Masayuki Kanamori

Publications (50)98.67 Total impact

• Article: The expression status of CD133 is associated with the pattern and timing of primary glioblastoma recurrence.

  Ichiyo Shibahara, Yukihiko Sonoda, Ryuta Saito, Masayuki Kanamori, Yoji Yamashita, Toshihiro Kumabe, Mika Watanabe, Hiroyoshi Suzuki, Takashi Watanabe, Chikashi Ishioka, Teiji Tominaga
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  ABSTRACT: Background Glioblastoma carries a poor prognosis primarily because of its high rate of recurrence. The ability to predict the recurrence pattern and timing would be highly useful for determining effective treatment strategies. We examined the correlation between prognostic factors and the pattern of recurrence in patients with primary glioblastoma. In particular, we examined whether there was a correlation between the expression of CD133 and glioblastoma recurrence.Methods We retrospectively analyzed 112 patients with primary glioblastoma. The timing and pattern (local or distant) of the initial recurrence were obtained from medical records. To identify factors predictive of recurrence, we examined CD133 expression by Western blots and immunohistochemistry, clinical (age, sex, KPS, Ki67 labeling index, surgery, ventricular entry) and genetic (IDH1, 7p, 9p, 10q, MGMT) factors.ResultsOf the 112 patients, 99 suffered recurrence. The first recurrence was local in 77 patients and distant in 22 patients. Among the factors to predict the pattern of recurrence, CD133 expression was significantly higher in distant than in local recurrence. Of the factors to predict the timing of recurrence, high CD133 expression was associated with shorter time to distant recurrence in both univariate and multivariate analyses (P = .0011 and P = .038, respectively).Conclusions The expression of CD133 may be a predictor of the pattern and timing of recurrence of primary glioblastoma.
  Neuro-Oncology 05/2013; · 5.72 Impact Factor
• Article: Pilomyxoid astrocytoma of the cerebellum with Williams syndrome: a case report.

  Masashi Chonan, Masayuki Kanamori, Toshihiro Kumabe, Ryuta Saito, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: CASE REPORT: A 3-year-old boy with Williams syndrome associated with supravalvular aortic stenosis was admitted to our hospital with disturbance of consciousness and a 2-month history of truncal ataxia. T1-weighted magnetic resonance imaging with contrast medium showed a heterogeneously enhanced tumor in the right cerebellum with severe hydrocephalus. The patient underwent tumor resection via suboccipital craniotomy. At the end of resection of the tumor, sudden cardiac arrest occurred after ST segment elevation. Despite immediate cardiopulmonary resuscitation, the patient died. Histological examination of the cerebellar tumor revealed that the tumor consisted of monomorphous bipolar spindle cells on a background of myxoid matrix, and angiocentric arrangement without Rosenthal fibers or eosinophilic granular body. The final diagnosis was pilomyxoid astrocytoma. CONCLUSION: This case of Williams syndrome with cerebellar pilomyxoid astrocytoma suggests the importance of investigation of the development of brain tumors and occurrence of intraoperative cardiac arrest associated with Williams syndrome.
  Child s Nervous System 04/2013; · 1.54 Impact Factor
• Article: Infarction of the lateral posterior choroidal artery territory after manipulation of the choroid plexus at the atrium: causal association with subependymal artery injury.

  Ryuta Saito, Toshihiro Kumabe, Yukihiko Sonoda, Masayuki Kanamori, Shunji Mugikura, Shoki Takahashi, Teiji Tominaga
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  ABSTRACT: Object The atrium of the lateral ventricle is often affected by tumors, and some patients with these tumors suffer neurological deficits, including hemiparesis after surgery. The authors of this study investigated the possible mechanisms causing the relatively high incidences of ischemic complications associated with surgery approaching the atrium of the lateral ventricle. Methods Clinical records and radiological images of 28 patients were retrospectively studied. These patients had their lateral ventricles opened at the atrium during the resection of gliomas as well as other nonbenign brain tumors, and were treated for gliomas at our tertiary referral center in the Tohoku district, Japan, between January 2008 and December 2010. Results Routine postoperative diffusion-weighted MR images obtained within 72 hours after surgery detected infarction in the periatrial/periventricular regions in 7 patients, presumably corresponding to the lateral posterior choroidal artery (LPChA) territory. Five of these 7 patients suffered neurological sequelae with varying severities. The choroid plexus at the atrium was coagulated to achieve hemostasis during the surgery in all of these patients. Detailed analysis of microangiograms revealed ventriculofugal arteries arising from the lateral ventricle. Damage of the subependymal artery that supplies the ventriculofugal arteries caused by coagulation of the choroid plexus at the atrium probably resulted in the infarction in these patients. Conclusions Neurosurgeons must be aware of the possibility of LPChA territory infarction during surgery in the atrial or periatrial regions caused by subependymal artery obstruction after manipulating or coagulating the choroid plexus near the atrium.
  Journal of Neurosurgery 03/2013; · 2.96 Impact Factor
• Article: Medial posterior choroidal artery territory infarction associated with tumor removal in the pineal/tectum/thalamus region through the occipital transtentorial approach.

