Ruptured abdominal aortic aneurysm: factors influencing operative mortality

Of fifty-eight consecutive patients surgically treated for aneurysm of the abdominal aorta, twenty were emergency cases following the rupture. Associated diseases were found in 85 per cent of patients; hypertension being the most common. Fifty per cent of patients were in shock on admission. The duration between rupture and operation was three hrs to two weeks with the average of 115.5 hrs. In six patients, the diagnosis of abdominal aortic aneurysm was known for over six months. The operative mortality rate in case of ruptured abdominal aortic aneurysm was 45 per cent. The most important determinants of survival were the incidence of shock on admission, the incidence of associated disease, the known duration of the aneurysm, and the time interval from rupture to admission. The intraoperative factors most influencing survival were the type of rupture, intraoperative hypotension, and total blood loss. Comparison of the mortality rate in elective surgery of abdominal aortic aneurysms (5.3 per cent) with that in ruptured aneurysms (45.0 per cent) suggests the necessity for early elective operations whenever abdominal aortic aneurysms are diagnosed.     

Early surgical repair of large intracranial saccular aneurysms

Summary Among 302 patients with cerebral aneurysms admitted between 1981 and 1986, 63 had a large (45) or giant (18) aneurysm with a diameter of more than 12 mm and 24 mm, respectively. 24 of these 63 patients were admitted early after a subarachnoid haemorrhage (SAH) so as to allow surgical repair within 72 hours. Eight of them were inoperable for various reasons and could not undergo definitive surgical repair and died. 16 patients underwent craniotomy and clipping of the aneurysm. 77% of the patients in preoperative grades I-IV made a good recovery with no or minimal neurologic deficit. During the same period 84% of patients with small aneurysms made a good recovery.The present data indicate, that large aneurysms rupture with a similar incidence compared to small aneurysms; saccular large ruptured aneurysms can be operated upon early with similar results as small aneurysms. However, devastating initial bleeds and poor outcome occur more frequently in patients with ruptured giant than in patients with small aneurysms. Most of the patients with ruptured giant aneurysms are comatose on early admission and cannot be considered for early surgery. Their poor prognosis is further reduced by a high rebleeding rate.     

颅内动脉瘤破裂早期血管内栓塞与手术治疗的探讨

目的　探讨颅内动脉瘤破裂早期血管内栓塞与显微手术的效果。方法　 160例颅内动脉瘤破裂在 3d内早期经血管内栓塞和显微手术得到治疗 ,其中 114例经血管内栓塞 ,46例显微手术。结果　 114例血管内治疗 ,78例完全闭塞 ,2 1例闭塞 95 % ,10例闭塞 90 % ,5例闭塞 85 %。出院时优 83例 ,良 19例 ,差 1例 ,死亡 11例。显微手术 46例 ,术后 2周行DSA检查证实动脉瘤全部夹闭。出院时 ,优 2 4例 ,良 10例 ,差 4例 ,植物生存 2例 ,死亡 6例。结论　颅内动脉瘤早期治疗 ,是杜绝再次出血的危险 ,有利于脑血管痉挛的防治 ,降低致残率和死亡率。     

Ruptured abdominal aortic aneurysm: Factors influencing operative mortality

Of fifty-eight consecutive patients surgically treated for aneurysm of the abdominal aorta, twenty were emergency cases following the rupture. Associated diseases were found in 85 per cent of patients; hypertension being the most common. Fifty per cent of patients were in shock on admission. The duration between rupture and operation was three hrs to two weeks with the average of 115.5 hrs. In six patients, the diagnosis of abdominal aortic aneurysm was known for over six months. The operative mortality rate in case of ruptured abdominal aortic aneurysm was 45 per cent. The most important determinants of survival were the incidence of shock on admission, the incidence of associated disease, the known duration of the aneurysm, and the time interval from rupture to admission. The intraoperative factors most influencing survival were the type of rupture, intraoperative hypotension, and total blood loss. Comparison of the mortality rate in elective surgery of abdominal aortic aneurysms (5.3 per cent) with that in ruptured aneurysms (45.0 per cent) suggests the necessity for early elective operations whenever abdominal aortic aneurysms are diagnosed. Presented at the Fifteenth Annual Meeting of the Japanese Association for Cardiovascular Surgery, Kanazawa, Japan, May 17–18, 1985.     

The mortality of abdominal aortic aneurysm.

