Characteristics of aneurysms of the internal carotid artery bifurcation

Summary Background. Arterial bifurcations are sites of maximal hemodynamic stress, where cerebral aneurysms commonly develop. However, in our experience with endovascular treatment for aneurysms of the internal carotid artery (ICA) bifurcation, we often experienced that the aneurysmal neck did not necessarily exist only at the ICA bifurcation (ICBi). In this study, we have retrospectively evaluated characteristics of aneurysms at the ICBi. Methods. Ten ICBi aneurysms in 10 consecutive patients were studied retrospectively. The size of the aneurysms, the angles formed between the ICA and the anterior cerebral artery (ACA) and middle cerebral artery (MCA), and the diameter of the ICA, ACA and MCA were measured. Furthermore, to study the relationship between the location of the aneurysmal neck and the bifurcation of the ICA, the distance between the midline of the aneurysmal neck and of the ICA was measured. Results. The average aneurysm size was 6.3 ± 3.2 mm and the average neck was 3.1 ± 1.2 mm. The average ICA-ACA angle was 57.3 ± 16.5 degrees, and the average ICA-MCA angle was 128.9 ± 24.1 degrees. The average diameters of the ICA, ACA and MCA were 2.9 ± 0.5 mm, 1.9 ± 0.4 mm and 2.5 ± 0.4 mm, respectively. The average distance between the midline of the aneurysmal neck and the ICA was 1.6 ± 0.6 mm, and all aneurysmal necks of the ICBi arose from the side of the ACA. Conclusion. ICBi aneurysms were deviated to the side of the A1 segment of the ACA, where the artery might suffer higher hemodynamic stress.     

Distal anterior cerebral artery mirror aneurysms and middle cerebral artery aneurysms

A 52-year-old woman presented with bilateral distal anterior cerebral artery (ACA) mirror aneurysms, in addition to two right middle cerebral artery (MCA) aneurysms. The left distal ACA and right MCA aneurysms were clipped through right interhemispheric and right pterional craniotomies. The right distal ACA aneurysm was thrombosed. Distal ACA aneurysms tend to be multiple, but mirror aneurysms are rare, especially in the absence of congenital vascular anomaly. Single stage unilateral craniotomy is recommended for surgical treatment.     

Complex middle cerebral artery aneurysms: a new classification based on the angioarchitecture and surgical strategies

Background

Because of the diversity of aneurysm morphology, complicated arterial anatomy and hemodynamic characteristics, tailored surgical treatments are required for cases of individual complex middle cerebral artery (MCA) aneurysms.

Methods

During an 8-year period, 59 complex MCA aneurysms in 58 patients were treated microsurgically in our department. Complex aneurysms were defined as having large (10–24 mm in diameter) or giant (diameter?≥?25 mm) size or non-saccular morphology (fusiform, dissecting or serpentine).

Results

Direct clipping of the aneurysmal necks was achieved in eight patients, while reconstructive clipping was performed in 25 patients. Indirect aneurysm occlusion was performed in 25 cases, including trapping or resecting the aneurysm in four cases, trapping or resecting the aneurysm with extra-intracranial (EC) or intra-intracranial (IC) bypass in 21 cases and internal carotid artery (ICA) sacrifice with EC-IC bypass in one case. Forty-eight aneurysms (81.4 %) were completely obliterated. Graft patency was confirmed in 20 of 21 cases (95.2 %) with bypass. A recurrent aneurysm was detected in one case and a re-operation was performed. Two patients with Hunt-Hess grade IV aneurysms died during the perioperative period. Overall, 52 cases (88.1 %) had good outcomes (Glasgow Outcome Scale?≥?4) during the late follow-up period.

Conclusion

The surgical modality and strategy for treating complex MCA aneurysm are decided according to the morphology of the aneurysm, vascular anatomy and the hemodynamic characteristics of each case. Thus, we developed a new classification based on the angioarchitecture. Favorable outcomes can be achieved by treating complex MCA aneurysms with appropriate surgical modalities, strategies and techniques.     

