We analyzed retrospectively, the usefulness of the radiological examinations for 15 cases of communicating arachnoid cysts in thoracic lesions experienced by our department over the last 12 years. Seven men and eight women(age range 32-71 years, mean age 53.8 years)were analyzed. Their symptoms on admission were sensory disturbance of the legs(13cases), leg weakness(4cases), back pain(4cases), and truncal abnormal sensations(2cases), etc. We performed myelography in 12 patients, and an additional 5 patients were diagnosed by this examination. CT-myelography showed deformity of the spinal cord, deviation of the spinal cord and enlargement of the subarachnoid space in all 12 patients. The axial view in 1.0T weighted MRI showed the same findings as CT-myelography. However, the cine 1.0T weighted MRI seemed to be insufficient to detect any spinal arachnoid cysts. As the results of their operations, 13 patients improved, 2 patients remained unchanged, and no cases become worse. The clinical and radiological diagnosis for communicating arachnoid cysts is not easy. Neurological examinations and radiological examinations with detailed readings are essential to obtain a correct diagnosis, when considering the possibility of the disease.

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Endoluminal evaluation was done with virtual vascular endoscopic imaging(VVE)using perspective volume rendering of 3D-MR angiography in 4 cases of unruptured cerebral aneurysms. Virtual endoluminal observation of the aneurysms in relation to their parent arteries was done from inside the parent arteries or in the intra-aneurysmal space. VVE delineated the orifices of the cerebral aneurysms and intra-aneurysmal spaces through the parent arteries. In a patient with a middle cerebral artery aneurysm, the direct opening of the efferent parent artery from the dome of the aneurysm was clearly demonstrated. Images of the aneurysms from the intra-aneurysmal space delineated the concave bleb of the inner wall of the aneurysms and the orifices of the parent arteries at the neck of the aneurysms. In a large aneurysm, the intra-aneurysmal structure may be incomplete due to flow artifact of the source volume data set. Viewing points are indicated by arrows shown either on the source axial images, reconstructed coronal and sagittal images, and reconstructed volume-rendering three-dimensional MR angiograms. These images provided the precise endoluminal orientation of VVE. The software we used shortened the reconstruction time(30 sec)to facilitate the clinical applications of VVE. As an alternative to "real" .intravascular endoscopy, VVE imaging of 3D-MRA may have a role in preoperative evaluation and simulation of interventional procedures, such as GDC coil embolization of cerebral aneurysms. Additionally, observation of the orifies of parent arteries and intra-aneurysmal spaces with VVE may be useful for the endoluminal diagnosis of cerebral aneurysms.

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A 22-year old woman who suffering from headache, visual disturbance and amenorrhea was admitted to our hospital. Enhanced magnetic resonance imaging revealed a suprasellar cysric tumor, 2×3×2.5cm in diameter, which was observed to be separated from the normal pituitary gland by the diaphragma sellae. The basal values of serum prolactin(PRL)and growth hormone(GH)were in the high range on the endocrinological examinations while the basal value of serum adrenocorticotropic hormone(ACTH), thyroid stimulating hormone(TSH), luteinizing hormone(LH)and follicle stimulating hormone(FSH)were all in the low range. Also each change in the concentration of these hormones showed poorly under the triple stimulation test using an intravenous injection of TRH(500μg), LH-RH(100μg)and human insulin(5 units). During the total removal of the tumor, we confirmed that the tumor was attached to the pituitary stalk and was clearly separated from the normal pituitary gland by the diaphragma sellae. The neuropathological examination of the tumor specimen showed positive for chromophobe pituitary adenoma using hematoxylin-eosin staining, and many tumor cells were also stained positively for PRL or GH by using an immunostaining technique. We concluded that this ectopic suprasellar pituitary adenoma originated from the pars tuberalis of the pituitary stalk and that many of the tumor cells produced PRL or GH. Postoperative endocrinological study indicated a slightly low level for the basal value of serum PRL and the change of serum PRL concentration under the triple stimulation test was poor. On the other hand, the basal values of GH, ACTH, TSH, LH and FSH improved to the normal range, and each change in the concentration of these hormones under the triple stimulation test was normal. The patient recovered from her headache and visual disturbance immediately after surgery, and she regained her regular menstruation at 6 months after surgery. Ectopic suprasellar pituitary adenomas are very rare, and we emphasize that the total removal of the ectopic pituitary functioning adenoma is necessary for neurological and endocrinological improvement.