During a five year period 153 patients presented with abdominal aortic aneurysms and 135 received grafts. The mortality was 4.2% (3 of 71) for elective cases, 16.7% (2 of 12) for acute cases (the preoperative diagnosis of rupture found to be incorrect) and 55.8% (29 of 52) for patients with ruptured aneurysms. For patients with ruptured aneurysms there was a trend towards larger amounts of blood and colloid infusion in patients who died compared with those who survived, but there was no statistically significant difference either for the amount transfused, or for age, distance of referral, preoperative blood pressure, operating theatre time, or seniority of operating surgeon, between the two groups. It is possible that increased attention to cardiac and renal disease might reduce mortality following elective surgery. Measures to reduce the high mortality from ruptured aneurysm must be early detection and treatment of intact aneurysms, rapid diagnosis of rupture and expeditious surgery with minimal blood loss and the accurate exclusion of rupture in acute cases to achieve the same mortality as elective surgery.     

Postoperative anticonvulsant prophylaxis for patients treated for cerebral aneurysms

The incidences of postoperative seizures and side effects were evaluated in 193 patients with cerebral aneurysm who received anticonvulsant prophylaxis and underwent 224 craniotomies for cerebral aneurysms between 1993 and 1995. The patients were 73 males and 120 females aged between 31 and 80 years. One hundred and sixteen patients had ruptured cerebral aneurysms and 108 had unruptured aneurysms. Phenytoin followed by valproic acid were administered. Early postoperative seizures occurred in five patients (4 with ruptured and 1 with unruptured aneurysms) within 14 days after surgery. Late postoperative seizures occurred in four different patients with ruptured aneurysms more than 14 days after surgery. The presence of cortical lesions detected by cerebral computed tomography and occurrence of symptomatic vasospasm were correlated with the occurrence of early postoperative seizure (p < 0.05). Three of the four patients with late postoperative seizure had cortical lesions and two were receiving continued medication. Side effects that warranted discontinuation of therapy were seen in the follow-up period in 12.9% of patients. Anticonvulsant prophylaxis is not recommended due to the higher incidence of side effects than seizure, except in patients in poor clinical condition for the purpose of brain protection. Otherwise, anticonvulsant medication should be initiated at the time of the initial seizure attack.     

A review of size and location of ruptured intracranial aneurysms

OBJECTIVE: To review our experience and examine the size at which aneurysms ruptured in our patient population. METHODS: Patient charts and angiograms for all patients admitted with a diagnosis of subarachnoid hemorrhage to the Thomas Jefferson/Wills Eye Hospital between April 1996 and March 2000 were reviewed. RESULTS: Of the 362 cases reviewed, definite measurements of the ruptured aneurysm were obtained in 245. The data clearly showed that most ruptured aneurysms presenting to our institution were less than 10 mm in diameter. We found that, regardless of location on the circle of Willis, 85.6% of all aneurysms presenting with rupture were less than 10 mm. Review by location shows that aneurysms of the anterior communicating artery most often presented with rupture at sizes less than 10 mm (94.4%). A large number of ruptured posterior communicating artery aneurysms also presented at sizes less than 10 mm (87.5%). This trend continued for all aneurysm sites in our review. The incidence of subarachnoid hemorrhage in Western countries is estimated at 10 per 100,000 people per year. Recent reports have indicated that aneurysms less than 10 mm in size are unlikely to rupture. CONCLUSION: We argue that the risk of small aneurysms rupturing is not insignificant, especially those of the anterior communicating artery. Our findings indicate that surgery on unruptured aneurysms should not be predicated on aneurysm size alone.     

Three-dimensional computerized tomography angiography-guided surgery of acutely ruptured cerebral aneurysms

