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Biomedical subjects

W Wichmann

Publications and source records attributed to W Wichmann.

At least 37 records · Page 2Linked to original sources
PubMed1995

Magnetic resonance imaging and intraoperative frozen sections in intratemporal facial schwannomas.

Seven cases of intratemporal facial schwannoma were assessed by preoperative magnetic resonance imaging (MRI) and intraoperative frozen sections to determine tumor boundaries. These results were then analyzed with respect to gross tumor appearance, under the operating microscope, and final histopathologic diagnosis, with immunostains. Gadolinium-enhanced MRI was helpful in planning the surgical and approach and in defining the extent of tumor involvement relative to the facial nerve. Frozen sections on the other hand were often unreliable in confirming the completeness of resection, frequently overestimating tumor infiltration. Ultimately, tumor-nerve interface, especially in the proximal facial segments, is best judged by its gross intraoperative appearance under high magnification, with the aid of MRI. The difficulty in establishing tumor infiltration in the presence of organized neutral fibers and artifacts is emphasized. Immunohistochemical assays are essential in this regard. Complete tumor removal was achieved in all seven cases, with acceptable functional outcome in those with sufficiently long follow-up.

Adolescent↗
PubMed1995

[Anatomy and pathology of the parotid gland. COrrelation with magnetic resonance tomography].

Due to a very complex embryological development a variety of different tissues are mixed together within the parotid gland. Secondary degenerative metaplastic and regenerative alterations result in additional tissue variety. Epithelial cells of distinct differentiation, lymphatic tissue, partly within lymph nodes, partly in clusters, sebaceous tissue, fat and peripheral nervous tissue may be the origin of a pathological neoplastic or inflammatory intraparotid lesion. MRI is an optimal tool for the delineation of the anatomy of the parotid gland and of various intraparotid lesions and often permits differentiation among malignant and benign neoplastic and inflammatory lesions. The morphology of the different pathological lesions on MRI reflects the underlying histopathology. Due to great interindividual variations in the tissue characterization of a specific intraparotid lesion, great differences in MR morphology have to be expected.

Humans↗
PubMed1994

Randomised double blind trial of the safety and efficacy of two gadolinium complexes (Gd-DTPA and Gd-DOTA).

The main difference between macrocyclic Gd-DOTA and linear Gd-DTPA complexes is the greater stability of the former which theoretically might reduce biological interactions in man. To evaluate the clinical relevance of this property, 300 unselected neurological patients were included in a randomised double-blind comparison involving five European centres, focused mainly on the tolerance of these two contrast media. Clinical tolerance was assessed immediately after the procedure and 24 h later. Adverse events were found with a similar frequency in the two groups (17.3% for Gd-DOTA and 19.3% for Gd-DTPA). Minor neurological symptoms were the most frequent (48.6%) headache being the most common (29.2% of adverse events). No difference in efficacy was found.

Adult↗
PubMed1994

Idiopathic, herpetic, and HIV-associated facial nerve palsies: abnormal MR enhancement patterns.

PURPOSE: To determine specific criteria that can be used to define normal versus abnormal MR contrast enhancement of the facial nerve. METHODS: Twenty-three patients with acute unilateral inflammatory peripheral facial nerve palsy were examined on a 1.5-T MR using multiplanar T1-weighted spin-echo sequences before and after injection of gadopentetate dimeglumine. These MR patterns were compared with those of healthy control subjects. RESULTS: The normal facial nerve usually showed a mild to moderate enhancement of the geniculate ganglion and the tympanic-mastoid segment. The intracanalicular-labyrinthine segment did not enhance. All patients showed abnormal enhancement of the distal intracanalicular and the labyrinthine segment. An intense enhancement could be observed in the geniculate ganglion and the proximal tympanic segment, especially in herpetic palsy. Associated enhancement of the vestibulocochlear nerve was seen in herpetic and idiopathic palsy. Enhancement of the inner ear structures was detected only in herpetic palsy. CONCLUSIONS: Abnormal contrast enhancement of the distal intracanalicular and the labyrinthine facial nerve segment is observed in all patients and is the only diagnostically reliable MR feature proving an inflammatory facial nerve lesion. The intense enhancement of the geniculate ganglion and the proximal tympanic segment is possibly correlated with the reactivation of the latent infection in the sensory ganglion. The abnormal enhancement results from breakdown of the blood-peripheral nerve barrier and/or from venous congestion in the venous plexuses of the epi- and perineurium.

