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Biomedical subjects

W Möller-Hartmann

Publications and source records attributed to W Möller-Hartmann.

17 recordsLinked to original sources
PubMed2002

Endovascular treatment of experimental aneurysms in rabbits using Guglielmi detachable coils -- a feasibility study.

The Guglielmi detachable coil (GDC) has been generally accepted for treatment of intracranial aneurysms. Preclinical testing of new coil developments requires animal models of aneurysms which imitate human aneurysms in size, configuration and neck morphology. We assessed in detail the technical requirements and steps for transfemoral treatment of experimentally induced aneurysms at the top of the brachiocephalic trunk (TBC) in rabbits. We created aneurysms in five rabbits by distal ligation and intraluminal incubation of the right common carotid artery with elastase. All animals were treated successfully 2-3 weeks after induction of the aneurysm, with dense packing of the coils. No complications related to the procedures occurred. The study demonstrates that our animal model can be a suitable method for testing the biocompatibility and occlusion rate of new embolic materials.

Aneurysm↗
PubMed2002

Clinical application of proton magnetic resonance spectroscopy in the diagnosis of intracranial mass lesions.

Diagnosis of primary and secondary brain tumours and other focal intracranial mass lesions based on imaging procedures alone is still a challenging problem. Proton magnetic resonance spectroscopy (1H-MRS) gives completely different information related to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumour tissues. Our purpose was to evaluate the clinical utility of 1H-MRS added to MRI for the differentiation of intracranial neoplastic and non-neoplastic mass lesions. 176 mostly histologically verified lesions were studied with a constant clinically available single volume 1H-MRS protocol following routine MRI. 12 spectra (6.8%) were not of satisfactory diagnostic quality; 164 spectroscopic data sets were therefore available for definitive evaluation. Our study shows that spectroscopy added to MRI helps in tissue characterization of intracranial mass lesions, thereby leading to an improved diagnosis of focal brain disease. Non-neoplastic lesions such as cerebral infarctions and brain abscesses are marked by decreases in choline (Cho), creatine (Cr) and N-acetyl-aspartate (NAA), while tumours generally have elevated Cho and decreased levels of Cr and NAA. Gliomas exhibit significantly increased Cho and lipid formation with higher WHO tumour grading. Metastases have elevated Cho similar to anaplastic astrocytomas, but can be differentiated from high-grade gliomas by their higher lipid levels. Extra-axial tumours, i.e. meningiomas and neurinomas, are characterized by a nearly complete absence of the neuronal marker NAA. The additive information of 1H-MRS led to a 15.4%-higher number of correct diagnoses, to 6.2% fewer incorrect and 16% fewer equivocal diagnoses than with structural MRI data alone.

Aspartic Acid↗
PubMed2002

Proton magnetic resonance spectroscopy of neurocytoma outside the ventricular region--case report and review of the literature.

Central neurocytoma is classically considered as an intraventricular benign tumour, largely based on data from small retrospective series and single case reports. We report on a 16-year-old girl who suffered from a large parietooccipital tumour that was diagnosed histologically as central neurocytoma. The features of CT, MRI and proton MR spectroscopy studies are discussed. This is the first report on spectroscopic findings in a case of extraventricular neurocytoma. As well as elevated choline (Cho), the tumour spectrum showed strongly decreased N-acetylaspartate (NAA). NAA is assumed to be produced in mature neurons, and we therefore expected to find high amounts of NAA in this well-differentiated tumour, which was histologically composed of mature neuronal tissue. This observation leads to the conclusion that even the highly differentiated cells of neurocytomas are too immature to produce NAA.

Adolescent↗
PubMed2002

Functional MRI and 18F FDG-positron emission tomography for presurgical planning: comparison with electrical cortical stimulation.

