also had facial pain). Ipsilateral facial pain was significantly correlated with lower medullary lesions, including those of the spinal trigeminal tract and/or nucleus, as documented by magnetic resonance imaging. The R2 blink reflex component was abnormal only in patients with facial pain. Likewise, pain and temper…

Altered effective connectivity in drug free schizophrenic patients

The present fMRI study aimed to investigate effective connectivity within a cortical-subcortical-cerebellar information processing network in drug free schizophrenic patients while performing a 2-back working memory task. The finding of enhanced thalamo-cortical and cortico-cortical intrahemispheric connectivity could be interpreted as a compensatory increase of neuronal connection strength consistent with a model of cortical inefficiency in schizophrenic patients. Additionally, the result could be integrated into a model of deficient thalamo-cortical filter functions. Conversely, lower interhemispheric connectivity of the frontal and parietal association cortex appears to be the functional…

Correlation of brain white matter diffusion anisotropy and mean diffusivity with reaction time in an oddball task.

&lt;i&gt;Background:&lt;/i&gt; Reaction time (RT) is a frequently used measure of information processing speed, but the underlying physiological and anatomical conditions are not yet fully understood. A correlation between measures of white matter (WM) ultrastructural properties and RT is expected – particularly for those WM tracts that are involved in the attentional system of the brain. &lt;i&gt;Methods:&lt;/i&gt; Diffusion tensor imaging data were acquired in 43 unrelated healthy subjects (age: 22.7 ± 1.8 years), and RT was measured during an attention-requiring visual oddball task in the same scanning session. Voxel-by-voxel and region of interest analyses were performed for the large a…

Brainstem Anatomy of White Matter Tracts Using Diffusion Weighted Imaging

3.5. Saccular activations in the brainstem and the cerebellum (fMRI)

EEG-related Functional MRI in Benign Childhood Epilepsy with Centrotemporal Spikes

The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG-assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children. As a model of extratemporal epilepsies, we studied 7 patients aged 5 to 12 (median 10) years with benign childhood epilepsy and centrotemporal (rolandic) spikes. Interictal spikes were recorded during the fMRI acquisition on a MR-compatible battery-powered digital EEG system with 16 channels. The fMRI sequences were correlated off-line with the EEG spikes and analyzed with the software Statistical Parametrical Mapping SPM99. The fM…

High opiate receptor binding potential in the human lateral pain system: A (FEDPN)PET study

Brain structural alterations in Fabry disease: ROI-based and voxel-based analyses of diffusion tensor imaging parameters

FMRI of the Cerebellum: Rostral Paravermal Activation in Tongue and Lip

We investigated with fMRI the cerebellar representation of articulatory vertical movements of the tongue and orofacial muscles in healthy volunteers and its correspondence to the area known to be affected in cerebellar dysarthria. fMRI stimulation is mainly unilateral in agreement with the frequent occurrence of dysarthria in unilateral infarction.

FAIR and dynamic susceptibility contrast-enhanced perfusion imaging in healthy subjects and stroke patients.

Purpose To compare dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) and the flow-sensitive alternating inversion recovery (FAIR) technique for measuring brain perfusion. Materials and Methods We investigated 12 patients with acute stroke, and 10 healthy volunteers with FAIR and DSC maps of regional cerebral blood volume (rCBV), mean transit time (MTT), and regional cerebral blood flow (rCBF). Results In volunteers good gray/white-matter contrast was observed in FAIR, rCBF, and rCBV maps. Regions with high signal intensities in FAIR matched well with high values of rCBV and rCBF. In ischemic stroke patients a high correlation (r = 0.78) of the ipsi- to contralate…

Left-hemisphere dominance in early nociceptive processing in the human parasylvian cortex.

Pain perception comprises sensory and emotional dimensions. While the emotional experience is thought to be represented in the right hemisphere, we here report a left-hemisphere dominance for the early sensory component of pain perception using brain electrical source analysis of laser-evoked potentials. Ten right-handed subjects underwent several series of laser radiant heat stimuli to pairs of parallel lines on the dorsum of the left or right hand. Stimulus location and intensity were randomised independently. The sensory-discriminative aspects of pain were emphasised by asking the subjects to perform either a spatial or an intensity discrimination task and were contrasted with active dis…

Pathophysiologische Aspekte hirnstruktureller Veränderungen bei Morbus Fabry: Literaturübersicht