  Ryuta Saito, Toshihiro Kumabe, Masayuki Kanamori, Yukihiko Sonoda, Shunji Mugikura, Shoki Takahashi, Teiji Tominaga
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  ABSTRACT: OBJECT: Damage to the deep venous system, occipital lobe, and/or corpus callosum is well known to cause complications associated with the occipital transtentorial approach (OTA), but ischemic complications are not well documented. The authors investigated the high incidences of ischemic complications associated with removal of pineal/tectal/thalamic tumors through the OTA. METHODS: Clinical records of 29 patients who underwent 31 surgeries using the OTA from December 2001 to May 2011 were retrospectively studied. Tumor locations were the pineal/tectal/thalamic region for 19, cerebellum for 7, and medial temporal lobe for 3. RESULTS: Postoperative diffusion-weighted magnetic resonance images obtained within 72h after surgery detected infarction in the tectal/splenial/thalamic region, presumably representing the medial posterior choroidal artery (MPChA) territory, in 10 patients. All these patients had tumor in the pineal/tectal/thalamic region. Deteriorated or newly developed eye symptoms including vertical gaze palsy tended to persist in these patients compared to those without ischemic complications. CONCLUSIONS: A relatively high incidence of MPChA territory infarction was associated with removal of tumors in the pineal/tectal/thalamic region through the OTA. Eye symptoms often occurred post-surgery and tended to persist in these patients. Neurosurgeons must be aware of the possibility of MPChA territory infarction to further increase the safety of the OTA.
  Clinical neurology and neurosurgery 12/2012; · 1.30 Impact Factor
• Article: Metachronous, multicentric glioma of pilocytic astrocytoma with oligodendroglioma-like component and oligodendroglioma through distinct genetic aberrations.

  Atsushi Kanoke, Masayuki Kanamori, Toshihiro Kumabe, Ryuta Saito, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: This patient presented with a rare case of metachronous, multicentric gliomas first manifesting as headache and nausea in 1983 when he was an 8-year-old boy. Computed tomography revealed a cerebellar tumor and the tumor was subtotally resected. The histological diagnosis was pilocytic astrocytoma, and radiation therapy to the posterior fossa and chemotherapy consisting of nimustine hydrochloride and fluorouracil were performed. In 1989, at age 14 years, the patient presented with local recurrence. He underwent gross-total resection of the tumor, and histological examination revealed that the tumor consisted of classic pilocytic astrocytoma with a biphasic pattern and a small oligodendroglioma-like component. In 2011, at age 36 years, he presented with seizure. Magnetic resonance imaging revealed a mass lesion in the right middle frontal gyrus. Gross-total resection of the tumor was performed, and the histological diagnosis was oligodendroglioma. Genetic analyses revealed amplification of the BRAF gene in both the primary cerebellar pilocytic astrocytoma and the recurrent tumor with biphasic features, as well as a BRAF V600E missense mutation in the oligodendroglioma-like component. On the other hand, the IDH1 R132H mutation, instead of aberrations of the BRAF gene, was identified in the oligodendroglioma arising in the right frontal lobe. Different types of aberrations of the BRAF gene in the classic and oligodendroglioma-like component in the recurrent pilocytic astrocytoma suggest that they had different cell origins or that amplification of BRAF was negatively selected under the de novo BRAF V600E mutation. In addition, the aberration profiles of IDH1 and BRAF suggest that the oligodendroglioma arose independent of cerebellar pilocytic astrocytoma.
  Journal of Neurosurgery 10/2012; · 2.96 Impact Factor
• Article: Clinical and histological characteristics of recurrent oligodendroglial tumors: comparison between primary and recurrent tumors in 18 cases.

