Biomedical subjects

D Hellwig

Publications and source records attributed to D Hellwig.

At least 55 records · Page 3Linked to original sources

PubMed1995

Stereotactic endoscopic interventions in cystic brain lesions.

Stereotactic endoscopic techniques are extremely helpful in diagnosis and therapy of cystic intracerebral space occupying lesions. Acute space occupying lesions can be managed effectively and without major tissue traumatization. Up to now we have operated on more than 70 cystic intracerebral space occupying lesions with a stereotactic endoscopic technique. The main diagnoses were colloid cysts, cystic craniopharyngeoma, arachnoidal and pineal cysts. In must be stressed that in cystic anaplastic astrocytomas and glioblastomas as well as metastases only an acute inner cerebral decompression can be achieved by neuroendoscopic techniques in combination with the application of reservoir systems. In benign parenchymal or intraventricular cysts neuroendoscopic intervention is performed for definitive treatment. The results are overall encouraging. There was no operative mortality and operative morbidity was below 3%. Postoperative follow-up in patients with benign cysts showed no evidence of recurrence.

Arachnoid Cysts↗

PubMed1995

[Effect of morphological changes on perfusion and metabolism in cerebral microangiopathy. A comparison of PET, SPECT, and magnetic resonance imaging findings].

51 patients with cerebral microangiopathy were studied with MRI, 18FDG-PET, and 99mTc-HMPAO-SPECT. Exact morphological correlation of MRI-findings to functional data from PET and SPECT was obtained by a special head holder system applied to the patient's head. Patients with less than four lacunar infarctions (LI) and without or only slight deep white matter lesions (DWML) in MRI showed no significantly changed parameters (rMRGlu, rCBF) compared to patients with four or more LI and severe DWML. Patients with medium to severe outer and inner brain atrophy showed significantly lower rMRGlu and rCBF values in both cortex and white matter than patients with no to only slight atrophy. Thus, in patients with cerebral microangiopathy only atrophy and not the presence of LI and DWML is associated with a significant reduction of rCBF and rMRGlu.

Brain↗

PubMed1995

[Comparison of relative 18FDG uptake with metabolic rate (MRGlucose) in the myocardium in CAD, classified by 99m-Tc-MIBI].

AIM: Are i) typical patterns of perfusion/metabolism (match, mismatch), gained from relative 99mTc-MIBI vs relative 18FDG uptake (normalized to the perfusion maximum) obtainable also vs absolute MRGlu and is ii) rMRGlu in the segment of maximum perfusion (MIBI = 100%) within the normal range for all degrees of coronary artery disease (CAD)? METHODS: In 55 non-diabetic patients with CAD, relative myocardial perfusion (99mTc MIBI SPECT at rest) and relative 18FDG uptake (PET after glucose load) were used to separate for various flow/metabolism constellations. In addition, regional glucose metabolic rate (rMRGlu in mumol/100 g/min; dynamic-graphic analysis from Gambhir/Patlak) was determined in 13 segments of the left ventricle each (i.e., in a total of 715 segments). RESULTS: rMRGlu revealed wide standard deviations (up to 51%). It decreased from normal (52.7 +/- 27.3 mumol/100 g/min), mismatch (45.3 +/- 17.3) and intermediate (35.2 +/- 12.4) to match ("non viable"; 26.7 +/- 13.3) significantly (p < 0.01). In 26% of the perfusion maxima, MRGlu was < 40 mumol/100 g/min. Out of these, only in five patients (of 28) with 3-vessel disease, it was even smaller (< 30 mumol). In three out of the latter, glucose blood levels were below euglycemia. CONCLUSION: rMRGlu in CAD revealed an identical perfusion/metabolism pattern as relative 18FDG uptake. Thus, the higher efforts employed to compute rMRGlu do not yield diagnostic advantage. The segmental perfusion maximum, used for normalization of relative 18FDG uptake (100% MIBI uptake = 100% FDG uptake) was reliable in euglycemic patients even with 3-vessel disease.

