[Refractory chronic subdural hematoma due to spontaneous intracranial hypotension].

Spontaneous intracranial hypotension (SIH) is reported to cause chronic subdurai hematoma (SDH), however diagnosis of SIH in patients with SDH is not always easy. We report a case of chronic SDH refractory to repeated drainage, which was attributed to SIH. A forty-five-year-old man who had been suffering from orthostatic headache for one month was admitted to our hospital presenting with unconsciousness and hemiparesis. CT on admission revealed a chronic subdural hematoma, which was successfully treated once with subdural drainage. However, the patient fell into unconscious again with recurrence of the hematoma within several days. After two more sessions of drainage, SIH due to cerebrospinal fluid leakage was diagnosed with spinal magnetic resonance imaging (MRI) and radionuclide cisternography. Spinal MRI demonstrated abnormal fluid accumulation in the thoracic epidural space, and the radionuclide cisternogram showed early excretion of tracer into urine as well as absence of intracranial tracer filling. After treatment with epidural blood patching, the hematoma rapidly disappeared and he was discharged without symptoms. In the treatment of chronic SDH, especially in young to middle aged patient without preceding trauma or hematological disorders, physicians should pay attention to underlying SIH to avoid multiple surgery. MRI of the spine as well as radionuclide cisternography is useful in evaluation of this condition.

Reduced expression of the transporter associated with antigen processing 1 molecule in malignant glioma cells, and its restoration by interferon-gamma and -beta.

OBJECT: It remains unclear whether malignant glioma cells can deliver tumor antigens efficiently to major histocompatibility complex (MHC) Class I molecules. To elucidate the mechanism of antigen presentation in malignant gliomas, the authors examined the expression of the transporter associated with antigen processing 1 (TAP1), which transports antigens to MHC Class I molecules, and low-molecular-mass polypeptide 2 (LMP2), which is a subunit of a proteasome. They also analyzed the effects of interferon (IFN)-gamma and IFN-beta on the expression of these molecules. METHODS: Five glioma cells expressed undetectable or very low levels of TAP1 protein and did not express TAP1 messenger (m)RNA. Normal brain tissue and glioma tissue specimens also showed undetectable levels of TAP1 protein and the same levels of LMP2 protein as lymphoblastoid B cells. Treatments of the tumor cells with IFN-gamma, or -beta enhanced the expression of both TAP1 protein and mRNA as well as the expression of MHC Class I molecules. The expression of LMP2 protein was not altered by the IFN treatments. The authors analyzed structural alterations in the TAP1 promoter region in eight malignant glioma cell lines. Single nucleotide polymorphism was found in 446 bp up-stream of the translation start site of the TAP1 gene, and a point mutation was found in 34 bp upstream of the TAP1 gene. CONCLUSIONS: Malignant glioma cells may be less immunogenic due to low levels of TAP1 expression. Upregulated expression of TAP1 and MHC Class I molecules by IFN-gamma and -beta may enhance antigen presentation in malignant glioma cells.

Phosphodiesterase 5 inhibitor, zaprinast, selectively increases cerebral blood flow in the ischemic penumbra in the rat brain.

BACKGROUND: Guanosine 3', 5'-cyclic monophosphate (cGMP) acts as a relaxant second messenger in the cerebral vessels. cGMP-specific phosphodiesterase type 5 (PDE5) inhibitor increases intracellular cGMP levels. This study investigated the effect of the PDE5 inhibitor on the ischemic brain. METHODS: Regional cerebral blood flow (rCBF), cGMP concentration, and infarction volume were measured in the rat middle cerebral artery occlusion model. Ten minutes after ischemia, the animals received an intravenous (i.v.) infusion of vehicle (phosphate-buffered saline), PDE5 inhibitor, zaprinast (10 mg/kg), or nitric oxide donor, S-nitroso-N-acetyl-penicillamine (SNAP, 100 microg/kg). rCBF was measured continuously by laser-Doppler flowmetry in the ischemic penumbra of the ischemic and contralateral sides under continuous blood pressure monitoring. cGMP concentrations were determined using the enzyme immunoassay and infarct volumes were estimated by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: The administration of zaprinast significantly increased rCBF in the ischemic brain compared with the pre-drug control value despite the decreased mean blood pressure, whereas it did not affect rCBF in the contralateral side. The cGMP concentration was significantly higher in the ischemic cortex compared with the contralateral side. SNAP infusion increased the cGMP concentration in the bilateral cortices to a similar extent. The volume of cerebral infarction was significantly decreased by zaprinast administration. CONCLUSIONS: The PDE5 inhibitor zaprinast may selectively increase CBF in the ischemic brain via increased cGMP levels, thus providing a new strategy against acute cerebral infarction.

