Continuous spinal analgesia. Comparison between patient-controlled and bolus administration of plain bupivacaine for postoperative pain relief

The purpose of this study was to examine the changing trends in surgical management of patients with abdominal aortic aneurysms at a tertiary care teaching hospital over the past 40 years, by analysis of demographic data, perioperative variables and outcomes on all patients having abdominal aortic aneurysm surgery between 1955 and 1993. Some 1604 abdominal aortic aneurysms were assessed. The annual rate of abdominal aortic aneurysm surgery increased from 17.6 to 67.8 cases per year. The non-ruptured to ruptured abdominal aortic aneurysm ratio increased from 2.4:1 in the first decade to 3.4:1 in the last 5 years. In non-ruptured abdominal aortic aneurysm repairs, the following variables changed over the four decades: patients age over 80 years increased (2.4% to 8.0%; P<0.04), concomitant lower-limb occlusive disease increased (12.2% to 23.7%; P<0.02), prevalence of smaller aneurysms (4-6 cm) increased (16.0% to 54.2%; P<0.0001); intraoperative hypotension decreased (9.0% to 0.7%; P<0.0001), postoperative hemorrhage decreased (8.2% to 0.0%, P<0.0001), postoperative leg ischemia decreased (5.7% to 1.1%; P<0.02) and postoperative amputation rate decreased (3.2% to 0.0%; P<0.03). There was a significant decrease in perioperative mortality (17.0% to 3.4%; P<0.0001). For ruptured aneurysms, early operation (within 1 h of admission) increased from 8.7% to 55.8% (P<0.0001), prevalence of intraoperative hypotension decreased (50.0% to 23.5%; P<0.001), and major venous injury decreased (18.0% to 5.2%; P<0.05). Mortality, however, did not decrease significantly (54.2% to 44.2%; P=0.32). In conclusion, there was a significant decrease in mortality and morbidity associated with non-ruptured abdominal aortic aneurysm repair over the four decades studied. In addition, older patients with smaller aneurysms and more co-morbid conditions were operated on during this period. Mortality for patients operated on for ruptured abdominal aortic aneurysm repair has not changed significantly.     

Saccular aneurysms of meningeal artery: case report

OBJECTIVE AND IMPORTANCE: A rare observation of double saccular aneurysms of the meningeal artery is presented. CLINICAL PRESENTATION: This 22-year-old man was referred to the Neurosurgical Institute with a suspicion of an aneurysm of the anterior communicating artery. Bilateral angiography of the carotid arteries was performed 1 week after the subarachnoid hemorrhage, but the aneurysms were not visualized. Routine angiography of both carotid arteries and selective studies of the left vertebral artery were performed again, and angiography of the right carotid artery revealed an aneurysm. The patient's neurological state at the time of admission was normal. Fundoscopic examination revealed papilledema and conjunctival injection of the left eye. INTERVENTION: The patient was treated using a right pterional approach. One aneurysm had caused spontaneous subarachnoid hemorrhage. The aneurysms were removed using a direct approach, with histological examination of dura matter fragment containing both aneurysms. The results of the patient's 2-week follow-up examination were normal. Follow-up angiography of the right carotid artery showed absence of the aneurysm with a clip on the branch of meningeal artery. CONCLUSION: Saccular aneurysms of the meningeal artery can be manifested by subarachnoid hemorrhage, and intradural arterial aneurysms are similar to saccular cerebral vessel lesions structurally.     

