Intracranial Anterior Circulation Research Articles

A giant internal carotid artery aneurysm: case report

Aneurysms greater than 2.5 cm in diameter are classified as giant aneurysms and represent 5-8% of all intracranial aneurysms. Giant intracranial aneurysms demonstrates the clinical course with symptoms related to subarachnoid haemorrhage, mass effect, thromboembolism and seizures. Not only because of their large sizes, but also because of their usually wide and calcified aneurysm neck, existing thrombus within and its proximity to cranial nerves; giant aneurysms causes serious surgical difficulties. Giant aneurysms of the anterior intracranial circulation are rare, slowly progressive vascular abnormalities, often presenting with neuro-ophthalmological symptoms before they rupture. Herein, a case of 77year-old woman with a giant aneurysm originated from intracavernous segment of internal carotid artery detected in magnetic resonance angiography who presented symptoms due to affected multiple cranial nerves related to mass effect.

MRI BRAIN APPEARANCES IN ANAPHYLAXIS: NOVEL OBSERVATIONS TO DIFFERENTIATE FROM GLOBAL HYPOXIC INSULT

Global ‘hypoxic brain injury’ commonly presents typically after hypoperfusion, although true hypoxia may be absent. MRI is used to confirm clinical diagnosis is sought. However, a potentially different pattern of...

Antegrade Flow Across Incomplete Vessel Occlusions Can Be Distinguished From Retrograde Collateral Flow Using 4-Dimensional Computed Tomographic Angiography

In acute stroke patients with intracranial vessel occlusion, angiographic demonstration of antegrade contrast opacification distal to the occlusion site (termed the "clot outline sign") has been associated with higher rates of vessel recanalization. We sought to determine whether antegrade flow can be demonstrated on time-resolved 4-dimensional computed tomographic angiography (4-dimensional CTA), whether it can be distinguished from retrograde collateral flow, and if it can be used to predict early recanalization. Fifty-seven acute stroke patients with intracranial anterior circulation vessel occlusion were retrospectively identified. All patients had received a multimodal computed tomography examination including thin-section 4-dimensional CTA and subsequent digital subtraction angiography as part of an endovascular procedure. Pretreatment 4-dimensional CTA and single-phase CTA were assessed for presence of antegrade contrast opacification distal to the occlusion site. Digital subtraction angiograms were reviewed for preintervention Thrombolysis in Cerebral Infarction grade, presence of the clot outline sign, as well as postintervention Thrombolysis in Cerebral Infarction grade. On 4-dimensional CTA, evidence of antegrade flow was present in 11 of 57 cases (19.3%). Compared with angiography, 4-dimensional CTA predicted antegrade flow with 100% sensitivity and 97.9% specificity. Single-phase CTA offered 40% sensitivity and 87.2% specificity. Early recanalization occurred in 3 patients (6.5%) after intravenous thrombolysis (n=46); all demonstrated antegrade flow on 4-dimensional CTA. Using 4-dimensional CTA, it is possible to noninvasively distinguish antegrade flow across a cerebral artery occlusion from retrograde collateral flow. Presence of antegrade flow on 4-dimensional CTA is associated with an increased chance of early vessel recanalization.

E-009 Reversible cerebral vasoconstriction syndrome following carotid artery stenting

IntroductionReversible cerebral vasoconstriction syndromes (RCVS) compromise a group of disorders characterized by prolonged but reversible vasoconstriction of the cerebral arteries. RCVS has been reported to occur in various clinical settings...

Abstract 2947: Differentiating Antegrade Flow Across Intravascular Thrombus from Retrograde Collateral Flow in Occluded Cerebral Arteries: Initial Experience Using Time-Resolved CT Angiography