Fabry Disease (FD) is a rare X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A (alpha-GAL) enzyme activity. Neutral glycosphingolipides (esp. Gb3) accumulate in lysosomes of several tissues, particularly in vascular endothelium and smooth muscle cells. Cerebral manifestations that might be mainly due to progressive cerebrovascular dysfunction, are one major and often life-threatening burden of the disease. We reviewed the present literature concerning brain structural alterations in FD and discuss the possibly relevant underlying pathophysiological aspects of these disturbances. Cerebrovascular events (TIA, stroke) occur in FD at a rather early age. In female…

P14. Impaired balance with brain stem infarcts

17. Masseter reflex abnormalities with meso-diencephalic lesions

different papers and some eponyms used to characterize a certain neurological state differ from the original description. Except for Wallenberg‘s syndrome, classical brainstem syndromes are rarely seen in clinical practice. Lacunar brainstem syndromes are the consequence of infarcts, which involve long tracts and spare intra-axial cranial nerve segments. This group includes pure motor or pure sensory stroke, dysarthriaclumsy hand syndrome, or ataxic hemiparesis. Such infarcts may also cause body lateropulsion with or without limb ataxia, internuclear ophthalmoplgia, skew-torsion sign, or ocular tilt reaction. Small deep infarcts, which solely affect certain nuclei, may be followed by horizo…

Voxel based analyses of diffusion tensor imaging in Fabry disease

Background: Fabry disease (FD) is a lysosomal storage disorder that is associated with marked cerebrovascular disease. Conventional MRI shows an extensive load of white matter lesions (WMLs) already at an early stage in FD. Objective: Investigator independent and sensitive quantification of brain structural changes in clinically affected men and women with FD. Methods: The authors performed a voxel-based analysis of diffusion tensor images (DTI) in 25 FD patients and 20 age-matched normal controls. Results: DTI revealed significant increases of cerebral white matter diffusivity (MD) in FD patients that were pronounced in the periventricular white matter. Even the subgroup of patients withou…

Subchronic haloperidol downregulates dopamine synthesis capacity in the brain of schizophrenic patients in vivo

Udgivelsesdato: 2003-Apr The antipsychotic effect of neuroleptics cannot be attributed entirely to acute blockade of postsynaptic D(2)-like dopamine (DA) receptors, but may arise in conjunction with the delayed depolarization block of the presynaptic neurons and reduced DA synthesis capacity. Whereas the phenomenon of depolarization block is well established in animals, it is unknown if a similar phenomenon occurs in humans treated with neuroleptics. We hypothesized that haloperidol treatment should result in decreased DA synthesis capacity. We used 6-[(18)F]fluoro-L-dopa (FDOPA) and positron emission tomography (PET) in conjunction with compartmental modeling to measure the relative activi…

fMRI-activation patterns in the detection of concealed information rely on memory-related effects

Recent research on potential applications of fMRI in the detection of concealed knowledge primarily ascribed the reported differences in hemodynamic response patterns to deception. This interpretation is challenged by the results of the present study. Participants were required to memorize probe and target items (a banknote and a playing card, each). Subsequently, these items were repeatedly presented along with eight irrelevant items in a modified Guilty Knowledge Test design and participants were instructed to simply acknowledge item presentation by pressing one button after each stimulus. Despite the absence of response monitoring demands and thus overt response conflicts, the experiment…

Medullary infarcts may cause ipsilateral masseter reflex abnormalities.

There is a suprasegmental influence on the masseter reflex (MassR) in animals, which is mediated via the fifth nerve spinal nucleus (5SpN). Corresponding data in humans are lacking. Out of 268 prospectively recruited patients with clinical signs of acute brainstem infarctions, we identified 38 with magnetic resonance imaging (MRI)-documented unilateral infarcts caudal to the levels of the fifth nerve motor and main sensory nuclei. All had biplanar T2- and echo planar diffusion-weighted MRI and MassR testing. Five patients (13%) had ipsilateral MassR abnormalities. In all, the infarcts involved the region of the 5SpN. Patients with medullary infarcts involving the region of the 5SpN may thus…

Time course of lesion development in patients with acute brain stem infarction and correlation with NIHSS score.

diffusion weighted magnetic resonance imaging (MRI) is highly sensitive in detecting acute supratentorial cerebral ischemia and Diffusion Weighted Imaging (DWI) lesion size has been shown to correlate strongly with the neurologic deficit in middle cerebral artery territory stroke. However, data concerning infratentorial strokes are rare. We examined the size and evolution of acute brain stem ischemic lesions and their relationship to neurological outcome.brain stem infarctions of 11 patients were analyzed. We performed DWI in all patients and in 7/11 patients within 24 h, T2W sequences within the first 2 weeks (10/11 patients) and follow-up MRI (MR2) within 3-9 months (median 4.8 months) la…