Carotid artery resection: preoperative temporary occlusion is not always an accurate predictor of collateral blood flow.

CONCLUSION: The morbidity predicted by means of preoperative PET studies does not always correlate with the morbidity experienced after permanent carotid artery occlusion. A pre-resection extracranial-intracranial bypass may be necessary to reduce the risk of neurologic morbidity, in particular when carotid artery resection is planned for tumors involving the skull base. OBJECTIVES: Carotid artery resection is generally considered the only curative treatment for patients with advanced head and neck carcinoma involving the carotid artery. PET can be used during temporary occlusion of the internal carotid artery to assess the safety of the procedure. The aims of this paper were to clarify the risk of carotid artery resection and the benefit of extracranial-intracranial bypass. MATERIAL AND METHODS: Twelve patients diagnosed with head and neck cancer adherent to the carotid artery and in proximity to the skull base who had shown good hemispheric collateral blood flow by means of PET underwent carotid artery resection without preoperative bypass. RESULTS: Of the 12 patients who underwent carotid artery resection without reconstruction, 10 suffered no serious neurologic complications; however, 2 suffered cerebral infarctions intraoperatively.

Establishment and partial characterization of five malignant glioma cell lines.

Five malignant glioma cell lines (YMG1, 2, 3, 4, and 5) were established from surgical specimens obtained from patients with glioblastoma or anaplastic astrocytoma, and these lines were partially characterized. Three glioma cell lines (YMG1, 3, and 5) were weakly positive for GFAP by Western blot analysis and two cell lines were negative. S-100 protein was positive in all glioma cell lines. The expression of p53, p16, p15, cyclin-dependent kinase 4 (CDK4), and EGF receptor (EGFR) proteins was examined by Western blotting. YMG1 and 2 cell lines showed accumulation of p53 protein and loss of p16 and p15 expression. YMG3 and 4 showed accumulation of p53 protein and expression of p16 and p15 proteins. YMG5 revealed weak expression of p53 protein, suggesting wild-type p53, and loss of p16 and p15 expression. All cell lines expressed various levels of CDK4 protein. YMG1, 2, and 3 showed higher EGFR protein expression and YMG4 and 5 showed lower EGFR expression compared to U251 glioblastoma cells, which express high levels of EGFR. Fluorescence in situ hybridization analysis for EGFR gene expression did not show any amplification in the glioma cell lines. Immunohistochemical studies revealed that the patterns of p53 and EGFR expressions in the original tumor tissues were mostly correlated with those in the malignant glioma cell lines. These results suggest that the characteristics of p53 and EGFR expression in the malignant glioma cell lines were passed over from the original tumor tissues. These newly established malignant glioma cell lines can be used for further analysis of the mechanisms of tumor growth and progression.

The magnetic resonance Matas test: Feasibility and comparison with the conventional intraarterial balloon test occlusion with SPECT perfusion imaging.