Biological Transport↗

PubMed1994

Minimally invasive endoscopic neurosurgery--a survey.

In 1989 we introduced "endoscopic stereotaxy" as a new operative procedure into neurosurgery. This technique was first scheduled to optimize stereotactic biopsy. In its further development it proved to be effective for other indications. We choose the term "Minimal Invasive (Endoscopic) Neurosurgery (MIEN)" for these interventions. Minimal invasive endoscopic techniques are applied preferably for diagnostic and therapeutic interventions on preformed or pathological cavities of the central nervous system. The indications are, endoscopic-stereotactic biopsy of space-occupying lesions, ventriculoscopy and endoscopic ventriculostomy in diagnosis and treatment of hydrocephalus, endoscopic evacuation of cystic space occupying lesions, endoscopic evacuation of intracerebral haematoma, endoscopic evacuation of septated chronic subdural haematoma, endoscopic evacuation of subacute or chronic brain abscesses, endocavitary syringostomy. Our results with minimal invasive endoscopic interventions for different indications are encouraging when compared to conventional microsurgical techniques. We have performed more than 300 minimal invasive endoscopic interventions. The mortality rate was below 1%, the operative morbidity was below 2%.

Biopsy↗

PubMed1994

Endoscopic stereotactic treatment of brain abscesses.

Treatment of brain abscess is still a subject of controversy. Craniotomy with primary extirpation and resection of the abscess membrane, burrhole craniotomy with puncture or insertion of a drain, marsupialization, or stereotactic aspiration are different therapeutic approaches. As a consequence of our experiences and results with neuro-endoscopic interventions we have introduced endoscopic stereotactic techniques in brain abscess treatment. Seven patients with brain abscesses were operated on stereotactically using an endoscope. In all cases the abscess contents were aspirated, while the abscess membrane was left in situ. The patients received postoperative antibiotic therapy according to microbial diagnosis. The longest follow-up period was 48 months. Six patients showed a marked improvement of neurological deficit after treatment. One patient died from sepsis caused by a bacterial endocarditis. The results emphasize that endoscopic stereotactic technique as a minimally invasive neurosurgical method can also be used for treatment of brain abscess.

Adult↗

PubMed1994

Endoscopic anatomy of the third ventricle.

42 cadaver brains in situ were examined endoscopically to work out topographical anatomical landmarks for orientation. The endoscopic route from the chosen precoronal trepanation point to the defined ventricular landmarks has been measured in 22 cases. The identification and measurements of the anatomical landmarks are helpful for safe and atraumatic endoscopical navigation within the ventricular system. Furthermore this article describes and discusses cerebral lesions during ventriculoscopy.

Brain Mapping↗

PubMed1994

F-18 fluorodeoxyglucose PET in vivo evaluation of pancreatic glucose metabolism for detection of pancreatic cancer.

PURPOSE: To evaluate positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (FDG) for detection of pancreatic cancer compared with computed tomography (CT) and ultrasonography (US). MATERIALS AND METHODS: Forty patients with suspected pancreatic cancer underwent static PET after intravenous injection of 150-300 MBq FDG. Focal FDG accumulation was regarded as a sign of malignancy and was quantitated by calculating differential uptake ratios (DURs) and tumor-liver ratios (TLRs). RESULTS: Malignancy was histologically proved in 27 patients. PET helped correctly classify 25 of 27 malignant conditions and 11 of 13 benign disorders. DUR and TLR were statistically significantly higher in malignant compared with benign disease (P < .01). False-negative findings were obtained in patients with insulin-dependent diabetes. False-positive findings were noted in a patient with retroperitoneal fibrosis and in one with pancreas divisum with chronic pancreatitis. PET was superior to CT and US in detection of lymph node metastases (13 of 17 vs three of 17 or one of 15, respectively. CONCLUSION: FDG PET has the potential to improve the detection of lymphadenopathy and the differential diagnosis of pancreatic masses.