Introduction: In acute stroke patients with occluded cerebral arteries, angiographic demonstration of antegrade opacification distal to an occlusion has been associated with higher rates of vessel recanalization. We sought to determine whether antegrade flow can be demonstrated on near-whole-brain time-resolved four-dimensional CT angiography (4D-CTA) and whether it can be differentiated from retrograde collateral flow. Methods: Among 123 consecutive patients with angiographically proven acute intracranial anterior circulation vessel occlusion, thin-section 4D-CTA data obtained as part of a diagnostic multi-modal CT exam were available in 48 cases, 47 of which met inclusion criteria. Pre-treatment thrombolysis in cerebral infarction (TICI) grade, presence of the outline sign (defined as antegrade contrast opacification distal to the thrombus) and presence of retrograde collateral flow extending to the distal thrombus end were assessed on 4D-CTA. Digital subtraction angiograms were reviewed for pre-treatment TICI grade, presence of the outline sign as well as post-intervention TICI grade. Results: On 4D-CTA, evidence of antegrade flow was present in 5 of 47 cases (10.6%). Compared to angiography, 4D-CTA correctly classified antegrade flow in 4 cases (80.0%), there was 1 false positive and no false negatives. Recanalization (TICI ≥2a) was achieved in all 5 cases with evidence of antegrade flow on 4D-CTA versus 34 out of the 42 cases (81.0%) without evidence of antegrade flow. Conclusion: Using 4D-CTA, it is possible to differentiate antegrade flow across a cerebral artery occlusion from retrograde collateral flow. Further studies, preferably with a larger sample size are needed to confirm our findings and assess whether 4D-CTA can be used to predict success of recanalization procedures in select cases.

Ocular Symptomatology, Management, and Clinical Outcome of a Giant Intracranial Aneurysm

Giant aneurysms of the anterior intracranial circulation are rare, slowly progressive vascular abnormalities, often presenting with neuro-ophthalmological symptoms before they rupture. This is a case of a 55-year-old woman with a double aneurysm of the anterior intracranial circulation, part of which was giant, diagnosed exclusively on the basis of ocular manifestations. We also describe successful management of the case throughout a long follow-up period.

Imaging-Based Endovascular Therapy for Acute Ischemic Stroke due to Proximal Intracranial Anterior Circulation Occlusion Treated Beyond 8 Hours From Time Last Seen Well

Current selection criteria for intra-arterial therapies in the anterior circulation use time windows of 8 hours. Modern neuroimaging techniques have identified individuals with salvageable penumbra who present beyond this timeframe. We sought to assess safety, procedural, and clinical outcomes of MRI or CT perfusion imaging-based endovascular therapy in patients with anterior circulation stroke treated beyond 8 hours from time last seen well. We conducted a multicenter retrospective review of consecutive patients meeting the following criteria: (1) acute proximal intracranial anterior circulation occlusion; (2) endovascular treatment initiated >8 hours from time last seen well; and (3) treatment selection based on MRI or CT perfusion imaging. Two hundred thirty-seven patients were identified (mean age, 63.8 ± 16 years; mean baseline National Institutes of Health Stroke Scale, 15 ± 5.5; mean time last seen well to treatment, 15 ± 11.2 hours; male gender, 46%). Successful revascularization was achieved in 175 of 237 (73.84%) patients. Parenchymal hematoma occurred in 21 of 237 (8.86%) patients. The 90-day mortality rate was 21.5% (51 of 237). The rate of good outcomes was 45% (100 of 223) in the 223 patients with available modified Rankin Scale data at 90 days or time of hospital discharge. In multivariate analyses, age (OR, 0.96; 95% CI, 0.94 to 0.98; P=0.002), admission National Institutes of Health Stroke Scale (OR, 0.93; 0.87 to 0.98; P=0.016), and successful revascularization (OR, 4.32; 1.99 to 9.39; P<0.0001) were identified as independent predictors of good outcomes. Endovascular therapy can be instituted with acceptable safety beyond 8 hours from time last seen well when selection is based on advanced neuroimaging. Successful revascularization is significantly associated with higher rates of good outcomes. The benefit of this approach compared with standard medical therapy should be assessed in a prospective randomized trial.

O-005 Endovascular therapy for acute ischemic stroke due to proximal intracranial anterior circulation occlusion treated beyond 8 h from time last seen well: a subset analysis of the merci registry

Background and PurposeCurrent selection criteria for reperfusion therapy are based on strict time windows. Recent data suggest that the mismatch between stroke severity and the amount of ischemic core at...

