The purpose of this study was to analyze tumor control and possible complications of gamma knife radiosurgery (GKRS) in patients with acoustic schwannomas treated using low marginal dose and conformal multiple shots with smaller collimators to fit irregular tumor shapes. The authors evaluated 183 patients with follow-up periods ranging from 3 to 11 years. Marginal doses were 9 to 15 Gy (median 12 Gy), with corresponding treatment volumes being between 0.1 and 18.7 ml (median 1.8 ml). The number of isocenter varied from 2 to 24 shots (median 9 shots). The actuarial tumor control rate (resection-free survival) was 96.5%. Useful hearing, trigeminal and facial functions were preserved at 75%, 97.4%, and 100%, respectively. Hydrocephalus was recognized in 5.7% of all patients, and seems to occur in cases with medium sized tumors where mild ventricular enlargement is evident prior to treatment. GKRS proves to be a safe and effective therapy for small to medium sized tumors. However, the indication for larger sized tumors (diameter 3+cm) should be carefully considered, larger tumors being less easy to control and liable to cause ataxia due to transient expansion.

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We report a case of medulloblastoma with atypical radiographical appearances on MRI. This 11-month-old girl has been visited a pediatrician with complaint of vomiting and activity loss. Distension of the anterior fontanel was pointed out and was promptly consulted to our institution. CT scan exhibited hydrocephalus and a posterior fossa mass. MRI study after emergency external ventricular drainage demonstrated a mass existed at the tectum of midbrain and showed minimum enhancement after gadolinium injection. Many textbooks mention that the majority of medulloblastomas show moderate to marked enhancement after injection of gadolinium. Because of the feeble enhancement and location of the tumor, we were not able to regard the tumor as medulloblastoma with confidence preoperatively. By reviewing past reports concerning radiological characteristics of medulloblastoma, minimum enhancement is not so rare. We emphasize that whenever we encounter a children's posterior fossa, regardless of MRI appearance, we should include medulloblastoma in differential diagnosis.

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The authors report a 12-year-old girl with moyamoya disease who was treated by unilateral combined extensive indirect revascularization surgery 8 years after initial bilateral encephalo-duro-arterio-synangiosis (EDAS) and encephalo-galeo-synangiosis (EGS). When she was 4 years old, she had frequent transient ischemic attacks (TIA) involving the lower extremities and had been treated by bilateral EDAS and EGS at another hospital. Thereafter, apparent TIA disappeared, but mental retardation developed gradually, associated with an occasional sense of weakness in the left lower limb. We performed combined extensive indirect vascular reconstruction covering the area of resting low cerebral blood flow (CBF) with no response to an acetazolamide challenge test, that resulted in an improvement of mental activity and the disappearance of weakness in the left lower limb. Postoperative examination 1 year after re-operation showed rich collaterals from the external carotid artery and improvement of both resting CBF and response to an acetazolamide challenge test. Thus we suggest that, after initial revascularization for pediatric moyamoya disease, we observe clinical signs first and periodically perform MRI/MR angiography and SPECT. When poor improvement of clinical signs or CBF is observed at one year after surgery, re-operation covering the whole area of low perfusion at rest with no response to an acetazolamide challenge test should be considered.

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We report 2 cases presenting ventriculitis, which were effectively treated by neuroendoscopic surgery. A 70-year-old woman showed progressing consciousness disturbance 18 days after clipping surgery for ruptured aneurysm of the middle cerebral artery. Computed tomography (CT) revealed fluid-fluid level layering in the lateral ventricles. Irrigation with antibiotics was not effective to control intraventricular infection. Resection of membranes created in the ventricle and evacuation of debris were performed using a neuroendoscope. A ventricular drainage was implanted in the posterior horn of the lateral ventricle. The cerebrospinal fluid data was improved immediately, and ventriculoperitoneal shunt was successful. A 31-year-old man deteriorated his consciousness level 6 days after pneumocephalus and skull base fracture caused by head trauma. CT demonstrated a marked ventriculomegaly. Unilateral ventricular drainage decreased a size of the ipsilateral ventricle, but contralateral ventricle remained to be enlarged. Neuroendoscopic irrigation of the ventricle and evacuation of debris were performed. After the CSF data was improved, septostomy of the septum pellucidum was performed with ventriculoperitoneal shunt, because stenosis of the foramen of Monro was observed. Neuroendoscopic treatment, including resection of the membrane and septum created in the ventricles and evacuation and irrigation of infectious debris, could be attempted with minimally invasive technique, and has advantage of spontaneous external drainage and irrigation. We believe that the endoscopic intervention should be considered as the initial treatment option.