Adenocarcinoma↗

PubMed1994

[Results and reliability of stereotactic and endoscopic biopsies in brain tumors].

Stereotactic neurosurgery was the first "minimal invasive method" in the field of neurosurgery, later followed and partly replaced by endoscopic techniques. One reason for such an approach is sampling of small tissue probes for diagnosis, e.g. in brain tumours not accessible to open surgery. The appropriate method in the hands of the experienced is the "Quetsch" or smear technique. Its reliability is limited by the fact, that the "architectural" or "tissular" components of tumours lack in those purely cytological preparations. Tissue architecture however is crucial for the assessment of different grades in glial tumour progression. The grade of a glial tumour is the most critical information for the patient and the therapist; grading of the supratentorialf gliomas of the adult by means of cellular and tissue pleomorphism therefore forms the basis of Zülchs system of classification and grading of all intracranial tumours by comparison of postoperative survival. The resulting four grade system--slightly modified--is part of the old and new issue of the WHO classification of brain tumours. In order to specify the possibility of correct diagnosis and grading in probes gained by the minimal invasive techniques, we present results of three diagnostic approaches: First: We report results of a study performed during the last twelve years in which a diagnosis of smear preparations had been made on neurosurgical specimens prior to conventional handling. The "blind" cytological diagnosis was then compared with the final diagnosis of the tumour using light and electron microscopy and immunohistochemistry. Second: We report results and estimates of tissue probes gained by the so called sandwich technique in which the removal of material for cytological analysis is done stepwise. By doing so, material representative for different compartments of the neoplasm is obtained. This implies collaboration between neurosurgeon and neuropathologist not only during the time of stereotactic action but also in the planing period; the correct interpretation of the different compartments delivered by imaging methods in this context is essential. Third: We present selected cases of probe sampling under direct visual control by endoscopy. This method is especially useful for tumours bordering the ventricular system. Surface structures and cyst linings can be visualized directly if the endoscopist is familiar with normal and pathological tissue appearance. The specimen for analysis may therefore be taken from the most relevant tumour region and the sandwich technic which means tissue damaging in multiple localisations can be partly or fully avoided.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1994

A method of correlating and merging cerebral morphology and function by a special head holder.

A method is introduced which records and correlates topographically identical morphological and functional image data by means of a special head holder system which is adaptable to different modalities (MRI, PET, SPECT). It is based on a commercially available thermoplastic headmask. A thermoplastic form is used to mold an individual headmask (time required: 7 min) for all modalities providing a fixation of the patient during acquisition. This method guarantees an exact repositioning and therefore the same slice orientation of the images. The in-plane correlation is performed by adapting standard offset parameters determined with a homogeneous head phantom. By fusion (merging) of the brain outline contours or images themselves the accuracy was tested in MRI vs. PET resp. SPECT (transaxial accuracy: < or = 2.0 mm, axial: < or = 3.0 mm in patients with MRI-slice thickness of 6.0 mm).

Brain↗

PubMed1993

Pancreatic cancer detected by positron emission tomography with 18F-labelled deoxyglucose: method and first results.

In order to evaluate the utility of positron emission tomography (PET) with 18F-labelled deoxyglucose (FDG) for detection of pancreatic cancer 15 patients with pancreatic masses shown by computed tomography were investigated. Static PET scans covering an axial field of view of 15 cm were obtained 45 min after intravenous injection of 150-300 MBq FDG. Focally increased FDG accumulation was present in 12 out of 13 patients with histologically proven adenocarcinoma, in particular in eight of nine lymph node and four of five liver metastases. Scans of two patients with chronic pancreatitis confirmed by surgery revealed a normal FDG distribution. Contrast between tumour and normal tissue depended the metabolic situation prior to FDG injection. High ratios were found in fasting patients whereas no elevated FDG uptake was measured in an insulin-dependent diabetic suffering from carcinoma of the pancreatic head. We conclude that FDG PET might have the potential for detection and even differentiation of pancreatic carcinoma from chronic pancreatitis. Further studies are necessary to substantiate these preliminary findings and to optimize results in diabetic patients.