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Intraventricular meningiomas are of rare occurrence. However, they are very interesting in the clinical and radiological points of view. Even though meningiomas usually appear gradually with a slow and progressive course, we experienced 2 cases with acute onsets. Case 1 : A 58-year-old male was transported to the hospital with an acute consiousness level deterioration. The CT scan exposed an intracerebral hematoma adjacent to a tumor which was located within the antrum of the lateral ventricle. The patient's neurological condition being life-threatening, an operation could not be performed. As expected, the autopsy revealed a round mass in the antrum with a massive hematoma in the adjacent cerebral hemisphere. Case 2 : A 20-year-old female complained of severe headaches accompanied by vomiting persisting for 3 days subsequent to a head trauma related to a traffic accident. CT and MRI revealed a huge mass occupying almost half of the left suprasentorial space. The tumor was successfully removed via a left parietal transcortical approach and the patient went back home without any neurological deficits. Both patients never had any symptoms suggesting the presence of an intraventricular tumor prior to the incident, intracerebral hemorrhage in the first case and blunt head injury in the second case. Clinical symptoms and signs related to intraventricular meningioma which includes headache, disturbed mentation, motor and sensory deficits, seizure, visual field defects, dysphagia, alexia and ataxia are sometimes vague because the tumor expands in a gradual manner, slowly increasing the capacity of the ventricle. We would like to stress that some intraventricular meningiomas can present acute symptoms when the tumor grows to be of considerable size and also as the result of buffering effect as the intracranial pressure becomes too small.

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A 60-year-old female presented with a massive left subdural hematoma caused by the rupture of a distal anterior cerebral artery aneurysm. On admission, she was comatose with fixed and dilated pupils, showing a decerebrate posture. She underwent an emergency operation. The subdural hematoma was removed and an external decompression was also undertaked. Her level of consiousness gradually improved and a left hemiplegia became evident. A T2-weighted MRI revealed a lesion in the right cerebral peduncle on the extending line of the tentorium. Such hyperintense lesions may represent the myelin desruction around Kernohan's notch.

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We report a case with MELAS(mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes)which was diagnosed after repeated stroke-like attacks in adulthood. A 29-year-old female had her first attack at age 23 when she presented with headache and high fever associated with a diffuse lesion in the right temporal lobe as revealed on her MRI. The symptoms and radiological abnormalities disappeared in a short time period. Her second attack was at age 27 when she had left homonymous hemianopia and generalized tonic convulsion associated with a right occipital lesion observed on a CT scan and MRI. Laboratory serum data showed in normal and angiographical studies demonstrated no pathological findings. The hemianopia improved progressively following medical treatment. The third attack was at age 29, when she had right homonymous hemianopia assoiated with a left occipital diffuse lesion depicted via CT scan and MRI. Angiography demonstrated early venous filling in the lesion. After the third attack, the serum level of lactic acid was studied and was found to be at a pathologically high level. Finally, blood screening was ordered, which revealed an A to G point mutation of mtDNA. Retrospectively, she had a history of diagnosis of WPW(Wolff-Parkinson-White)syndrome at age 6 and diabetes mellitus since she was twenty-five. MELAS is commonly diagnosed in childhood and adolescence by a variety of symptoms in the systemic organs. MELAS with only stroke-like onset, in particular in adulthood, is potentially misdiagnosed as a cerebrovascular disease. This entity is rare for neurosurgeons to encounter but should be considered as one of the possible differential diagnosis in casess with unknown cause of stroke-like episodes.