  Masayuki Kanamori, Toshihiro Kumabe, Ichiyo Shibahara, Ryuta Saito, Yoji Yamashita, Yukihiko Sonoda, Hiroyoshi Suzuki, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: Changes in histological and genetic characteristics were investigated in 18 paired primary and recurrent oligodendroglial tumors, using sequencing analysis for isocitrate dehydrogenase (IDH) 1 and 2 gene mutation, Ki-67 and p53 immunohistochemistry, and fluorescent in situ hybridization for loss of heterozygosity of chromosomes 1p and 19q (1p/19q co-deletion). Malignant transformation occurred in 5 of 8 cases with World Health Organization (WHO) grade II tumors, but in 0 of 10 cases with WHO grade III tumors progressing to glioblastoma. Thirteen of the 18 cases carried IDH1 gene mutation. Tumors with IDH1 mutation tended to survive for longer, even after recurrence, but newly developed microvascular proliferation, tumor necrosis, and elevated Ki-67 labeling index were common. Eleven of the 13 IDH1-mutation tumors had either 1p/19q co-deletion or nuclear expression of p53, but all 5 IDH1/2 wild-type tumors had neither. All cases had the same profile for 1p/19q status at recurrence, but nuclear expression of p53 changed from negative to positive in 2 of 6 cases with IDH1 mutation and 1p/19q co-deletion. WHO grade II oligodendroglial tumors show a high rate of malignant transformation, possibly involving p53 in tumors with IDH1 mutation and 1p/19q co-deletion. Tumors with IDH1 mutation had a more aggressive histological phenotype despite their better prognosis.
  Brain Tumor Pathology 10/2012; · 1.19 Impact Factor
• Article: Distinctive flow pattern of wall shear stress and oscillatory shear index: similarity and dissimilarity in ruptured and unruptured cerebral aneurysm blebs.

  Tomohiro Kawaguchi, Shinjitsu Nishimura, Masayuki Kanamori, Hiroki Takazawa, Shunsuke Omodaka, Kenya Sato, Noriko Maeda, Yoko Yokoyama, Hiroshi Midorikawa, Tatsuya Sasaki, Michiharu Nishijima
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  ABSTRACT: Object The difference in the hemodynamics of wall shear stress (WSS) and oscillatory shear index (OSI) between ruptured and unruptured aneurysms is not well understood. The authors investigated the hemodynamic similarities and dissimilarities in ruptured and thin-walled unruptured aneurysm blebs. Methods Magnetic resonance imaging-based fluid dynamics analysis was used to calculate WSS and OSI, and hemodynamic and intraoperative findings were compared. The authors also compared ruptured and unruptured thin-walled blebs for the magnitude of WSS and OSI. Results Intraoperatively, 13 ruptured and 139 thin-walled unruptured aneurysm blebs were identified. Twelve of the ruptured (92.3%) and 124 of the unruptured blebs (89.2%) manifested low WSS and high OSI. The degree of WSS was significantly lower in ruptured (0.49 ± 0.12 Pa) than in unruptured (0.64 ± 0.15 Pa; p < 0.01) blebs. Conclusions Ruptured and unruptured blebs shared a distinctive pattern of low WSS and high OSI. The degree of WSS at the rupture site was significantly lower than in the unruptured thin-walled blebs.
  Journal of Neurosurgery 08/2012; 117(4):774-80. · 2.96 Impact Factor
• Article: Clinicopathological analysis of nine consecutive central nervous system primitive neuroectodermal tumors in a single institute.