Acquired Immunodeficiency Syndrome↗
PubMed1993

[Reversible spinal cord compression caused by extramedullary hematopoietic foci in thalassemia].

A now 42-year-old Thai woman was known to have been anaemic since childhood. When aged 33 years she was diagnosed as having beta zero/HBE thalassaemia. Computed tomography demonstrated a tumour in the posterior mediastinum, histologically found to be an extramedullary haematopoietic focus. Subcutaneous infusion of deferoxamine (2 g five times weekly), initiated because of massive iron overload, reduced the serum ferritin level from 3,460 ng/ml to less than 500 ng/ml. The haemoglobin level in the subsequent years was between 6 and 8 g/dl. Five years later sensory deficits were noted from the 5th thoracic vertebra downwards. Magnetic resonance imaging demonstrated a tumour which compressed the spinal cord: it, too, was an ectopic haematopoietic focus. The neurological symptoms disappeared after radiotherapy with 3,000 cGy, but they recurred 4 years later. Because of the low radiation reserve of the spinal cord, hypertransfusion treatment was initiated, namely 16 RBC concentrates within 4 months and afterwards two transfusions every 3 months. By this means the haemoglobin level was kept at about 9 g/dl. The tumour had regressed 4 months after onset of treatment. For 2 years since the beginning of the hypertransfusion treatment the patient has remained free of neurological symptoms.

Adult↗
PubMed1993

Age distribution and iron dependency of the T2 relaxation time in the globus pallidus and putamen.

Heavily T2-weighted spin echo sequences of the brain show age-dependent low signal intensity in many extrapyramidal nuclei. Although it has been suggested that this low intensity results from non-haem iron, the specific influence of non-haem iron on the T2 relaxation time has not been quantified and remains controversial. The T2 relaxation times of the globus pallidus and putamen were measured from MRI at 1.5T in 27 healthy patients, by using a mathematical model. They were then plotted as a function of age and compared to the curve of age-dependent iron concentration determined post mortem. The curves of T2 relaxation time in the basal ganglia are congruent with published curves of iron concentration, indicating a high probability that the changes in T2 relaxation times and the low signal in the basal ganglia result from the local, age-dependent iron deposition. Individual measurements of T2 relaxation time show less variation before than after 45 years of age, indicating the influence of a second, more individual factor.

Adolescent↗
PubMed1993

Pituitary stalk thickening with diabetes insipidus preceding typical manifestations of Langerhans cell histiocytosis in children.

In up to 25% of cases of children with central diabetes insipidus no organic cause can be documented. We present three boys (age 2.2, 2.3 and 6 years at diagnosis) with acute onset central diabetes insipidus, in whom the only pathological finding using MRI was a thickened central part of the pituitary stalk (> 2.5 mm). Recent reports demonstrate similar MRI findings in adults with Langerhans cell histiocytosis (LCH), sarcoidosis, or tuberculosis, and in children with proven LCH and diabetes insipidus. In those adults with LCH, the pituitary stalk lesion has been histologically verified as a sequela of LCH. In contrast, in two of our three patients pituitary stalk thickening preceded the typical peripheral lesions of LCH by several months, whereas in the third patient there is as yet no evidence of systemic disease. We conclude that thickening of the central part of the pituitary stalk might represent the first manifestations of LCH clinically presenting with diabetes insipidus. MRI investigation of the pituitary stalk in children with unexplained central diabetes insipidus and accurate follow up in patients with thickening of the pituitary stalk in necessary to avoid missing other manifestations of a systemic disease.