PURPOSE: To evaluate a new MR Matas test that uses a form of contrast-enhanced MR angiography (MRA) with temporary manual occlusion of the common carotid artery whose internal carotid artery (ICA) is to be permanently sacrificed. MATERIALS AND METHODS: The MR Matas test was performed on eight patients using an open type MR imager (Signa Profile 0.2 Tesla ver. 7.5, GE-YMS, Tokyo, Japan). Conventional balloon occlusion Matas test and single-photon emission computed tomography (SPECT) of the brain were performed in all cases within a week before or after the MR Matas test. RESULTS: The MR Matas test was successful in all eight patients without any complications. The image quality of the MR Matas test was generally sufficient to confirm cross-flow from the patent side to the occluded side in comparison with selective intraarterial digital subtraction angiography (IADSA) except in one case. CONCLUSION: Brain perfusion information using MR Matas test is comparable to brain SPECT.

Solitary plasmacytoma of the skull: immunohistochemical study of angiogenic factors and syndecan-1--two case reports.

Two cases of solitary plasmacytomas of the skull are presented, and some biological aspects of the tumor examined. A 75-year-old woman presented with a tumor in the right parietal region. The serum level of immunoglobulin G (IgG) was high and a urine test for Bence Jones protein was negative. A reddish vascular mass was totally removed at surgery. The serum level of IgG was within normal limits after the operation. Postoperative radiotherapy was not performed. A 58-year-old woman presented with a tumor in the occipital region. Serum levels of Igs were within normal limits. A urine test for Bence Jones protein was positive for Ig kappa chain. Bone marrow aspiration revealed no evidence of systemic myelomatosis. The tumor mass was totally removed at surgery and she received local radiation therapy (total 50 Gy). Three months after the surgery, Bence Jones protein (kappa chain) was detected in both the urine and serum and bone scintigraphy showed a weak hot spot in the iliac bone, suggesting development to multiple myeloma. Immunohistochemical studies showed that most tumor cells were positive for vascular endothelial growth factor and syndecan-1, and some tumor cells were strongly positive for basic fibroblast growth factor in both cases. The Ki-67 staining indices were 11.3% and 15.6%. Tumor tissues were negative for p53. These results suggest that solitary plasmacytoma of the skull expresses the angiogenic factors, vascular endothelial growth factor, and basic fibroblast growth factor, in accordance with the high vascularity of the tumors, and syndecan-1 may be an immunohistochemical marker of solitary plasmacytoma of the skull.

Trastuzumab (Herceptin) enhances class I-restricted antigen presentation recognized by HER-2/neu-specific T cytotoxic lymphocytes.

PURPOSE: Numerous examples from animal models and clinical trials showed that HER-2-derived peptides are naturally processed as a CTL epitope and can be recognized by tumor-specific CTLs in several tumors with HER-2 overexpression. The humanized anti-HER-2 monoclonal antibody, Herceptin, has been designed to specifically antagonize the HER-2 function by directing against the extracellular domain of the HER-2 protein. One of the actions of Herceptin includes the internalization and degradation of HER-2, which might increase the amount of HER-2-derived peptides available for loading to MHC class I. EXPERIMENTAL DESIGN: In the present study, we investigated how Herceptin treatment of HER-2-overexpressing targets affects lysis by HER-2-specific CTLs. RESULTS: We showed that Herceptin sensitized HER-2-overexpressing tumors to lysis by HLA-A2-restricted or HLA-A24-restricted CTLs, without any effect of the expression of MHC class I, costimulatory molecules, adhesion molecules, or TAP-1 on the targets. Furthermore, the enhancement of cytolytic activity with Herceptin was inhibited by addition of a specific proteasome inhibitor, lactacystin. CONCLUSIONS: These results suggested that Herceptin treatment might enhance the class I-restricted presentation of endogenous HER-2 antigen via the proteasome step, resulting in higher susceptibility of HER-2-overexpressing tumors to lysis by the HER-2-specific CTLs.

Size of cerebral aneurysms and related factors in patients with subarachnoid hemorrhage.

