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Papers by Muhittin Belirgen
Meningiomas, 2009
347 36 Anterior Clinoidal Meningiomas Joung H. Lee and Burak Sade Introduction ... a Mean tumor s... more 347 36 Anterior Clinoidal Meningiomas Joung H. Lee and Burak Sade Introduction ... a Mean tumor size 38 mm. b Mean tumor size 34 mm. TABLE 36-3. Involvement of the Optic Canal (OC) by the Tumor and Pre-Operative Visual Status in 46 Patients with Clinoidal Meningiomas. ...
Neurosurgery, 2007
To analyze pituitary adenoma volume changes after gamma knife radiosurgery (GKRS) in patients wit... more To analyze pituitary adenoma volume changes after gamma knife radiosurgery (GKRS) in patients with 3 years of follow-up and to investigate factors that might affect these changes. Between January 1997 and March 2004, a total of 1930 patients were treated in the Gamma Knife Unit of the Marmara University Department of Neurosurgery in Istanbul, Turkey. Three hundred sixty of these patients had pituitary adenomas (PAs). This prospectively designed clinical study documents the radiological-volumetric analysis for the first 100 of these patients with PAs who had a minimum of 3 years of follow-up and met the study requirements. Each tumor was assessed with serial magnetic resonance imaging scans after radiosurgery; at each time point, adenoma volume was expressed as a percentage of the tumor's initial volume. Volume changes were investigated relative to margin dose, the cavernous sinus infiltration, and endocrinological type of adenoma. At the end of the first year after GKRS, the PA volumes had decreased to approximately 90% of the initial volume on average. The corresponding approximate averages for the ends of Years 2 and 3 were 80 and 70% of the initial volume, respectively. At 3 years after GKRS, the PAs in the group with a peripheral dose of less than 17 Gy were reduced to approximately 80% of the initial volume on average. In contrast, the tumors in the patients with marginal doses of 21 to 23 Gy were reduced to approximately 60% of the initial volume at this stage. The adenomas treated with the highest marginal doses (>27 Gy) showed the earliest volume decreases after GKRS (6-9 mo after the procedure). Cavernous sinus noninfiltrating adenomas showed greater volume decreases after GKRS; on average, these masses were reduced to approximately 50% of their initial volume at 3 years. In contrast, the PAs that had infiltrated the cavernous sinus had only dropped to approximately 80% of their initial volume at this stage. The growth hormone-secreting PAs showed the maximum volume decrease with GKRS. On average, these lesions were approximately 60% of their initial volume at the 3-year stage. The nonfunctioning tumors and the prolactin-secreting adenomas showed similar volume changes over time. On average, these tumors had dropped to approximately 75 and 70% of the initial volume, respectively, by 3 years after GKRS. Gamma knife radiosurgery halts the growth of pituitary adenomas. Cavernous sinus extension and margin dose are the most important determinants of adenoma volume after this type of therapy.
Child's Nervous System, 2012
The aim is to describe the behavior of pilocytic astrocytoma (PAs) and its effects on patient pro... more The aim is to describe the behavior of pilocytic astrocytoma (PAs) and its effects on patient prognosis by using flow cytometric, immunohistochemical and cytogenetic methods. We also aim to find out whether there is any difference between differently localized tumors by the above mentioned analyses. We studied DNA index, expression of p53, p16, pRb, MMAC/PTEN1, VEGF, MIB-1 index and chromosomal anomalies which can be detected by array comparative genomic hybridization (CGH) technique. We analyzed the association of the results of these studies with clinical prognosis and tumor localization. We included 53 patients (18 cerebellar, 20 chiasmatic/hypothalamic and 15 hemispheric). Samples were studied from paraffin embedded tumors. We found that PAs are mostly diploid and ploidy pattern does not affect the prognosis. The expression of p53, p16, pRb, MMAC/PTEN1 and VEGF was not significantly different between different localizations and could not predict the prognosis. Frequently seen copy number aberrations (CNAs) are: amplification in 1p36.33, 2p11.2, 9p11.2, 9q12, 16p11.2, 19q13.12-q13.2, Xp22.2-p21.3, Xp11.3-p11.22, Xq11.1-q12, Xq13.1, Xq21.1-q21.31, Xq22.3, Xq26.3 and homozygous deletion in 2p11.2, 8p23.1, 16p12.3. Among them, 2p11.2 amp, 9p11.2 amp and 1p36.21 hom del were correlated with prognosis. Moreover, we found a significant correlation between 16p11.2 amp and tumor localization. Differently localized PAs have different properties which make them behave with different biological aggressiveness. PAs demonstrate a significant amount of CNAs that can be detected by a high-resolution study. However, tumor suppressor genes p53, p16, pRb, MMAC/PTEN1 and expression patterns do not play a significant role in PAs.