  Misaki Aizawa-Kohama, Toshihiro Kumabe, Ryuta Saito, Masayuki Kanamori, Yoji Yamashita, Yukihiko Sonoda, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: The objective of this study was to determine the outcome of central nervous system primitive neuroectodermal tumors (CNS PNETs) and to clarify the histopathological findings as prognostic factors. We performed a retrospective analysis of nine consecutive patients with CNS PNETs who underwent treatment at our institute between 1993 and 2011. All patients were treated by surgical resection followed by chemoradiotherapy. Additional treatment, including surgical resection, was performed at relapse. Expression of immunohistochemical markers was examined for neuronal, astrocytic, mesenchymal, and epithelial differentiation, and also for TP53, O(6)-methylguanine-DNA methyltransferase, and Ki-67. Five-year progression-free survival was 18.2 % and the overall survival was 52.5 %. Five the 9 patients had recurrence and 4 patients died during the median follow-up period of 41.1 months. All 4 patients died of dissemination not local recurrence. After relapses, the extent of differentiation was different in each case and TP53 changed to positive or negative, but the Ki-67 labeling index did not reveal any differences between primary and recurrent tumors. A treatment procedure to prevent and treat dissemination of CNS PNETs should be established. Because the pathological change after relapse was different in each case, definitive histopathological prognostic factors for CNS PNETs are still difficult to propose.
  Brain Tumor Pathology 03/2012; · 1.19 Impact Factor
• Article: IDH1/2 gene status defines the prognosis and molecular profiles in patients with grade III gliomas.

  Ichiyo Shibahara, Yukihiko Sonoda, Masayuki Kanamori, Ryuta Saito, Yoji Yamashita, Toshihiro Kumabe, Mika Watanabe, Hiroyoshi Suzuki, Shunsuke Kato, Chikashi Ishioka, Teiji Tominaga
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  ABSTRACT: BACKGROUND: The discovery of isocitrate dehydrogenase 1 and 2 gene (IDH1/2) mutations has enabled grade III glioma to be divided into mutated and wild-type IDH1/2 groups, which are known to carry different prognosis and molecular features. However, detailed subgroup analysis of grade III glioma is limited. To address this, we investigated molecular and prognostic features of grade III glioma with and without IDH1/2 mutation. METHODS: We retrospectively analyzed 115 grade III glioma patients. Clinical parameters were obtained from medical records. The mutation of IDH1/2 and TP53 was analyzed by direct sequencing. O(6)-methylguanine methyltransferase gene (MGMT) gene promoter methylation status was determined by methylation-specific polymerase chain reaction. Detection of chromosome copy number changes of 1p, 7p (EGFR), 9p (CDKN2A), 10q (PTEN), and 19q was carried out by multiple ligation-dependent probe amplification. Patients were divided into two groups, mutated IDH1/2 and wild-type IDH1/2, for correlation with the factors analyzed. RESULTS: In our series, as previously reported, IDH1/2 mutation was an independent prognostic marker for improved progression-free and overall survival (OS) (P < 0.0001 and P < 0.0001, respectively) in patients with grade III gliomas. Subgroup analysis found that incomplete resection, 7p gain, and TP53 mutation were independent prognostic factors of poor outcome in grade III glioma patients with mutated IDH1/2 (P = 0.0092, P = 0.015 and P = 0.026, respectively), while there were none in patients with wild-type IDH1/2. CONCLUSIONS: IDH1/2 gene status was significantly associated with prognosis in grade III gliomas. Subgroup analysis found that poor prognostic factors existed even in patients with IDH1/2 mutation.
  International Journal of Clinical Oncology 10/2011; · 1.41 Impact Factor
• Article: New insights into glioma classification based on isocitrate dehydrogenase 1 and 2 gene status.

  Ichiyo Shibahara, Yukihiko Sonoda, Masayuki Kanamori, Ryuta Saito, Toshihiro Kumabe, Teiji Tominaga
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  ABSTRACT: In glioma, mutations in the isocitrate dehydrogenase 1 and 2 (IDH1/2) genes have been receiving attention. IDH1/2 mutations are frequently found in grade II and III gliomas. These genetic alterations occur very early in gliomagenesis and strongly predict favorable outcome in patients with high-grade gliomas. Despite the evolution of studies on this topic, the underlying mechanism of the IDH1/2 mutations remains unknown. Here, we briefly review the current knowledge of IDH1/2 and discuss molecular diagnostics based on IDH1/2 gene status.
  Brain Tumor Pathology 07/2011; 28(3):203-8. · 1.19 Impact Factor
• Article: Combination chemotherapy with ifosfamide, cisplatin, and etoposide for medulloblastoma: single-institute experience and differences in efficacy for subgroups of medulloblastoma.

