Volume measurement on 3D-SPGR MR imaging was a suitable method to assess tumor changes. Volume changes beyond twofold or continuous enlargement for longer than 2 years after radiosurgery are key criteria in rating the effects of radiation. Some cases of hydrocephalus after radiosurgery resolved spontaneously and their rates of occurrence were similar to the typical incidence of hydrocephalus associated with VS.

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Radiotherapy is the primary and most important adjuvant therapy for malignant gliomas. Although the mechanism of radiation resistance in gliomas has been studied for decades, it is still not clear how the resistance is related with functions of molecular chaperones in the endoplasmic reticulum. Calreticulin (CRT) is a Ca 2+ -binding molecular chaperone in the endoplasmic reticulum. Recently, it was reported that changes in intracellular Ca 2+ homeostasis play a role in the modulation of apoptosis. In the present study, we found that the level of CRT was higher in neuroglioma H4 cells than in glioblastoma cells (U251MG and T98G), and was well correlated with the sensitivity to ;-irradiation. To examine the role of CRT in the radiosensitivity of malignant gliomas, the CRT gene was introduced into U251MG cells, which express low levels of CRT, and the effect of overexpression of CRT on the radiosensitivity was examined. The cells transfected with the CRT gene exhibited enhanced radiationinduced apoptosis compared with untransfected control cells. In CRT-overexpressing cells, cell survival signaling via Akt was markedly suppressed. Furthermore, the gene expression of protein phosphatase 2AcA (PP2AcA), which is responsible for the dephosphorylation and inactivation of Akt, was up-regulated in CRT-overexpressing cells, and the regulation was dependent on Ca 2+. Thus, overexpression of CRT modulates radiation-induced apoptosis by suppressing Akt signaling through the up-regulation of PP2AcA expression via altered Ca 2+ homeostasis. These results show the novel mechanism by which CRT is involved in the regulation of radiosensitivity and radiation-induced apoptosis in malignant glioma cells.

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Intracranial endodermal cysts are rare, particularly when associated with the cranial nerves. To our knowledge, this is the second case of endodermal cyst located on the oculomotor nerve. A detailed discussion and review of these case reports are presented.

A 63-year-old woman presented with right hearing disturbance and vertigo. Magnetic resonance (MR) imaging revealed the presence of right vestibular schwannoma (VS). Stereotactic radiosurgery (SRS) was performed with a tumor marginal dose of 14 Gy using two isocenters. She was followed up clinically and neuroradiologically using three-dimensional spoiled gradient-echo MR imaging. She experienced temporal neurological deterioration due to peritumoral edema in her right cerebellar peduncle and pons for a few months beginning 1.5 years after SRS, when she experienced transient right facial dysesthesia and hearing deterioration. Ten years after SRS, the patient presented with sudden onset of vertigo, gait disturbance, diplopia, dysarthria, and nausea. MR imaging demonstrated a new lesion in the right cerebellar peduncle, which was diagnosed as radiation-induced stroke. The patient was followed up conservatively and her symptoms disappeared within a few months. Multiple delayed onset radiation injuries are possible sequelae of SRS for VS.

No abstract