Oncocytic meningioma is a recently described rare variant of meningothelial neoplasms that probab... more Oncocytic meningioma is a recently described rare variant of meningothelial neoplasms that probably shows more aggressive behavior and high recurrence. Up till now, only fifteen cases were described. We reported a case of recurrent oncocytic meningioma that was operated four years ago. He had a left frontal tumor measuring 4 cm in diameter. The tumor was composed of large polygonal neoplastic cells with eosinophilic cytoplasm forming predominantly sheets, nests, and cords. Neoplastic cells showed nuclear pleomorphism with prominent nucleoli. Immunohistochemistry revealed a strong and diffuse positivity for vimentin, a focal reactivity for EMA and S100 protein.
Journal of …, 2008
Results: GCGB accounts for 5% of all glioblastomas. The average survival is 31 and 16 months in G... more Results: GCGB accounts for 5% of all glioblastomas. The average survival is 31 and 16 months in GCGB and UGB respectively. There were significant differences between GCGB and UGB including the tumor infiltrating lymphocyte, perivascular lymphocyte, giant cell and ...
Journal of Neurological Sciences (Turkish)
Summary Introduction: Radiotherapy (RT) has various effects such as apoptosis stimulation, mitosi... more Summary Introduction: Radiotherapy (RT) has various effects such as apoptosis stimulation, mitosis inhibition, mutagenic effect, chromosomal aberration and neoplastic transformation. Aim: The aim of this study was to investigate the effect of RT administered to diffuse glial tumors on the proliferation activity and mitotic activity of the tumor.
Acta Neurochirurgica, 2005
Background. Current literature on tuberculum sellae meningiomas is very heterogenous due to wide ... more Background. Current literature on tuberculum sellae meningiomas is very heterogenous due to wide variation in nomenclature, diagnostic and operative techniques. The aim of this study is specifically to analyze the results of pterional craniotomy for tuberculum sellae meningiomas. A homogenous cohort of 42 consecutively operated tuberculum sellae meningioma cases are reviewed with special emphasis on the effects of pterional microsurgery on visual outcome.
Acta Neurochirurgica, 2008
Background. Anterior clinoidal meningiomas are considered different from meningiomas of the media... more Background. Anterior clinoidal meningiomas are considered different from meningiomas of the medial sphenoid wing, but there is still some confusion about identification. The current classification scheme only considers tumour origin and invasion pattern around the clinoid process as indicators of resectability. However, the size of the tumour has important effects on surgical outcome. The purpose of this study was to analyze our clinical experience with anterior clinoidal meningiomas and refine the current classification scheme.
Meningiomas, 2009
347 36 Anterior Clinoidal Meningiomas Joung H. Lee and Burak Sade Introduction ... a Mean tumor s... more 347 36 Anterior Clinoidal Meningiomas Joung H. Lee and Burak Sade Introduction ... a Mean tumor size 38 mm. b Mean tumor size 34 mm. TABLE 36-3. Involvement of the Optic Canal (OC) by the Tumor and Pre-Operative Visual Status in 46 Patients with Clinoidal Meningiomas. ...
Neurosurgery, 2007
To analyze pituitary adenoma volume changes after gamma knife radiosurgery (GKRS) in patients wit... more To analyze pituitary adenoma volume changes after gamma knife radiosurgery (GKRS) in patients with 3 years of follow-up and to investigate factors that might affect these changes. Between January 1997 and March 2004, a total of 1930 patients were treated in the Gamma Knife Unit of the Marmara University Department of Neurosurgery in Istanbul, Turkey. Three hundred sixty of these patients had pituitary adenomas (PAs). This prospectively designed clinical study documents the radiological-volumetric analysis for the first 100 of these patients with PAs who had a minimum of 3 years of follow-up and met the study requirements. Each tumor was assessed with serial magnetic resonance imaging scans after radiosurgery; at each time point, adenoma volume was expressed as a percentage of the tumor's initial volume. Volume changes were investigated relative to margin dose, the cavernous sinus infiltration, and endocrinological type of adenoma. At the end of the first year after GKRS, the PA volumes had decreased to approximately 90% of the initial volume on average. The corresponding approximate averages for the ends of Years 2 and 3 were 80 and 70% of the initial volume, respectively. At 3 years after GKRS, the PAs in the group with a peripheral dose of less than 17 Gy were reduced to approximately 80% of the initial volume on average. In contrast, the tumors in the patients with marginal doses of 21 to 23 Gy were reduced to approximately 60% of the initial volume at this stage. The adenomas treated with the highest marginal doses (>27 Gy) showed the earliest volume decreases after GKRS (6-9 mo after the procedure). Cavernous sinus noninfiltrating adenomas showed greater volume decreases after GKRS; on average, these masses were reduced to approximately 50% of their initial volume at 3 years. In contrast, the PAs that had infiltrated the cavernous sinus had only dropped to approximately 80% of their initial volume at this stage. The growth hormone-secreting PAs showed the maximum volume decrease with GKRS. On average, these lesions were approximately 60% of their initial volume at the 3-year stage. The nonfunctioning tumors and the prolactin-secreting adenomas showed similar volume changes over time. On average, these tumors had dropped to approximately 75 and 70% of the initial volume, respectively, by 3 years after GKRS. Gamma knife radiosurgery halts the growth of pituitary adenomas. Cavernous sinus extension and margin dose are the most important determinants of adenoma volume after this type of therapy.