Spontaneous dissecting aneurysms of anterior and middle cerebral artery associated with brain infarction: a case report and review of the literature

BACKGROUND

Intracranial dissecting aneurysms have been reported with increasing frequency and are recognized as a common cause of stroke. In some reviews and case reports, attempts have been made to compare the outcomes of surgical and medical treatments. However, the appropriate management of dissecting aneurysms in the anterior circulation remains controversial, especially in patients who also manifest cerebral infarction.

CASE DESCRIPTION

A 45-year-old male was diagnosed as having a dissecting aneurysm of the right middle cerebral artery (MCA) with cerebral infarction. In the course of conservative treatment, he developed a new cerebral infarction in the territory of the right anterior cerebral artery (ACA). Repeat cerebral angiograms revealed an increase in the aneurysmal dilatation of the right M2 and the appearance of a segmental dilatation of the right A2. He continued to be treated conservatively and his course was satisfactory. On subsequent angiograms, we observed resolution of the right A2 dissection and no further progression of the dilatation of the right M2.

CONCLUSION

This is the first reported case of simultaneous idiopathic dissecting aneurysms of different major arterial branches in the anterior circulation. Our review of the literature disclosed 36 and 23 cases, respectively, of dissecting aneurysms of the ACA and MCA. Many previously reported patients with these dissecting aneurysms involving subarachnoid hemorrhage (SAH) underwent surgery, which resulted in better outcome. More than half of the patients with ACA and MCA dissecting aneurysms had cerebral infarction. All ACA dissecting aneurysms involving ischemia occurred in the A2 region. The outcomes of both surgical and conservative management were equally satisfactory. On the other hand, in patients with MCA dissecting aneurysms, the area of ischemia frequently involved the M1 region; in these patients, conservative treatment resulted in poor outcomes. Therefore, revascularization distal to the compromised artery should be considered in patients with MCA-dissecting aneurysms who have ischemia. Careful interpretation of serial angiograms and/or magnetic resonance (MR) images is necessary because of the possibility of disease progression. If the aneurysmal size increases or there is progression of ischemic symptoms in the course of conservative treatment, surgery must be urgently evaluated.     

Two cases of main trunk artery occlusion associated with multiple cerebral aneurysms

We report 2 cases of multiple aneurysms (AN) associated with main trunk artery occlusion. CASE 1: A 52-year-old male was admitted to our hospital with dysarthria and weakness of the right side of the body. Computed tomography (CT) showed cerebral infarction in the left corona radiata. MR angiography and conventional angiography showed occlusion of the left middle cerebral artery (MCA) and saccular aneurysms (ANs) at the origin of the anterior communicating artery (A-com) and bifurcation of the right MCA. Subsequent 123I-IMP-single photon emission tomography (SPECT) revealed marked reduction of cerebral blood flow and disturbed reactivity to acetazolamide in the left cerebral hemisphere. Superficial temporal artery (STA)-MCA anastomosis was performed to improve cerebral blood flow and reduce hemodynamic stress for AN of the A-com and right MCA. At 5 months after the first operation, neck clipping was performed successfully for the non-ruptured A-com AN and right MCA AN. CASE 2: A 65-year-old male was admitted to our hospital. CT revealed subarachnoid hemorrhage (SAH), and 3D-computed tomographic angiography (CTA) and cerebral angiography showed basilar top AN, A-com AN and right MCA AN associated with right internal carotid artery occlusion. Right ACA and MCA territories were visualized from the A-com artery and posterior cerebral artery. STA-MCA anastomosis was performed to improve cerebral blood flow and reduce hemodynamic stress for ANs. In the same operation, successful neck clipping was performed for BA top AN and right MCA AN. In such cases as these, particularly in ischemic cases associated with main trunk artery occlusion, it was important to consider surgery for AN after STA-MCA anastomosis in anticipation of improved cerebral blood flow and reduce hemodynamic stress for AN.     

Combined microsurgical and endovascular treatment of a giant left middle cerebral artery aneurysm

Giant fusiform aneurysms of the middle cerebral artery (MCA) bifurcation pose significant treatment challenges. A giant fusiform aneurysm of the left MCA in a pediatric patient, which persisted despite Hunterian ligation of the M1 and double barrel superficial temporal artery (STA) to M2 bypasses, is reported. The aneurysm was trapped by endovascular coiling of the feeding M2 trunk through the STA anastamosis. Hunterian ligation combined with extracranial-intracranial bypass is an effective technique for treating giant fusiform aneurysms of the MCA bifurcation for patients who fail balloon test occlusions. However, in certain cases, flow reversal may not eliminate the aneurysm and continued aneurysm filling may occur through retrograde filling from the bypass recipient vessels. In these cases, endovascular trapping of the aneurysm may be undertaken through the bypass graft. The feasibility of this management scheme is demonstrated.     

