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Biomedical subjects

T Mindermann

Publications and source records attributed to T Mindermann.

At least 19 recordsLinked to original sources
PubMed2001

[Palliative treatment of brain metastases with gamma knife].

The gamma knife is a stereotactic radiosurgery device which allows well defined, deep seated brain tumors or arteriovenous malformations with a maximal volume of about 25 ccm and a diameter not greater than 3.5 cm, to be treated in a single session under local anesthesia. The gamma knife offers an alternative treatment method to the classical approach of treating brain metastases by surgical excision and/or whole brain radiotherapy. The advantages of this technique are evident: the method is non-invasive, the treatment is carried out in a single session with a very short hospitalisation of two to three days, it is exempt from physical and psychical stress, the head does not need to be shaved and no hair loss occurs, a good quality of life is obtained for a reasonably prolonged survival time and it offers an economically favourable treatment method. Up to December 1999, over 30,000 patients suffering from brain metastases have been treated worldwide using the gamma knife. In Zürich, from September 1994 to December 2000 140 received this treatment. In the literature selection criteria may differ, and this may have determined some of differences in outcome. However, our results are comparable with those in the majority of publications with an average survival time of 263 days and a maximum survival of 1080 days. Good prognostic factors for survival and local control of brain metastases are a Karnofsky Performance Scale Score approaching 90 to 100, but not lower than 70, tumour volume, controlled primary cancer, and absence or stable extracranial metastases.

Adult↗
PubMed2000

[Diagnosis of cerebrospinal fluid leakage at the base of the skull].

There are still several problems surrounding the diagnosis of cerebrospinal fluid leak. Currently the method of choice for cerebrospinal fluid detection is qualitative determination of beta-2-transferrin. Faster and more efficient methods (beta-trace) are under clinical investigation. The major problem is localisation of the site of leakage. Combination of several radiological methods increases the rate of correct diagnosis. In surgery the use of intrathecal sodium-fluorescein improves visualisation of the site of leakage and thus increases the chances of secure and stable closure of the cerebrospinal fluid fistula.

Cerebrospinal Fluid↗
PubMed1999

Treatment of syringomyelia after posttraumatic paraparesis or tetraparesis.

This retrospective study of 12 patients with syringomyelia related to spinal cord trauma with paraplegia or tetraplegia and secondary progressive neurologic deficits was conducted to evaluate various surgical treatments. Judging by the results of postoperative neuroradiologic examinations, 75% had incomplete reduction of the spinal fracture at the time of initial surgery. The secondary neurologic deterioration occurred within a delay of 146 +/- 16 months and included ascending sensory deficits in 92%, deafferentation pain in 83%, and increased motor weakness in 33%. There was a positive correlation between the severity of symptoms, incomplete reduction of spinal fracture, and the degree of arachnoid scarring in preoperative neuroradiologic examinations. Syringoperitoneal shunting was performed in 83% of patients, and laminectomy with arachnoid lysis and dural grafting were performed in 17%. Pain was improved in 75%, sensory deficits in 25%, and motor weakness in 8%. During the follow-up period of 44 +/- 25 months, 30% of patients with syringoperitoneal shunting required repeated operation for obstruction or infection, whereas the syringomyelia remained collapsed in the two patients with laminectomy with arachnoid lysis and dural grafting, but this did not require additional surgery. In conclusion, laminectomy with arachnoid lysis and dural grafting seems to be a promising alternative treatment for patients with secondary neurologic deterioration after traumatic paraplegia or tetraplegia. Syringoperitoneal shunting may be reserved for patients without severe arachnoid scarring.

Adult↗
PubMed1998

Interhemispheric pressure gradients in severe head trauma in humans.

Interhemispheric pressure gradients may occur following severe head trauma in patients even in the absence of intracranial space occupying lesions. A higher ICP of the contralateral hemisphere may escape routine unilateral ICP monitoring. Clinical signs and CT scans do not seem to predict reliably a lateralized ICP. According to our data with a limited number of patients, interhemispheric pressure gradients seem to occur in the initial posttraumatic phase in some patients, and they seem to resolve following adequate ICP treatment after several hours. Therefore, simultaneous bilateral ICP measurement may be warranted in the initial posttraumatic phase.

Adolescent↗
PubMed1998

Symptomatic granular cell tumor of the pituitary gland: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: The posterior pituitary lobe is rarely the site of symptomatic primary tumors. The most common lesions arising from the neurohypophysis and the pituitary stalk seem to be granular cell tumors (GCTs), of which only 42 symptomatic cases have been reported. Here we present an unusually well-documented case of a GCT, which has implications for the differential diagnosis of sellar masses. CLINICAL PRESENTATION: A 75-year-old woman presented with decreased visual acuity, visual field loss, and a 2-year history of progressive vertigo and headaches. Neuroradiological studies showed a supra- and intrasellar, 25 x 20-mm mass, containing calcifications, that compressed the optic chiasm and extended into the third ventricle. INTERVENTION: The tumor was subtotally resected through a transsphenoidal approach. The tumor was tough and vascular and could not be suctioned. Histological examination revealed a typical GCT. The postoperative course was uneventful. Residual tumor was treated with fractionated radiation therapy. Ophthalmological testing 10 months after surgery showed a slight improvement in the visual symptoms. CONCLUSION: Tumor calcifications in computed tomographic scans do not exclude a GCT. The diagnosis requires histological confirmation. Surgical removal by the transsphenoidal approach is the therapy of choice, as for other sellar tumors. Radiation therapy may be advisable after subtotal resection. Our literature review suggests the possibility of gender-related tumor biology in GCTs.