  Ryuta Saito, Toshihiro Kumabe, Yukihiko Sonoda, Masayuki Kanamori, Yoji Yamashita, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: Treatment for medulloblastoma consists of surgical resection, radiation therapy, and chemotherapy. In Japan, ICE chemotherapy consisting of cisplatin, ifosfamide, and etoposide is one of the most common regimens. Here, we summarize the toxicity and efficacy of ICE chemotherapy and evaluate the usefulness of the recently introduced molecular classification scheme to predict the outcome. Seventeen patients with medulloblastoma treated by ICE chemotherapy as an initial therapy at our institute were retrospectively reviewed. Eleven were categorized in the standard-risk group and six in the high-risk group. All patients underwent maximum cytoreductive surgery, radiation therapy, and ICE chemotherapy. Operative specimens were subjected to immunohistochemical staining using four antibodies-DKK1, SFRP1, NPR3, and KCNA1-to classify the cases into four subgroups, WNT group, SHH group, group C, and group D, respectively. ICE chemotherapy following surgery and radiation therapy was tolerable in most patients with appropriate management, although myelosuppression and hearing disturbance occurred. There was no significant difference in survival between patients with standard-risk disease and high-risk disease. Five-year survival and 5-year progression-free survival for the 17 patients were 80.7% and 63.5%, respectively. Three patients were classified as WNT group, 2 as SHH group, 1 as group C, and 11 as group D. Group D tended to have poorer prognosis after ICE chemotherapy. ICE chemotherapy was tolerable and active against medulloblastomas. Patients categorized as group D tended to have worse outcome after ICE chemotherapy.
  Child s Nervous System 05/2011; 27(9):1399-406. · 1.54 Impact Factor
• Article: [Flow dynamics analysis in patients with a ruptured middle cerebral artery aneurysm. A case report].

  Tomohiro Kawaguchi, Masayuki Kanamori, Hiroki Takazawa, Shunsuke Omodaka, Shingo Yonezawa, Noriko Maeda, Kenya Sato, Hiroshi Midorikawa, Tatsuya Sasaki, Michiharu Nishijima
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  ABSTRACT: Despite advancement of diagnostic and treatment modalities, subarachnoid hemorrhage (SAH) is still an entity of neurosurgical emergency with poor outcome. Recent reports indicated that hemodynamic stress might play an important role in rupture or the growth of cerebral aneurysms, but there is no consensus about how or which hemodynamic factor contribute to this phenomenon. In this report, magnetic resonance (MR)-based flow dynamics analysis was performed for a patient with SAH and the data obtained were directly compared with intraoperative findings. This 74-year-old woman was admitted for sudden onset headache. Head computed tomography scan showed SAH on the right sylvian fissure and intracerebral hematoma on the right temporal tip. Digital subtraction angiography showed a right middle cerebral artery aneurysm, which was considered to be the ruptured one. The aneurysm had two blebs, and the bleb around the aneurysm tip was exposed to low magnitude and high oscillation of wall shear stress (WSS). On the other hand, another bleb was exposed to high magnitude and low oscillation of WSS. Next day, the patient underwent open surgery and intraoperative findings showed the aneurysm tip was the ruptured point. MR-based flow dynamics analysis might be a useful diagnostic modality for patients with SAH. Although low magnitude and high oscillation of WSS might contribute to the aneurysm rupture, further case accumulation is necessary to reach a conclusion whether or not this is so.
  No shinkei geka. Neurological surgery 03/2011; 39(3):281-6. · 0.13 Impact Factor
• Article: Prognostic factors for patients with gliomatosis cerebri: retrospective analysis of 17 consecutive cases.

