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Subarachnoid hemorrhage (SAH) due to a ruptured saccular aneurysm is uncommon in children. Pediatric traumatic aneurysms have been reported relatively frequently, tending to bleed after an interval of weeks after head injury. The authors describe three children with acute SAH after head injury caused by intracranial dissecting aneurysms. When head trauma in children is complicated by SAH in basal cisterns, dissecting aneurysms should be considered and treated, because rebleeding may occur.

Objective: High-flow, extracranial-intracranial (EC-IC) bypass operations are performed to prevent strokes among patients with giant aneurysms who cannot tolerate internal carotid artery (ICA) occlusion. However, the volume flow through the bypass, compared with preoperative ICA flow, has not been evaluated for any type of bypass. We describe a prospective case study that tested the ability of the high-flow EC-IC bypass to replace the volume flow of the ipsilateral ICA after deliberate ICA occlusion., Methods: Seven consecutive patients with giant aneurysms of the ICA who experienced test occlusion failure underwent nonocclusive, excimer laser-assisted, EC-IC bypass surgery before permanent ICA occlusion. Volume flow values in the ICAs, the basilar artery, the EC-IC bypass, and the middle cerebral arteries were measured with magnetic resonance angiography., Results: No significant changes in volume flow to the ipsilateral and contralateral hemispheres were observed after bypass surgery and therapeutic ICA occlusion. Before bypass surgery, the volume flow through the ipsilateral ICA was 243 +/- 74 ml/min, that through the contralateral ICA was 264 +/- 32 ml/min, and that through the basilar artery was 141 +/- 43 ml/min. After bypass surgery and therapeutic occlusion of the ipsilateral ICA, the volume flow through the bypass was 199 +/- 72 ml/min, that through the contralateral ICA was 303 +/- 82 ml/min, and that through the basilar artery was 153 +/- 72 ml/min. No significant preoperative versus postoperative changes in middle cerebral artery flow were observed on either side., Conclusion: The flow through the high-flow EC-IC bypass was able to replace the volume flow of the ipsilateral ICA after deliberate ICA occlusion for the treatment of giant aneurysms.

Object: The purpose of this study was to compare computerized tomography (CT) angiography and digital subtraction (DS) angiography studies in patients with subarachnoid hemorrhage (SAH) to assess their vascular anatomy relevant to cerebral aneurysm surgery., Methods: From a prospective series of 100 patients with SAH, the authors selected 73 patients whose CT angiography studies were of adequate quality and in whom DS angiography of both carotid arteries had been performed. Eleven patients with no DS angiographic studies of the vertebrobasilar artery were only evaluated for the anterior half of the circle of Willis. Anterior communicating arteries (ACoAs), both precommunicating anterior cerebral arteries (A1 segments), both posterior communicating arteries (PCoAs), and both precommunicating posterior cerebral arteries (P1 segments) were assessed on CT angiography and DS angiography by two independent observers., Conclusions: Computerized tomography angiography compares well with DS angiography for visualizing normal-sized arteries, and is superior for visualizing ACoAs and hypoplastic A1 and P, segments. Important preoperative aspects such as dominant A1 segments and PCoAs are equally well seen using either modality. Neither method enabled the authors to visualize more than 50% of PCoAs. Use of CT angiography can provide the required preoperative anatomical information for aneurysm surgery in most patients with SAH.

