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Biomedical subjects

Heinrich Lanfermann

Publications and source records attributed to Heinrich Lanfermann.

At least 19 recordsLinked to original sources
PubMed2006

Ipsilateral silent period: a marker of callosal conduction abnormality in early relapsing-remitting multiple sclerosis?

OBJECTIVE: The corpus callosum (CC) is commonly affected in multiple sclerosis (MS). The ipsilateral silent period (iSP) is a putative electrophysiological marker of callosal demyelination. The purpose of this study was to re-assess, under recently established optimised protocol conditions [Jung P., Ziemann U. Differences of the ipsilateral silent period in small hand muscles. Muscle Nerve in press.], its diagnostic sensitivity in MS, about which conflicting results were reported in previous studies. METHODS: ISP measurements (onset, duration, and depth) were obtained in the abductor pollicis brevis (APB) muscle of either hand in 49 patients with early relapsing-remitting MS (RRMS) (mean EDSS, 1.3). Standard central motor conduction times to the APB (CMCT(APB)) and tibial anterior muscles (CMCT(TA)), and magnetic resonance images (MRI) were also obtained. RESULTS: ISP measurements showed a similar diagnostic sensitivity (28.6%) as CMCT(APB) (24.5%), while diagnostic sensitivities of CMCT(TA) (69.4%) and MRI of the CC (78.6%) were much higher. Prolongation of iSP duration was the most sensitive single iSP measure. ISP prolongation occurred more frequently when CMCT(APB) to the same hand was also prolonged (40.0% vs. 8.4%, p<0.0001). The correlation between iSP duration and CMCT(APB) was significant (Pearson's r=0.24, p<0.02), suggesting that iSP duration can be contaminated by demyelination of the contralateral corticospinal tract. ISP duration did not correlate with MRI abnormalities of the CC. CONCLUSIONS: ISP measures are neither a sensitive nor a specific marker of callosal conduction abnormality in early RRMS.

Adult↗
PubMed2006

Detection of lesions in multiple sclerosis by 2D FLAIR and single-slab 3D FLAIR sequences at 3.0 T: initial results.

The aim of this study was to compare conventional 2D FLAIR and single-slab 3D FLAIR sequences in the detection of lesions in patients with multiple sclerosis. Eight patients with MS were examined at 3.0 T by using a 2D FLAIR sequence and a single-slab 3D FLAIR sequence. A comparison of lesion detectability was performed for the following regions: periventricular, nonperiventricular/juxtacortical and infratentorial. The contrast-to-noise ratios (CNRs) between lesions and brain tissue and CSF were calculated for each sequence. A total of 424 lesions were found using the 2D FLAIR sequence, while with the 3D FLAIR sequence 719 lesions were found. With the 2D FLAIR sequence, 41% fewer lesions were detected than with the 3D FLAIR sequence. Further, 40% fewer supratentorial and 62.5% fewer infratentorial lesions were found with the 2D FLAIR sequence. In images acquired with the 3D FLAIR sequence, the lesions had significantly higher CNRs than in images acquired with the 2D FLAIR sequence. These are the first results using a single-slab 3D FLAIR sequence at 3.0 T for detection of lesions in patients with MS. With the 3D FLAIR sequence significantly higher CNRs were achieved and significantly more lesions in patients with MS were detected.

Adult↗
PubMed2005

Cortical plasticity associated with stuttering therapy.

UNLABELLED: Neuroimaging studies have indicated that persistent developmental stuttering (PDS) may be associated both with an abnormality in white matter of left-hemispheric speech areas and a right-hemispheric hyperactivity. The latter may compensate for the deficient structural connectivity in the left hemisphere. To investigate the effects of stuttering therapy on brain activity nine male adults with PDS underwent functional magnetic resonance imaging (fMRI) before and within 12 weeks after fluency shaping therapy. Brain response differences during overt sentence reading before and after therapy were assessed by utilizing random effects analyses. After therapy, a more widespread activation was observed in frontal speech and language regions and temporal areas of both hemispheres, particularly and more pronounced on the left side. Interestingly, distinct posttreatment left-sided activation increases were located directly adjacent to a recently detected area of white matter anomaly [M. Sommer, M.A. Koch, W. Paulus, C. Weiller, C. Buchel (2002). Disconnection of speech-relevant brain areas in persistent developmental stuttering. The Lancet, 360, 380-383] suggesting that fluency shaping techniques reorganize neuronal communication between left-sided speech motor planning, motor execution, and temporal areas. Hence, a therapeutic mechanism can be assumed to remodel brain circuitry close to the source of the dysfunction instead of reinforcing compensation via homologous contralateral brain networks. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) describe brain activation changes detected shortly after fluency-shaping therapy; (2) identify left-hemispheric regions where a (re)functionalization after fluency-shaping therapy seems to occur adjacent to a recently described abnormal white matter region in PDS subjects; and (3) discuss how an effective cerebral compensation mechanism for stuttering could work.