BACKGROUND: As the indication for surgical treatment of incidentally discovered small aneurysms remains controversial. METHODS: We retrospectively investigated the characteristics of small ruptured aneurysms and examined the relationship between the size and location of ruptured intracranial aneurysms and the sex, age, lifestyle, and medical history of 280 patients with ruptured aneurysm treated at our institute. RESULTS: The mean diameter of ruptured aneurysms in this series was 7.6 mm. In diameter, 135 (48.2%) ranged between 5 and 10 mm; 73 (26.1%) were smaller than 5 mm. The size of the ruptured aneurysms was significantly smaller (mean 6.5 mm) in patients with non- or poorly controlled hypertension than in normotensive patients (mean 8.3 mm) (p < 0.05). Ruptured aneurysms in the anterior communicating artery (AcomA) and anterior cerebral artery (ACA) were significantly smaller (p < 0.01) than those in the internal carotid artery or middle cerebral artery. Among 58 patients with multiple aneurysms, only 7 (12%) suffered rupture of aneurysms smaller than 5 mm (p < 0.01). Patients younger than 40 years and patients with a family history of subarachnoid hemorrhage appeared to predispose to the rupture of small-sized aneurysms, although those did not affect the statistical significance. CONCLUSIONS: This study shows that even aneurysms smaller than 10 mm may rupture. However, treatment decisions for unruptured aneurysm should not be based solely on the size of the unruptured aneurysms. Our data implies that even small aneurysms in the AcomA and ACA had an increased tendency for rupture, and that hypertensive patients were at higher risk for the rupture of small aneurysms.

Quantification of thrombospondin-1 secretion and expression of alphavbeta3 and alpha3beta1 integrins and syndecan-1 as cell-surface receptors for thrombospondin-1 in malignant glioma cells.

Malignant glioma cells secrete thrombospondin-1 (TSP-1) which participates in the motility of glioma cells, and binds to cell surface alphavbeta3 and alpha3beta1 integrins, and syndecan-1. This study evaluated the amount of TSP-1 secretion from malignant glioma cells, and the expression of alphavbeta3 and alpha3beta1 integrins, and syndecan-1. The amounts of TSP-1 in the supernatants from 10 malignant glioma cell lines and eight non-glioma malignant tumor cell lines were measured by enzyme-linked immunosorbent assay. Expression of alphavbeta3 and alpha3beta1 integrins, and syndecan-1 were examined by flow cytometry. The amounts of TSP-1 secreted by malignant glioma cells were 43 to 2431 ng/l x 10(6) cells/24 h (mean +/- SD = 626 +/- 792). Seven of 10 glioma cell lines secreted more than 100 ng of TSP-1 and three of these cell lines secreted more than 1 microg. Seven of eight non-glioma cell lines secreted less than 100 ng of TSP-1. All glioma cell lines expressed alpha3beta1 integrin and syndecan-1, and seven of 10 glioma cell lines expressed alphavbeta3 integrin. Treatment of the glioma cell lines with TGF-beta2 did not change the expression of alphavbeta3 integrin. These results suggest that malignant glioma cells secrete high levels of TSP-1, which may be important in the migration of glioma cells via interactions with alphavbeta3 and alpha3beta1 integrins, and syndecan-1.

Overexpression of heparin-binding growth-associated molecule in malignant glioma cells.

The highly invasive and angiogenic characteristics of malignant gliomas depend on the production of growth factors and angiogenic factors. Heparin-binding growth-associated molecule (HB-GAM) is a secreted growth factor that is mitogenic for endothelial cells. To examine the expression profile of HB-GAM in malignant glioma cells, messenger ribonucleic acid (mRNA) expression was analyzed in 10 malignant glioma cell lines, two glioblastoma tissue specimens, and two normal brain tissue specimens by the reverse transcription-polymerase chain reaction. HB-GAM mRNA was expressed in all specimens including normal brain tissue specimens. Western blot analysis revealed that HB-GAM protein contents in glioma cell lines and glioblastoma tissues were 1.8 to 6.3 times higher than those in normal brain tissues. The effect of neutralizing anti-platelet-derived growth factor (PDGF) antibody was also examined on the production of HB-GAM in malignant glioma cells, since malignant glioma cells secrete PDGF that upregulates HB-GAM expression. Treatment of U251 and T98G glioblastoma cells with the anti-PDGF antibody did not affect the HB-GAM production. These results suggest that HB-GAM is overexpressed in malignant glioma cells and is involved in tumor growth.