Objective: MR angiography may be an appropriate tool to screen for unruptured intracranial aneurysms. Feasibility, test characteristics, and interobserver agreement in evaluation of MR angiograms were assessed by members of the MARS (Magnetic resonance Angiography in Relatives of patients with Subarachnoid hemorrhage) Study Group., Subjects and Methods: We screened 626 first-degree relatives of a consecutive series of 193 patients with subarachnoid hemorrhage examined at two institutions. We used MR imaging and MR angiography (three-dimensional time-of-flight imaging at both institutions and additional three-dimensional phase-contrast imaging at one institution). Three observers independently assessed the MR angiograms. Conventional angiography was performed in relatives with possible or definite aneurysms on MR angiography and was considered the standard of reference., Results: Thirty-three aneurysms were found in 25 (4%; 95% confidence interval [CI], 3-6%) of 626 relatives. Thirteen (8%) of 169 relatives who refused screening had MR-related reasons; an additional six persons could not be screened because of contraindications for MR imaging (pregnancy, n = 1; claustrophobia, n = 5). The positive predictive value of MR angiography was 100% (95% CI, 79-100%) for "definite" aneurysms and 58% (95% CI, 28-85%) for "possible" aneurysms. Sensitivity of MR angiography was estimated at 83% (95% CI, 65-94%) and specificity at 97% (95% CI, 94-98%). Interobserver agreement in the evaluation of MR angiograms was poor (kappa < .30), probably because different diagnostic strategies used by individual observers resulted in different use of the assessment category "possible aneurysm.", Conclusion: MR angiography is a feasible screening tool for detection of intracranial aneurysms. Positive predictive value, sensitivity, and specificity are acceptable when at least two neuroradiologists independently assess MR angiograms.

Object: The purpose of this study was to determine prospectively whether and to what extent computerized tomography (CT) angiography can serve as the sole imaging method for a preoperative workup in patients with ruptured intracranial aneurysms., Methods: During a 1-year period, all patients who presented to the authors' hospital with subarachnoid hemorrhage demonstrated by unenhanced CT scanning or lumbar puncture underwent CT angiography. Two radiologists evaluated the CT angiography source images and maximum intensity projection slabs and arrived at a consensus. They categorized the quality of the CT angiography as adequate or inadequate and classified aneurysms that were detected as definitely or possibly present. The parent artery of anterior communicating artery aneurysms was identified by asymmetrical anterior cerebral artery size and asymmetrical aneurysm location. The parent artery was indicated by the larger A1 segment in cases of asymmetrical A1 size. Only CT angiograms of adequate quality that revealed aneurysms classified as definitely present and with an unequivocal parent artery were presented to the neurosurgeons, who decided whether preoperative digital subtraction (DS) angiography should still be performed. Forty-nine of the 100 studied patients did not undergo surgery because of poor clinical condition, nonaneurysmal cause of the hemorrhage, or endovascular treatment of the ruptured aneurysm. Of the 51 patients who underwent surgery, radiologists required DS angiography in 17 patients; the imaging technique provided greater certainty in 13 instances. The neurosurgeons required DS angiography 11 times; this provided additional information in two instances. Twenty-three (45%) of the 51 patients were surgically treated successfully on the basis of CT angiography findings alone., Conclusions: Computerized tomography angiography can replace DS angiography as the preoperative neuroimaging technique in a substantial proportion of patients with ruptured intracranial aneurysms.

Background and Purpose: It is important to recognize a perimesencephalic pattern of hemorrhage in patients with subarachnoid hemorrhage (SAH), because in 95% of these patients the cause is nonaneurysmal and the prognosis is excellent. The purpose of this study was to investigate whether CT angiography can accurately exclude vertebrobasilar aneurysms in patients with perimesencephalic patterns of hemorrhage and therefore replace digital subtraction angiography (DSA) in this setting., Methods: In 40 patients with posterior fossa SAH as shown on unenhanced CT, 2 radiologists independently evaluated unenhanced CT for distinguishing between perimesencephalic and nonperimesencephalic pattern of hemorrhage and assessed CT angiography for detection of aneurysms. All patients subsequently underwent DSA or autopsy., Results: Observers agreed in 38 of 40 patients (95%) in differentiating perimesencephalic and nonperimesencephalic patterns of hemorrhage on unenhanced CT. On the CT angiograms, both observers detected a vertebrobasilar aneurysm in 16 patients and no aneurysm in 24 patients. These findings were confirmed by DSA or autopsy. No patients with a perimesencephalic pattern of hemorrhage were found to have an aneurysm on either CT angiography or DSA., Conclusions: Good recognition of a perimesencephalic pattern of hemorrhage is possible on unenhanced CT, and CT angiography accurately excludes and detects vertebrobasilar aneurysms. DSA can be withheld in patients with a perimesencephalic pattern of hemorrhage and negative CT angiography.

