Biomedical subjects

Heinrich Lanfermann

Publications and source records attributed to Heinrich Lanfermann.

30 records · Page 2Linked to original sources

PubMed2003

Cerebrovascular complications of L-asparaginase in the therapy of acute lymphoblastic leukemia.

L-asparaginase is frequently used in combination therapy for the treatment of lymphoid malignancies. We report 5 children aged between 8 and 14 years with neurologic complications presenting with headache and seizures during the first three weeks of L-asparaginase treatment. Three patients had venous thrombosis, one presented a parenchymal hemorrhage, and one showed a peculiar encephalopathy with extended cortical and subcortical lesions suggesting a neurotoxic reaction. Decreased fibrinogen and antithrombin III levels were found. Early MRI is critical even in cases with mild neurologic symptoms. Diagnosis should be followed by early cessation of l-asparaginase application.

Adolescent↗

PubMed2003

Determination of histopathological tumor grade in neuroepithelial brain tumors by using spectral pattern analysis of in vivo spectroscopic data.

OBJECT: In this study, 1H magnetic resonance (MR) spectroscopy was prospectively tested as a reliable method for presurgical grading of neuroepithelial brain tumors. METHODS: Using a database of tumor spectra obtained in patients with histologically confirmed diagnoses, 94 consecutive untreated patients were studied using single-voxel 1H spectroscopy (point-resolved spectroscopy; TE 135 msec, TE 135 msec, TR 1500 msec). A total of 90 tumor spectra obtained in patients with diagnostic 1H MR spectroscopy examinations were analyzed using commercially available software (MRUI/VARPRO) and classified using linear discriminant analysis as World Health Organization (WHO) Grade I/II, WHO Grade III, or WHO Grade IV lesions. In all cases, the classification results were matched with histopathological diagnoses that were made according to the WHO classification criteria after serial stereotactic biopsy procedures or open surgery. Histopathological studies revealed 30 Grade I/II tumors, 29 Grade III tumors, and 31 Grade IV tumors. The reliability of the histological diagnoses was validated considering a minimum postsurgical follow-up period of 12 months (range 12-37 months). Classifications based on spectroscopic data yielded 31 tumors in Grade I/II, 32 in Grade III, and 27 in Grade IV. Incorrect classifications included two Grade II tumors, one of which was identified as Grade III and one as Grade IV; two Grade III tumors identified as Grade II; two Grade III lesions identified as Grade IV; and six Grade IV tumors identified as Grade III. Furthermore, one glioblastoma (WHO Grade IV) was classified as WHO Grade I/II. This represents an overall success rate of 86%, and a 95% success rate in differentiating low-grade from high-grade tumors. CONCLUSIONS: The authors conclude that in vivo 1H MR spectroscopy is a reliable technique for grading neuroepithelial brain tumors.

Brain Neoplasms↗

PubMed2003

Correlation between preoperative magnetic resonance spectroscopic data on high grade gliomas and morphology of Ki-67-positive tumor cell nuclei.

OBJECTIVE: To investigate possible statistical correlations between metabolic data from preoperative proton magnetic resonance spectroscopy (1HMRS) and morphology of proliferating tumor cell nuclei in anaplastic gliomas and glioblastomas. STUDY DESIGN: Ki-67-positive tumor cell nuclei in paraffin sections of surgical specimens from 36 patients (7 anaplastic gliomas, World Health Organization grade 3; 29 glioblastomas, World Health Organization grade 4) were investigated by means of a digital image analysis system. Stringent inclusion criteria were formulated for all cases with respect to histologic quality and spectroscopic examination. As morphometric variables, nuclear area, shape variables (roundness factor, size-invariate Fourier amplitudes) and density of Ki-67-positive tumor cell nuclei per reference area were determined. RESULTS: Correlation analysis according to Spearman revealed a significant positive correlation between the total creatine (TCR) peak and nuclear area (P = .005). This correlation was also found within the glioblastoma group (P = .019). There was also a significant negative correlation of nuclear area with the ratio between choline and TCR in all cases (P = .014) and within the glioblastoma group (P = .046). No significant correlation of spectroscopic data was found with nuclear shape or density of Ki-67-positive tumor cell nuclei. CONCLUSION: The results demonstrate a correlation between spectroscopic data and morphology of proliferating tumor cell nuclei (nuclear size) in high grade gliomas. This study is part of a detailed investigation of the interrelationship between preoperative 1HMRS and quantitative histomorphology of gliomas.