Spontaneous occlusion of supraclinoid aneurysms after the creation of extra-intracranial bypasses using long grafts: report of two cases

OBJECTIVE: We describe two cases of giant supraclinoid aneurysms, treated by means of saphenous vein grafting between the external carotid artery and the middle cerebral artery, which unexpectedly spontaneously occluded. CLINICAL PRESENTATION: Two patients presented with subarachnoid hemorrhage and headache, respectively. In the first case, angiography showed an aneurysm of the right internal carotid artery (ICA), which had been treated by clipping. Repeat angiography showed a giant aneurysm of the right ICA, the formation of which was probably caused by sliding of the clip that had been applied during the previous operation. The patient was operated on again, but it was impossible to exclude the aneurysm because no clear neck could be identified. In the second case, magnetic resonance imaging and cerebral angiography showed a large, partially thrombosed aneurysm of the supraclinoid segment of the left ICA. TECHNIQUE: In view of the patients' ages and the statuses of compensatory circulation, each patient underwent cerebral revascularization with a long saphenous vein graft placed between one branch of the middle cerebral artery and the external carotid artery, in anticipation of subsequent endovascular treatment of the aneurysm and/or closure of the ICA in the neck. Postoperative angiography demonstrated spontaneous occlusion of the aneurysms. CONCLUSION: Thrombosis of an aneurysm may occur spontaneously or after explorative surgery. However, it should be remembered that spontaneous occlusion of an aneurysm may be induced or favored by hemodynamic vascular alterations that take place inside the aneurysm after a high-flow extra-intracranial bypass has been created.     

Embolization of a ruptured aneurysm in classic polyarteritis nodosa presenting as perirenal hematoma

A 26-year-old man was admitted with abdominal pain, anemia, and hypertension. Ultrasonography and computed tomography revealed a perirenal hematoma. Soon after admission, the patient went into shock, and emergency angiography was performed. Two active bleeding sites were found in the left kidney and were successfully embolized. Also, multiple aneurysms, consistent with the diagnosis of classic polyarteritis nodosa, were seen. After treatment was initiated, the patient recovered fully. When a spontaneous perirenal hematoma is a presenting symptom of classic polyarteritis nodosa, a delay in making the right diagnosis is likely to occur. Angiography not only may provide a quick diagnosis, but it can also be used to perform therapeutic embolization. In patients with classic polyarteritis nodosa and hemorrhage from a ruptured aneurysm, angiography may be a therapeutic alternative to surgery.     

Popliteal aneurysm: surgical treatment is mandatory before complications occur

Between 1972 and 1995, surgical repair was undertaken for 94 popliteal aneurysms diagnosed in 71 patients (69 men and 2 women) with a mean age of 66 years. Ninety-one femoropopliteal bypasses, 2 lumbar sympathectomies and one primary amputation were performed. Postoperative results of 28 elective bypasses performed for asymptomatic aneurysms (AA) were compared with 63 revascularisations needed for symptomatic aneurysms (SA) secondary to thrombosis (31%), embolization (30%), venous or nerve compression (13%), or rupture (2.1%). Occlusion of at least one tibial vessel was documented angiographically in 40% of the asymptomatic aneurysms and in 80% of the symptomatic aneurysms. No significant difference was observed between 5-year graft-patency of asymptomatic aneurysms (64%, mean followup 30 months +/- 37.2) and symptomatic aneurysms (50%, mean followup 39 months +/- 40.9). Furthermore, 5-year graft patency was not influenced by the number of patent tibial vessels in either of these populations. No statistically significant difference between these two groups was observed with respect to morbidity (AA: 10.7%, SA: 19%), or early reintervention (AA: 7.1%, SA: 9.5%). However, 12 secondary amputations were needed, all of which were performed after repair of a symptomatic aneurysm (19%, p < 0.05). No postoperative mortality was observed after an elective bypass while 3 patients (4.8%) with symptomatic aneurysms died after an emergency surgery. Ischemic symptoms persisted in 56% of patients who were initially symptomatic. Surgical correction should therefore be performed once the diagnosis of a popliteal aneurysm has been established in order to prevent amputation and late sequelae.     