Background and Objective: In families with two or more relatives with subarachnoid hemorrhage (SAH), other first-degree relatives have an increased risk of SAH. We studied the presence of unruptured intracranial aneurysms in 125 members of 23 families with familial SAH, defined as two or more affected first-degree relatives, in a cross-sectional design., Methods: MR angiography was performed in 116 relatives; CT angiography was performed in the remaining 9 relatives because they had been treated for intracranial aneurysms in the past., Results: Overall, we found 16 aneurysms in 10 of 125 relatives (8%; 95% CI, 4 to 14%). Of the nine patients with previous surgery for ruptured or unruptured intracranial aneurysms, three had new aneurysms. Two factors were associated with a significantly higher risk of intracranial aneurysms: 1) a history of treatment for ruptured or unruptured intracranial aneurysms (relative risk 5.5; 95% CI, 1.7 to 17.8) and 2) having three or more affected relatives (relative risk 3.3; 95% CI, 1.0 to 10.6). Siblings tended to have a higher risk of intracranial aneurysms than did children of SAH patients, although the difference was not significant., Conclusions: Because the yield is high, screening is recommended in first-degree members of families with familial SAH. Repeated screening should be considered in relatives who have been treated for familial intracranial aneurysms.

Purpose: To evaluate if computed tomographic (CT) angiography can replace digital subtraction angiography (DSA) for aneurysm detection and as preoperative work-up in patients with subarachnoid hemorrhage (SAH)., Materials and Methods: Prospectively, 100 patients with SAH underwent CT angiography; 80 also underwent DSA. Two observers independently evaluated CT angiographic source images and maximum intensity projection slabs. Neurosurgeons compared CT angiograms and DSA images for presurgical evaluation., Results: On CT angiograms, the observers detected 73 and 70 of 75 symptomatic aneurysms; 96% of the detected aneurysms were classified as definitely present. Of 16 incidental aneurysms, 12 and 10 were detected by the observers. With adequate CT angiographic quality, parent artery side of anterior communicating aneurysms was correctly predicted in 100% (95% confidence interval [CI]: 87%, 100%). Neurosurgeons assessed CT angiography as equal or superior to DSA in 83% (95% CI: 73%, 90%) of 87 aneurysms, and in 74% (95% CI: 63%, 82%) operation might have been based on CT angiographic findings alone., Conclusion: CT angiography depicted 90% of all aneurysms, and 90% were classified as definitely present. CT angiography must be of high quality with adequate depiction of the aneurysm and the parent artery for surgery to be performed on the basis of CT angiographic findings alone.

We describe a characteristic distribution of cisternal blood in 52 patients with nonaneurysmal subarachnoid hemorrhage proved by a normal angiogram. On CT, the center of the bleeding was located immediately anterior to the brainstem in all patients, which was confirmed in four patients who were studied with MR imaging. Extension to the ambient cisterns or to the basal parts of the sylvian fissures was common, but the lateral sylvian or anterior interhemispheric fissures were never completely filled with blood. Rupture into the ventricular system did not occur. MR demonstrated downward extension of the blood anterior to the brainstem as far as the medulla, but failed to detect the source of hemorrhage. Our aim was to determine whether this so-called nonaneurysmal perimesencephalic hemorrhage could be distinguished from aneurysmal subarachnoid hemorrhage on early CT scans. Two neuroradiologists were shown a consecutive series of 221 CT scans of patients with subarachnoid hemorrhage who subsequently underwent angiography. Only one patient with a basilar artery aneurysm on angiography was incorrectly labeled by both observers as having a nonaneurysmal perimesencephalic pattern of hemorrhage. The high predictive value of the perimesencephalic pattern of hemorrhage for a normal angiogram (0.95 and 0.94, respectively, for the two observers) and the excellent interobserver agreement (kappa 0.87) demonstrate that nonaneurysmal perimesencephalic hemorrhage can be distinguished on CT in the majority of patients. Recognition of this pattern of hemorrhage is important as patients with this subset of subarachnoid hemorrhage have an excellent prognosis.