SHA 62. The role of delayed contrast-enhanced cardiac magnetic resonance in the differential diagnosis between myocarditis and myocardial infarction

Objectives: Stroke has been the most feared of the peri-operative complication of cardiac surgery especially with significant carotid disease >70%. This study was conducted to evaluate if there is any benefit of CEA with concomitant CAD for CABG. Methods: Retrospective chart review of 100 patients with asymptomatic high grade carotid artery stenosis (>70% undergoing CABG + valve surgery) during 9-years period. Those patients are divided into two groups: Group A (CABG + CEA): 33 patients had prophylactic CEA (either staged or combined) along with CABG + valve surgery with prophylactic CEA. Group B (CABG): 67 patients had only CABG + valve replacement without prophylactic CEA). The data of the two groups were collected and analyzed. Results: Demographic data in both groups is identical. No significant difference in the incidence of stroke rate in both groups. Bilateral carotid artery disease with good communication between anterior and posterior intracranial circulation as proved by MRA and MRI has the same result of unilateral significant carotid artery disease. Conclusion: Prophylactic CEA is unnecessary in asymptomatic patients. In bilateral carotid artery disease: MRA and MRI should be considered to evaluate communication between anterior and posterior intracranial circulation. Tracks: Cardiovascular Surgery.

The microsurgical treatment patient with 21 cases of anterior circulation aneurysms by pterional approach

Objective To investigate the related issues on surgical treatment of anterior circulation aneurysms by pterion approach. Methods 21 patients were diagnosed with intracranial anterior circulation aneurysms by CTA or DSA, and were treated by micro-surgery of pterion approach, the clinical data on 21 patientswas analysed retrospectively, and surgical timing and short-term effect was evaluated. Results The results of preoperative Hunt-Hess grade respectively is grade Ⅰ in 7 patients, grade Ⅱ 9 cases, grade Ⅲ 4 cases, grade Ⅳ 1 cases. The 21 patients were taken operations successfully ,4 aneurysms ruptured and bleeded during operations.Followed-up for 2 ～ 12 months, 16 cases were in good ,3 cases was light residual, 1 case was severe disability and 1 case was dead. According to Short-term effect on this group ,the good rate was 85.8% (20/21), the mortality was 6. 6% ( 1/21 ), the intraoperative rupture rate was 19. 05 % (4/21 ). Conclusion The patient with anterior circulation aneurysm in Hunt-Hess grade Ⅰ～Ⅲ should be taken an operation as soon as possible, the pterional approach is the classical approach in the treatment of anterior circulation intracranial aneurysms, the controlled hypotension can increase the safety of operation, the skillful microsurgical technique involves guarantee of successful surgery. Key words: Intracranial aneurysms; Micro-surgery; Pterional approach

015 Population based neurovascular modeling

Purpose: The goal of this study is to build a population representative silicone arterial model with lubricated lumen for easy deployment and testing of neuroendovascular devices. Materials and Methods: We...

Diagnosing Brain Death by CT Perfusion and Multislice CT Angiography

Although the diagnosis of brain death (BD) is usually based on clinical criteria, in sedated patients, ancillary techniques are needed. This study was designed to assess the accuracy of cerebral multislice computed tomographic angiography (CTA) and CT perfusion (CTP) in diagnosing BD. Prospective observational study in 27 BD patients. All patients were diagnosed as BD based on clinical and electroencephalogram findings. After BD diagnosis, CTP was performed followed by 64-detector multislice CTA from the aortic arch to the vertex. Images were reconstructed from 0.5 mm sections. In 24 patients, a lack of cerebral blood flow (CBF) was detected by CTP, and CTA revealed luminal narrowing of the internal carotid artery in the neck and absence of anterior and posterior intracranial circulation (sensitivity 89%). CTA detected CBF exclusively in extracranial portions of the internal carotid and vertebral arteries. Two patients with anoxic brain injury and decompressive craniectomy showed CBF in the CTA such that the CTP results were considered false negatives, given BD had been confirmed by clinical and EEG findings, along with evoked potentials. In one clinically BD patient, in whom an alpha rhythm was detected in the electroencephalogram, CBF was only observed in the intracranial internal carotid with no posterior circulation noted. This patient was therefore considered exclusively brain stem dead. The radiological protocol used shows a high sensitivity and excellent specificity for detecting the cerebral circulatory arrest that accompanies BD. As a rapid, non-invasive, and widely available technique it is a promising alternative to conventional 4-vessel angiography.