Adenocarcinoma↗

PubMed1993

[Primary cerebral lymphoma. Current status of diagnosis and therapy].

Primary cerebral lymphomas are rare tumors. In the last years the frequency of these space occupying lesions is increasing. Diagnosis by image-generating methods is often difficult. Stereotactic biopsy is a reliable diagnostic tool. Explorative craniotomy with tumor resection should be avoided if possible. An effective multimodal therapeutic regimen is the combination of radiotherapy and chemotherapy. Epidemiologic data, diagnostic methods and therapeutic proceedings are presented and discussed on a series of 7 patients with primary cerebral lymphomas treated in our department.

Aged↗

PubMed1992

Minimally invasive neurosurgery by means of ultrathin endoscopes.

The term "minimally invasive neurosurgery" (MIN) is defined and the present indications for MIN are described. They include endoscopic stereotactic interventions, endoscopic evacuations of chronic subdural haematomas and intracerebral mass-haemorrhages, endoscopic spinal and ventriculoscopic procedures. The advantages compared to conventional diagnostic and therapeutic neurosurgical approaches consist of less operative risk and reduced tissue-traumatization. Endoscopy makes interventions under (real-time) conditions possible. The operative stress for the patient is minimized.

Cerebral Hemorrhage↗

PubMed1991

Endoscopic procedures in stereotactic neurosurgery.

A new prototype of an endoscope for stereotactic interventions is described. This endoscope is adapted to the Mundinger-Birg stereotactic system. Stereotactic endoscopic procedures are carried out for brain-tumour-biopsy as well as for evacuation of haematomas, brain-cysts and abscesses. Ventriculoscopy is performed on hydrocephalus and biopsy of ventricle-relating tumours. One-year experience with stereotactic endoscopy is reviewed.

Brain Diseases↗

PubMed1991

Stereotactic-endoscopic procedures on processes of the cranial midline.

The term "midline tumour" is defined partly from the topographic and from the pathogenetic point of view. Problems of modern imagegenerating procedures in establishing the diagnosis of cerebral midline lesions are described. The role of stereotactic diagnostic and therapeutic interventions is emphasized. Stereotactic brain tumour biopsy, installation of shunts and reservoirs under visual control are performed. Interstitial radiotherapy is carried out for low-grade gliomas. As an important innovation, stereotactic procedures are combined with endoscopic techniques. Particular diagnostic and therapeutic difficulties of typical midline tumours such as craniopharyngeoma, germinoma, glioma and primary cerebral lymphoma as a local extension are discussed. A reasonable concept in diagnosis and therapy of cerebral midline lesions is proposed.

Adolescent↗

PubMed1991

[Stereotactic intervention as a contribution to diagnosis and therapy of paramedian processes].

In open brain surgery, access to processes in the midline region is difficult. Exact diagnosis of the tumour type is crucial to the choice of therapeutic modality. In many cases, modern imaging procedures such as CT and MRI are useful diagnostic tools. The diagnosis is confirmed by direct biopsy and histological examination. Selected cases of tumours close to the midline (germinoma, pilocytic astrocytoma, primary cerebral malignant lymphoma) are presented. CT and MRI are helpful in demonstrating space-occupying processes. The tumour's histological type is determined by CT-stereotactic biopsy. The histopathological diagnosis is established by means of a crush preparation. Appropriate forms of therapy are proposed on the basis of the diagnosis of tumour type. The results are impressive, due to the efficacy of stereotactic procedures as an additional means of diagnosing and treating space-occupying processes of the midline region.

Astrocytoma↗

PubMed1991

[Epithelial cyst of the central nervous system. A rare abnormality].