Biomarkers, Tumor↗

PubMed2002

Spinal cord infarction: MR imaging and clinical features in 16 cases.

Spinal cord infarctions are rare and due to heterogeneous etiologies. The aim of the study was to analyze the MR imaging findings and evaluate their correlations with clinical symptoms in ischemic spinal cord lesions. MR images and clinical features of 16 patients (11 male, 5 female) with typical sudden onset of neurological deficits caused by spinal cord ischemia were evaluated. MR imaging was performed within 2 h to 14 days after the initial neurological symptoms. Eight patients had follow-up examinations including contrast-enhanced MR imaging. MR abnormalities were best demonstrated on sagittal T2-weighted images, with "pencil-like" hyperintensities (16/16) and cord enlargement (9/16). Axial T2-weighted images showed bilateral (13/16) and unilateral (3/16) hyperintensities according, in 15 patients, to anterior spinal artery (ASA) territory, with three of them located particularly in the spinal sulcal artery territory. In one patient only the posterior spinal artery (PSA) territory was involved. Spinal cord was affected at the cervical level (especially C2-C3) in seven patients, at the upper thoracic level (T3-T5) in two patients and at the thoracolumbar region including the conus medullaris (T10-L1) in seven patients. Presumed etiologies were vascular surgery (3 patients), infrarenal aortic aneurysm (1 patient), bilateral vertebral artery dissection (1 patient), hypotension (1 patient), spine operation (1 patient), excessive cocaine misuse (1 patient) and cardioembolic vertebral artery occlusion (1 patient); six of seven patients with unclear etiologies had vascular risk factors such as hypertension, diabetes and cigarette smoking. MR imaging is therefore useful in detecting spinal cord infarction, with axial T2-weighted images showing hyperintensities in the ASA territory in 15 of 16 patients. Contrary to the presumed spinal cord watershed at the lower cervical and upper thoracic level, and despite numerous central arteries in the cervical cord, our data suggest a high ischemic vulnerability of the cervical spinal cord at level C2-C3.

Female↗

PubMed2002

Wernicke encephalopathy: MR findings and clinical presentation.

Wernicke encephalopathy (WE) is a severe neurological disorder caused by vitamin B1 deficiency. The aim of the study was to analyse MRI findings typical for this disease and to evaluate the significance of their correlations with clinical symptoms. Magnetic resonance images and clinical features of 12 patients with WE were analysed. The patients underwent MR imaging within 3-14 days after onset of clinical symptoms. In 7 of 12 patients MR imaging showed symmetrical diencephalic and midbrain lesions. Postcontrast T1-weighted images from 5 of 9 patients examined during the initial 6 days of acute WE showed a subtle enhancement of the mamillary bodies, the tectal plate, the periaqueductal area and the periventricular region of the third ventricle including the paramedian thalamic nuclei. In addition, T2-weighted and fluid-attenuated inversion recovery (FLAIR) images revealed hyperintense signals in these regions (except for 2 patients where the mamillary bodies were normal). Hyperintense lesions on T2-weighted images without any enhancement on postcontrast T1-weighted images were detected in 2 patients by MR imaging performed 11 or 14 days after onset of WE. Patients with hyperintensities on T2-weighted images of the periventricular region of the third ventricle and the paramedian thalamic nuclei had poor recovery from their mental dysfunction. The MR examination in case of WE shows a typical pattern of lesions in 58% of cases. Enhancement of the mamillary bodies, the periventricular region of the third ventricle including the paramedian thalamic nuclei, and the periaqueductal area on postcontrast T1-weighted images can be observed in the initial period after clinical onset of symptoms and are characteristic signs of the acute stage of WE. Hyperintense lesions in the periventricular region and the paramedian thalamic nuclei on T2-weighted and FLAIR images in the subacute stage of WE and enhancement on postcontrast T1-weighted images of the mamillary bodies and the paramedian thalamic nuclei are indicators of poor prognosis despite vitamin B1 substitution.

Adult↗

PubMed2002

Apparent motion: event-related functional magnetic resonance imaging of perceptual switches and States.

When spatially segregated visual stimuli are presented in alternation, subjects may perceive a single stimulus moving between the two positions (apparent motion). By adjusting spatial and temporal parameters, an ambiguous condition can be created in which perception of back-and-forth motion alternates with the perception of two stationary blinking stimuli. We presented subjects with such ambiguous stimuli, asked them to signal periods of perceived motion and blinking, and measured brain activity with functional magnetic resonance imaging. Multiple regression analysis revealed that early visual areas responded with equal strength during both perceptual conditions, whereas hMT+(V5) (the human motion complex that includes the human homolog of MT and its satellites) was more active during the perception of apparent motion. These results indicate that neurons in hMT+ participate in the constructive process that creates a continuous motion percept from a discontinuous visual input.