BACKGROUND: In patients with mass lesions near "eloquent" cortical areas different preoperative mapping techniques can be used. Two of the most widely used approaches include positron emission tomography (PET) and functional MRI (fMRI). We employed both methods in the same patients undergoing presurgical evaluation and compared the results to those obtained by direct electrical cortical stimulation (DECS). METHOD: 22 patients with tumours of different aetiology near the central region were investigated. FMRI was performed using a T2(*)-weighted gradient-echo BOLD sequence at 1.5 T, PET was performed after injection of 122-301 MBq (18)F-Fluorodeoxyglucose (18-FDG) under rest and activation conditions. DECS was performed in all patients with recordings of muscles primarily involved in the investigated tasks. FINDINGS: In 19 patients all three modalities could be compared, 1 patient demonstrated discordance between fMRI and PET with DECS speaking in favour of fMRI, 6 patients had neighbouring results of PET and fMRI (between 1-2 cm distance), 12 patients had overlapping results. INTERPRETATION: The high incidence of neighbouring results is presumably related to fMRI specific artefacts. Advantages of fMRI are: Higher spatial and temporal resolution, more and different functional runs, shorter examination time, wider availability, longitudinal examinations, non-invasiveness and cost-effectiveness, easy registration to anatomical images. Advantages of PET are: higher signal-to-noise ratio, lesser susceptibility to artefacts (motion, draining veins), evaluation of tumour metabolism. It is our opinion that the neurosurgeon has to decide on a case-by-case basis which study suits his specific needs in the presurgical evaluation of his patient.

Adult↗
PubMed2001

Metabolic and electrophysiological validation of functional MRI.

OBJECTIVES: Although functional MRI is widely used for preoperative planning and intraoperative neuronavigation, its accuracy to depict the site of neuronal activity is not exactly known. Experience with methods that may validate fMRI data and the results obtained when coregistering fMRI with different preoperative and intraoperative mapping modalities including metabolically based (18)F-fluorodeoxyglucose PET, electrophysiologcally based transcranial magnetic stimulation (TMS), and direct electrical cortical stimulation (DECS) are described. METHODS: Fifty patients were included. PET was performed in 30, TMS in 10, and DECS in 41 patients. After coregistration using a frameless stereotactic system, results were grouped into overlapping (<1 cm distance), neighbouring (<2 cm), or contradictory (>2 cm). RESULTS: Comparing fMRI with PET, 18 overlapping, seven neighbouring, and one contradictory result were obtained. In four patients no comparison was possible (because of motion artefacts, low signal to noise ratio, and unusual high tumour metabolism in PET). The comparison of TMS and fMRI showed seven overlapping and three neighbouring results. In three patients no DECS results could be obtained. Of the remaining 38 patients, fMRI hand motor tasks were compared with DECS results of the upper limb muscles in 36 patients, and fMRI foot motor tasks were compared with DECS results of the lower limb on 13 occasions. Of those 49 studies, overlapping results were obtained in 31 patients, and neighbouring in 14. On four occasions fMRI did not show functional information (because of motion artefacts and low signal to noise). CONCLUSIONS: All validation techniques have intrinsic limitations that restrict their spatial resolution. However, of 50 investigated patients, there was only one in whom results contradictory to fMRI were obtained. Although it is not thought that fMRI can replace the intraoperatively updated functional information (DECS), it is concluded that fMRI is an important adjunct in the preoperative assessment of patients with tumours in the vicinity of the central region.

Adult↗
PubMed2001

Brain abscess.

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Brain Abscess↗
PubMed2000

Brain abscess decades after a penetrating shrapnel injury.

We describe a patient who developed a brain abscess 52 years after sustaining a penetrating craniocerebral shrapnel injury. For 10 years he had suffered from diabetes mellitus, a disorder known to predispose to infections from a diminished body defence. The treatment and aetiology of this rare occurrence is discussed.

Aged↗
PubMed1999

Acute necrotising encephalopathy of childhood after exanthema subitum outside Japan or Taiwan.

Acute necrotising encephalopathy of childhood (ANE) is an uncommon disease which predominantly affects infants and young children living in Japan and Taiwan. A multifocal encephalopathy with symmetrical lesions in the thalamus, tegmentum of the brain stem, cerebral periventricular white matter and cerebellar medulla is characteristic. We present the imaging features in a 4-year-old Japanese boy who had been living in Germany for 2 1/2 years before presentation.