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Anterior spinal artery syndrome of the cervical hemicord is very rare and there have been few reports in the literature. A 63-year-old woman was admitted for left arm numbness and gait disturbance. On admission, she showed severe dysesthesia in her left arm, mild left hemiparesis, right-sided hypalgesia and thermohypesthesia below T-1 level. Magnetic resonance (MR) imaging of the cervical spine showed a high intensity lesion on both diffusion-weighted and T2-weighted images in the left ventral portion of the spinal cord at C-7. Serologic test for syphilis, antinuclear antibodies and anticardiolipin antibody were negative. Serum IgM titers for various viral antigens were also negative. In addition, CSF analysis including tests for oligoclonal band and for myelin basic protein were normal. Therefore, we suspected unilateral infarction of the cervical cord and immediately administered corticosteroid and antihypertonic agent. She developed right hemiplegia one week later, however, her motor symptoms gradually improved in the two weeks after her admission. She was discharged on foot with minimal left hemiparesis predominantly revealed in the fingers of her left hand and persistent right hemisensory disturbance 60 days after onset. Although anterior spinal artery syndrome of the cervical hemicord is extremely rare, prompt diagnosis using diffusion-weighted MR imaging and immediate treatment may ameliorate the functional outcome.

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A 73-year-old woman underwent a frontotemporal craniotomy and aneurysmal clipping for both an unruptured internal carotid-posterior communicating aneurysm (ICPC AN) and a basilar tip aneurysm (BA tip AN). The ICPC AN was completely clipped whereas the BA tip AN was not because of kinking of the perforating arteries due to neck clipping. As the perforating arteries were tightly adherent to the aneurysm body, intentional neck plasty was achieved to spare the perforating arteries. Subsequently, obliteration of the residual BA tip AN was performed by endovascular treatment. The patient was discharged with mild oculomotor nerve palsy. Combined open and endovascular surgery for complete obliteration of the wide neck BA tip AN could be one option for preserving thalamoperforating arteries.

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Two cases of subdural hematoma secondary to metastatic dural carcinomatoses are reported herein. In the first case, the subdural hematoma was assumed to be the result of obstruction of the dural veins by tumor cells and from the subsequent bleeding from the capillaries in the inner areolar layer of the dura. Furthermore, the elevation of intracranial pressure seemed to be caused by the occlusion of the dural sinus by the tumor cells. In the second case, a coagulation defect or DIC played significant role in the development of the subdural hematoma. Also, bleeding from the immature outer membrane of the hematoma caused a large amount of intermittent subdural hemorrhage. The relevant literature about subdural hematoma due to dural metastasis of malignant tumors was reviewed, and the mechanism of the hemorrhagic phenomenon was discussed.

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We report a case treated successfully by CEA for pseudo-occlusion of the ICA. A 77-year-old man was admitted with brain infarction. Carotid angiography showed a nearly occluded right ICA at the origin. The intracranial portion of the early arterial phase showed back-filling of the carotid siphon via the ophthalmic artery. The late arterial phase of the same right common carotid angiography revealed extremely delayed antegrade flow through the patent ICA. Conventional carotid ultrasonography and transoral carotid ultrasonography enabled us to decide that CEA was indicated. Intraoperative doppler showed the patent of the distal ICA. Flow patterns of the ICA and the ECA after CEA were normalized. Doppler is a very useful tool to evaluate the dynamic change of the flow pattern during the operative procedure.

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A 37-year-old woman had received human menopausal gonadotropin-human chorionic gonadotropin (hMG-hCG) therapy for sterility. An abdominal ultrasound examination on the 15th day of hMG-hCG therapy revealed ovarian hypertrophy and ascites, leading to a diagnosis of ovarian hyperstimulation syndrome. The patient suddenly became comatose with decerebrated rigidity, bilateral mydriasis with absent light reflex, and doll's eye phenomenon on the 20th day of hMG-hCG therapy. Blood tests revealed an elevated red blood cell and hematocrit. Serum examination showed a high level of thrombin-antithrombin III complex, D-dimer, FDP and a estradiol, and low level of antithrombin III. Cerebral angiography revealed an occlusion of the left posterior cerebral artery. The occluded artery was partially recanalized by local thrombolysis using tissue plasminogen activator. Magnetic resonance imaging after the treatment showed an infarction in the bilateral midbrain and thalami. The patient settled in her disability with disorientation and upper gaze palsy. We suppose that ovarian hyperstimulation syndrome induced the hypercoagulability, which in larn led to the basilar artery embolism in this case.

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