Distal anterior cerebral artery aneurysms: report of 26 cases

Distal anterior cerebral artery (ACA) aneurysms are rare, and constitute approximately 1.5% to 9% of all intracranial aneurysms. They show some unique features compared with other aneurysms in the cerebral circulation and are frequently treated with a different technique. Twenty-six of 364 patients with cerebral aneurysms treated at our department between 1996 and 2004 had distal ACA aneurysms (7.1%). Twenty-three of the 26 patients were treated through an anterior interhemispheric approach and two with a pterional approach. All saccular aneurysms were successfully clipped except one which was embolized after the surgery. The only fusiform aneurysm spontaneously thrombosed and resolved with parent artery occlusion. Two of the 26 patients had multiple aneurysms. The surgical mortality was 8%. Distal ACA aneurysms have higher mortality and morbidity than other anterior circulation aneurysms. They should be aggressively treated even if very small because of the tendency to rupture. Endovascular treatment is an alternative in the management of these aneurysms. The most important factors affecting the outcome are grade on admission and the neurosurgeon's experience.     

Observation of de novo formation and growth of an intracranial aneurysm: a case report

We observed a de novo formation and growth of an aneurysm in a 43-year-old woman who was followed up after treatment of a subarachnoid hemorrhage (SAH). In 2002, the patient, whose mother had a history of SAH, presented with SAH at the age of 36. Three-dimensional computed tomography angiography (3D-CTA) and digital subtraction angiography showed an aneurysm in the right internal carotid-posterior communicating artery. The aneurysm was clipped and postoperative course was uneventful without neurological deficit. The patient was followed up by 3D-CTA and magnetic resonance angiography every 6 months, because of an untreated small aneurysm, 3 mm in diameter, in the left middle cerebral artery (MCA). The MCA aneurysm remained unchanged but a de novo aneurysm, 1.5 mm in diameter, developed in the right anterior cerebral artery (ACA) 6 years after the first surgery. The ACA aneurysm grew to 4 mm in diameter during the following 10 months but the MCA aneurysm remained unchanged. Both aneurysms were clipped in one session. The MCA aneurysm had a smooth wall but the ACA aneurysm had an irregular and thin wall. The postoperative course was uneventful. Young female patients who have developed SAH with familial history, like this case, should receive long-term follow up to check whether a de novo aneurysm has developed.     

Subdural hematoma due to ruptured intracranial aneurysm.

Subdural hematoma (SDH) was observed in 15 of 484 cases of aneurysmal subarachnoid hemorrhage (SAH). There were four males and 11 females, with ages ranging from 39 to 75 years. The clinical grades (Hunt and Hess) on admission were 11 in three cases, III in two, IV in four, and V in six. The ruptured aneurysms were located in the middle cerebral artery (MCA) in six cases, anterior communicating artery in three, internal carotid artery in two, and distal anterior cerebral artery (ACA) in two, with two cases unconfirmed. A high proportion of aneurysms occurred in the MCA and distal ACA. Aneurysmal neck clipping and removal of SDH were performed in the acute stage of seven cases, without intraoperative rerupture. The outcomes 1 year after SAH of the seven patients undergoing surgery were good recovery in five, but in two, vegetative state due to preoperative rerupture or medical complications. All eight patients without surgical intervention died. A good prognosis for patients with ruptured intracranial aneurysms accompanied by SDH can be expected with direct surgical intervention in the acute stage, even if the clinical grade on admission is poor.     