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We report a case of ruptured fusiform aneurysm of the supraclinoid internal carotid artery. A 78-year-old woman was admitted to our hospital with subarachnoid hemorrhage on June 15, 1998. Cerebral angiograms showed a fusiform aneurysm in the supraclinoid segment of the left internal carotid artery with bleb formation. This bleb was considered to be the cause of subarachnoid hemorrhage. The patient was operated on by left pterional approach on July 8. A bleb was found on the posteromedial side of the fusiform aneurysm in the supraclinoid segment of the left internal carotid artery. Finally, it was clipped with a Sugita's angled clip applied at 90 degrees to the artery and coated with Bemsheet soaked in Biobond because of intraoperative aneurysmal bleeding. Fourteen months after surgery the patient was alert and could walk with a cane. We also review 13 Previously reported cases of ruptured fusiform aneurysm of the anterior circulation. In cases of subarachnoid hemorrhage without apparent saccular or dissecting aneurysm, rupture of a fusiform aneurysm should be considered in the differential diagnosis. The treatment of choice for a ruptured fusiform aneurysm is clipping with vascular reconstruction. However, in our case, this was impractical and the final treatment was bleb clipping without vascular reconstruction, which is considered to have the risk of rebleeding. We consider that the strict follow-up, including the control of blood pressure is important in our case.

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Two cases of fenestration of the middle cerebral artery(MCA)associated with aneurysms were reported. Case 1 : A 60-year-old female suddenly became unconsious. Left carotid angiography demonstrated a fenestration of the sphenoidal segment of the left MCA and 3 aneurysms, in the bifurcation of the left MCA, in the anterior communicating artery and in the left anterior cerebral artery, were also demonstrated. Surgical intervention was performed on the day of the onset, and all aneurysms were successfully clipped. Case 2 : A 53-year-old female was admitted to our hospital complaining of loss of consciousness. Cerebral angiography demonstrated a fenestration of the sphenoidal segment of the left MCA and an aneurysm at the distal end of the fenestration, and a marked dilatation of the bifurcation of the right MCA. A fenestration of the left MCA was confirmed and an unruptured aneurysm was found arising from the distal end of the fenestration. In tha literature, fenestration of the MCA has been reported in 32 cases, and concomitant aneurysms were found in 21 of these. In most cases, the aneurysms arose from the ipsilateral artery of the fenestration or from the anterior communicating artery. Moreover, a defect in the media at both the proximal and distal ends of the fenestrations has been reported in autopsy cases. From these findings, it is suggested that maldevelopment of intracranial arteries plays an important role in the pathogenesis of the aneurysms as well as in the fenestration pathology itself.

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We report a case of idiopathic brain stone occurring in the right frontal lobe. A 49-year-old man was transferred to our department for post-ictal drowsiness. He had 40 year history of generalized convulsion and slight mental deficiency. Head CT scan revealed, without enhancement effect, a dense bony mass in the right frontal lobe. MRI clearly showed the shape, heterogeneous composition and the anatomical relation to the surrounding structures of the mass. Only an avascular huge mass was observed on the 3D-helical CT scan and cerebral angiography. The mass lesion was removed totally through the pterional approach. The postoperative course was uneventful and anticonvulsants could be reduced with good controlled symptomatic epilesy. In the pathological findings, cystic wall was composed of fibrous connective tissue and calcification including myeloid metaplasia, and its lumen was filled with necrotic amorphous eosinophilic material. The mass was diagnosed as an idiopathic brain stone because of its unkown etiology. Because an idiopathic brain stone, especially over 5cm in diameter, is extremely rare, the etiology and clinical symptoms of this condition are briefly discussed.

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A rare case of desmoplastic astrocytoma developing in an adult was reported. A 23-year-old man presented with headache and a right homonymous hemianopsia. Computed tomography revealed a solid tumor(3×4×4cm)with a cyst-like portion in the left parietal lobe. Subsequent magnetic resonance imaging more clearly depicted a densely enchncing solid tumor with a suspicious dural attachment along the parieto-occipital convexity. A left parieto-occipital craniotomy was performed under the preoperative diagnosis of meningioma and the tumor was totally resected. Histological examination revealed areas of spindle-shaped tumor cells in a storiform pattern quite compactly arranged in sheets, bundles, and lobules separated by thick connective tissue. The tumor cells were immunoreactive to glial fibrillary acidic protein(GFAP). No ganglion cells were identified among the tumor cells. There were some areas with no demarcation from brain tissue and the tumor appeared to partially invade the brain parenchyma. Some mitotic figures and necrotic areas were also noticed, but no endothelial proliferation was seen. This tumor was diagnosed as a desmoplastic astrocytoma.

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