Brain lipid peroxidation and antioxidant levels in fetal lambs 72 hours after asphyxia by partial umbilical cord occlusion

Giant middle cerebral artery (MCA) trifurcation aneurysms that cannot be excluded directly can be treated by flow inversion achieved by creation of an extracranial-intracranial bypass distal to the aneurysm, followed by occlusion of the parent vessel proximal to the aneurysm. As opposed to surgical occlusion, endovascular occlusion avoids dissection of the aneurysm area, and the site of occlusion can be chosen according to the flow distribution demonstrated on angiography performed during test occlusions. Two patients with giant aneurysms of the MCA trifurcation benefited from flow inversion treatment. Forty-eight hours after an MCA-superficial temporal artery bypass had been created, the M1 segment was occluded by inserting a coil in the first patient and the internal carotid artery was occluded with balloons in the second patient (there was no communicating artery in the latter case). Both occlusions were performed immediately after a clinical test of occlusion tolerance. The patients were clinically intact during the postoperative course. Follow-up angiography performed 11 and 4 months, respectively, after vessel occlusion showed that the aneurysm occlusion was stable.     

Refusion of anterior cerebral artery after aneurysm clipping--a case report

Herein, we are describing an unusual case suffering from a left anterior cerebral artery aneurysm (A1). Both the anterior cerebral arteries were supplied by the left internal carotid artery as was found in digital substraction angiography (DSA) preoperatively. The postoperative angiograms revealed that left anterior cerebral artery was supplied from the left internal carotid artery and the right anterior cerebral artery by the right internal carotid artery respectively. This finding of cerebral angiograms is interesting and rarely mentioned in the literature. Its hemodynamic change and pathogenesis were unclear and different to that of the coronary circulation, ischemic change of gut and skeletal muscle. The causes may include: 1) vasospasm at the anterior communicating artery after manipulation at surgery; 2) desiccation or shrivelling the adjacent artery by intraoperative electrocoagulation; 3) occlusion the anterior communicating artery by the wing of clip. 4) the deprivation of the blood flow from the left internal carotid artery after totally or partially narrowing left A1 by an aneurysm clip. The redistribution of blood volume in the previously hypoplastic right anterior cerebral artery and decreased caliber of the left anterior cerebral artery (A1) are likely playing a role in this case.     

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 +/- 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3-0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 +/- 0.12 cm vs 1.09 +/- 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients.     

Experience with computed tomographic angiography for the detection of intracranial aneurysms in the setting of acute subarachnoid hemorrhage

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 presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysms lobes, aneurysm neck size (< or = 4 mm), and the number of adjacent arterial branches were suggested. The images obtained with CTA were then compared with the images obtained with DSA, with the later 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 aneurysms, six CT angiogram 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.     

A combined microsurgical skull-base and endovascular approach to giant and large paraclinoid aneurysms

BACKGROUND: The treatment of giant and large paraclinoid aneurysms remains challenging. To improve exposure, facilitate the dissection of aneurysms, assure vascular control, reduce brain retraction and temporary occlusion time, enable simultaneous treatment of associated lesions, and achieve more successful treatment of "difficult" (atherosclerotic and calcified) aneurysms, we combined the skull-base approach with endovascular balloon occlusion of the internal carotid artery (ICA) and suction decompression of the aneurysm. METHODS: Sixteen female patients were treated, eight with giant aneurysms and eight with large aneurysms. Eight aneurysms occurred on the right side and eight on the left. Eight patients had an additional aneurysm; five were clipped during the same procedure. Three patients had infundibular arterial dilation. One patient had an associated hemangioma of the ipsilateral cavernous sinus. The cranio-orbital-zygomatic approach was used for all patients. The anterior clinoid was drilled, and the optic nerve was decompressed, dissected, and mobilized. Transfemoral temporary balloon occlusion of the ICA in the neck was followed by placement of a temporary clip proximal to the posterior communicating artery. Suction decompression was then applied. All aneurysms were then successfully clipped, except one that had a calcified neck and wall that could not be collapsed. Intraoperative angiography performed in 13 of 15 patients with clipped aneurysms confirmed obliteration of the aneurysm and patency of the blood vessels. RESULTS: Postoperative results were good in 14 patients. One patient had right-sided hemiplegia and expressive aphasia, which improved after rehabilitation. One patient with an additional basilar tip aneurysm clipped simultaneously died on the fifth postoperative day because of intraventricular hemorrhage. The origin of bleeding could not be determined on autopsy. Surgical difficulties and morbidity stemmed mainly from a severely calcified or atherosclerotic aneurysmal neck. CONCLUSION: The combination of skull-base approaches and endovascular balloon occlusion coupled with suction decompression is a successful option for the treatment of these challenging aneurysms.     