The course and outcome of unilateral intracranial arteriopathy in 79 children with ischaemic stroke

Arteriopathies are the commonest cause of arterial ischaemic stroke (AIS) in children. Repeated vascular imaging in children with AIS demonstrated the existence of a ‘transient cerebral arteriopathy’ (TCA), characterized by lenticulostriate infarction due to non-progressive unilateral arterial disease affecting the supraclinoid internal carotid artery and its proximal branches. To further characterize the course of childhood arteriopathies, and to differentiate TCA from progressive arterial disease, we studied the long-term evolution of unilateral anterior circulation arteriopathy, and explored predictors of stroke outcome and recurrence. From three consecutive cohorts in London, Paris and Utrecht, we reviewed radiological studies and clinical charts of 79 previously healthy children with anterior circulation AIS and unilateral intracranial arteriopathy of the internal carotid bifurcation, who underwent repeated vascular imaging. The long-term evolution of arteriopathy was classified as progressive or TCA. Clinical and imaging characteristics were compared between both groups. Logistic regression modelling was used to determine possible predictors of the course of arteriopathy, functional outcome and recurrence. After a median follow-up of 1.4 years, 5 of 79 children (6%) had progressive arteriopathy, with increasing unilateral disease or bilateral involvement. In the others (94%), the course of arteriopathy was classified as TCA. In 23% of TCA patients, follow-up vascular imaging showed complete normalization, the remaining 77% had residual arterial abnormalities, with improvement in 45% and stabilization in 32%. Stroke was preceded by chickenpox in 44% of TCA patients, and in none of the patients with progressive arteriopathies. Most infarcts were localized in the basal ganglia. In 14 (19%) of TCA patients, transient worsening of the arterial lesion was demonstrated before the arteriopathy stabilized or improved. Thirteen TCA patients (18%) had a recurrent stroke or TIA. Thirty TCA patients (41%) had a good neurological outcome, compared with none of the five patients with progressive arteriopathy. Arterial occlusion, moyamoya vessels and ACA involvement were more frequent in progressive arteriopathies. Cortical infarct localization was significantly associated with poor neurological outcome (OR 6.14, 95% CI 1.29–29.22, P = 0.02), while there was a trend for occlusive arterial disease to predict poor outcome (OR 3.00, 95% CI 0.98–9.23, P = 0.06). Progressive arteriopathy was associated with recurrence (OR 18.77, 95%CI 1.94–181.97, P = 0.01). The majority of childhood unilateral intracranial anterior circulation arteriopathies (94%) have a course that is consistent with TCA, in which transient worsening is common. Although the arterial inflammation probably causing TCA is ‘transient’, most children are left with permanent arterial abnormalities and residual neurological deficits.

Intracranial Hemodynamic Changes During Adult Moyamoya Disease Progression

Background and purposeThis study evaluated the changes in blood flow velocity in the anterior and posterior intracranial circulations according to the progression of moyamoya disease in adult patients.MethodsWe evaluated Suzuki's angiographic stage and mean blood flow velocity (MBFV) changes in intracranial vessels from both sides in 19 adult moyamoya patients. We then analyzed the linearity of MBFV changes from early to late moyamoya stages in each intracranial vessel using piecewise linear regression models.ResultsThe MBFV in the middle cerebral artery, terminal internal carotid artery, and anterior cerebral artery increased non linearly until stage III, and then decreased progressively up to stage VI. The ophthalmic artery also showed nonlinear velocity changes, with an increase in MBFV up to stage IV, followed by a decrease in MBFV up to stage VI. The MBFV of the basilar artery increased linearly from a normal velocity at an early moyamoya stage to a stenotic velocity at a late stage. There was no statistically significant regression model for the relationship between the MBFV in the posterior cerebral artery and moyamoya stage.ConclusionsThe nonlinear and/or linear MBFV changes associated with variable intracranial vessels might be useful in initial and follow-up evaluations of different stages of moyamoya disease.

A prospective single-center analysis of the safety and efficacy of the HydroCoil embolization system for the treatment of intracranial aneurysms