Brain Mapping↗

PubMed2002

Magnetic resonance imaging in basilar artery occlusion.

CONTEXT: Acute basilar artery occlusion has particularly high mortality and morbidity. OBJECTIVE: To determine the potential utility of advanced magnetic resonance imaging (MRI) methods, including diffusion-weighted imaging, for the early management of patients with basilar artery thrombosis. DESIGN: Case series. SETTING: Institute of Neuroradiology and Department of Neurology, Johann Wolfgang Goethe University, Frankfurt, Germany. PATIENTS: In 4 patients with occlusion of the basilar artery, MRI was performed, including T2-weighted and diffusion-weighted imaging (DWI) sequences and magnetic resonance angiography (MRA) in the short-term phase (<12 hours). Three patients underwent intra-arterial thrombolysis. Clinical outcome was obtained 10 days after symptom onset. RESULTS: The MRA was performed 3.5 to 11.5 hours after symptom onset and showed basilar artery occlusion in all cases. The DWI revealed different patterns of ischemic lesions. In 2 patients, no or only small lesions could be identified; the remaining showed multiple and large lesions within the posterior circulation territory. Initial clinical status was severely impaired in all cases (Rankin scale score, 4-5). Thrombolysis was initiated in 3 patients, leading to successful recanalization in 2. Clinical outcome was favorable in the 2 patients with small DWI lesions and successful reperfusion (Rankin scale score, 2), whereas it was worse in those with large DWI lesions and persisting occlusion (death, persisting coma). CONCLUSIONS: In critically ill patients with acute basilar occlusion, the extent of DWI lesion involvement can be highly variable. Small DWI lesions seem to be associated with a favorable outcome if reperfusion is achieved with thrombolysis. This could potentially be the case independent of time from symptom onset.

Aged↗

PubMed2002

Increased choline levels coincide with enhanced proliferative activity of human neuroepithelial brain tumors.

Proton MR spectroscopy ((1)H MRS)-visible total choline-containing compounds (tCho-compounds) are derivatives of membrane phospholipids and, in part, may act as a long-term second-messenger system for cellular proliferation. Experimental evidence suggests increasing concentrations of tCho-compounds during cellular proliferation. The present study was conducted in order to test the hypothesis that in vivo measurements of tCho-concentrations using (1)H MRS allow assessment of the proliferative activity of neuroepithelial brain tumors presurgically. Single-voxel (1)H MRS (PRESS, TR 1500 ms, TE 135 ms) was performed in 101 patients with neuroepithelial brain tumors prior to surgery and 19 healthy volunteers. Histological diagnoses were confirmed postsurgically according to the WHO classification. Measured tCho-compound signal intensities were corrected for coil loading, numbers of acquisitions and voxel size, and tCho concentrations calculated as institutional arbitrary units. They were matched with the mean immunohistochemical marker of cell proliferation, the Ki-67 (MIB.1) labeling index, using correlation analysis according to Spearman. Compared with low-grade tumors (i.e. WHO grade I/II) and normal white brain matter, high-grade tumors (i.e. WHO grade III/IV) revealed significantly (p < 0.05) elevated labeling indices paralleled by increasingly elevated tCho-concentrations. In contrast tCho-concentrations in low-grade tumor did not differ significantly from physiological values. A highly significant positive correlation (p < 0.0001, r(2) = 0.81) was found between the tCho-concentration and the labeling index. It was concluded that the determination of tCho-concentrations using in vivo (1)H MRS could provide a novel and noninvasive assessment of the proliferative activity of neuroepithelial brain tumors, pointing at (1)H MRS as a useful method for differentiating proliferating from non-proliferating tissues. Hence, potential indications for the clinical application of (1)H MRS are grading tumors presurgically, early detection of anaplastic transformation, and monitoring treatment.

Brain↗

PubMed2002

Distributed cortical systems in visual short-term memory revealed by event-related functional magnetic resonance imaging.

