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Biomedical subjects

W Wichmann

Publications and source records attributed to W Wichmann.

16 recordsLinked to original sources
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↗
PubMed1976

ERG of humans without C-wave.

Three out of 18 healthy persons investigated with the DC-ERG do not show a c-wave. By varying the adaptation levels and intensities of the stimuli four components in the human ERG can be isolated, the cone and rod late receptor potentials, the positive DC response, and a c-wave in most subjects. It is suggested that investigation of these components reveals a more detailed understanding of the pathophysiologic mechanisms in some retinal diseases.

Action Potentials↗
PubMed1976

Experiments concerning the human C-wave.

The dependence of the human c-wave from the step amplitude was studied qualitatively. The maximum of the c-wave is achieved with light stimuli longer than 10 sec. After a dark period of 10 sec a fully developed c-wave appears. Also, in response to a brilliant photoflash a c-wave could be recorded. The influence of a mobile pupil on the response in the DC-ERG is demonstrated. Responses of the retinal potential to square wave and sinusoidal stimuli of different period times have been registered.

Action Potentials↗
PubMed1976

A method for DC-ERG recording of alert humans.

We developed a technique for DC-coupled ERG recording of the alert human. The equipment consists of three units: a new cornea suction glass, a separate electrode, and a vacuum control device. We get stable recordings of more than one-half hour. By comparison with the EOG the identity of the EOG "on"-peak and ERG c-wave is assured. A fine structure of DC-ERG recording of 100 muV amplitude is closely correlated to the variation of the blood pressure in the ophthalmic artery. It may either be caused by the variable electric conductivity of the eyeball due to the blood pressure or it may reflect a variation of the retinal potential itself.

Attention↗
PubMedDate not supplied

Relationships between MR-imaged total amount of tissue removed, resection scores of specific mediobasal limbic subcompartments and clinical outcome following selective amygdalohippocampectomy.

Of 204 patients who underwent a selective amygdalohippocampectomy at our hospital, we studied 30 in whom special pre- and postoperative MR imaging was carried out and who were followed up for at least 1 year postoperatively. We measured the total size of the resection and the extent to which the following specific mediobasal temporal lobe structures had been removed: amygdala, hippocampus, pes hippocampi, dentate gyrus, parahippocampal gyrus, uncus and subiculum. Postoperative seizure control was correlated with the overall size of the resection as well as with the resection scores of the above mentioned limbic subcompartments. The mean size of the removed tissue was 7.2 cm3 (range: 2.1-17.7). The mean resection scores of the limbic subcompartments (in percentages) are: amygdala 92%, hippocampus 46%, pes hippocampi 92%, dentate gyrus 45%, parahippocampal gyrus 32%, uncus 92%, subiculum 40%. Although a small resection did not exclude a good outcome, the general tendency was that a better outcome was obtained from a larger resection. With regard to the resection scores of the limbic subcompartments, a positive correlation emerged between good postoperative outcome and the radicality of the removal of the parahippocampal gyrus (and the subiculum, which has been evaluated separately). These findings support our previously formulated amplifier hypothesis for the parahippocampal gyrus.

Adult↗
PubMedDate not supplied

Blood-brain-barrier disruption in acute Wernicke encephalopathy: MR findings.

The clinical and MR features of an alcoholic woman with Wernicke encephalopathy are reported. During the acute stage Gd-diethylenetriamine pentaacetic acid enhanced MR revealed damage of the blood-brain barrier bilaterally and symmetrically adjacent to the third ventricle, cerebral aqueduct, and fourth ventricle. The enhancement disappeared after successful thiamine therapy, as demonstrated in a repeat postcontrast MR 1 week later.

Adult↗
PubMedDate not supplied

Correction of myopia by implantation of a concave Worst-iris claw lens into phakic eyes.

The Worst-Fechner Biconcave Lens for the correction of myopia in phakic eyes is fixated to the anterior iris. Of the 125 eyes implanted between November 1986 and November 1990, 109 eyes ("core group") had a follow-up period of at least 12 months (mean, 25.0; range, 13 to 51). Sixty-eight of these eyes were reexamined at Giessen University Eye Clinic by an independent investigator using a laser flare cell meter; 23 of the eyes also were examined by iris fluorescence angiography. Seventy-five of the 109 eyes (68.8%) were corrected within 1.00 diopters of the desired refraction, and only 10 eyes (9.2%) deviated more than 2.00 D from the calculated correction. The anatomical results were characterized by good fixation, absence of glaucoma, inflammation, and leak from iris vessels. However, the corneal endothelium was damaged in five eyes by surgical trauma, three resulting in corneal edema. In addition, in five eyes the endothelial density decreased during the follow-up period despite an uncomplicated operation, resulting in corneal edema in one eye. These eyes may have had anterior chambers that were too shallow.

Adolescent↗
PubMedDate not supplied

Retarded corneoscleral wound healing associated with high preoperative doses of systemic steroids in glaucoma surgery.

We compared two groups of human eyes with corneoscleral wounds. One group consisted of 100 phakic myopic eyes which received an iris fixated "claw" intraocular lens with a minus power optic. Prior to the operation, 350 mg of prednisone was administered systemically. Ten of these eyes (10%) developed a wound dehiscence requiring resuturing. The other group consisted of 1002 cataract operations where 20 mg of prednisone was administered subconjunctivally after the operation. No wound dehiscences occurred in this group. Pretreatment may be of value where fistual formation is desired, ie, with glaucoma surgery.

Cataract Extraction↗