Cell density regulates thrombospondin-1 production in malignant glioma cells.

Thrombospondin-1 (TSP-1) is a multifunctional matrix protein implicated in cancer cell adhesion, migration, and invasion, inhibition of angiogenesis, and activation of latent transforming growth factor-beta (TGF-beta). The effect of cell density was investigated on the production of TSP-1, basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) by two glioblastoma cell lines. The effect of TGF-beta was also examined. The amount of intracellular TSP-1 protein decreased significantly as the cell density increased in cultures of both T98G and A172 cells. The amount of intracellular TSP-1 was highest in sparse tumor cell cultures and lowest in densely confluent tumor cell cultures. The maximum reduction of TSP-1 protein production was 56.8% and 44.6% in T98G and A172 cells, respectively. The cell density did not affect the production of bFGF or VEGF. TGF-beta2 treatment did not affect the production of TSP-1, bFGF, or VEGF proteins. Treatment with excess TGF-beta2 resulted in a slight but significant decrease (22%; P < 0.02) of TGF-beta2 production by A172 cells, but not by T98G cells. The present results indicate that the production of TSP-1 protein is regulated by cell density of glioblastoma cells, while that of angiogenic factors is not affected by tumor cell density. This suggests that high tumor cell density may tilt the angiogenic balance in favor of angiogenesis.

Extracranial-intracranial bypass for reconstruction of internal carotid artery in the management of head and neck cancer.

Extracranial-intracranial bypass surgery was performed prior to carotid resection in eight patients with head and neck carcinoma that involved the carotid artery near the skull base. Four patients underwent the standard one-stage extracranial-intracranial bypass procedure. A two-stage procedure was performed in the remaining four patients. The procedure first involved an anastomosis between the M3 segment of the middle cerebral artery and the superficial temporal artery, followed by a bypass between the M2 segment of the middle cerebral artery and the internal carotid artery. One of the patients who underwent the standard one-stage extracranial-intracranial bypass procedure suffered an intraoperative infarction. Despite even longer occlusion times of the M2 segment, none of the patients who underwent the two-stage bypass suffered from any serious neurologic consequences. Three of seven patients who underwent the curative operations, survived more than 4 years, however, the remaining patients died within 1 year from recurrence. Our results show that carotid artery resection yields an opportunity for cure. In extracranial-intracranial bypass surgery, the temporary occlusion of the middle cerebral artery may also induce serious ischemia; however, the two-stage extracranial-intracranial bypass procedure appears to minimize the risk.

[A case of multiple mycotic intracranial aneurysms].

A patient with multiple mycotic aneurysms associated with infective endocarditis is reported. A 45-year-old man was admitted on February 16, 2001 under the diagnosis of infective endocarditis. After alpha-streptococcus was identified by a blood culture, he was treated with high doses of antibiotics. However, 2 weeks after admission, he suddenly suffered from headache and mild left hemiparesis. A CT showed a parenchymal hematoma in the right parietal lobe. Cerebral angiography demonstrated aneurysms of the bilateral middle cerebral artery and the left posterior cerebral artery. At first, we trapped and resected the ruptured right middle cerebral aneurysm. After the surgery, we tried to treat two unruptured aneurysms by endovascular treatment. During the provocation test for the posterior cerebral artery, the arterial wall was perforated by a guide wire. The parent artery was occluded by coils at this site. Although the aneurysm was still filled by retrograde blood flow, it finally disappeared six months after treatment. The left middle cerebral artery aneurysm could not be treated because the provocation test showed cognitive deficits. The patient recovered from infective endocarditis after four-months of antibiotic therapy; and the unruptured aneurysm had not changed in size for 11 months. Recently, the outcome of patients with intracranial mycotic aneurysm is improved by development of multimodality management. Especially, endovascular therapy may become an effective treatment for unruptured aneurysms, but it is necessary to take risks, such as arterial perforation into consideration.