Aged↗
PubMed1998

Rifampin concentrations in various compartments of the human brain: a novel method for determining drug levels in the cerebral extracellular space.

Antimicrobial therapy for brain infections is notoriously difficult because of the limited extent of knowledge about drug penetration into the brain. Therefore, we determined the penetration of rifampin into various compartments of the human brain, including the cerebral extracellular space (CES). Patients undergoing craniotomy for resection of primary brain tumors were given a standard dose of 600 mg of rifampin intravenously before the operation. A microdialysis probe (10 by 0.5 mm) was inserted into the cortex distantly from the resection and was perfused with two different rifampin solutions. Rifampin concentrations in the CES were calculated by the no-net-flux method. Intraoperatively, samples were taken from brain tumor tissue, perifocal tissue, and normal brain tissue in the case of pole resections. Rifampin concentrations in the various samples were determined by using a bioassay with Sarcinea lutea. In the various compartments, rifampin concentrations were highest within tumors (1.37 +/- 1.34 microg/ml; n = 8), followed by the perifocal region (0.62 +/- 0.67 microg/ml; n = 8), the CES (0.32 +/- 0.11 microg/ml; n = 6), and normal brain tissue (0.29 +/- 0.15 microg/ml; n = 7). Rifampin concentrations in brain tumors do not adequately reflect concentrations in normal brain tissue or in the CES. Rifampin concentrations in the CES, as determined by microdialysis, are the most reproducible, and the least scattered, of the values for all compartments evaluated. Rifampin concentrations in all compartments exceed the MIC for staphylococci and streptococci. However, CES concentrations may be below the MICs for some mycobacterial strains.

Adult↗
PubMed1997

Extensive splice variation and localization of the EHK-1 receptor tyrosine kinase in adult human brain and glial tumors.

EHK-1 is a neuronal ELK-related receptor tyrosine kinase which interacts with multiple, membrane-anchored ligands. Recent experiments have suggested a role for some of these ligands in the formation of neuronal pathways. Here, we report the isolation of human EHK-1 cDNAs and the localization of the human EHK-1 gene to chromosome 4q12. Six EHK-1 mRNA splice variants encoding cell-surface receptors with catalytic domains were identified in adult human brain where a 120-kDa EHK-1 protein predominates. Immunohistochemistry for EHK-1 reveals a dendritic staining pattern in cortical neurons and cerebellar Purkinje cells and a marked accumulation of EHK-1 in the somas of pyramidal neurons within the cortex and hippocampus. Interestingly, we have identified lineage aberrant expression of EHK-1 in a number of human gliomas. In addition to functions during development, EHK-1 may be involved in the maintenance of the adult nervous system and contribute to glioma development.

Adult↗
PubMed1995

Extrasellar, intracavernous sinus adrenocorticotropin-releasing adenoma causing Cushing's disease.

This report describes a patient with pituitary-dependent Cushing's disease who had a preoperative ACTH gradient to the left at the level of the cavernous sinus. Intraoperatively, an adenoma was found entirely within the left cavernous sinus, with no direct connection to the pituitary gland. To our knowledge, such a tumor has not been reported previously. This case has implications for the diagnosis, treatment, and follow-up of patients with pituitary-dependent Cushing's disease. The presence of an entirely extrasellar ACTH-releasing adenoma in the cavernous sinus could explain why pituitary-dependent Cushing's disease may persist postoperatively, even after total hypophysectomy. The diagnosis of an intracavernous tumor can be established by cavernous sinus venography. An extrasellar intracavernous adenoma can be diagnosed intraoperatively after careful negative exploration of the sellar contents followed by incision of the cavernous sinus on the side of the ACTH gradient established by venous sampling.

Adenoma↗
PubMed1995

Pediatric pituitary adenomas.