  Tomoo Inoue, Toshihiro Kumabe, Masayuki Kanamori, Yukihiko Sonoda, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: Gliomatosis cerebri (GC) is a rare fatal glial neoplasm of the central nervous system. Neuroimaging, histological, and clinical outcome data were reviewed of 17 consecutive patients, 8 males and 9 females aged 15-68 years (median, 37 years), treated for GC between April 1992 and October 2007. All patients received cranial irradiation to include the hyperintense area on T2-weighted magnetic resonance imaging. The total dose of the radiotherapy was 50-72 Gy (median, 60). Intravenous nimustine hydrochloride was administered in all patients, combined with temozolomide in four patients. The median survival time was 23.3 months, with a median follow-up of 23.3 months. Kaplan-Meier analysis demonstrated the overall survival rate which was 70.6% for 1 year, 23.5% for 3 years, and 17.7% for 5 years. Spinal enhanced lesions and nodular malignant transformation to glioblastoma were observed during follow-up in two patients each. Poor survival showed correlation with higher Ki-67 labeling index, higher choline/N-acetylaspartate ratio on magnetic resonance spectroscopy, tumor volumes, lower Karnofsky performance status on admission, cognitive/behavioral deterioration, poor response to the initial radiochemotherapy, and emergence of paraventricular enhanced lesions during the clinical course. The prognosis for patients with GC is unfavorable, but radiochemotherapy may prolong survival.
  Neurosurgical Review 02/2011; 34(2):197-208. · 2.04 Impact Factor
• Article: Logarithmic decrease of serum alpha-fetoprotein or human chorionic gonadotropin in response to chemotherapy can distinguish a subgroup with better prognosis among highly malignant intracranial non-germinomatous germ cell tumors.

  Tomohiro Kawaguchi, Toshihiro Kumabe, Masayuki Kanamori, Ryuta Saito, Yoji Yamashita, Yukihiko Sonoda, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: Intracranial non-germinomatous germ cell tumors (NGGCTs) are a heterogeneous group of tumors. Although alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) are considered reliable markers for making diagnosis, the relationship between serum concentration of them and prognosis remains unclear. The present study investigated the decrease of serum tumor markers AFP and HCG as prognostic factors for patients with highly malignant NGGCTs. Eight consecutive patients with AFP > 1000 ng/ml or HCG > 2000 mIU/ml at initial treatments after January 2004 were retrospectively reviewed. Serum AFP or HCG concentration and tumor volume were sequentially measured during the therapeutic period. Six patients were treated by neoadjuvant chemotherapy consisting of ifosfamide, cisplatin, and etoposide, followed by salvage surgery and/or radiation therapy. A 14-year-old boy with choriocarcinoma and a 2-year-old boy with yolk sac tumor underwent radical resection because of acute hydrocephalus and mass effect on the brain stem, followed by chemotherapy and radiation therapy. Five patients showed complete response and survived at follow-up periods of 9, 26, 41, 63, and 75 months, and the other three showed partial response but subsequent recurrence, finally died. Patients with complete response showed logarithmic decrease of serum AFP to the normal range in response to chemotherapy, but the others did not. Logarithmic decrease and normalization of serum AFP and HCG levels during neoadjuvant chemotherapy can distinguish a subgroup with better prognosis within highly malignant NGGCTs. To determine it, sequential measurement of serum tumor marker level was efficient. Outcomes were still dismal for slow responding patients, but this simple method may indicate more aggressive therapy.
  Journal of Neuro-Oncology 02/2011; 104(3):779-87. · 3.21 Impact Factor
• Article: Early detection of venous thromboembolism in patients with neuroepithelial tumor: efficacy of screening with serum D-dimer measurements and Doppler ultrasonography.

  Tomohiro Kawaguchi, Toshihiro Kumabe, Masayuki Kanamori, Taigen Nakamura, Ryuta Saito, Yoji Yamashita, Yukihiko Sonoda, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: The efficacy of combined serum D-dimer level measurement and Doppler ultrasonography of the lower extremity was investigated for screening of venous thromboembolism (VTE) in patients with neuroepithelial tumor. Eighty-one patients with neuroepithelial tumor were prospectively studied. All patients underwent measurement of serum D-dimer levels and Doppler ultrasonography of the lower extremity. The serum D-dimer level was measured every week, and Doppler ultrasonography was performed two and two weeks after surgery, then every two weeks until discharge, or every two weeks for patients who did not undergo surgery. If the serum D-dimer level increased over 10.0 μg/ml, Doppler ultrasonography or computed tomography was performed to detect VTE. VTE occurred in 12 (14.8%) patients (seven males and five females; age 34-75, mean 59.0 years). Only one patient was symptomatic, whereas 11 patients identified by the screening were without symptoms. Five patients were treated with anticoagulant therapy, one with prophylactic inferior vena cava filter placement with anticoagulant therapy, and the other six were closely followed up without medication. No patient died of pulmonary embolism. Serial Doppler ultrasonography showed thrombus regression or organization and no thrombus extension. The maximum serum D-dimer value was significantly higher in patients with VTE than in those without VTE (mean 14.5 vs. 3.46 μg/ml, P < 0.001). The D-dimer cutoff value of 5.4 μg/ml could be used to identify VTE with 83% sensitivity and 84% specificity. The combination of sequential serum D-dimer measurement and Doppler ultrasonography of the lower extremity is an efficient and non-invasive procedure for identifying asymptomatic VTE in patients with neuroepithelial tumor.
  Journal of Neuro-Oncology 02/2011; 101(3):495-504. · 3.21 Impact Factor
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  Available from: brainlife.org

  Article: Pilocytic astrocytoma with histological malignant features without previous radiation therapy--case report.