Intracranial aneurysms

MR angiography provides a rapid, accurate, and extremely flexible noninvasive evaluation of intracranial aneurysms without the cost and risk of conventional angiography. TOF and phase contrast techniques each have specific advantages and disadvantages that can be selectively exploited to optimize aneurysm evaluation. Present indications for MR angiography in aneurysm evaluation include: (1) the presence of incidental findings on a CT or MR examination that suggest the possibility of aneurysm (Figs. 7 and 8), (2) when angiography is contraindicated or when the risk is too high, (3) non-invasive follow-up of patients with known aneurysms, (4) patient refusal of contrast angiography, and (5) evaluation of patients with specific clinical symptoms (i.e., third cranial nerve palsy) or patients with non-specific subacute symptoms in whom an aneurysm might explain the clinical presentation. Although MR angiography certainly can detect aneurysms with a high rate of sensitivity and specificity, detailed decision analyses generally have not supported the overall benefit of this type of screening. Future technical advances as well as advances in the overall understanding of aneurysms may one day prove unequivocally the benefit of MR angiography in screening high-risk patient groups. MR angiography has not yet been clinically evaluated as a tool in the evaluation of acute subarachnoid hemorrhage. Potential obstacles to such an evaluation include the clinical instability of SAH patients, limited spatial resolution of the MR angiography acquisitions, the potential for subarachnoid blood or focal intraparenchymal hematomas to obscure or mimic small aneurysms, and the unreliability of MR angiography in demonstrating vasospasm. Currently these factors continue to provide an integral role for contrast angiography in aneurysm evaluation.     

Vasospasm diagnosis: theoretical and real transcranial Doppler sensitivity

In 40 patients middle cerebral artery trunk (M1) flow velocity was recorded just before 54 carotid angiography in 54 cases exhibiting vasospasm after aneurysm rupture. Angiographic vasospasm distribution was studied; cases of symptomatic vasospasm were noted and were compared with transcranial Doppler data. Angiographic vasospasm was present in M1 in 41/54 carotid angiograms. Postulating that all the cases of M1 angiographic vasospasm should be identified by transcranial Doppler, the theoretical sensitivity of TCD was 76%. In this series however the real sensitivity of TCD in vasospasm diagnosis was only 70%: besides 13 cases where vasospasm was not present in M1 (mainly after ACoA Aneurysm rupture), TCD failed to identify 3 cases of M1 angiographic vasospasm. Vasospasm may not be located in M1 even when severe and symptomatic (4 cases in this series). Transcranial Doppler remains a mediocre tool for identifying vasospasm after anterior communicating artery aneurysm rupture (sensitivity: 55%). Its reliability is better after internal carotid aneurysm rupture (sensitivity: 72%) and excellent after middle cerebral artery aneurysm rupture (sensitivity: 93%). In order to test the drugs or methods used to prevent or combat vasospasm, angiography has to be considered when during the vasospasm risk period TCD does not demonstrate vasospasm in M1, either in patients in whom clinical deterioration is occurring without other obvious explanation, or in all patients.     

