Tatsuya Nagashima

Endoscopic treatment for a huge neonatal prepontine-suprasellar arachnoid cyst: a case report.

A huge prepontine-suprasellar arachnoid cyst was identified by fetal sonography and magnetic resonance imaging. It was successfully treated with a two-stage operation using a neuroendoscope. The first operation during the neonatal period consisted of implantation of a cyst-peritoneal shunt. In the second operation, the cyst was fenestrated with the aid of a neuroendoscope. The cyst membrane was seen to cover the foramen magnum and to extend continuously to the ventral surface of the brain stem. At the foramen magnum, it was pulsating synchronously with the pulsation of the vertebral artery, which was suggestive of the mechanism of cyst growth. A ventriculo-peritoneal shunt was inserted to replace the cyst-peritoneal shunt. Endoscopic cyst fenestration is a less invasive alternative for the treatment of arachnoid cysts and can also be used for young children. In that case, however, special care should be taken to avoid complications, especially if the cyst exerts considerable pressure on the critical areas of the brain.

Quantitative analysis of hyperosmotic and hypothermic blood-brain barrier opening.

Hyperosmotic opening of the blood-brain barrier (BBB) by mannitol is being used to enhance drug transport in human brains. Recently, cooling of the solution has been reported to have potential to open the BBB. However, the mechanism in barrier opening and closure remains elusive. We studied the rapid changes in cerebrovascular permeability after hyperosmotic and hypothermic BBB opening in rats, and then demonstrated that the Na+/Ca++ exchange blocker (KB-R7943) prolongs opening. BBB opening was attained by using intra-arterial infusion of hyperosmotic mannitol (1.6 M) and 1.1 M mannitol (which is less hyperosmotic than commonly used mannitol) at 4 degrees in Sprague-Dawley (SD) rats. To measure the changes in cerebrovascular permeability, perfusate-containing [14C]-sucrose was infused intra-arterially at different time points following hyperosmotic and hypothermic stress. Cerebrovascular permeability was then measured with the in situ brain perfusion technique. 1.6 M Mannitol produced opening of the BBB but the duration of the opening was less than 30 minutes. Use of 1.1 M Mannitol at 4 degrees indicated the same results. We then investigated the effect of a Na/Ca ion exchange blocker (KB-R7943) in both hyperosmotic and hypothermic BBB opening. KB-R7943 extended BBB opening up to 30 min without affecting the peak level of BBB permeability at 5 minutes. Our findings represent important experimental information regarding pharmacological manipulation of BBB opening. The possibility of prolonging the transient opening of the BBB has major clinical implications.

Optimized Surgical Approach to Third Ventricular Choroid Plexus Papillomas of Young Children Based on Anatomical Variations

BACKGROUND Choroid plexus papilloma (CPP) in the third ventricle is a rare benign intracranial tumor. METHODS We report 3 pediatric cases of CPP in the third ventricle. The lesions were totally removed by a different surgical approach in each case. RESULTS When remarkable hydrocephalus is present, the transcortical approach is easier to perform, but may expose the patient to epilepsy and subdural effusion postoperatively. The transcallosal approach offers direct exposure of the ventricle system with minimal risk of cortical damage. The transcallosal-transforaminal approach with posterior enlargement of the foramen of Monro along the choroidal fissure provides a direct trajectory into the third ventricle through the natural cleft. The transcallosal-interforniceal approach does not depend on the size of the foramen of Monro, but it carries a risk for damage to the both fornices. The midline plane of the septum pellucidum and the forniceal columns in children are sometimes easily identifiable and separable, and in such cases the transcallosal-interforniceal approach appears to be a safe route for tumors extending to the posterior third ventricle. The interforniceal approach should be reserved for lesions that cannot be removed safely via the transforaminal approach. CONCLUSIONS Young children have a small total blood volume and fragile cardiovascular status. Therefore, it is critical to preserve the venous system and to ligate the feeding artery before extirpation of the tumor. The surgical approach to the third ventricular CPPs should be tailored to individual children based on tumor size, location, and vascularity.

Ependymoma with "granular cell" features: report of two cases.

We report two cases of ependymoma which showed prominent “granular cell” changes of the cytoplasm. The patients were a 7‐year‐old boy with a tumor in the cerebellum (case 1) and a 70‐year‐old man with a tumor in the frontal lobe (case 2). The tumor of case 1 showed a histopathological appearance of ependymoma containing many focal aggregates of large polygonal cells in which the cytoplasm was stuffed with numerous eosinophilic granules. The tumor of case 2 predominantly showed the features of papillary ependymoma, and some tumor cells were swollen and contained similar eosinophilic granules. Intracytoplasmic granules in both tumors were immunoreactive for GFAP and ubiquitin, but not for epithelial membrane antigen, CD68 or mitochondria. Ultrastructurally, they were found as aggregates of membrane‐bound, electron‐dense, globular structures. Karyotypic analysis of the tumor in case 1 demonstrated 2, 11 and 12 trisomies. Intracytoplasmic eosinophilic granules occasionally occur in astrocytic and oligodendroglial neoplasms, but an appearance of similar granules is very rare in ependymoma. The two cases presented here may represent a new histopathological variant of ependymoma, and the term “granular cell ependymoma” is appropriate for them.

Medulloblastoma with suprasellar solitary massive metastasis: Case report.

It is extremely rare for metastasised medulloblastoma to form a large tumour in the suprasellar region. We present a case of medulloblastoma with large suprasellar metastasis at initial presentation. A 3-year and 5-month-old boy presented with a 1-month history of vomiting and loss of appetite, and body weight. Computed tomography and magnetic resonance imaging revealed a 20 mm × 20 mm mass in the suprasellar region and a 30 mm × 30 mm mass in the fourth cerebral ventricle. We performed endoscopic biopsy of the suprasellar tumour, and subsequently totally removed the vermian tumour through a suboccipital craniotomy. The histopathological findings revealed that both the suprasellar and vermian tumours were classic type and non SHH/WNT type medulloblastoma. The postoperative course was uneventful. The patient showed complete remission after chemotherapy. The tumour in the suprasellar region was most likely metastatic from the vermis. Endoscopic biopsy of the tumour in the suprasellar region and total removal of the tumour in the vermis in a one-stage operation followed by intensive chemotherapy with reduced dose radiotherapy may provide a satisfactory outcome.