The HydroCoil embolization system is a helical platinum coil coated with a polymeric hydrogel that expands when it contacts aqueous solutions to increase filling volumes, improve mesh stability, and possibly elicit a healing response within the aneurysm. In this paper, the authors report the 1-year recurrence and complication rates of 67 aneurysms embolized with the HydroCoil system. Sixty-four consecutive patients (67 total aneurysms) with small (< or =7 mm), large (8-15 mm), very large (16-24 mm), and giant (> or =25 mm) aneurysms in the anterior and posterior intracranial circulations were treated with HydroCoils between March 2003 and September 2004. All aneurysms were embolized by the senior author (A.S.B) with HydroCoils alone or in combination with bare platinum coils, until either there was no further angiographic contrast filling of the aneurysm or the microcatheter was pushed out of the dome by the coil mass. Balloon assistance was used in three cases and combined Neuroform stent-coil embolization in eight other cases. To evaluate the safety and 1-year efficacy of the HydroCoil system, periprocedural complications were recorded, and angiographic recurrences were categorized using the Raymond-Roy Occlusion Classification (RROC) system. The 1-year aneurysm recurrence rate independent of size was 15% in patients treated with HydroCoils. Seventy percent of the patients had stable occlusions. The recurrence rate for small aneurysms was 3.7%, and the combined recurrence rate for small and large aneurysms was 6%. Fifteen percent of the aneurysms initially categorized as RROC Type 2 or 3 with stasis of contrast material at the time of initial embolization improved in RROC type, allowing the authors to develop the aneurysm embolization grade to predict recurrence. The neurological complication rate was 14.9%, of which 4.5% represented permanent neurological deficits. The HydroCoil embolization system is safe and provides excellent 1-year occlusion of small and large aneurysms with initial RROC Type 1, as well as those with RROC Types 2 and 3 with stasis of contrast material at the time of embolization. Very large and giant aneurysms were not as successfully occluded with this system. Treatment of large and giant internal carotid artery aneurysms was more likely to result in cranial nerve palsies and postembolization headaches than treatment in other locations. The aneurysm embolization grade the authors developed using the results of this study accurately predicted 1-year recurrence rates based on the immediate postembolization angiographic characteristics of the treated aneurysm.

A Pterion Keyhole Approach for the Treatment of Anterior Circulation Aneurysms

The supraorbital keyhole approach is most frequently used in treatment for lesions within the anterior cranial base. However, it has some drawbacks, including cosmetically poor appearance of the scar, forehead deformity, and difficulty in dealing with some kinds of middle cerebral artery (MCA) and internal carotid artery (ICA) aneurysms. Therefore, we have developed a small pterion keyhole approach for an alternative access to treat anterior circulation aneurysms. An oblique skin incision about 3-5 cm in length was made just from 1.0 cm anterior to the superficial temporal artery at the level of the zygomatic arch, curved just below the temporal line to the forehead, and stopped at the hairline over the sylvian fissure. Then a small craniotomy (2-3 cm) was made just over the sylvian fissure and the aneurysms were exposed through the lateral cerebral fissure. We used this approach to treat 40 patients with aneurysms located in posterior communicating arteries (n=14), the MCA (n=10), the anterior communicating arteries (n=9), the anterior cerebral artery (n=1), the ophthalmic arteries (n=3), and the ICA (n=3). The general outcome of all patients was good without serious complications from the surgical technique even though 3 cases underwent intraoperative premature rupture of the aneurysms. No approach-related complication occurred except that one patient had vasospasm 2 days after the aneurysm clipping. In conclusion, this pterion keyhole approach can achieve the best operative effect for the treatment of intracranial anterior circulation aneurysms in a selective group of patients with several advantages over traditional craniotomy including minor tissue damage, less brain retraction, a superior cosmetic result, and shorter duration of surgery. Moreover, the operative field becomes wider in the deep area, providing sufficient space for microscope-assisted surgery without the need for highly specialized instruments.

Cerebral CT and MRI findings in cervicocephalic artery dissection.

To explore the frequency and patterns of brain infarction and other brain manifestations in cervicocephalic artery dissection (CCAD) and to evaluate the correlation between vessel wall findings and infarctions. The medical records and films of 136 consecutive CCAD patients diagnosed in Oulu University Hospital during the 20-year period since 1982 were reviewed. Five patients with no brain imaging were excluded. One-hundred-and-twenty-seven patients underwent cerebral CT and four patients MRI. Brain infarction was detected in 73 patients (56%), 43 of whom had cerebral infarction associated with anterior circulation dissection and 30 cerebellar infarction associated with posterior circulation dissection. Occlusion of the dissected vessel was accompanied by infarction in 76%, irregular stenosis in 40%, and other findings in 12%. Of the anterior circulation infarctions, territorial and subcortical infarctions and territorial infarctions with fragmentation, which are considered embolic, accounted for 95%, while only 5% were in the watershed area and considered hemodynamic. Intracranial posterior circulation dissection rarely caused infarction (in 1/11 of the dissected vessels), whereas intracranial anterior circulation dissection resulted in infarction more commonly (9/12). Altogether 23% of patients with intracranial CCAD had subarachnoid hemorrhage. Hemorrhagic transformation was present in five patients. More than half of CCAD patients have cerebral or cerebellar infarction at CT or conventional MR imaging. Occlusion of the dissected vessel is accompanied by infarction more often than other vessel wall abnormalities. Most cerebral infarctions caused by arterial dissections are of embolic origin. Intracranial dissections cause subarachnoid hemorrhage in more than 20% of patients.