OBJECT: The aim of this study was to assess whether aneurysm surgery can be performed in patients with ruptured cerebral aneurysms by using three-dimensional computerized tomography (3D-CT) angiography alone, without conventional catheter angiography. METHODS: In a previous study, 60 patients with subarachnoid hemorrhage (SAH) from ruptured aneurysms were prospectively evaluated using both 3D-CT and conventional angiography, which resulted in a 100% accuracy for 3D-CT angiography in the diagnosis of ruptured aneurysms, and a 96% accuracy in the identification of associated unruptured aneurysms. The results led the authors to consider replacing conventional angiography with 3D-CT angiography for use in diagnosing ruptured aneurysms, and to perform surgery aided by 3D-CT angiography alone without conventional angiography. Based on the results, 100 consecutive patients with SAH who had undergone surgery in the acute stage based on 3D-CT angiography findings have been studied since December 1996. One hundred ruptured aneurysms, including 41 associated unruptured lesions, were detected using 3D-CT angiography. In seven of 100 ruptured aneurysms, which included four dissecting vertebral artery aneurysms, two basilar artery (BA) tip aneurysms, and one BA-superior cerebellar artery aneurysm, 3D-CT angiography was followed by conventional angiography to acquire diagnostic confirmation or information about the vein of Labbé, which was needed to guide the surgical approach for BA tip aneurysms. All of the ruptured aneurysms were confirmed at surgery and treated successfully. Ninety-three patients who underwent operation with the aid of 3D-CT angiography only had no complications related to the lack of information gathered by conventional angiography. The 3D-CT angiography studies provided the authors with the aneurysm location as well as surgically important information on the configuration of its sac and neck, the presence of calcification in the aneurysm wall, and its relationship to the adjacent vessels and bone structures. CONCLUSIONS: The authors believe that 3D-CT angiography can replace conventional angiography in the diagnosis of ruptured aneurysms and that surgery can be performed in almost all acutely ruptured aneurysms by using only 3D-CT angiography without conventional angiography.     

Epidemiology and Outcome of Aortic Aneurysms in Hong Kong

Abstract The objective of this study was to determine epidemiology and mortality statistics for abdominal aortic aneurysms (AAAs) in Hong Kong. Data from three sources were obtained and analyzed: (1) Hong Kong Hospital Authority discharge statistics for 1999 and 2000; (2) a survey on aortic aneurysms in public hospitals conducted by the Working Group of Vascular Surgery; and (3) the Department of Surgery, University of Hong Kong Medical Center aortic aneurysm database. The disease pattern, distribution, and operative mortality were determined. The annual incidence of AAA in Hong Kong is 13.7 per 100,000 population and 105 per 100,000 for those aged 65 and above. About 10% of the AAAs that presented were ruptured. The mean age of the AAA patients was 74 years, with 84% of them over age 65. The operative repair rate for AAAs was low, being only 8% for intact aneurysms and 54% for ruptured ones. Overall, 45% of all aneurysm repairs were performed for a ruptured AAA. There is diverse practice between major vascular centers and smaller regional hospitals. The territory-wide operative mortality rates for intact and ruptured aneurysms were 10% (range 4–24%) and 70% (range 38––100%), respectively. There was no gender bias in the rupture and operative rates. The overall mortality was 17% for intact AAAs and 78% for ruptured AAAs. The average length of hospital stay was 19 days for elective AAA surgery and 13 days for ruptured AAAs. The number of operations in high-volume centers is increasing with a concomitant decrease in operative mortality. There are no definitive data to indicate that the incidence of AAAs is rising, but a trend toward an increasing number of operations in referral centers is noted. The low repair rates for intact AAAs and the high proportion of repairs for ruptured aneurysms suggest that AAAs are undertreated in Hong Kong.     

Recent advances in the surgical treatment of aortic disease in Japan

The annual survey by the Japanese Association for Thoracic Surgery in 2010 found that the nationwide hospital mortality rate after surgery was 11.1% in 3,628 patients with acute type A aortic dissection, 18.9% in 158 patients with acute type B dissection, 6.0% in 866 patients with chronic type A dissection, 6.6% in 724 chronic type B dissection, 4.3% in 6,348 patients with nondissection thoracic aortic aneurysm, and 24.8% in 715 ruptured thoracic aneurysms. For abdominal aortic aneurysms, the hospital mortality rate after elective surgery was 2.3% and 15.3% in ruptured aneurysms among 7,906 patients nationwide. These results are superior to the results of aortic surgery in Western countries.     

Solitary aneurysms of the iliac arterial system: an estimate of their frequency of occurrence

Solitary iliac artery aneurysms are rare, and most reports have been presented as case reports. By combining autopsy records and operating records, a total of 13 cases were found: during a 15-year period (1971 to 1985), 42,010 of the inhabitants of Malm? died (population 230,000) and 35,265 (including 9014 forensic autopsies) underwent autopsy (84%). Solitary iliac artery aneurysms were found in seven (0.03%) of the 26,251 patients who underwent autopsy at the hospital; six of those had been asymptomatic and one was ruptured. Among the 9014 persons who underwent forensic medical autopsy, there were two with ruptured solitary iliac artery aneurysms. Four patients had clinically detected solitary iliac artery aneurysms, three of which were ruptured. All patients underwent surgery, and two of the three patients with ruptured solitary iliac artery aneurysms left the hospital well. The rupture rate of iliac aneurysm among those found at autopsy was one of seven (14%) and among those clinically detected three of four.     

