Characteristics of Cerebral Aneurysms in Japan
Fusao IkawaToshikazu HidakaMichitsura YoshiyamaHideo OhbaShingo MatsudaIori OzonoKoji IiharaHiroyuki KinouchiKazuhiko NozakiYoko KatoAkio MoritaNobuaki MichihataHideo YasunagaKaoru Kurisu
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Abstract:
The characteristics of cerebral aneurysms in Japan differ from other countries in the higher incidence of unruptured cerebral aneurysm detected by brain check-up screening, higher rupture rate of unruptured cerebral aneurysm, higher incidence of subarachnoid hemorrhage, and superior outcome after subarachnoid hemorrhage based on meta-analysis. Head shape, genetic features, environmental factors, demographics, and medical system in Japan are also different from other countries. Unruptured cerebral aneurysms are 2.8 times more likely to rupture in Japanese than western aneurysms, resulting in the highest incidence of subarachnoid hemorrhage in the world. The exact and specific mechanisms of de novo, growth, and rupture of cerebral aneurysms have not been elucidated. Investigations will contribute to the understanding of cerebral aneurysms and subarachnoid hemorrhage worldwide. Some features of cerebral aneurysm in Japan are discussed for possible research guidance in the elucidation of the predominance of subarachnoid hemorrhage in Japan.Keywords:
Demographics
The purpose of this study was to compare CT angiography with digital subtraction angiography (DSA) in the detection and measurement of intracranial aneurysms in patients with acute subarachnoid hemorrhage. Thirty consecutive patients with recent subarachnoid hemorrhage shown by unenhanced CT scanning or lumbar puncture were studied with CT angiography and DSA. Using a shaded surface display format and source images, two reviewers working independently blindly interpreted CT angiograms for presence and size of aneurysms. Sensitivity and specificity for aneurysm detection were calculated for each reviewer. Aneurysm size measurements were compared between reviewers and between the two imaging techniques. Thirty aneurysms were found in 22 patients with DSA; eight patients had no aneurysms. The sensitivity and specificity of CT angiography for reviewer A were 0.97 and 1.0, respectively. For reviewer B, the sensitivity and specificity were 0.77 and 0.87, respectively. All cases with single aneurysms on DSA (18 patients) had surgical confirmation of aneurysm location and rupture. In each case with multiple aneurysms (four patients), the aneurysm thought responsible for the hemorrhage was surgically confirmed. In those cases with no aneurysms found on DSA, follow-up DSA studies did not reveal additional findings. Differences between reviewers in aneurysm size measurements made with CT angiography were not significant (p = .10). Mean aneurysm measurements for reviewer A, reviewer B, and DSA were 6.6 mm, 7.0 mm, and 6.9 mm, respectively. CT angiography shows potential in the detection and measurement of aneurysms in patients with acute subarachnoid hemorrhage when compared with DSA.
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Background and Objectives The incidence of subarachnoid hemorrhage (SAH) has been very low in earlier studies conducted at Shiraz University compared with reports in the literature. We determined the incidence in our study and compared it to an earlier study and international statistics. In the other part of our study, we examine the factors that contribute to the rerupture of cerebral aneurysms. Method During 3 years from 2006 to 2009 (1385 to 1388), we handled 230 subarachnoid hemorrhage patients referring to Namazi hospital and recorded their data of age, GCS, count and size and location of aneurysms, and abnormal CT findings. We examined the effect of these factors on early rebleeding with χ2 and t tests. Results The incidence of SAH in a earlier study conducted at Shiraz University 10 years ago was 0.7 per 100,000 persons per year. Incidence has risen in our study to 1.3 per 100,000 persons per year, which is still much lower than the incidence reported in developed countries, which is nearly 10 per 100,000 persons per year. Of 162 patients with aneurysmal SAH 17 patients rebled before surgery within 48 hours of admission. We found a significant relationship between GCS on admission, size of aneurysm, and intracerebral hemorrhage in first CT scan and early aneurysm rebleeding (P-values less than 0.05). Conclusions Our lower incidence compared with developed countries could be owing to our younger population, fewer diagnostic facilities distributed in the regions, and a very larger geographic area we are sampling from with 1 referral center. On the other aspect, we suggest paying particular attention to those patients who have large aneurysms, who present with intracerebral hemorrhage in CT scan, and who are in poor clinical grade on admission. Surgery must be done on an emergency basis for these patients to prevent mortality and morbidity.
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Magnetic resonance angiography
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The overall management results after aneurysmal rupture were studied in 158 patients admitted to the hospital on day 0--3 and 175 patients admitted on day 4--7 following subarachnoid hemorrhage. In this series surgery was planned no sooner than 12 days following the ictus. Despite effective medical and surgical therapy overall results were disappointing: 3 months following the initial hemorrhage only 43% of patients in the 0--3 day group and 53% of patients in the 4--7 day group were capable of independent functional living. Patients admitted on days 4--7 also had a lower mortality rate, re-bled less frequently, and had lower postoperative mortality and morbidity than those admitted on days 0--3. For reasons not well defined, time of admission following aneurysmal SAH has an important influence on outcome. Accordingly, in evaluating outcome for patients with ruptured aneurysms treated with different therapeutic modalities, time of admission must be carefully controlled.