Asymmetrie des Planum temporale bei Zwillingen und Schizophrenen

Anhand eines Zwillingskollektivs und einer Gruppe ersterkrankter Schizophrener (zehn eineiige und zehn zweieiige Zwillingspaare, 38 ersterkrankte Schizophrene, 15 Kontrollen) wird ein moglicher genetischer Einflus auf Grose und Windungsmuster des Planum temporale untersucht. MRT: FLASH-3D-T1-gewichtete Datensatze aus koronaren 3-mm-Schichten; 3D-Rekonstruktion mit ISG-Workstation Allegro. Gemessen wurden Lange und Flache des Planum temporale und Lange des Heschlschen Gyrus. Der Windungsverlauf wurde nach qualitativen Kriterien beurteilt. Schizophrene zeigen im Gegensatz zu gesunden Kontrollen, eineiigen und zweieiigen Zwillingen vor allem bei der Lanlge und weniger bei der Flache des Planum…

58. White matter abnormalities in attention-deficit/hyperactivity disorder: A diffusion tensor imaging study in adult patients

Spatial resolution of fMRI in the human parasylvian cortex: Comparison of somatosensory and auditory activation

Abstract In spite of its outstanding spatial resolution, the biological resolution of functional MRI may be worse because it depends on the vascular architecture of the brain. Here, we compared the activation patterns of the secondary somatosensory and parietal ventral cortex (SII/PV) with that of the primary auditory cortex and adjacent areas (AI/AII). These two brain regions are located immediately adjacent to each other on opposite banks of the Sylvian fissure, and are anatomically and functionally distinct. In 12 healthy subjects, SII/PV was activated by pneumatic tactile stimuli applied to the index finger (0.5 cm 2 contact area, 4 bar pressure), and AI/AII by amplitude-modulated tones…

'Prefrontal' cognitive performance of healthy subjects positively correlates with cerebral FDOPA influx: an exploratory [18F]-fluoro-L-DOPA-PET investigation.

Dopamine neurotransmission influences those cognitive processes, which are generally regarded as prefrontal cortical functions. In previous positron‐emission‐tomography (PET) studies, net blood‐brain clearance of [(18)F]‐fluoro‐l‐DOPA (FDOPA) correlated with impaired cognitive performance in patients with Parkinson's disease or schizophrenia. We hypothesized that FDOPA influx also correlates with performance of cognitive tasks associated with prefrontal functioning in healthy volunteers. The net blood‐brain clearance of FDOPA (K [Formula: see text]) was mapped in a group of 11 healthy volunteers and calculated in striatal volumes‐of‐interest. The Wisconsin‐Card‐Sorting‐Test (WCST), Stroop‐T…

COMT genotype predicts BOLD signal and noise characteristics in prefrontal circuits.

Abstract Objective: Prefrontal dopamine (DA) is catabolized by the COMT (catechol- O -methyltransferase) enzyme. Literature suggests that the Val/Met single nucleotide polymorphism (SNP) in the COMT gene predicts executive cognition in humans with Val carriers showing poorer performance due to less available synaptic DA. Recent fMRI studies are thought to agree with these studies having demonstrated prefrontal hyperactivation during n -back and attention-requiring tasks. This was interpreted as “less efficient” processing due to impaired signal-to-noise ratio (SNR) of neuronal activity. However, electrophysiological studies of neuronal SNR in primates and humans imply that prefrontal cortex…

P23. Large demyelinating lesion of the pons as a cause of a locked-in syndrome in multiple sclerosis

Somatotopic organization of the corticospinal tract in the human brainstem: a MRI-based mapping analysis.

To investigate the incompletely understood somatotopical organization of the corticospinal tract in the human brainstem, we performed a voxel-based statistical analysis of standardized magnetic resonance scans of 41 prospectively recruited patients with pyramidal tract dysfunction caused by acute brainstem infarction. Motor hemiparesis was rated clinically and by the investigation of motor evoked potentials to arms and legs. Infarction affected the pons in 85% of cases. We found the greatest level of significance of affected brainstem areas between the pontomesencephalic junction and the mid pons. Lesion location was significantly more dorsal in patients with hemiparesis affecting more prox…

Diffusion-weighted MRI of cholesteatomas of the petrous bone

Purpose To investigate if primary cholesteatomas of the petrous bone show high signal in diffusion-weighted imaging (DWI). Materials and methods In this blinded study, we compared 15 patients with clinically certain cases and later surgically proven cholesteatomas vs. 12 patients with clinically acute otitis of the middle ear and 20 volunteers without petrous bone disease. Two blinded readers without knowledge of the clinical data decided in consensus agreement whether there was a pathologic signal increase in the petrous bone in an anisotropic single-shot echo-planar imaging (EPI) DWI sequence, an artifact, or no signal increase. Results Thirteen of 15 patients with cholesteatomas showed b…

Covariations among fMRI, skin conductance, and behavioral data during processing of concealed information.