Bleeding Risk in Unruptured and Residual Cerebral Aneurysms – Angiographic Annual Growth Rate in Nineteen Patients

Summary  Whether and when unruptured aneurysms or aneurysmal rests following incomplete surgery result in subsequent bleeding are major concerns for neurosurgeons. By calculating the annual growth rate of aneurysms in long-term follow-up angiography (partly supplemented with MR-imaging and/or MR-angiography), we attempted to determine the surgical indications for these aneurysms. Long-term follow-up angiography ranging from one to 20 years was carried out on five patients whose ruptured aneurysms had been incompletely occluded, six patients with multiple aneurysms, of which the ruptured ones had been completely oblitered at operation and the small unruptured aneurysms, missed or misdiagnosed, and eight patients with unruptured aneurysms which were asymptomatic or symptomatic. The correlation of annual aneurysm growth rate to subsequent bleeding was investigated. Four out of six fast-growing aneurysms with high annual growth rates (more than 8% increase per year) resulted in subsequent bleeding whereas none of the fourteen slow-growing aneurysms with low annual growth rates (less than 8% increase per year) led to bleeding (Fisher's exact test; p<0.01). Hypertension, patient age and aneurysmal location showed no significant correlation to the annual growth rate (Fisher's exact test; p>0.05). This study suggests that aneurysmal rests after incomplete surgery and missed or misdiagnosed multiple or incidental aneurysms which are fast growing have a high possibility of subsequent bleeding and should be operated on as soon as possible.     

Abdominal aortic aneurysms. 1. Selection of patients and operative results

Between 1958--1976 204 patients with abdominal aortic aneurysms were admitted to the surgical ward for evaluation. One hundred and thirty-eight patients were operated on, 7 died prior to operation and 59 patients were not recommended operation for different reasons. Elective surgery was performed in 60 patients and 78 underwent acute surgery. The aneurysm had ruptured in 40 of the acutely operated patients. The operative mortality was 33% for the whole series, 65% among the ruptured aneurysms and 10% for the planned operations. The early mortality diminished successively and was during the last 5-year period 4% for planned and 40% for emergency operations. The main causes of the early mortality was renal or cardiac insufficiency and abdominal or gastrointestinal haemorrhage. Intestinal infarction was the cause of death in two patients. Twenty-nine re-operations were made in 24 patients. Abdominal haemorrhage, gastro-intestinal bleeding or arterial embolus in the leg were the most common reasons for the re-operations. An analysis of the factors that may influence the operative mortality revealed that age, sex, pre-operative shock, re-operations and number of blood transfusions may be of importance for prediction of the survival. Previously known hypertension, infarction, myocardial ischaemia or the operation time did not seem to have any predictive value. The most common reasons for not recommending surgery were small aneurysms, technical inoperability, advanced age or severely complicating disease.     

Initial experience of abdominal aortic aneurysm repairs in Borneo

Background: Abdominal aortic aneurysms (AAA) repairs are routineoperations with low mortality in the developed world. There arefew studies on the operative management of AAA in the Asian population.This study reports the initial results from a unit with no previousexperience in this surgery by a single surgeon on completion oftraining. Methods: All patients with AAA repair from a prospective databasebetween 1996 and 1999 in the south‐east Asian state of Sarawak inBorneo Island were analyzed. Three groups were identified on presentationaccording to clinical urgency of surgery. Elective surgery was offeredto all good risk patients with AAA of ≥ 5 cm.All symptomatic patients were offered surgery unless contraindicatedmedically. Results: AAA repairs were performed in 69 patients: 32 (46%)had elective repairs of asymptomatic AAA; 20 (29%) hadurgent surgery for symptomatic non‐ruptured AAA; and 17 (25%)had surgery for ruptured AAA. The mortality rate for elective surgery was6%; the two deaths occurred early in the series with thesubsequent 25 repairs recorded no further mortality. The mortalityrates for the urgent, symptomatic non‐ruptured AAA repair and rupturedAAA repair were 20% and 35%, respectively. Cardiacand res­piratory complications were the main morbidities.Sixty‐three patients seen during this period had no surgery; threepresented and died of ruptured AAA, 34 had AAA of ≤ 5 cmin diameter, and 26 with AAA of ≥ 5 cmdiameter had either no consent for surgery or serious medical contraindications. Conclusion: This study showed that AAA can be repaired safely byhighly motivated and adequately trained surgeons in a hospital withlittle previous experience.     