Adult↗
PubMed2004

Assessment of paramedian thalamic infarcts: MR imaging, clinical features and prognosis.

Considering the highly variable vascular supply of the thalamic nuclei, MRI and clinical syndromes can be heterogeneous in ischemic diseases. We attempt to determine MRI pattern and to analyse neurological features and prognosis of paramedian infarcts. In a prospective case series within 5 years from 1999 to 2003, MRI, MRA and clinical symptoms of 38 consecutive patients were analysed. The inferomedial (posterior thalamoperforating artery) territory was affected in 89%, and lesions in the anterolateral (tuberothalamic artery) territory occurred in 42%. However, definite attribution to anterolateral or inferomedial territories was not possible in 13%. Neurological manifestations were somnolence (87%), hemisyndromes (79%), cognitive deficits (58%), oculomotor nerve palsies (53%) and vertical gaze palsies (39%). The most common aetiologies were cardiac embolism (42%), intraarterial embolism (16%), small vessel disease (13%) and large artery arteriosclerosis (13%). Pathological MRA findings were encountered in 55%, and in 18%, lesions were only visible on diffusion-weighted imaging. Correlation of MRI pattern and neurological symptoms points out anterolateral thalamic lesions as the cause of amnestic deficits. Intracranial MRA allows a non-invasive prediction of basilar tip occlusion. Our results underline the necessity of additional diffusion-weighted imaging in detecting small thalamic and midbrain lesions.

Adolescent↗
PubMed2004

Multiple spin-echo spectroscopic imaging for rapid quantitative assessment of N-acetylaspartate and lactate in acute stroke.

Monitoring the signal levels of lactate (Lac) and N-acetylaspartate (NAA) by chemical shift imaging can provide additional knowledge about tissue damage in acute stroke. Despite the need for this metabolic information, spectroscopic imaging (SI) has not been used routinely for acute stroke patients, mainly due to the long acquisition time required. The presented data demonstrate that the application of a fast multiple spin-echo (MSE) SI sequence can reduce the measurement time to 6 min (four spin echoes per echo train, 32 x 32 matrix). Quantification of Lac and NAA in terms of absolute concentrations (i.e., mmol/l) can be achieved by means of the phantom replacement approach, with correction terms for the longitudinal and transversal relaxation adapted to the multiple spin-echo sequence. In this pilot study of 10 stroke patients (symptom onset < 24 hr), metabolite concentrations obtained from MSE-SI add important information regarding tissue viability that is not provided by other sequences (e.g., diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI)). Metabolic changes extended beyond the borders of the apparent diffusion coefficient (ADC) lesion in nine of the 10 patients, showing a rise in Lac concentrations up to 18 mmol/l, while NAA levels sometimes dropped below the detection level. Considerable differences among the patients in terms of the Lac concentrations and the size of the SI-ADC mismatch were observed.

Acute Disease↗
PubMed2004

[Convergence of psychotherapeutic and neurobiological outcome measure in a patient with OCD].

We used psychotherapeutic measures and functional magnetic resonance imaging (fMRI) to assess the effect of a combined psychodynamic and cognitive behavioral treatment of a patient suffering from a severe obsessive compulsive disorder (OCD). The clinical outcome was controlled by a detailed case description and psychometric test instruments. Intensive exploration of the patient made possible the creation of an idiosyncratic imagination paradigm suitable for fMRI. The patient shows at the end of treatment a decrease in symptoms as assessed by clinical as well as psychometric instruments. Especially recapitulation and cleaning obsessions decreased, but the cognitive avoidance strategies remained almost unchanged. fMRI showed no orbito-fronto-striatothalamic activation corresponding to obsessive compulsive symptoms, but an increased activation of the medial prefrontal (MFC) and anterior cingulate cortex (ACC). The lack of activation of the orbito-fronto-striatothalamic circuits and at the same time the occurrence of the increased activation of the MFC and ACC reflects the cognitive avoidance strategies still triggered by the symptom provoking stimulus.