Velocity-coded colour magnetic resonance angiography and perfusion-weighted magnetic resonance imaging for the evaluation of extracranial-to-intracranial arterial bypass surgery.

BACKGROUND AND PURPOSE: Velocity-coded colour magnetic resonance angiography (VCCMRA) and perfusion magnetic resonance imaging (pMRI) were evaluated as methods for investigating the efficacy of extracranial-to-intracranial arterial bypass (EC-IC bypass) by comparing the findings of VCCMRA and those of cerebral angiography and by measuring the improvement ratio after EC-IC bypass by pMRI compared to that by single photon emission computed tomography (SPECT) using the autoradiographic technique. METHODS: Thirteen patients who underwent VCCMRA, angiography, SPECT, and pMRI before and after surgery were analyzed. Findings of VCCMRA were compared to those of angiography. Improvement ratio was calculated compared to the cerebellum for cerebral blood volume, mean transit time (MTT), and regional cerebral blood flow (rCBF) as measured by pMRI and quantitative SPECT. RESULTS: Findings of VCCMRA were in good agreement with those of angiography and clearly showed the direction of bypass flow. No statistically significant correlation was observed between the improvement ratios in CBF in the hemisphere and middle cerebral artery territory on the surgical and non-surgical sides and in rCBF in the same regions of interest (ROIs) (r=-0.574, 0.09). However, a statistically significant correlation was observed between the cerebrovascular reserve capacity (CVRC) in the hemisphere on the surgical side and in MTT in the same ROIs (r=0.955, P<0.001). CONCLUSION: VCCMRA may clearly show the direction of flow in the EC-IC bypass. MIT measured by pMRI may indicate the postoperative state of CVRC. These techniques could replace angiography and positron emission tomography or SPECT in patients undergoing EC-IC bypass.

Technical considerations of transsphenoidal removal of fibrous pituitary adenomas and evaluation of collagen content and subtype in the adenomas.

Pituitary adenomas are usually soft, but 5-13.5% are fibrous adenomas which are difficult to remove. Magnetic resonance (MR) imaging and operative findings were evaluated in eight patients (12.1%) with fibrous pituitary adenoma among 66 patients. Tumor specimens were examined histologically and immunohistochemically for collagen content and subtypes. Seven patients had clinically inactive non-functioning pituitary adenomas and one patient growth hormone-secreting adenoma. All patients underwent transsphenoidal surgery. Four cases were giant adenomas with suprasellar extension of more than 2 cm. T1- and T2-weighted MR imaging showed the tumors as nearly isointense to the surrounding brain, except in one case where the tumor was high intense on T2-weighted MR imaging. All tumors required piecemeal resection using a micro-dissector and tumor forceps. Four tumors of maximum size more than 3 cm needed a second operation. The interface between the thinned normal pituitary gland and fibrous adenoma was intended to identify at the anterior-superior portion in recent four cases, which was helpful to remove the tumors and preserve pituitary functions. Histological examination revealed prominent deposition of collagen in the perivascular area. The percentage of collagen content in fibrous adenomas was more than 5% and significantly higher than that in soft adenomas and normal pituitary glands. Immunohistochemical examination showed positive staining for collagen types I and III in the fibrous adenomas, but only for type V collagen in the normal pituitary glands. Large fibrous adenomas can be resected by transsphenoidal surgery which may require two-stage operations. Identification of the interface between the normal pituitary gland and adenoma is helpful to remove fibrous adenomas and to preserve pituitary functions. We propose that firm adenomas containing more than 5% collagen are "fibrous" adenomas.

Magnetic resonance angiographic evidence of sex-linked variations in the circle of willis and the occurrence of cerebral aneurysms.