Characteristics and management of ruptured distal middle cerebral artery aneurysms

Summary Objective. Distal middle cerebral artery (dMCA) aneurysms are very rare with a reported frequency of 2–6%. Typically, patients with ruptured distal MCA aneurysms have poor clinical outcomes because often there is both a subarachnoid haemorrhage (SAH) and an intracerebral haematoma (ICH). The goals of this study were to identify the characteristics of the distal MCA aneurysms and evaluate the optimal treatment for a good outcome. Methods. The clinical, neuroradiological and operative records of 8 patients with a ruptured distal MCA aneurysm who underwent surgical management were reviewed retrospectively. The outcomes were presented according to the Glasgow Outcome Scale (GOS). Results. The clinical characteristics of the patients with ruptured dMCA aneurysms included the following: (1) a fusiform appearance in five out of eight (63%) patients. (2) Mean aneurysm size of 9.4 mm (range 2–35 mm). (3) The location being M2 (insular segment) in three, M2-3 junction in three, and M3 (opercular segment) in two patients. (4) Brain CT images revealed both SAH and an ICH in six of eight (75%) patients with the mean size of the ICH being 10 cc (range 5–25 cc). (5) Re-bleeding occurred in four out of eight (50%) of patients. All patients underwent early surgical treatment and the procedures used for surgical repair were, clipping in five patients, trapping in two, and trapping with end-to-end bypass surgery in one patient. Clinical outcomes were poor in two patients (death) due to severe brain swelling. Conclusions. In this study, dMCA aneurysms had a fusiform shape and a high re-bleeding rate; if ruptured, there was generally ICH and SAH. A good clinical outcome was associated with adequate control of brain swelling and early surgery to prevent re-bleeding.     

Management and postoperative mortality related to time of clipping for supratentorial aneurysms a personal series

Summary An analysis of all 197 consecutive cases of intracranial aneurysms treated by one of us (B. W.) was carried out. 82% were ruptured anterior circle aneurysms. 144 cases were analyzed with respect to post-operative and management mortality where patients were eligible for definitive clipping. Grade-time interactions on transfer to the neurosurgeon were considered. Early operation was not associated with significantly higher post-operative and management mortality. 116 cases clipped and discharged from hospital had longer follow-ups to see if earlier operation was associated with a poorer neurological and social outcome. This was not the case. We therefore believe that since the prime rationale for surgery following subarachnoid haemorrhage is the prevention of rebleeding and since this is more common immediately following the initial haemorrhage, early surgery is indicated whenever this is technically feasible. Since 1978, with a deliberate policy of trying to operate early, for all grades there has been a post-operative mortality of 3%, a case management mortality of 20% and 87% of patients operated upon have been able to go home.     

Surgical treatment of multiple intracranial aneurysms

Summary A retrospective review of 126 patients with multiple aneurysms seen over a 10 year period was undertaken. They had a total of 302 aneurysms. Thirty-seven percent of the patients were males, and 63% were females. Direct operations were performed on 97 cases. Both the ruptured and unruptured aneurysms were treated in 71% (69 of the 97 cases), and only the ruptured aneurysms were treated in 29% (28). In 69 cases in whom both ruptured and unruptured aneurysms were treated, one-stage operations were used for 48 cases, and two-stage operations were used for 21 cases. Thirty-four of the 48 cases, who were treated in one-stage operations, were operated on by day 4 after subarachnoid haemorrhage. In 12 cases, a total of 13 small unruptured aneurysms, which had not been found by preoperative angiograms, were discovered during surgery, and 9 of the 13 were discovered while removing blood clots to reduce cerebral vasospasm. Regardless of the operative method selected and the timing of operations, the surgical outcome of patients with multiple aneurysms was comparable to that of the 228 cases with single aneurysms treated during the same period at the same hospital.The analysis of this study suggests that surgical results for multiple aneurysms are satisfactory, even for early operations. Further, the actual incidence of multiple aneurysms may be higher than has been reported to date because small unruptured aneurysms which have been discovered during clot removal may not have been reported.     