Adult↗
PubMed2004

Morphology of proliferating and non-proliferating tumor cell nuclei in glioblastomas correlates with preoperative data from proton-MR-spectroscopy.

In contrast to the growing interest in proton-MR-spectroscopy (1HMRS) for preoperative examination of patients with brain tumors, there is nearly no knowledge about a correlation between data from 1HMRS and histomorphology as confirmed by quantitative morphological methods. Whether a correlation can be confirmed between data from 1HMRS and quantitative histomorphology of glioblastomas representing the most frequent type of brain tumors was investigated in the present study. Furthermore, it was of interest, whether correlations between spectroscopic data and histomorphology can be confirmed for proliferating and non-proliferating tumor cell nuclei independently. Using stringent inclusion criteria for this study, 24 patients were investigated by means of preoperative 1HMRS and by means of digital image analysis of paraffin sections from the surgical specimen. Proliferating and non-proliferating tumor cell nuclei were investigated separately in the region with the highest proliferative activity in each tumor using immunohistological staining for the proliferation marker Ki67. Main results showed highly significant correlations between total creatine and variables of nuclear size, as well as correlations between choline and variables of nuclear shape. These results were confirmed for both proliferating and non-proliferating tumor cell nuclei. A significant correlation between N-acetyl-aspartate level and topometric variables (number of neighbors per nucleus, variables describing distances between tumor cell nuclei) was confirmed for proliferating tumor cell nuclei. Discriminant analysis provided a good separation of cases with high and with low values for these spectroscopic variables based on histomorphometric data. In conclusion, the results confirm a direct correlation between data from preoperative 1HMRS and histomorphological characteristics of glioblastomas supporting the biological relevance of spectroscopic data for the examination of brain tumor patients.

Cell Nucleus↗
PubMed2003

Brain metabolism in Alzheimer disease and vascular dementia assessed by in vivo proton magnetic resonance spectroscopy.

Proton magnetic resonance spectroscopy (MRS) allows the assessment of various cerebral metabolites non-invasively in vivo. Among 1H MRS-detectable metabolites, N-acetyl-aspartate and N-acetyl-aspartyl-glutamate (tNAA), trimethylamines (TMA), creatine and creatine phosphate (tCr), inositol (Ins) and glutamate (Gla) are of particular interest, since these moieties can be assigned to specific neuronal and glial metabolic pathways, membrane constituents, and energy metabolism. In this study on 94 subjects from a memory clinic population, 1H MRS results (single voxel STEAM: TE 20 ms, TR 1500 ms) on the above metabolites were assessed for five different brain regions in probable vascular dementia (VD), probable Alzheimer's disease (AD), and age-matched healthy controls. In both VD and AD, ratios of tNAA/tCr were decreased, which may be attributed to neuronal atrophy and loss, and Ins/tCr-ratios were increased indicating either enhanced gliosis or alteration of the cerebral inositol metabolism. However, the topographical distribution of the metabolic alterations in both diseases differed, revealing a temporoparietal pattern for AD and a global, subcortically pronounced pattern for VD. Furthermore, patients suffering from vascular dementia (VD) had remarkably enhanced TMA/tCr ratios, potentially due to ongoing degradation of myelin. Thus, the metabolic alterations obtained by 1H MRS in vivo allow insights into the pathophysiology of the different dementias and may be useful for diagnostic classification.

Aged↗
PubMed2003

Enactment effect in memory: evidence concerning the function of the supramarginal gyrus.

Experimental behavioral data show that written action descriptions are remembered better when encoded by enacting them compared with merely verbal encoding. To explore this facilitating effect of encoding by performing actions ('enactment effect'), a functional magnetic resonance imaging (fMRI) study was conducted with n=18 normal subjects. During a learning condition, subjects encoded action phrases like 'cut the bread' either by reading aloud or by enacting them. The same phrases plus additional distractors were presented during fMRI scanning, and the task was to decide (yes/no key press) whether a displayed phrase was previously learned or whether it was a new one. Retrieval--independent of encoding type--activated anterior cingulate, SMA, and visual cortex bilaterally. Activations of the inferior frontal and sensorimotor cortex, and the precentral sulcus, were only left sided. The right cerebellum was also activated. The subtraction of the brain activations in the verbal condition from the enactment condition resulted in significant clusters located in middle temporal and inferior parietal left cortical areas, and, on the right side, in superior temporal, postcentral and inferior parietal cortical areas. Most striking were the bilateral inferior parietal activations, covering the supramarginal gyrus (SMG). Therefore it is concluded that SMG may be a central structure in a neurofunctional explanation of the enactment effect.

