Medulloblastoma is the most common childhood malignant brain tumor. Medulloblastoma is a chemosensitive tumor, with a high response rate to a variety of chemotherapies, including cisplatinum and cyclophosphamide and drug combination regimens. There is increasing evidence that the addition of chemotherapy during and following radiotherapy improves survival for children with medulloblastoma ; as survival rates of greater than 80% as 5 years following diagnosis have been reported. The addition of chemotherapy may allow a reduction in the amount of radiotherapy required for disease control. Chemotherapy alone may be effective therapy for some infants with medulloblastoma. High-dose chemotherapy supplemented with autologous bone marrow rescue or peripheral stem cell support benefits children with recurrent disease and may have a role for patients with newly-diagnosed extensive medulloblastomas or very young children with disease.

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The results of treatment of astrocytic tumors are reviewed. Astrocytic tumors are oncopathologically defined as carcinomas of the brain. Even well-differentiated (non-pilocytic) astrocytomas grow invasively and cannot be Cured by extensive surgery followed by radiation therapy. The 10-year survival rate of patients with favorablerisk astrocytomas is approximately 50% ; recurrent tumors are usually more malignant histologically. Astrocytomas should be treated in the same manner as malignant gliomas. In patients with poorly differentiated glioblastomas, the median survival time is only 60 to 70 weeks. In an attempt to improve these poor treatment results, the delivery of localized high-dose irradiation to bulky tumors should be combined with radiation therapy. Iodine-125 brachytherapy and intraoperative radiation therapy result in a better prognosis. However it is necessary to develop an effective combination of conventional radiation therapy in combination with the administration of radiosensitizing agents. In addition, adjuvant chemotherapy after radiation and chemotherapy may prolong the lives of patients who have undergone surgery for cerebral glioblastomas.

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Molecular genetic analyses have revealed that the genesis and progression of tumors are the result of accumulated changes in positive and negative growth-regulatory genes. Several sequential genetic alterations are considered to be required to direct cells toward the malignant phenotype. Recent studies have demonstrated that glial oncogenesis is also involved in multiple, but relatively consistent genetic alterations. The most frequent chromosomal alterations observed in astrocytic tumors include amplification of chromosome 7 and losses on chromosomes 9p, 10, and 17p. The p53 gene and the CDKN2/pl6 gene have been indicated as target genes for losses of chromosome 17p and 9p, respectively. The biochemical characters of these tumor suppressor proteins are discussed in this review.

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We described endoscopic findings in 2 cases of chronic subdural hematoma (CSDH) and discuss the advantages and disadvantages of this new technology and the possibility of using endoscopy in the treatment of CSDH. Although only 2 cases were examined, the disadvantages of this new technology are the difficulties of smooth movements near the brain surface and visual problems when the fluid Is bloody. Moreover, because most cases of CSDH are satisfactorily treated with current methods, this new technology is not always necessary. Further improvement will be needed in endoscopic techniques and equipment if CSDH is to be routinely treated with neuroendoscopy. However, endoscopic findings of hematoma cavities, such as fibrous membrane or the various stages of hematoma, may provide greater insight into the prognosis and pathogenesis of CSDH.

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We report on 4 cases of acute cerebrovascular ischemia treated with staged revascularization. Fibrinolytic therapy for acute cerebral ischemia is often not sufficient to improve the hemodynamic status, and in these patients prevention of ischemia recurrence and achievement of stable hemodynamics are necessary. We used intravascular techniques, consisting of intraarterial infusion of urokinase or percutaneous transluminal angioplasty as the first procedure, in 4 such patients. Carotid endarterectomy or superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis was subsequently performed as the second procedure. All 4 acute stage, critical patients recovered hemodynamic stability and their symptoms were ameliorated. We suggest that staged revascularization is an useful treatment modality in selected patients with acute cerebral ischemia and impaired hemodynamic status.

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Hydroxyapatite ceramics are currently used for anterior cervical fusion following discectomy and osteophytectomy. However, there are few reports describing the biomechanical properties of hydroxyapatite intervertebral grafts such as structural capacity and mechanical resistance. The purpose of this study is to evaluate the biomechanical properties of a porous hydroxyapatite intervertebral graft. We used cadaveric porcine cervical spine that had undergone C3/4 discectomy and dissection of the posterior longitudinal ligament as an instability model. The experimental groups included the intact (n= 11), instability (n= 11) , autogenous bone-implanted (n=6) and hydroxyapatite graft-implanted (n= 5) groups. Porous hydroxyapatite with 40% porosity and scapular bone were used as the hydroxyapatite and autogenous bone graft, respectively. The displacement rates of the cervical spine by compressive forces to flexural, extensional, and lateral bending directions were evaluated using a video recording followed by computer-assisted analysis. The stiffness at 80 N of compressive load was calculated from the load-displacement curve. Further, linear and nonlinear coefficients, possibly representing the biomechanical characteristics of the grafts, were calculated based on Fung's theory. Compared with the intact group, the instability group showed significant decreases in the stiffness in all directions except flexural compression. Both the hydroxyapatite and the autogenous bone graft had significantly increased the stiffness in all directions except extensional load. There were no statistical differences in the stiffness between the hydroxyapatite and the autogenous bone graft in all directions except right lateral bending load. The nonlinear coefficient value in Fung's equation was far larger in the hydroxyapatite than in those observed in the autogenous graft. The present study indicates that the porous hydroxyapatite graft exhibits compressive strength equal to the autogenous graft in vitro. A larger nonlinear coefficient value may represent the brittleness of the hydroxyapatite graft.