  Ichiyo Shibahara, Tomohiro Kawaguchi, Masayuki Kanamori, Shingo Yonezawa, Hiroki Takazawa, Kenichiro Asano, Hiroki Ohkuma, Mitsuomi Kaimori, Tatsuya Sasaki, Michiharu Nishijima
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  ABSTRACT: Pilocytic astrocytoma sometimes transforms to a malignant type, and previous radiation therapy is considered to be a key factor. We report a case of pilocytic astrocytoma with histological malignant features without previous radiation therapy. A 21-year-old man presented a sudden onset of severe headache. Neuroimaging had detected a cystic mass in the posterior fossa at the age of one year without therapeutic intervention. On admission, computed tomography depicted a brain tumor in the posterior fossa with cystic components, intratumoral hemorrhage, and upward herniation. Urgent surgery was performed, and histological examination revealed some features of pilocytic astrocytoma but also broad necrosis, high cellularity, and MIB-1 labeling index of more than 20%. The histological diagnosis was pilocytic astrocytoma with malignant features. This tumor had continued a benign clinical course for 20 years, but had eventually transformed to a malignant type. Therefore, pilocytic astrocytoma may undergo spontaneous malignant transformation during its natural clinical course.
  Neurologia medico-chirurgica 01/2011; 51(2):144-7. · 0.61 Impact Factor
• Article: Ruptured peripheral aneurysms in a collateral pathway associated with stenosis of a major cerebral artery: Report of two cases.

  Ichiyo Shibahara, Shingo Yonezawa, Hiroki Takazawa, Tomohiro Kawaguchi, Masayuki Kanamori, Kensuke Murakami, Hiroshi Midorikawa, Tatsuya Sasaki, Michiharu Nishijima
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  ABSTRACT: While hemodynamic stress can result in aneurysm formation, it rarely contributes to the development of peripheral aneurysms in collateral pathways. We report two patients with ruptured distal aneurysms in a collateral pathway associated with stenosis of a major cerebral artery. A 67-year-old man presented with intracerebral hemorrhage in the right frontal lobe. Digital subtraction angiography (DSA) revealed severe stenosis of the right middle cerebral artery and two aneurysms in the collateral pathway of the right anterior cerebral artery. The ruptured aneurysm was trapped and resected; histologically, it was a true saccular aneurysm. The unruptured aneurysm was clipped and the patient was discharged without additional neurological deficits. The second patient was a 73-year-old woman with subarachnoid hemorrhage. DSA revealed three arterial dilations. On the 7(th) day of hospitalization, one of the aneurysms in a posterior inferior cerebellar artery-anterior inferior cerebellar artery anastomosis that functioned as a collateral pathway in the presence of severe basilar artery stenosis was found to be enlarged. It was treated by selective aneurysmal coil embolization with parent artery preservation. Her postoperative course was uneventful and she was discharged without any neurological deficits. We document the successful treatment of two patients with ruptured aneurysms in the peripheral portion of a collateral pathway. We discuss the histology of peripheral aneurysms and present a review of the literature.
  Surgical neurology international. 01/2011; 2:81.
• Article: [The safety of combination chemotherapy with ifosfamide, cisplatin, and etoposide (ICE): single-institution retrospective review of 108 cases].

