While some avian retroviruses have been shown to induce gliomas in animal models, human herpesviruses, specifically, the most extensively studied cytomegalovirus, and the much less studied roseolovirus HHV-6, and Herpes simplex viruses 1 and 2, currently attract more and more attention as possible contributing or initiating factors in the development of human brain tumors. The aim of this review is to summarize and highlight the most provoking findings indicating a potential causative link between brain tumors, specifically malignant gliomas, and viruses in the context of the concepts of viral oncomodulation and the tumor stem cell origin.

Objective: This study is to analyze fluorescence sensitivity in the diagnosis of brain and spinal cord tumors.Material and methods: The authors conducted a multicenter retrospective analysis of data on 653 cases in 641 patients: 553 of them had brain tumors and 88 spinal cord tumors. Brain tumor resection was performed in 523 patients, of whom 484 were adults and 39 children. The analyzed series was presented by 320 gliomas, 101 meningiomas, and 72 metastases. A stereotactic biopsy was performed in 20 patients and endoscopic surgery in 10 patients. In all cases, 20 mg/kg of 5–Aminolaevulinic acid was administered orally 2-h before surgery. All surgical interventions were performed with a microscope BLUE 400 to visualize fluorescence, while endoscopic surgery—with an endoscope equipped with a fluorescent module. Fluorescence spectroscopy was conducted in 20 cases of stereotactic biopsies and in 88 cases of spinal cord tumors.Results: Among adult brain tumors operated by microsurgical techniques, meningiomas showed the highest 5-ALA fluorescence sensitivity 94% (n = 95/101), brain metastases 84.7% (n = 61/72), low-grade gliomas 46.4% (n = 26/56), and high-grade gliomas 90.2% (n = 238/264). In children the highest 5-ALA visible fluorescence was observed in anaplastic astrocytomas 100% (n = 4/4) and in anaplastic ependymomas 100% (n = 4/4); in low-grade gliomas it made up 31.8% (n = 7/22). As for the spinal cord tumors in adults, the highest sensitivity was demonstrated by glioblastomas 100% (n = 4/4) and by meningiomas 100% (n = 4/4); Fluorescence was not found in gemangioblastomas (n = 0/6) and neurinomas (n = 0/4). Fluorescence intensity reached 60% (n = 6/10) in endoscopic surgery and 90% (n = 18/20) in stereotactic biopsy.Conclusion: 5-ALA fluorescence diagnosis proved to be most sensitive in surgery of HGG and meningioma (90.2 and 94.1%, respectively). Sensitivity in surgery of intracranial metastases and spinal cord tumors was slightly lower (84.7 and 63.6%, correspondingly). The lowest fluorescence sensitivity was marked in pediatric tumors and LGG (50 and 46.4%, correspondingly). Fluorescence diagnosis can also be used in transnasal endoscopic surgery of skull base tumors and in stereotactic biopsy.

Surgical resection of gliomas affecting functionally important brain structures is associated with high risk of permanent postoperative neurological deficit and deterioration of the patient's quality of life. The availability of modern neuroimaging and neuronavigation permits the application of minimally invasive stereotactic cryodestruction of the tumor in such cases. The authors used this treatment in 88 patients with supratentorial gliomas of various WHO histopathological grades not suitable for microsurgical resection. Postoperative mortality (1.1%) and rate of surgical complications (11.4%) were comparable to reported results of stereotactic brain tumor biopsy, whereas the rate of neurological morbidity (42%) was comparable to outcome after resection of gliomas within eloquent brain areas. The majority of complications were temporary, and permanent deterioration of neurological function was noted in 8% of cases only. The median survival after treatment in patients with glioblastoma and anaplastic astrocytoma was 12.4 and 46.9 months, respectively, and was not reached in cases of diffuse astrocytoma, which compared favorably both with historical controls and literature data. Therefore, it seems reasonable to consider stereotactic cryodestruction in multimodality management strategies of "unresectable" intracranial gliomas, and further studies directed at evaluation of its efficacy are definitely needed.

Novel approach for statistical inference in survival analysis based on factor or dichotomic variables is proposed. We are seeking for the most informative finitely linear combinations (symptoms) of variables in the finite field. This procedure necessarily yields the new variable of the same nature (e.g. factor). Different measures can be used as an optimality criterion of such combination: entropy, the uncertainty coefficient, p-level of some statistical tests. We use this method to determine the major factors of the glioma postoperation survival. These factors were found to be age, high-grading factor, stage of illness and a factor of the stereotactic cryodestruction.

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