Brain↗
PubMed1996

[Circular dissection of the ascending aorta with intimo-intimal invagination. CT diagnosis of a rare form of aortic dissection].

Intimointimal intussusception is a rare type of aortic dissection. The intimal tear occurs circumferentially with intussusception of the intimal flap downstream into the aortic arch causing obstruction of the great supraaortic vessels. A CT diagnosis has only once been reported. CT and angiographic findings of this rare complication of aortic dissection are described.

Aortic Dissection↗
PubMed1995

[Abdominal involvement in neurofibromatosis type 1].

Neurofibromas are benign tumours that arise from neuroectodermal tissues. They may occur as solitary lesions, or multiple, then referred to as neurofibromatosis, or von Recklinghausen's disease. We report on a 27-year old patient with large involvement of many nerve trunks and plexus (elephantiasis nervosa), responsible for bowel obstruction and anuria.

Abdominal Neoplasms↗
PubMed1995

[Emboliform sarcoma of the right pulmonary artery].

Sarcoma of the pulmonary artery is a rare tumor. The histopathologic features of these tumors differ widely, with leiomyosarcomas representing less than 20% of all pulmonary sarcomas. Diagnosis is very difficult because most of the cases have no specific clinical signs: the major differential diagnosis is that of pulmonary thromboembolism. We report the case of a 45-year-old woman, who was first treated for pulmonary thromboembolism until the diagnosis of an intravascular growing tumor was made by means of computed tomography, pulmonary angiography and nuclear magnetic resonance tomography. The patient underwent right pneumonectomy and microscopically a leiomyosarcoma of the right pulmonary artery was found.

Diagnosis, Differential↗
PubMed1994

[Diagnosis of a left-sided cervical aortic arch with nuclear magnetic resonance tomography].

Aortic arch anomalies are rare. They arise as a failure of the normal development of the left fourth dorsal arch. Cervical aortic arches are believed to result from persistence of the third dorsal arch, which re-routes the aortic arch in the cervical region. We describe a case of a left-sided cervical aortic arch in which the diagnosis was confirmed, and the anatomy defined, using magnetic resonance tomography.

Angiography, Digital Subtraction↗
PubMed1991

Nephrotoxicity of paracetamol in the rat--mechanistic and therapeutic aspects.

Besides hepatotoxicity, paracetamol may exert nephrotoxic effects in experimental animals and patients. The present study in rats shows that antidotes known to protect against hepatotoxicity, such as methionine or N-acetylcysteine, are not effective in preventing paracetamol-induced kidney damage. Only diethyldithiocarbamate, an inhibitor of microsomal monooxygenases, provided complete protection against both hepato- and nephrotoxicity. While a marked depletion of glutathione was observed in the liver, no such effect was seen in the kidney. These data suggest that the mechanism of paracetamol nephrotoxicity seems to be quite different from that responsible for the hepatotoxicity. The hypothesis that a C-S-lyase-mediated final metabolism of paracetamol-S conjugates in the kidney might be responsible for nephrotoxicity needs support by further experimental investigations.

Acetaminophen↗
PubMed1989

Cholestyramine as an antidote against paracetamol-induced hepato- and nephrotoxicity in the rat.

Besides hepatotoxicity, paracetamol may exert nephrotoxic effects in experimental animals and man. The present study in rats shows that cholestyramine given 4 and 24 h after paracetamol provided protection against both hepato- and nephrotoxicity; this was evidenced by reduced increments in plasma enzyme activities (SDH, GPT), indicating liver damage, and diminished retention of plasma and creatinine, indicating renal failure. The recovery of paracetamol and its conjugates in urine was markedly reduced by cholestyramine at 24-48 h after treatment. The protective effects of cholestyramine are explained by adsorption of paracetamol and conjugates in the intestine undergoing biliary excretion and enterohepatic circulation.

Acetaminophen↗