Adult↗
PubMed2003

Cerebral Erdheim-Chester disease: case report and review of the literature.

Erdheim-Chester disease is a rare systemic non-Langerhans histiocytosis of unknown etiology that affects multiple organ systems. Cerebral involvement is most often caused by extra-axial masses of foamy histiocytes, whereas intraparenchymal manifestations are less frequent. Review of the literature yielded a total of seven patients with increased signal intensities on T2-weighted images in both dentate nuclei and the peridentate regions. We report on a 44-year-old man with biopsy-proven Erdheim-Chester disease and slowly progressive cerebellar dysfunction. MRI showed additional symmetrical hyperintense signal changes in the superior cerebellar peduncle as well as in the trigonum lemnisci on coronal FLAIR images. The widespread neurological manifestations of cerebral Erdheim-Chester disease and differential diagnosis are discussed.

Adult↗
PubMed2003

Cerebral networks linked to the event-related potential P300.

P300 is an event-related potential that is elicited by an oddball paradigm. In several neuropsychiatric diseases, differences in latencies and amplitude compared to healthy subjects have been reported. Because of its clinical significance, several investigations have tried to elucidate the intracranial origins of the P300 component. In the present study we could demonstrate a network of P300 generators. Investigated were 15 healthy subjects with an acoustical oddball paradigm within a fMRI block design, which enabled us to exclude attention or acoustical processing effects. The inferior and middle frontal, superior temporal, lower parietal cortex, the insula and the anterior cingulum were significantly activated symmetrical in both hemispheres.

Acoustic Stimulation↗
PubMed2003

The nature and treatment of stuttering as revealed by fMRI A within- and between-group comparison.

UNLABELLED: This article reviews some of our recent functional magnetic resonance imaging (fMRI) studies of stuttering. Using event-related fMRI experiments, we investigated brain activation during speech production. Results of three studies comparing persons who stutter (PWS) and persons who do not stutter (PWNS) are outlined. Their findings point to a region in the right frontal operculum (RFO) that was consistently implicated in stuttering. During overt reading and before fluency shaping therapy, PWS showed higher and more distributed neuronal activation than PWNS. Immediately after therapy differential activations were even more distributed and left sided. They extended to frontal, temporal, and parietal regions, anterior cingulate, insula, and putamen. These over-activations were slightly reduced and again more right sided two years after therapy. Left frontal deactivations remained stable over two years of observation, and therefore possibly indicate a dysfunction. After therapy, we noted higher activations in persons who stutter moderately than in those who stutter severely. These activations might reflect patterns of compensation. We discuss why these findings suggest that fluency-inducing techniques might synchronize a disturbed signal transmission between auditory, speech motor planning, and motor areas. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) identify regions of brain activations and deactivations specific for PWS; (2) describe brain activation changes induced by fluency shaping therapy; and (3) discuss the correlation between stuttering severity and brain activation.

Adult↗
PubMed2003

Functional MRI using sensitivity-encoded echo planar imaging (SENSE-EPI).

Parallel imaging methods become increasingly available on clinical MR scanners. To investigate the potential of sensitivity-encoded single-shot EPI (SENSE-EPI) for functional MRI, five imaging protocols at different SENSE reduction factors (R) and matrix sizes were compared with respect to their noise characteristics and their sensitivity toward functional activation in a motor task examination. At constant echo times, SENSE-EPI was either used to shorten the single volume acquisition times (TR(min)) at matrix size 128 x 100 (22 slices) from 3.9 s (no SENSE) to 2.0 s at R = 3, or to increase the matrix size to 192 x 153 (22 slices), resulting in TR(min) = 5.3 s for R = 2 or TR(min) = 3.4 s for R = 3. At the lower resolution, the bisection of echo train length (R = 2) substantially reduced distortions and blurring, while signal-to-noise and statistical power (measured by cluster size and maximum t value per unit time) were hardly reduced. At R = 3 the additional gain in speed and distortion reduction was quite small, while signal-to-noise and statistical power dropped significantly. With enhanced spatial resolution the time course signal-to-noise was better than expected from theory for purely thermal noise because of a reduced contribution of physiological noise, and statistical power almost reached that of the regular, low-resolution single-shot EPI, with a slight drop off toward R = 3. Thus, SENSE-EPI allows to substantially increase speed and spatial resolution in fMRI. At SENSE reduction factors up to R = 2, the potential drawbacks regarding signal-to-noise and statistical power are almost negligible.