Cranial bone flap fixation clamps: compatibility at MR imaging

To evaluate the compatibility of a commercially pure titanium aneurysm clip associated with magnetic resonance (MR) imaging at 1.5 T. Artifacts of the Spetzler titanium aneurysm clip were compared with those produced by six different nonferromagnetic aneurysm clips. With the titanium clip, no magnetic attraction was present, heating was minor, and the artifacts involved a small signal void. With the six other aneurysm clips, artifacts were larger. The presence of Spetzler titanium aneurysm clips is safe at MR imaging at 1.5 T or less.     

Intracranial aneurysms: detection and characterization with MR angiography with use of an advanced postprocessing technique in a blinded-reader study

PURPOSE: To assess magnetic resonance (MR) angiography for the detection and characterization of angiographically proved intracranial aneurysms by using an advanced method of postprocessing, in a blinded-reader study. MATERIALS AND METHODS: One hundred fifty-eight vessels were examined with catheter angiography and three-dimensional time-of-flight MR angiography in 44 patients with 63 aneurysms and 15 patients with no aneurysm at catheter angiography. Postprocessing was performed off-line with an advanced multifeature-extraction, ray-tracing algorithm. MR angiograms were interpreted independently by three neuroradiologists blinded to the catheter angiographic results for presence, location, size, and morphology of the aneurysm. Proof of diagnosis was consensus reading of catheter angiograms. RESULTS: Mean sensitivity for detection of aneurysms was 75% (range, 70%-79%). As a screening tool (ie, detection of at least one aneurysm necessitating catheter angiography), mean sensitivity was 91% for all aneurysms and 95% for aneurysms larger than 3 mm. This method was not adequate for detection of lobulation or size of aneurysm. CONCLUSION: MR angiography with an advanced method of postprocessing can result in highly sensitive, specific studies for the diagnosis of intracranial aneurysms that are of sufficient size to be considered for surgical treatment, but it is inadequate for characterization of aneurysms.     

Effect of growth hormone therapy in children with achondroplasia: growth pattern, hypothalamic-pituitary function, and genotype

PURPOSE: To evaluate the success rates of the implantation of stent grafts in the treatment of peripheral aneurysms. MATERIALS AND METHODS: In 13 patients with 15 aneurysms at the common iliac artery (n = 6), external iliac artery (n = 1), hypogastric artery (n = 2), femoral artery (n = 2) or popliteal artery (n = 4), implantation of dacron-covered nitinol stents was performed. The patients were followed up for three to 20 months (mean, 8.8 months) with intravenous digital subtraction angiography, CT or colour-coded Doppler sonography. RESULTS: In all cases, the aneurysm was successfully occluded after stent implantation. In one case with a popliteal aneurysm, kinking of the vessel caused thrombosis of the stent. The stent was successfully reopened. The aneurysm however, had to be surgically treated 9 months later. The primary and secondary patency rates at 6 months were 93% and 100%, respectively. CONCLUSION: The method described might be an alternative therapy to surgery. There are some limitations in respect of treatment of popliteal aneurysms.     

Interlocking-clipping technique for giant aneurysms of the internal carotid artery: technical case report

OBJECTIVE AND IMPORTANCE: Direct clipping of giant intracranial aneurysms is sometimes difficult. A unique technique using multiple fenestrated clips for closing a giant aneurysm is described. CLINICAL PRESENTATION: A 65-year-old woman presented with a 10-month history of headache and gait disturbance. Cerebral angiography disclosed an unruptured giant aneurysm of the right internal carotid artery. INTERVENTION: Surgical exposure confirmed the presence of a giant aneurysm with the splaying and incorporation of the parent artery and a number of perforating arteries originating from the dome. Four angled and three straight fenestrated clips were applied in tandem to the aneurysm to reconstruct the parent artery and preserve the perforating vessels. Through their blades and heads, the closely arranged clips were successfully interlocked. CONCLUSION: This "interlocking-clipping" technique is a modification of the tandem clipping technique. The aim of this approach is to enhance closing pressure and allow a more stable "seating" of the clips in giant cerebral aneurysms.     