Imaging techniques have been used to elucidate the neural correlates that underlie deception. The scientifically best understood paradigm for the detection of deception, however, the guilty knowledge test (GKT), was rarely used in imaging studies. By transferring a GKT‐paradigm to a functional magnetic resonance imaging (fMRI) study, while additionally quantifying reaction times and skin conductance responses (SCRs), this study aimed at identifying the neural correlates of the behavioral and electrodermal response pattern typically found in GKT examinations. Prior to MR scanning, subjects viewed two specific items (probes) and were instructed to hide their knowledge of these. Two other spec…

3.2. Brain stem and cerebellar activation during optokinetic stimulation

Direction‐dependent visual cortex activation during horizontal optokinetic stimulation (fMRI study)

Looking at a moving pattern induces optokinetic nystagmus (OKN) and activates an assembly of cortical areas in the visual cortex, including lateral occipitotemporal (motion‐sensitive area MT/V5) and adjacent occipitoparietal areas as well as ocular motor areas such as the prefrontal cortex, frontal, supplementary, and parietal eye fields. The aim of this functional MRI (fMRI) study was to investigate (1) whether stimulus direction‐dependent effects can be found, especially in the cortical eye fields, and (2) whether there is a hemispheric dominance of ocular motor areas. In a group of 15 healthy subjects, OKN in rightward and leftward directions was visually elicited and statistically compa…

Cerebrovascular Brainstem Diseases with Isolated Cranial Nerve Palsies

There is a significant number of individual patients with cranial nerve palsies as the sole manifestation of MRI- and, less frequently, CT-documented small brainstem infarctions or hemorrhages. The 3rd and 6th nerves are most commonly involved and, less frequently, the 4th, 5th, 7th, and 8th nerves. An intra-axial basis for such lesions may be underestimated if the diagnosis is based solely on MRI. The electrophysiologic abnormalities indicating brainstem lesions may be independent of MRI-documented morphological lesions. This paper reviews the literature on cerebrovascular brainstem diseases manifesting as isolated cranial nerve palsies. It supports the concept that small pontine and mesen…

Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study.

The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the …

Anatomical Correlate of Impaired Covert Visual Attentional Processes in Patients with Cerebellar Lesions

In the past years, claims of cognitive and attentional function of the cerebellum have first been raised but were later refuted. One reason for this controversy might be that attentional deficits only occur when specific cerebellar structures are affected. To further elucidate this matter and to determine which cerebellar regions might be involved in deficits of covert visual attention, we used new brain imaging tools of lesion mapping that allow a direct comparison with control patients. A total of 26 patients with unilateral right-sided cerebellar infarcts were tested on a covert visual attention task. Eight (31%) patients showed markedly slowed responses, especially in trials in which an…

P24. Classical brain stem syndromes: Myth or reality?

Left-hemispheric dominance for articulation: a prospective study on acute ischaemic dysarthria at different localizations.

Dysarthria is a frequent symptom in cerebral ischaemia. However, speech characteristics of these patients have not previously been investigated in relation to lesion site in a prospective study. We investigated the auditory perceptual features in 62 consecutive patients with dysarthria due to a single, non-space-occupying cerebral infarction confirmed by MRI. Standardized speech samples of all patients were stored within 72 h after stroke onset using a digital tape recorder. Speech samples were assessed independently by two experienced speech therapists, who were unaware of the clinical and neuroradiological findings, using an interval scale ranging from 0 to 6. Separately assessed were fea…

Brain electrical source analysis of primary cortical components of the tibial nerve somatosensory evoked potential using regional sources.

Tibial nerve somatosensory evoked potentials (SEPs) show higher amplitudes ipsilateral to the side of stimulation, whereas subdural recordings revealed a source in the foot area of the contralateral hemisphere. We now investigated this paradoxical lateralization by performing a brain electrical source analysis in the P40 time window (34-46 ms). The tibial nerve was stimulated behind the ankle (8 subjects). On each side, 2048 stimuli were applied twice. SEPs were recorded using 32 magnetic resonance imaging (MRI)-verified electrode positions (bandpass 0.5-500 Hz). In each case, the P40 amplitude was higher ipsilaterally (0.45 +/- 0.14 microV) than contralaterally (-0.49 +/- 0.16 microV). The…

IC‐P‐122: Association of hippocampus head diffusivity and episodic memory performance in early Alzheimer's disease