A cystic process in the right frontal lobe of the brain in a man of 35 years of age, and an intramedullary cyst in the upper cervical spinal cord in a 29-year old woman, are described. In both cases, the wall of the cyst consisted of mucosal cells and cells having cilia pointing to the inside, located on a thin tissue layer, the structure of which resembled that of a meningioma. Central nervous cysts of this kind are usefully classified together with other, similar cysts (bronchogenic, ependymal and others) as "epithelial cysts". They must be differentiated from neoplastic tumours. Analysis of the cystic contents can prove helpful.

Adult↗

PubMed1990

Epithelium-derived inhibition of [3H]acetylcholine release from the isolated guinea-pig trachea.

To investigate presynaptic, regulatory mechanisms on parasympathetic nerve fibres innervating the airways, the release of newly-synthesized [3H]acetylcholine from the isolated trachea was studied. Reverse phase HPLC followed by liquid scintillation spectrometry was used to separate and quantify the radioactive compounds choline, phosphorylcholine and acetylcholine in the incubation medium and the tissue. During the incubation of the tracheae with [3H]choline a significant synthesis of [3H]acetylcholine (35,000 dpm/preparation) and [3H]phosphorylcholine (500,000 dpm/preparation) occurred. In epithelium-deficient tracheae the formation of [3H]phosphorylcholine was enhanced, whereas the content of [3H]acetylcholine remained unchanged. The spontaneous outflow of tritium consisted mainly of [3H]phosphorylcholine (900 dpm/3 min) and [3H]choline (800 dpm/3 min); [3H]acetylcholine was only a minor fraction (50 dpm/3 min). Electrical stimulation of tracheae with intact epithelium caused only a small release of [3H]acetylcholine (460 dpm in the sample obtained during stimulation), but a considerable outflow of [3H]phosphorylcholine (1,900 dpm) without affecting the outflow of [3H]choline. Electrical stimulation of epithelium-deficient tracheae, however, induced a substantial release of [3H]acetylcholine (2,400 dpm), but only a small outflow of [3H]phosphorylcholine. Chemical stimulation (30 mumol/l veratridine) also caused a large release of [3H]acetylcholine (1,700 dpm) without affecting the outflow of [3H]phosphorylcholine or [3H]choline. Indomethacin (3 mumol/l) enhanced the electrically-evoked release of [3H]acetylcholine from tracheae with intact epithelium by 89%. The present experiments demonstrate a strong inhibition by the epithelium of the electrically-evoked release of [3H]acetylcholine from the isolated guinea-pig trachea. Cyclooxygenase products of arachidonic acid do not appear as the main mediators of the epithelium-derived inhibition of acetylcholine release.

Acetylcholine↗

PubMed1990

Assessment of histogenesis and proliferative potential in cytologic specimens of human brain tumors. Value of immunocytochemistry and nucleolar organizer regions.

The value of immunocytochemistry and nucleolar organizer regions (NORs) for the histogenetic identification and the estimation of the proliferative potential of brain tumors was assessed by the investigation of imprint smears of 51 neurosurgical tumor specimens. A panel of five monoclonal antibodies was used to cover a broad range of immunohistochemical markers. For the assessment of NORs, a silver staining technique (AgNOR) was used. NORs were enumerated and measured by means of an interactive image analysis system. The immunocytochemical results were similar for the smears and paraffin-embedded sections for 95.6% of the investigations performed and for 76.2% of the cases. Glial fibrillary acidic protein (GFAP) was positive in 9 of 17 tumors of glial origin, but was negative in 9 metastatic tumors. Vimentin was positive in 10 of 10 and fibronectin in 9 of 10 meningiomas investigated. The number of NORs increased steadily with the increasing grade of malignancy. Especially in glioblastomas, the number of NORs per cell exhibited a wide range, which might reflect the heterogeneity of these neoplasms. Metastases revealed a higher number of NORs per cell than did glioblastomas. In the cytologic differential diagnosis of these tumors, an absence of GFAP expression combined with a high NOR count is suggestive of a metastatic tumor.

Adult↗