Acute Disease↗
PubMed1993

[The imaging diagnosis of acute cerebral tuberculosis].

5 unusual cases of cerebral tuberculosis are reported. Three of the cases initially showed the typical history and aspect of herpes simplex encephalitis, and two of a cerebral tumour. Both CT and MRI, and also the clinical neurological symptoms, were confusing. Microbiological culture in three and histological preparation in two cases confirmed the diagnosis of cerebral tuberculosis. Three cases showed the development of tuberculomas under therapy. The study of the literature suggests that this is not rare, which is explained by pathogenetic reflexions concerning the allergic genesis of the tuberculomas.

Adult↗
PubMed1993

[Magnetic resonance imaging in neuroradiology. Indications and applications].

On the basis of own experience with 250 MR-Angiographies and with reference to the literature the authors report on the role MR-Angiography is assuming in neuroradiological diagnostic procedures. As a noninvasive method MR-Angiography contributes to the evaluation of vessel stenosis and occlusion, venous sinus thrombosis and neurovascular compression syndromes. It supports the work-up of space-occupying lesions, as well as arteriovenous malformations and aneurysms. In addition to the diagnosis, follow-up examinations serve as a noninvasive means of therapy control particularly after interventional endovascular procedures. Knowledge of the diagnostic capabilities and limitations, the choice of the correct examination technique and modification of technical variables contribute to establish MR-Angiography as a valuable adjunct to MR imaging.

Aneurysm↗
PubMed1992

Central neurocytoma: histopathological variants and therapeutic approaches.

The central neurocytoma has recently been added to the differential diagnosis of intraventricular tumors. Histopathologically, this tumor is characterized by a uniform neoplastic cell population with features of neuronal differentiation. Central neurocytomas occur in young adults, develop in the area of the foramen of Monro, and are usually associated with the septum pellucidum. Initial reports appeared to indicate that these tumors are benign lesions with a favorable postoperative prognosis. The authors present clinical and neuropathological findings in a series of eight patients with central neurocytoma. An anterior transcallosal microneurosurgical approach yielded good outcomes. Postoperative radiation therapy was restricted to two patients with a malignant variant of central neurocytoma and one patient with a recurrent tumor. Observations of anaplastic variants of this neoplasm in two cases and local tumor recurrences in three indicate that the biological behavior and postoperative prognosis of central neurocytoma may not always be as favorable as previously assumed.

Adult↗
PubMed1991

Neuroradiology of central neurocytoma.

Central neurocytomas (CN) are rare, usually benign cerebral intraventricular neuroepithelial tumors, which occur in adult patients. Retrospective evaluation of the CT- and MRI-findings in eight cases as well as review of the cases reported in the literature showed that CN usually presents as a primarily slightly hyperdense and/or hyperintense mass within the body of the lateral ventricle with moderate contrast enhancement. The majority of tumors contain both multiple small cysts and calcifications and exhibit a characteristic broad based attachment to the superolateral ventricular wall. We conclude that these criteria appear to be reliable to exclude other intraventricular tumors such as astrocytoma, giant cell astrocytoma, ependymoma, subependymoma, intraventricular oligodendroglioma and meningioma. Preoperative diagnosis of CN may prove of value for planning therapy, because this tumor type seems to have a better prognosis than other intraventricular tumors.

Adult↗
PubMed1991

[MRT morphology and classification of cerebral cavernomas].

An MRI review of 54 histologically verified cavernomas allowed the introduction of a system classifying this cavernous venous malformation into four types: type I (20%) corresponds to the classic morphology of a cavernoma without hemorrhage; type II (67%) is characterized by intralesional hemorrhage; type III (11%) is associated with an extra-lesional hemorrhage that compresses or displaces the cavernoma itself; and type IV (2%) corresponds to a totally calcified cavernoma. These variable cavernoma types represent different possible stages of the natural evolution of a cavernoma and limit the differential diagnosis, especially in the group of occult or cryptic cerebral vascular malformations.