The value of intraoperative angiography in surgery of intracranial aneurysms: a prospective study in 126 patients.

The value of intraoperative digital subtraction angiography in surgery for intracranial aneurysms, the benefits and cost-effectiveness are a matter of discussion. We prospectively studied 126 patients with 144 aneurysms, most on the anterior intracranial circulation, who underwent clipping and intraoperative angiography. Follow-up was 28.4 +/- 13.1 months. We tried to work out the indications for intraoperative angiography of the anterior circulation and its cost-effectiveness. In 10.3 % of patients (9 % per aneurysm) unexpected findings were shown by intraoperative angiography: inadequately clipped aneurysms in 10 (7.9 %), a completely unclipped aneurysm in one (0.8 %) and occluded major arteries in two (1.6 %). A broad neck was a variable of statistical significance for inadequate clipping or stenosis or occlusion of an adjacent vessel. There was a strong trend for aneurysms more than 15 mm in diameter to be "risky". Their site was not a predictive factor. We believe that intraoperative angiography is indicated in surgery not only on large and giant aneurysms, but also broad-based aneurysms of the anterior cerebral circulation regardless of their size. It is cost-effective compared to postoperative angiography. The rate of stroke in our hands was 0.8%.

Posterior circulation ischemia: then, now, and tomorrow. The Thomas Willis Lecture-2000.

To know and appreciate where we are now and where we are going in the future, it is essential to know where we have been. We cannot afford to relive and repeat the history of stroke every several decades. Posterior circulation stroke represents a microcosm of stroke in general. In this presentation I first review the development of ideas regarding brain and posterior circulation ischemia and its recognition and treatment. I then share some recent data from a large prospective registry of patients with posterior circulation ischemia. Finally, I look ahead to reflect on what I believe should be the future directions for research and for the care of patients with posterior circulation disease. Patients who present to physicians and hospitals with symptoms that suggest posterior circulation ischemia are handled differently from patients who have symptoms that suggest anterior circulation disease in the great majority of medical facilities in the United States and in the world. A patient who has an attack of dizziness with diplopia and ataxic gait usually has a brain image but seldom has vascular or cardiac investigations. A diagnosis of “vertebrobasilar insufficiency” (VBI) is often made, and physicians then debate whether or not to treat with warfarin-type anticoagulants, and, if so, for how long and at what intensity. In contrast, a patient who has right-hand weakness and aphasia is usually evaluated and treated quite differently at the very same facilities. Brain imaging, cardiac investigations, noninvasive vascular tests of the carotid and intracranial anterior circulation with the use of extracranial and transcranial ultrasound and/or MR angiography (MRA) and CT angiography, and catheter angiography are often pursued, depending on the local technological capabilities and experience of the treating physicians. An effort is made to identify the etiology and mechanism of the ischemia. Treatment is then chosen among a …

Ruptured giant intracranial aneurysms. Part I. A study of rebleeding

Object The present study was conducted to estimate the frequency and timing of rebleeding after initial subarachnoid hemorrhage (SAH) from ruptured giant aneurysms. Methods The authors reviewed records of 109 patients who suffered an initial SAH from a giant aneurysm and were treated at the Mayo Clinic between 1973 and 1996. They represented 25% of patients with giant intracranial aneurysms seen at this institution during that 23-year period. Seven of the patients were residents of Rochester, Minnesota, and the rest were referred from other institutions. The aneurysms ranged from 25 to 60 mm in diameter, and 74% were located on arteries of the anterior intracranial circulation. The cumulative frequency of rebleeding at 14 days after admission was 18.4%. Cerebrospinal fluid drainage, cerebral angiography, and delayed aneurysm recurrence were implicated in rebleeding in some of the patients. Rebleeding was not precluded by intraaneurysm thrombosis. Among those who suffered recurrent SAH at the Mayo Clinic, 33% died in the hospital. Conclusions Rebleeding from giant aneurysms occurs at a rate comparable to that associated with smaller aneurysms, a finding that should be considered in management strategies.