Long-term results of arthroscopic meniscectomy

A 13-year-old boy with a rare giant fusiform aneurysm at the horizontal portion of the middle cerebral artery (M1) presented with progressively severe throbbing headache. The aneurysm was reconstructed by tandem application of nine fenestrated clips and coating of the remnant of the aneurysm. However, he was readmitted 3 months later because of recurrent aneurysms at the proximal and distal M1 portions which had been coated. The aneurysms were trapped after rupture occurred during a second operation. Aneurysm trapping combined with superficial temporal artery-middle cerebral artery bypass surgery may be a better method to treat such aneurysms.     

Rupture of a previously documented small asymptomatic intracranial aneurysm in a patient with autosomal dominant polycystic kidney disease. Case report

Intracranial aneurysms are common extrarenal manifestations of autosomal dominant polycystic kidney disease (ADPKD). Although their natural history is not completely understood, small asymptomatic intracranial aneurysms in patients with ADPKD often are not treated but are followed with serial magnetic resonance (MR) angiography. The authors report the unique case of a patient with ADPKD who bled from a previously documented asymptomatic 3-mm intracranial aneurysm. This 42-year-old man with ADPKD suffered a subarachnoid hemorrhage (SAH) from a 7-mm left pericallosal artery aneurysm. This aneurysm was clipped and the patient made an excellent recovery. An irregular asymptomatic 3-mm right middle cerebral artery (MCA) aneurysm had also been demonstrated on angiography. While the patient was considering elective surgery for the MCA aneurysm, he suffered a hemorrhage from this lesion 10 weeks after the initial SAH. The aneurysm was clipped and the patient made a satisfactory recovery (he was moderately disabled). In this report the authors indicate that small asymptomatic intracranial aneurysms are not always innocuous in patients with ADPKD, and they suggest that treatment should be strongly considered for these lesions in this group of patients when there is a history of SAH or the aneurysm is irregular in appearance. Because MR angiography studies may not adequately define the configuration of small aneurysms and irregularity may easily be missed, conventional angiography is recommended for patients with ADPKD who are found to have an intracranial aneurysm on screening with MR angiography.     

Long-term follow-up study of unruptured intracranial aneurysms

OBJECTIVE: The purpose of this study was to clarify the risk of rupture of unruptured intracranial aneurysms among large groups of patients with various underlying diseases or conditions. METHODS: A long-term follow-up study of unruptured intracranial aneurysms was performed with 360 patients who were treated conservatively during the period from April 1969 to December 1992. RESULTS: Follow-up evaluation (between February and June 1994) could be performed for 234 (65%) of the patients. The underlying diseases included multiple aneurysms with subarachnoid hemorrhage for 60 patients, cerebral infarction for 108, intracerebral hemorrhage for 27, and other diseases for 39. Single aneurysms were present in 171 patients and multiple aneurysms in 63. The mean follow-up period was 75 months (range, 3-270 mo). Of the 234 patients, 132 (56.4%) survived, 59 (25.2%) died because of other diseases, 9 (3.8%) underwent surgery, and 34 (14.5%) showed bleeding from unruptured aneurysms, which was fatal for 18 of the patients. The average annual rupture rate for all patients was 2.3% (subarachnoid hemorrhage, 3.2%; cerebral infarction, 2.2%; intracerebral hemorrhage, 3.2%; other diseases, 3.6%). There were no significant differences among the patients according to underlying disease or aneurysm site. The cumulative rate of bleeding for all patients was 20% at 10 years after diagnosis and 35% at 15 years. The cumulative probability of rupture was significantly higher for the multiple aneurysms than the single aneurysms (P < 0.001). CONCLUSION: The risk of rupture of unruptured aneurysms is high, especially for multiple aneurysms, but there are no significant differences in the risk of rupture according to the underlying disease or the aneurysm location. Radical treatment should be considered for patients with unruptured intracranial aneurysms.