Adult↗
PubMed2003

Event-related fMRI for the suppression of speech-associated artifacts in stuttering.

The purpose of this study was to establish functional magnetic resonance imaging (fMRI) for the investigation of brain function during overt speech production in stuttering. Up to now this technique has rarely been used for the investigation of speech production paradigms because artifacts related to overt speaking largely impair the sensitivity toward task-related activation. Recently, the temporal delay of the hemodynamic response has been exploited to achieve a suppression of speech-related artifacts. By the limitation to very short utterances (one word), a temporal segregation of the respective effects was accomplished by means of an event-related experimental design. However, the investigation of speech production in persons who stutter requires a more extensive speaking situation. Since longer and more complex utterances evoke more symptoms of stuttering than reading of single words, a useful task should at least include the reading of full sentences. In this study we performed simulations to investigate the correlation of speech-related artifacts with the respective hemodynamic response in dependency on speech duration and rate of data sampling. Furthermore, we show that prolonged stimulus durations and repetition times of 3 s still allow an effective suppression of speech-related artifacts in fluent as well as in nonfluent speakers. Not only were obvious false activations at high contrast cerebrospinal fluid tissue borders widely eliminated, subjects also displayed consistent activation in speech-related and motor areas. As these results widely resemble those obtained by earlier neuroimaging studies on language production, event-related fMRI seems to be capable of recording neurophysiological correlates of overt speech production.

Adult↗
PubMed2003

Evidence for compensation for stuttering by the right frontal operculum.

There is recent evidence of focal alteration in fibre tracts underlying the left sensorimotor cortex in persistent developmental stuttering (PDS) [Lancet 360 (2002) 380]. If, as proposed, this anatomical abnormality is the cause of PDS, then overactivation in the right hemisphere seen with functional neuroimaging in stutterers may reflect a compensatory mechanism. To investigate this hypothesis, we performed two functional magnetic resonance imaging (fMRI) experiments. The first showed systematic activation of a single focus in the right frontal operculum (RFO) in PDS subjects during reading, which was not observed in controls. Responses in this region were negatively correlated with the severity of stuttering, suggesting compensation rather than primary dysfunction. Negative correlation was also observed during the baseline task that consisted in passive viewing of meaningless signs, indicating that RFO compensation acts independently of specific demands on motor speech output. The second experiment, that involved a covert semantic decision task, confirmed that RFO activation does not require overt utterances or motor output. In combination these findings suggest that the RFO serves a nonspecific compensatory role rather than one restricted to the final stages of speech production.

Adult↗
PubMed2003

Preoperative proton-MR spectroscopy of gliomas--correlation with quantitative nuclear morphology in surgical specimen.

A comparison between data from proton-MR spectroscopy (1HMRS) and quantitative histomorphology of tumor cell nuclei in gliomas has not been reported up to now. Therefore, the question must be answered, if there are any significant correlations between histomorphology of gliomas and quantitative data from 1HMRS concerning tissue metabolites. Surgical glioma specimen (glioblastomas, astrocytomas, oligodendrogliomas) from 46 patients with tumor grades II-IV according to WHO have been evaluated by means of a digital image analysis system using Ki-67-immunostained paraffin sections. Nuclear density, Ki-67-proliferation index, nuclear area and shape variables (roundness factor, Fourier-amplitudes) have been determined from 200 randomly selected tumor cell nuclei in each tumor specimen. These data have been correlated with preoperative data from 1HMRS. A positive correlation between Fourier-amplitudes, choline peak and lipide peak was observed, as well as a negative correlation between these variables and the nuclear roundness factor. This result indicates higher choline and lipide peaks with increasing irregularity of nuclear outlines. Proliferation index Ki-67 was positively correlated with the lipide peak, nuclear density showed a positive correlation with the choline peak. Glioblastomas (n = 29) showed an additional positive correlation between mean nuclear size and total creatine. Anaplastic gliomas (n = 12) showed a positive correlation between lactate peak and the standard deviation of the nuclear roundness factor. Further multivariate analyses have shown, that for the present collective of 46 cases, histometric variables have a higher significance than spectroscopic data for the differentiation of the different tumor grades. These results verify a significant correlation between preoperative data from 1HMRS and histomorphology of tumor cell nuclei in gliomas, supporting the biological significance of both histomorphometry and 1HMRS for the evaluation of these tumors.

Brain Neoplasms↗