The spatio-temporal distribution of brain activity as revealed by non-invasive functional imaging helps to elucidate the neuronal encoding and processing strategies required by complex cognitive tasks. We investigated visual short-term memory for objects, places and conjunctions in humans using event-related time-resolved functional magnetic resonance imaging that permitted segregation of encoding, retention and retrieval phases. All conditions were accompanied by the activation of a widespread network of parietal and prefrontal areas during the retention phase, but this retention-related activity showed additional modulations depending on task instructions. These modulations confirmed a posterior-anterior and right-left dissociation for spatial versus non-spatial memory and revealed that conjunction memory does not rely on a linear addition of the component processes.

Adult↗

PubMed2002

Functional magnetic resonance imaging in acute unilateral optic neuritis.

Despite good clinical criteria for diagnosing optic neuritis (ON), only a few techniques can precisely assess its impact on visual brain function. The authors studied whether functional magnetic resonance imaging (fMRI) of visual activation reliably reflects the cerebral consequences of acute unilateral ON, and how fMRI correlates with clinical function and visual evoked potentials (VEPs). Twenty ON patients, before and after steroid treatment, were compared to 20 controls. Each eye was stimulated separately with a checkerboard pattern reversing at 1, 2, 4, and 8 Hz. VEPs were recorded the same day. Initially, affected eye responses differed significantly from those of unaffected counterparts and controls in 12 patients. Post hoc classification by fMRI criteria was correct in approximately 85%. fMRI and VEP response parameters (as well as visual acuity) correlated significantly. The higher stimulation frequencies yielded greater fMRI responses from unaffected eyes, but not from affected eyes, in controls. The fMRI responses were quantifiable in every subject, whereas in 11 ON eyes, no VEPs were obtained during the acute stage. The authors conclude that fMRI is sensitive to the cerebral response alteration during ON and might therefore contribute to evaluating the temporal evolution of the visual functional deficit during recovery or therapy.

Acute Disease↗

PubMed2002

Recanalization results after carotid stent placement.

BACKGROUND AND PURPOSE: The details of stent reconstruction in the vascular lumen and of the adaptation of carotid stents, the vessel wall, and the vascular anatomy are only occasionally reported. The purpose of this study was to determine the immediate and longer-term anatomic results after implantation of self-expanding carotid stents. METHODS: In a retrospective study, pre- and postprocedural angiograms and duplex sonograms from 40 consecutive carotid stent procedures in 39 patients (22 men, 17 women; mean age, 67 years; age range, 53-84 years) with high-grade (> or =70 %) internal carotid artery (ICA) stenoses were evaluated to assess the expansion of the vascular lumen, apposition of the stent, and geometric changes in the ICA after the implantation of rolling-membrane and carotid Wallstents (n = 22) or Easy Wallstents (n = 18). RESULTS: Optimal widening of the lumen and apposition of the stent were achieved in 11 (28%) of 40 arteries. Residual stenoses (n = 16), free stent filaments not attached to the vessel wall (n = 21), and stent-induced kinking of the ICA (n = 6) were minor shortcomings of stent reconstruction. Because of one death, peri-interventional morbidity and mortality rates were 3%. During follow-up (median, 24 months), one high-grade restenosis, one ipsilateral stroke, and two ipsilateral transient ischemic attacks were observed. CONCLUSION: Suboptimal anatomic results frequently occur after endovascular treatment of atherosclerotic carotid artery stenosis with self-expanding Wallstents. With the exception of one symptomatic restenosis, no major complications or longer-term sequelae were clearly related to these findings, but further controlled follow-up studies of larger samples are required.

Aged↗

PubMedDate not supplied

Engagement of lateral and medial prefrontal areas in the ecphory of sad and happy autobiographical memories.

Autobiographic memory is usually affect-laden, either positively or negatively. A central question is whether the retrieval of both emotive forms of memory engages the same or a different neural net. To test this we studied 13 normal subjects with functional magnetic resonance imaging while they retrieved a number of distinct episodes, all of which were either rated as strongly positive (happy) or strongly negative (sad) in affect. Comparing the retrieval of sad with that of happy episodes revealed activation in both lateral orbital cortices symmetrically (extending into the ventrolateral prefrontal cortex as well), together with a small region in the right lateral temporal cortex and the left cerebellum. Vice versa, comparing the retrieval of happy with that of sad episodes revealed a major activation in the left hippocampal region, bilateral (though more right-sided) activation in the medial orbitofrontal/subgenual cingulate and a left sided activation in the dorsolateral prefrontal activation. These findings point to the importance of the orbitofrontal cortex for affect-laden information processing and to the existence of distinct neural nets for the re-activation of positively and negatively viewed autobiographic episodes.

Adult↗