Child's Nervous System, 2012
The aim is to describe the behavior of pilocytic astrocytoma (PAs) and its effects on patient pro... more The aim is to describe the behavior of pilocytic astrocytoma (PAs) and its effects on patient prognosis by using flow cytometric, immunohistochemical and cytogenetic methods. We also aim to find out whether there is any difference between differently localized tumors by the above mentioned analyses. We studied DNA index, expression of p53, p16, pRb, MMAC/PTEN1, VEGF, MIB-1 index and chromosomal anomalies which can be detected by array comparative genomic hybridization (CGH) technique. We analyzed the association of the results of these studies with clinical prognosis and tumor localization. We included 53 patients (18 cerebellar, 20 chiasmatic/hypothalamic and 15 hemispheric). Samples were studied from paraffin embedded tumors. We found that PAs are mostly diploid and ploidy pattern does not affect the prognosis. The expression of p53, p16, pRb, MMAC/PTEN1 and VEGF was not significantly different between different localizations and could not predict the prognosis. Frequently seen copy number aberrations (CNAs) are: amplification in 1p36.33, 2p11.2, 9p11.2, 9q12, 16p11.2, 19q13.12-q13.2, Xp22.2-p21.3, Xp11.3-p11.22, Xq11.1-q12, Xq13.1, Xq21.1-q21.31, Xq22.3, Xq26.3 and homozygous deletion in 2p11.2, 8p23.1, 16p12.3. Among them, 2p11.2 amp, 9p11.2 amp and 1p36.21 hom del were correlated with prognosis. Moreover, we found a significant correlation between 16p11.2 amp and tumor localization. Differently localized PAs have different properties which make them behave with different biological aggressiveness. PAs demonstrate a significant amount of CNAs that can be detected by a high-resolution study. However, tumor suppressor genes p53, p16, pRb, MMAC/PTEN1 and expression patterns do not play a significant role in PAs.
Oncocytic meningioma is a recently described rare variant of meningothelial neoplasms that probab... more Oncocytic meningioma is a recently described rare variant of meningothelial neoplasms that probably shows more aggressive behavior and high recurrence. Up till now, only fifteen cases were described. We reported a case of recurrent oncocytic meningioma that was operated four years ago. He had a left frontal tumor measuring 4 cm in diameter. The tumor was composed of large polygonal neoplastic cells with eosinophilic cytoplasm forming predominantly sheets, nests, and cords. Neoplastic cells showed nuclear pleomorphism with prominent nucleoli. Immunohistochemistry revealed a strong and diffuse positivity for vimentin, a focal reactivity for EMA and S100 protein.
Journal of …, 2008
Results: GCGB accounts for 5% of all glioblastomas. The average survival is 31 and 16 months in G... more Results: GCGB accounts for 5% of all glioblastomas. The average survival is 31 and 16 months in GCGB and UGB respectively. There were significant differences between GCGB and UGB including the tumor infiltrating lymphocyte, perivascular lymphocyte, giant cell and ...
Journal of Neurological Sciences (Turkish)
Summary Introduction: Radiotherapy (RT) has various effects such as apoptosis stimulation, mitosi... more Summary Introduction: Radiotherapy (RT) has various effects such as apoptosis stimulation, mitosis inhibition, mutagenic effect, chromosomal aberration and neoplastic transformation. Aim: The aim of this study was to investigate the effect of RT administered to diffuse glial tumors on the proliferation activity and mitotic activity of the tumor.
Acta Neurochirurgica, 2005
Background. Current literature on tuberculum sellae meningiomas is very heterogenous due to wide ... more Background. Current literature on tuberculum sellae meningiomas is very heterogenous due to wide variation in nomenclature, diagnostic and operative techniques. The aim of this study is specifically to analyze the results of pterional craniotomy for tuberculum sellae meningiomas. A homogenous cohort of 42 consecutively operated tuberculum sellae meningioma cases are reviewed with special emphasis on the effects of pterional microsurgery on visual outcome.
Acta Neurochirurgica, 2008
Background. Anterior clinoidal meningiomas are considered different from meningiomas of the media... more Background. Anterior clinoidal meningiomas are considered different from meningiomas of the medial sphenoid wing, but there is still some confusion about identification. The current classification scheme only considers tumour origin and invasion pattern around the clinoid process as indicators of resectability. However, the size of the tumour has important effects on surgical outcome. The purpose of this study was to analyze our clinical experience with anterior clinoidal meningiomas and refine the current classification scheme.