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PURPOSE To determine the usefulness of CT angiography in the setting of suspected acute subarachnoid hemorrhage or intracranial aneurysm. METHODS We prospectively studied 68 patients suspected of having subarachnoid hemorrhage or an intracranial aneurysm with noncontrast CT of the head followed immediately by contrast-enhanced helical CT of the circle of Willis with three-dimensional reconstruction. Twenty-seven patients with CT findings positive for subarachnoid hemorrhage or intracranial aneurysm were evaluated with digital subtraction angiography or MR angiography within 12 hours of CT angiography. Patients with negative CT/CT angiography findings were followed up with lumbar puncture. RESULTS CT angiography showed 23 of 24 aneurysms and 2 of 2 arteriovenous malformations (sensitivity, 96%; specificity, 100%). Aneurysm size ranged from 2 to 40 mm (mean, 7.9 mm). Interobserver variability was 10%. In the 23 cases of subarachnoid hemorrhage, cisternal blood did not limit the three-dimensional reconstruction. Two patients with aneurysms on CT angiography had normal noncontrast scans. CONCLUSIONS CT angiography of the circle of Willis is a useful technique for evaluation of suspected acute subarachnoid hemorrhage and intracranial aneurysm. It provides anatomic display of intracranial aneurysms, allowing for planning of conventional angiography and surgical approach. In selected cases, CT angiography may eliminate the need for preoperative conventional angiography.
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OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for the presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysm lobes, aneurysm neck size (≤ 4 mm), and the number of adjacent arterial branches were assessed. The images obtained with CTA were then compared with the images obtained with DSA, with the latter images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysm, six CT angiograms showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes(<3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.
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OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for the presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysm lobes, aneurysm neck size (≤ 4 mm), and the number of adjacent arterial branches were assessed. The images obtained with CTA were then compared with the images obtained with DSA, with the latter images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysm, six CT angiograms showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes(<3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.
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Identification of the source of subarachnoid haemorrhage (SAH) can be a challenge in the presence of multiple aneurysms. This study was carried out to assess whether radioanatomical features on noncontrast enhanced computerised tomography (CT) scans may be of value in localizing ruptured intracranial aneurysms. The diagnostic CT scans of 56 consecutive patients, investigated for SAH with cerebral angiography, over a period of six months were available for review. Various radioanatomical features were assessed: (1) pattern of subarachnoid blood (e.g. predominant site and location near major vessel bifurcation), (2) presence of intraparenchymal haematoma, (3) presence of aneurysm contour and (4) hydrocephalus. On the basis of the findings an estimation of the anatomical location of the source of bleeding was made and then compared with the angiogram findings to which the reviewer was blinded. The location of the aneurysm was correctly identified in 89.5% of cases. Careful analysis of the pattern of bleeding was essential for the successful localization of the aneurysm in all these cases. The presence of an aneurysm contour was also associated with correct identification of the source of bleeding (chi(2) = 6.067, P = 0.02). Our findings suggest that radioanatomical features on CT scans in SAH can be a valuable aid in the correct identification of the location of the ruptured aneurysm. This would be of particular significance in the presence of multiple intracranial aneurysms.
Subarachnoid haemorrhage
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Objective:To compare DSA,3D TOF MRA and CT in diagnosis of intracranial aneurysm(IA).Methods:Thirty patients with IA verified by surgery and angiography were studied by CT,3D TOF MRA and DSA.Their imaging manifestations were compared.Results:All of 30 aneurysms were identified at intracranial DSA.28 aneurysms (2 false) were depicted and 4 aneurysms were missed by MRA.Sensitivity and false positive of MRA for detecting IA were 86.6% and 6.7% respectively.CT demonstrated aneurysm itself and acute subarachnoid hemorrhage (SAH) suggesting aneurysm in 15 patients(50%).No aneurysm was found in 8 patients (6.7%) on CT scanning.Conclusion:DSA is still the gold standard for diagnosis of IA.3D TOF MRA is one of sensitive methods to identify IA and is currently inferior to DSA in assessment of IA.CT can display aneurysm itself and acute subarachnoid hemorrhage and cue aneurysm with lower sensitivity.
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Magnetic resonance angiography
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Subarachnoid hemorrhage cases with multiple cerebral aneurysms frequently demonstrate a hemorrhage pattern that does not definitively delineate the source aneurysm. In these cases, rupture site is ascertained from angiographic features of the aneurysm such as size, morphology, and location.To examine the frequency with which such features lead to misidentification of the ruptured aneurysm. METHODS : Records of patients who underwent surgical clipping of a ruptured aneurysm at our institution between 2004 and 2014 and had multiple aneurysms were retrospectively reviewed. A blinded neuroendovascular surgeon provided the rupture source based on the initial head computed tomography scans and digital subtraction angiography images. Operative reports were then assessed to confirm or refute the imaging-based determination of the rupture source.One hundred fifty-one patients had multiple aneurysms. Seventy-one patients had definitive hemorrhage patterns on initial computed tomography scans and 80 patients had nondefinitive hemorrhage patterns. Thirteen (16.2%) of the cases with nondefinitive hemorrhage patterns had discordance between the imaging-based determination of the rupture source and intraoperative findings of the true ruptured aneurysm, yielding an imperfect positive predictive value of 83.8%. Of all multiple aneurysm cases with subarachnoid hemorrhage treated by surgical or endovascular means at our institution, 4.3% (13 of 303) were misidentified.Morphological features cannot reliably be used to determine rupture site in cases with nondefinitive subarachnoid hemorrhage patterns. Microsurgical clipping, confirming obliteration of the ruptured lesion, may be preferentially indicated in these patients unless, alternatively, all lesions can be contemporaneously and safely treated with endovascular embolization.
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Digital subtraction angiography
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