Biomedical subjects

Andras A Kemeny

Publications and source records attributed to Andras A Kemeny.

5 recordsLinked to original sources

PubMed2005

Ultrastructural changes in arteriovenous malformations after gamma knife surgery: an electron microscopic study.

OBJECT: The authors analyzed morphological alterations at the subcellular level by undertaking transmission electron microscopy in arteriovenous malformations (AVMs) after gamma knife surgery (GKS). METHODS: Histological, immunohistochemical, and electron microscopic investigations were performed in a series of pathological specimens obtained in seven patients. The patients harbored cerebral AVMs that had been previously treated with GKS and had suffered subsequent bleeding 10 to 52 months after treatment. Histological studies revealed spindle cell proliferation in the connective tissue stroma and in the subendothelial region of the irradiated AVM vessels. Electron microscopy demonstrated different ultrastructural characteristics of this spindle cell population. There were cells with a smooth-edged oval nuclei surrounded by massive bundles of collagen fibers in the extracellular matrix. Other cells with the same nuclear morphology contained abundant intracytoplasmic filaments. Nuclear deformation was connected to a fibrillary system developed within the cytoplasm, and peripheral attachment sites were related to an extracellular layer of basement membrane-like material arranged parallel to the cell border. Also present were cells containing well-developed cisterns of rough endoplasmic reticulum and dense bodies at the periphery of the cytoplasm with folded, irregular nuclei. CONCLUSIONS: The ultrastructural and histological characteristics of the spindle cell population in the GKS-treated AVMs are similar to those designated as myofibroblasts in wound healing processes and pathological fibromatoses. Because similar cell modifications have not been demonstrated in control nonirradiated AVM specimens, these myofibroblasts may contribute to the shrinking process and final occlusion of AVMs after radiosurgery.

Cell Movement↗

PubMed2002

Stereotactic radiosurgery for type 2 neurofibromatosis acoustic neuromas: patient selection and tumour size.

Acoustic neuromas which are secondary to type 2 neurofibromatosis (NF2) respond less well to radiosurgery than unilateral sporadic disease. To refine the selection of these patients, a regression analysis was performed examining the response to radiosurgery of 114 NF2 tumours. The major determinant of outcome was tumour volume (p < 0.001). Calculating sensitivity and specificity values for different tumour volume limits gives a sensitivity value of 0.96 for a volume limit of 10 cm(3). This suggests that the size constraints that apply to the radiosurgical management of NF2 acoustic neuromas differ and are more restricted than those which are accepted for acoustic neuromas in general.

Adolescent↗

PubMed2002

Radiosurgery for residual or recurrent nonfunctioning pituitary adenoma.

OBJECT: Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study is to evaluate the efficacy and role of gamma knife radiosurgery (GKS) in the management of residual or recurrent nonfunctioning pituitary adenomas. METHODS: A review was conducted of the data obtained in 42 patients who underwent adjuvant GKS at the University of Pittsburgh between 1987 and 2001. Prior treatments included transsphenoidal resection, craniotomy and resection, or conventional radiotherapy. Endocrinological, ophthalmological, and radiological responses were evaluated. The duration of follow-up review varied from 6 to 102 months (mean 31.2 months). Fifteen patients were observed for more than 40 months. The mean radiation dose to the tumor margin was 16 Gy. Conformal radiosurgery planning was used to restrict the dose to the optic nerve and chiasm. Tumor control after GKS was achieved in 100% of patients with microadenomas and 97% of patients with macroadenomas. Gamma knife radiosurgery was equally effective in controlling adenomas with cavernous sinus invasion and suprasellar extension. No patient developed a new endocrinological deficiency following GKS. One patient's tumor enlarged with an associated decline in visual function. Another patient experienced a deterioration of visual fields despite a decrease in tumor size. CONCLUSIONS: Gamma knife radiosurgery can achieve tumor control in virtually all residual or recurrent nonfunctioning pituitary adenomas. Dose sparing facilitates tumor management even when the adenoma is close to the optic apparatus or invades the cavernous sinus.

Adenoma↗

PubMed2002

Surgery for epilepsy.

While medical treatment remains the first line of treatment for epilepsy, surgery provides effective long-term control in suitable patients. Detailed investigations are necessary to prove suitability and in order to choose the appropriate procedure. This article gives an outline of the investigative programme and the various operative approaches. Novel methods and those under investigation are also discussed.

Brain↗

PubMed2002

Surgery.

Explore the source record for details and available documents.

Adolescent↗