Adolescent↗
PubMed1990

[Diminished vision, loss of libido, headache].

A 34-year old patient was diagnosed to suffer from a carcinoma of the pituitary gland. A developing panhypopituitarism was seen first and the complete extirpation of a chromophobe, non-secreting adenoma of the pituitary gland was preliminary not successful. During half a year the patient relapsed clinically and morphologically by scanning methods and the progression of the malignancy of the tumor from WHO grad (adenoma) to WHO grad III (carcinoma) was histologically confirmed.

Adenoma↗
PubMed1990

Oculomotor disturbances during visual-vestibular interaction in Wallenberg's lateral medullary syndrome.

Transient and lasting oculomotor disturbances during visual-vestibular interaction are described in 9 patients with Wallenberg's lateral medullary syndrome. In all patients magnetic resonance imaging (MRI) demonstrated a single focal area of pathological signal intensity in the (dorso)-lateral medulla suggesting infarction. In 2 of these 9 patients and in 3 further patients with no medullary signs, the infarction involved the cerebellar territory of the posterior inferior cerebellar artery (PICA). Acutely, all patients with Wallenberg's syndrome (except 1) had saccadic lateropulsion and spontaneous nystagmus in light with the horizontal fast component beating to the contralateral normal side. The velocity of the slow drift to the side of the lesion was dependent on eye position and induced a characteristic asymmetry of the visually and vestibularly elicited slow eye movements. In most patients smooth pursuit, optokinetic nystagmus and visual suppression of the vestibulo-ocular reflex were still impaired when this spontaneous drift was minimal or absent. The oculomotor disturbances in patients with and without cerebellar infarction are compared. The following conclusions are made. (1) The spontaneous drift that is dependent on eye position is mostly created by 'ocular lateropulsion', that is, a tonic bias within the oculomotor system which may have several sources. (2) The abnormalities and asymmetries of oculomotor responses during visual-vestibular stimulation cannot solely be explained by this spontaneous drift and its interaction with otherwise normal eye movements. Instead, structures and pathways are damaged in Wallenberg's syndrome which mediate visual and/or motor signals important for the cerebellar control of visually-guided slow eye movements. (3) Damage to these pathways occurs in the lateral medulla, as the MRI findings show that in most patients the cerebellum is rarely involved, but no definite conclusion can be made as to which of the fibres travelling in the inferior peduncle to the cerebellum may be interrupted.

Adult↗
PubMed1989

Cerebrospinal fluid immunoglobulins and multiple sclerosis. Correspondence with magnetic resonance imaging and visually evoked potential changes.

The clinical (disability) and paraclinical (visually evoked potential [VEP]/magnetic resonance imaging [MRI]) data of patients with definite or probable multiple sclerosis (MS) were compared with their cerebrospinal fluid (CSF) immunoglobulins taken within the same period of time. For patients with definite diagnosis by the Schumacher criteria (n = 61) we found significant correlations between CSF immunoglobulin content (absolute gamma-globulin value [aggv]) and quantified MRI factors (r = .47), between aggv and the sum of VEP latencies of both eyes (r = .53), and also between MRI and VEP changes (r = .62). This was not true for the patients with a probable MS diagnosis and for patients with first attacks. No correlations were evident between aggv and disability status or duration of the illness. The results give support to recent neuropathologic and experimental findings in animals indicating close pathogenic connections between CSF immunoglobulins and demyelination in MS.

Adolescent↗
PubMed1989

MRI in Cockayne syndrome type I.

MRI findings are reported from two patients with Cockayne syndrome (CS) type I, aged 11 and 37 years. Changes were compatible with diffuse white matter hypomyelination. Basal ganglia calcification was present in both, marked cerebellar atrophy in the older patient. MRI may support the diagnosis of CS in the appropriate clinical context. The view that CS is a dysmyelinating disorder is further substantiated.

Adult↗