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We report a child with moyamoya disease who was successfully treated by one-staged extensive indirect vascular reconstructive surgery by a combination of encephalo-duro-arterio-synangiosis (EDAS), encephalo-myo-arterio-synangiosis (EMAS) and encephalo-galeo-synangiosis (EGS). An 8-year-old girl had frequent transient ischemic attacks involving the bilateral extremities starting at 2 years of age. Magnetic resonance imaging showed border zone infarcts on bilateral hemispheres. Cerebral angiogram revealed bilaterally typical moyamoya vessels in the basal ganglia, middle cerebral artery occlusion, and anterior cerebral artery stenosis. Cerebral blood flow (CBF) measurement by SPECT using ^<133>Xe inhalation method demonstrated low CBF at rest and no response to Diamox loading in either cerebral hemisphere except for that in part of the occipital lobe. We performed one-staged indirect vascular reconstruction ; EDAS on the bilateral posterior branches of superficial temporal artery (STA) and on the left occipital artery, EMAS on the anterior branch of the left STA, and EGS on the left parietal and temporo-occipital regions and on the right frontal and parieto-occipital regions, resulting in the disappearance of transient ischemic attacks by the second postoperative week. Postoperative examination 3 months after surgery showed rich collaterals from the bilateral external carotid arteries and a 38% increase in resting CBF throughout the cerebrum. Thus, one-staged extensive indirect vascular reconstructive surgery may be prudent in treating pediatric moyamoya disease, covering whole areas where preoperative CBF measurement revealed low CBF at rest and impaired vascular reactivity on Diamox loading.

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A 29-year-old woman was admitted to our hospital on March 28, 1994, complaining of left hemiparesis and dysesthesia. CT and MRI on admission revealed a large, homogeneous, contrast-enhanced mass in the right thalamus with a large cystic component extending to the right basal ganglia, although an incidental CT scan performed 3 years prior to adimission had revealed no visible tumor. The patient underwent frontotemporal craniotomy on April 12, 1994, and the tumor was completely resected using the transsylvian approach. Histological examination revealed that the tumor was composed of ganglion cells and astrocytic cells. Immunohistochemical examination showed that the ganglion cells had positive immunoreactivity to synaptophysin, neuron-specific enolase (NSE) , and 68-kDa neurofilament protein (NFP) , and that the astrocytic cells immunoreacted positively to glial fibrillary acid protein (GFAP). Upon review of the literature, only 4 previous reports of thalamic ganglioglioma were found. In those 4 cases (excluding ours) , radical resection was not performed even though it has been indicated that surgical extirpation of the tumor contributes to a favorable long-term survival rate and good functional outcome in cerebral ganglioglioma patients. The clinical status of the previously reported 4 patients, including hemiparesis and mental retardation, was unchanged from that prior to initial resection. Thus it appears that thalamic ganglioglioma is rare and difficult to treat.

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A 9-year-old boy who had multiple brain abscesses associated with congenital biliary atresia (CBA) . He had successful hepatic portoenterostomy at 46th day after birth. His liver dysfunction persisted after the elimination of icterus. He was admitted with complaint of high grade fever and convulsions. The brain CT scan on admission showed multiple brain abscesses with remarkable midline shift and we performed emergent drainage of one abscess. The pathogenic organism was methicillin sensitive Staphylococcus aureus. Afterward we carried out drainage of the abscesses twice, ventricle drainage twice and V-P shunt. In addition he received local and systematic medication of antibiotics and γ-globulin, and all of them had vanished. Cyanopathy was recognized at admission, but polycythemia was not detected. Standard echocardiography didn't show any cardiac arteriovenous shunt. But contrast echocardiography revealed arteriovenous shunts in the lungs. Pulmonary scintigraphy using ^<99m>Tc-MMA showed cold areas in the peripheral lung fields and it was supposed that there were pulmonary arteriovenous fistulas (PAVFs) in the areas. It is known that brain abscess is a serious complication of pulmonary arteriovenous fistula. The origin of the infection was untreated dental caries. The patient has left the hospital with aftereffects of homogeneous hemianopsia and unilateral spatial neglect. Recent advances in surgical treatments and their wide availability made it possible for patients with CBA to live longer and to increase complications as above mentioned, so we should pay attention to them.

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We present a case of pituitary abscess in a Rathke's cleft cyst. A 14-year-old woman was admitted to our hospital with complaints of headache and visual field defect. Her past history was unremarkable except for Garre's myelitis at age 10. Endocrinological examination revealed panhypopituitarism. Plain skull X-ray films showed normal sella, but CT and MRI showed a cystic lesion with a ring-like enhancement in the intrasellar and suprasellar region. Transsphenoidal surgery confirmed an abscess formation in the pituitary fossa. The postoperative course was uneventful. A histological examination of the abscess wall revealed a ciliated cuboidal to columnar epithelium and inflammatory cell infiltration beneath the epithelium. We discuss the mechanism, MR appearance, and treatment of abscess formation in a Rathke's cleft cyst.

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