  Masayuki Kanamori, Toshihiro Kumabe, Ryuta Saito, Yoji Yamashita, Yukihiko Sonoda, Teiji Tominaga
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  ABSTRACT: The adverse effects of combination chemotherapy of ifosfamide, cisplatin, and etoposide (ICE) were evaluated in the treatment of various intracranial brain tumors. 108 cases were retrospectively reviewed. The histological diagnosis was newly diagnosed or recurrent germ cell tumor in 45 cases, medulloblastoma in 19, primitive neuroectodermal tumor (PNET) in 7, anaplastic ependymoma in 6, recurrent glioblastoma in 13, and others in 18 cases. Patients received 1-8 cycles of ICE chemotherapy with or without radiation therapy. The adverse effects were analyzed based on the the clinical or laboratory examinations. Common Terminology Criteria for Adverse Events ver. 3.0 (CTCAE v3.0) grade 4 neutropenia, anemia, and thrombocytopenia occurred in 81.4%, 14.8%, and 35.2% of patients, respectively. Non-hematological adverse effects, including infection, elevated aspartate aminotransferase (AST)/alanine aminotransferase (ALT), high or low levels of serum sodium, and seizure, occurred in 26.8%, 29.6%, 28.7%, and 11.1% of patients, respectively. One patient died of opportunistic infection with neutropenia. The proportion of ICE cycles associated with CTCAE v3.0 grade 4 neutropenia, transfusion of platelets, and elevated AST/ALT significantly decreased after enforcement of dose reduction criteria. The high rate of adverse effects requires close follow up and dose reduction.
  No shinkei geka. Neurological surgery 11/2010; 38(11):997-1005. · 0.13 Impact Factor
• Article: O(6)-Methylguanine DNA methyltransferase determined by promoter hypermethylation and immunohistochemical expression is correlated with progression-free survival in patients with glioblastoma.

  Yukihiko Sonoda, Michiko Yokosawa, Ryuta Saito, Masayuki Kanamori, Yoji Yamashita, Toshihiro Kumabe, Mika Watanabe, Teiji Tominaga
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  ABSTRACT: The prognostic significance of O(6)-methylguanine DNA methyltransferase (MGMT) was evaluated by analysis of both MGMT promoter methylation and protein expression in a series of patients with newly diagnosed glioblastoma. Seventy-three patients with glioblastomas treated with alkylating agents were analyzed for MGMT expression by immunohistochemistry. Genomic DNA was isolated from frozen surgical specimens obtained from 62 of 73 patients. MGMT promoter methylation was determined by methylation-specific polymerase chain reaction. The prognostic significance of MGMT was evaluated together with other well-known prognostic factors. MGMT promoter hypermethylation was detected in 35 of 62 patients (56.4%). MGMT immunoreactivity was low in 26 (35.6%) tumors, moderate in 24 (32.9%), and high in 23 (31.5%). Significant correlation was observed between MGMT expression and MGMT promoter methylation (P < 0.001). Both MGMT promoter methylation and low MGMT expression were independently associated with better progression-free survival but not with longer overall survival. However, in the subgroup analysis, MGMT promoter hypermethylation was significantly associated with longer overall survival in patients treated with temozolomide (TMZ) after nimustine hydrochloride (ACNU) treatment. Low MGMT expression and MGMT promoter methylation are both predictive markers for slower tumor progression in patients with glioblastoma.
  International Journal of Clinical Oncology 03/2010; 15(4):352-8. · 1.41 Impact Factor
• Article: [A case of symptomatic arachnoid cyst, that had been growing for 14 years, at the posterior part of the left temporal lobe].

  Emiko Hori, Tomoaki Fujita, Shinjitsu Nishimura, Tomohiro Kawaguchi, Shingo Yonezawa, Masayuki Kanamori, Michiharu Nishijima
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  ABSTRACT: The authors report a 54-year-old woman with headache in whom a cyst was detected at the posterior part of the left temporal lobe following a traffic accident in 1993. Symptoms had recently worsened and computed tomography demonstrated an enlarged cyst in 2007. Thereafter, the patient underwent cyst fenestration. Intraoperative findings showed multilocular cysts with calcification. Symptoms improved immediately. Histological findings showed that the cyst was composed of collagenous membrane and a monolayer of cells compatible with arachnoid cyst. These findings also showed calcification and we considered that growth of the arachnoid cyst had been induced by trauma. We expected an arachnoid cyst with a single cavity, but this lesion was multilocular. Retrospectively, cine magnetic resonance image (MRI) seemed to show multilocular cysts. Cine MRI might be an effective tool to determine whether a cyst is multilocular.
  No shinkei geka. Neurological surgery 02/2010; 38(2):157-62. · 0.13 Impact Factor