OBJECT: In this study the authors investigated the relationship between variations in the circle of Willis observed on magnetic resonance (MR) angiograms and locations of cerebral aneurysms, and evaluated the risk of aneurysm formation. METHODS: One hundred thirty-one patients with cerebral aneurysms were retrospectively selected from a series of 4518 patients who underwent MR angiography at one neurosurgical institute. Variations in the anatomy of the circle of Willis were simply classified into Type A, in which there was no visualization of a unilateral A1 segment, and Type P, in which there was a fetal type of posterior cerebral artery that was continuously delineated from the internal carotid artery (ICA) through the posterior communicating artery. All other variations in the circle of Willis were defined as Type O (ordinary type of variations). An additional 440 patients who did not harbor cerebral aneurysms were randomly selected for a comparison. Anterior communicating artery aneurysms were significantly related to the Type A anatomy and ICA aneurysms to Type P anatomy. Male patients who did not harbor aneurysms tended to have Type A anatomy, whereas women had a significantly greater incidence of Type P. CONCLUSIONS: This sex-linked difference in anatomical variations may be correlated to the well-known sex-linked difference in aneurysm distribution.

Surgical management of aneurysms of the bifurcation of the internal carotid artery.

Internal carotid artery (ICA) bifurcation aneurysms are rare and easily bleed in younger patients, but are difficult to treat surgically, due to perforators surrounding and adherent to the aneurysm. A series of 25 patients treated by clipping under the operating microscope are analyzed and compared with previous cases. Twenty-five patients, 11 men and 14 women (mean age 51 years), were treated by the same neurosurgeon. Seventeen patients presented with subarachnoid hemorrhage (Hunt & Kosnik Grade I in three, II in five, III in two, IV in seven), five with unruptured ICA bifurcation aneurysms, and three with unruptured ICA bifurcation aneurysms but another ruptured aneurysm. There were 23 small, one large, and one giant ICA bifurcation aneurysms. The projection was superior in 12, anterior in seven, and posterior in six cases. Pterional approach was employed for all cases. Outcomes were evaluated at discharge with the Glasgow Outcome Scale. Favorable outcomes (good recovery (GR) and moderate disability (MD)) were obtained in ten of 17 patients with ruptured ICA bifurcation aneurysm. Favorable outcomes were significantly greater in Grades I and II (three in I, four in II) than in Grades III and IV (one in III, two in IV; P=0.0498). Seven of eight patients with unruptured ICA bifurcation aneurysm had favorable outcomes. Temporary clipping and projection of the aneurysm did not affect the outcome. Causative factors of unfavorable outcomes were primary brain damage in cases of small and large aneurysms and perforator damage in the case of giant aneurysm. Poor clinical grade and vasospasm are the causative factors of poor outcome in patients with ruptured ICA bifurcation aneurysm. Preservation of perforators is crucial in cases of giant aneurysm. Clipping of unruptured ICA bifurcation aneurysms is recommended since they tend to bleed at a lower age than other aneurysms.

Retrospective analysis of the prevalence of asymptomatic cerebral aneurysm in 4518 patients undergoing magnetic resonance angiography--when does cerebral aneurysm develop?

The natural history of cerebral aneurysms was investigated by measuring the prevalence of incidentally found unruptured aneurysms in the general population and evaluating the characteristics including risk factors. 'De novo' formation of aneurysm was also demographically estimated. The prevalence of incidental aneurysm was evaluated among 4518 patients who underwent magnetic resonance (MR) angiography for various reasons in a neurosurgical institute. Double the number of patients were randomly selected from the remaining patients without aneurysm as the Control group so that sex and age group were matched to the Aneurysm group. 127 patients (2.8%) had diagnoses of aneurysm. The prevalence of asymptomatic aneurysm among middle-aged and elderly patients was predominant in women and increased with age in both sexes. Patients with aneurysms had significantly more hypertension and family history of subarachnoid hemorrhage compared to the controls. The prevalence was markedly increased in the 8th decade in men and the 7th decade in women, and new aneurysms seemed to develop predominantly around these decades. Cerebral aneurysms become detectable on MR angiography in the middle or later decades, and women tend to develop aneurysm earlier than men. Hypertension and family history of subarachnoid hemorrhage are probably risk factors for the development of aneurysm.