Previous series of pediatric pituitary adenomas have been small and have not been analyzed by age group. We analyzed the frequency, manifestation, course, and biology of these tumors before, during, and after puberty in 136 children younger than 20 years old at surgery, identified by review of 2230 patients treated from 1969 to 1993. Tumors were classified by clinical phenotype. Adrenocorticotropic hormone-releasing adenomas were most common before puberty, and prolactinomas were most common during and after. The frequencies of adrenocorticotropic hormone-releasing adenomas, prolactinomas, and endocrine-inactive adenomas differed from those in adults. Growth arrest was common with all types except growth hormone (GH)-releasing adenomas; menstrual irregularities were common with all but adenomas causing Nelson syndrome. Among girls with prolactinomas, the preoperative duration of primary amenorrhea was longer than that of other symptoms. Tumor size differed by adenoma type. Serum hormone levels shortly after surgery correlated with the recurrence of prolactinomas and GH-releasing adenomas. The prolactinoma size correlated with the maximum preoperative serum prolactin level; boys had larger tumors and higher preoperative and postoperative prolactin levels. We conclude that pediatric pituitary adenomas vary in size, age at symptom onset, and frequency before, during, and after puberty. Most adenomas can cause menstrual irregularities, and primary amenorrhea should prompt investigation of the sella. Growth arrest is common with all adenomas except GH-releasing adenomas. Serum prolactin and GH levels measured at 1 to 5 days after surgery indicate the risk of recurrence of prolactinomas and GH-releasing adenomas, respectively.

Adenoma↗
PubMed1994

Age-related and gender-related occurrence of pituitary adenomas.

OBJECTIVE: To evaluate the various types of pituitary adenomas according to sex and age group. Few studies have attempted such an analysis, and most have focused on specific age groups, especially children. Recent data suggest that the frequency of different types of pituitary adenomas varies according to age and sex. DESIGN: A retrospective review of the records of 2230 patients who underwent surgery for a pituitary adenoma at the University of California, San Francisco (UCSF), between January 1969 and June 1993. METHODS: The distribution of tumours was analysed according to age at surgery, sex, and the clinical phenotype of the tumour. Age groups were defined as the decades of life. RESULTS: Prolactinomas were the most common tumours (39%), followed by endocrine-inactive adenomas, growth-hormone-releasing adenomas, and adrenocorticotrophic hormone-releasing adenomas causing Cushing's disease; ACTH-releasing adenomas causing Nelson's syndrome and thyrotrophin (TSH)-releasing adenomas were rare. The female-to-male ratio differed considerably between the various adenoma types and between age groups. Prolactinomas, ACTH-releasing adenomas, and TSH-releasing adenomas occurred mostly in females; endocrine-inactive and GH-releasing adenomas occurred mostly in males. In older age groups, all adenoma types, except for endocrine-inactive adenomas, tended to assume a more balanced gender distribution. Among patients with prolactinomas, endocrine-inactive, ACTH-releasing, and to a lesser extent GH-releasing adenomas, the greatest discrepancy in gender distribution seemed to coincide with the peak occurrence of each tumour type. The peak occurrence was from the second to the fifth decade of life for prolactinomas and from the fourth to the eighth decade for endocrine-inactive adenomas. GH-releasing, ACTH-releasing, and TSH-releasing adenomas were more evenly distributed throughout the adult life span. CONCLUSIONS: The frequency of pituitary adenomas varies greatly according to age and sex. The various adenoma types have their peak occurrence in distinctly different age groups and differ greatly in their female-to-male ratios. The female-to-male ratio for a given adenoma type varies greatly with age.

Adenoma↗
PubMed1994

Changes in the immunophenotype of recurrent pituitary adenomas.

Only two cases have been reported of a pituitary adenoma that changed phenotype between its initial resection and recurrence. To determine the frequency of such cases among our patients, we examined the clinical course of these tumors and characterized any patterns. We reviewed the charts of 1023 patients with pituitary adenomas who underwent surgery between 1984 and 1992 at the University of California at San Francisco. Of the 65 patients (6.4%) who had operations for or clinical evidence of tumor recurrence, five (7.7%) had tumors that changed phenotype. The female-to-male ratio was 4:1, and age at the onset of symptoms was 33.2 +/- 15.3 years (mean +/- standard deviation). Changes occurred in hormone production and hormone release after 6.4 +/- 3.4 years. At some point, all five tumors were invasive and four were macroadenomas. Two patients had more than one operation for tumor recurrence; three had silent or symptomatic pituitary apoplexy; and three had undergone sellar irradiation before the changes in phenotype occurred. The behavior of these tumors therefore seems to be aggressive. We do not yet know whether phenotypic changes in pituitary adenomas have any treatment implications. Therefore, we advocate the complete immunostaining of primary and recurrent pituitary adenomas so that additional data about their clinical course can be collected.

Adenoma↗
PubMed1993

[Cerebral microdialysis in neurological and neurosurgical research and clinical application in neurology and neurosurgery].

Microdialysis of the cerebral extracellular space (CES) provides information on the cortical metabolic state by measurement of the concentrations of metabolites and transmitters as well as of the extracellular pH. In trauma patients, this kind of monitoring should reveal damage from secondary cortical ischemia in an early, hopefully reversible state. The method further allows in vivo measurement of drug levels in the CES and investigation of their effect on metabolism. Although microdialysis has mainly been used experimentally, it is now beginning to be applied clinically. We report on our experience with both experimental and clinical work.

Animals↗