The role of surgery when endovascular treatment is considered the first choice therapy for ruptured intracranial aneurysms

AIM: Nowadays endovascular therapy is more and more considered as first choice treatment for ruptured intracranial aneurysms. The aim of this study was to understand the impact that endovascular treatment (EVT), chosen as first therapeutic strategy, has had in the selection of ruptured intracranial aneurysms submitted to surgery at our Institution and what role neurosurgeons still play in this setting. METHODS: From 1998 to 2002, 272 consecutive patients were treated at the Hospital of Toulouse for ruptured intracranial aneurysms: 222 by embolization and 50 by surgery. The two groups were homogeneous for sex, age and aneurysms multiplicity. RESULTS: The patients of the surgical group had a worst clinical-radiological status at the treatment time than those treated by EVT. Clipping was performed for different reasons: 16% for failure of attempted EVT; 32% for intracranial hematoma requiring surgical evacuation; 30% for aneurysm morphology unsuitable for EVT and 22% for absence of the endovascular operator. Aneurysms of the middle cerebral artery (MCA) represented the main surgical group. The aneurysms judged unsuitable for EVT and addressed to surgery had often a complex morphology representing a challenge also for surgery. Mid-term outcome is significantly better for patients treated by EVT. CONCLUSION: The results show that microsurgery continues to have a role in the treatment of ruptured intracranial aneurysms even when EVT is the first choice. The precarious clinical conditions of the patients submitted to surgery and the frequent complexity of their aneurysms explain their worst outcome. This would advise training dedicated vascular Neurosurgeons to guaranty a high level treatment when EVT is not possible.     

Management of elderly patients with aneurysmal subarachnoid hemorrhage]

Clinical features of 61 elderly patients aged over 70 years with ruptured intracranial aneurysms were compared with those of 328 younger patients aged under 70 years. According to a policy of early operation, elderly patients with Hunt and Kosnik's grade I, II and younger patients with grade I, II, III were operated on in the acute stage. In elderly patients with grade III, IV and younger patients with grade IV, the indication for surgery was determined case by case. Surgery was performed on 29 patients (48%) in the elderly group and 277 patients (86%) in the younger group. Our conclusions are as follows: 1. Regarding cases of grade I, II and III of Hunt and Kosnik's classification, the rate of good outcome in the elderly group was similar to that in the younger group, following early surgery and meticulous post-operative care. 2. In the elderly group, no patient in cases of grade IV obtained good surgical outcome. 3. Symptomatic vasospasm was less frequent in elderly patients (18.8%) than in younger cases (37%). 4. Delayed operation was planned for some patients in the elderly group, but none of them underwent surgery because of rerupture of aneurysms and deterioration of general condition.     

False localization of rupture site in patients with multiple cerebral aneurysms and subarachnoid hemorrhage

OBJECTIVE: Patients with subarachnoid hemorrhage and multiple intracranial aneurysms present a unique challenge to the neurosurgeon. Unless all aneurysms can be clipped through a single craniotomy, the surgeon must accurately determine which aneurysm has ruptured. Misjudgment may result in disastrous postoperative rebleeding from the untreated but true ruptured lesion. We assessed the risk of false localization of the rupture site and subsequent rebleeding and documented the problems in predicting the true rupture site when patients have multiple intracranial aneurysms. METHOD: We reviewed the records of a consecutive series of 93 patients treated over a period of 12 years who presented with their first subarachnoid hemorrhage and who had multiple intracranial aneurysms. The rupture site was determined on the basis of computed tomographic and angiographic findings, and the supposed ruptured aneurysm was clipped within 2 days of hemorrhage in each patient. Additional aneurysms that could not be accessed in the same surgical session were operated on at a later stage. All patients' records were reviewed, and all computed tomographic scans and angiograms, including repeat studies performed in some patients, were retrospectively reevaluated by the authors, who had no knowledge of the patients' clinical information. RESULTS: The location of the aneurysm that ruptured was verified at the time of surgery or during the autopsy in 76 patients (82%). The aneurysm that ruptured was the one predicted as ruptured by the surgeon before surgery in 69 patients (91%) and in retrospect in 72 patients (95%). Five of the 6 patients in whom the ruptured aneurysm was not correctly identified were thought to have only a single aneurysm. Four patients rebled after surgery, and 2 patients died as a result of the rebleeding. CONCLUSION: In the reported series, the most common cause of rebleeding soon after aneurysm surgery was failure to obliterate the ruptured aneurysm, usually because it was missed on the initial angiogram. The results support not only meticulous radiological investigation of all intracranial arteries before surgery but also thorough surgical inspection of the target aneurysm in all cases of subarachnoid hemorrhage even after one candidate lesion has been discovered.