STA-ACA bypass using the contralateral STA as an interposition graft for the treatment of complex ACA aneurysms: report of two cases and a review of the literature

Bypass surgery has been used as a remedy for the complex cerebral aneurysm, which was unsolved with the clipping method. However, little has been reported about bypass options for anterior cerebral artery (ACA) aneurysms. The authors experienced two patients with complex ACA aneurysms, large fusiform and large thrombosed aneurysms involving the distal A1 and proximal A2 segments, respectively. To achieve complete obliteration of the aneurysm, we performed a superficial temporal artery (STA)-ACA bypass using contralateral STA as interposition grafts with endovascular trapping without any ischemic events. These cases show that STA-ACA bypass using contralateral STA interposition graft is a feasible option to maintain blood supply to the ACA territory if a proximal ACA lesion requires trapping.     

Delayed ischemic deterioration in patients with early aneurysm operation and intravenous nimodipine

A consecutive series of 100 individuals with aneurysmal subarachnoid hemorrhage were subjected to early aneurysm operation followed by subsequent intravenous administration of the calcium antagonist nimodipine during the critical period for symptomatic vasospasm. A total of 85 patients were in Hunt and Hess neurological Grades I through III, and 15 were in Grade IV or V before operation. In 39 individuals the aneurysm was located in the anterior cerebral artery complex (ACA), in 29 it originated from the internal carotid artery complex (ICA), and in 32 individuals the ruptured aneurysm arose from the middle cerebral artery (MCA). Of the patients, 71% made a good neurological recovery; the morbidity was 22%, and the mortality was 7%. Of the Grade I-III patients, 79% made a good neurological recovery, and the mortality was 6%. Delayed ischemic cerebral deterioration with permanent dysfunction occurred in five patients, all with ruptured ACA aneurysms. No single patient in the ICA or MCA populations developed delayed ischemic deterioration with fixed neurological deficit despite the presence of several potential risk factors, especially among the MCA aneurysm patients.     

Regional cerebral blood flow (rCBF) in patients with ruptured cerebral aneurysm: site of aneurysm and rCBF

To investigate the relationship between the site of ruptured cerebral aneurysm and rCBF, 92 measurements of rCBF were conducted in 57 patients with ruptured cerebral aneurysm. Excluded from this study were patients with multiple aneurysms, intracerebral hematoma, and/or hydrocephalus. Twenty-four patients had the anterior communicating aneurysm (A-com), 20 patients had the internal carotid aneurysm (ICA), and 13 patients had the middle cerebral aneurysm (MCA). All patients underwent unilateral fronto-temporal craniotomy for clipping of the aneurysm and their rCBF measurements, using the xenon-133 inhalation method, were performed in the first three weeks after surgery. In each rCBF measurement, the hemispheric mean value of initial slope index (meanISI) was calculated in both cerebral hemispheres, that is, in the cerebral hemispheres ipsilateral and contralateral to craniotomy. The authors defined the "symmetry index of the meanISI (%): symmetry index" as the ratio of the meanISI in the cerebral hemisphere ipsilateral to craniotomy compared to the meanISI in the cerebral hemisphere contralateral to craniotomy. There was no significant relationship between the site of aneurysm and the meanISI in both hemispheres, and this result suggests that the site of aneurysm makes no difference in the incidence of vasospasm. In the postoperative first week, the "symmetry index" was 91.2 +/- 7.4% in MCA, 95.3 +/- 4.1% in ICA, and 97.9 +/- 8.2% in A-com; that is, MCA had significant asymmetry of meanCBF compared with A-com (p less than 0.05). In the second and third postoperative weeks, there was no significant relationship between the site of aneurysm and the asymmetry of meanCBF.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Ruptured dissecting aneurysms of the A1 segment of the anterior cerebral artery: three case reports and a review of the literature

Dissecting aneurysms in the anterior cerebral artery (ACA), although rare, can cause ischemic and/or hemorrhagic stroke. Hemorrhagic dissecting aneurysms in the A1 portion of the ACA are often associated with a poor prognosis. We retrospectively investigated three rare cases of hemorrhagic dissecting aneurysms in the A1 portion. Dissecting aneurysms were diagnosed by carotid angiography or computed tomography angiography to visualize morphological changes in the vessel. All patients presented with diffuse subarachnoid hemorrhage. In one case, computed tomography angiography performed at the onset of the subarachnoid hemorrhage revealed fusiform dilatation at the right ACA (A1), which did not appear on a magnetic resonance angiogram obtained 1 year prior to the onset of the subarachnoid hemorrhage. In the other two cases, A1 dissecting aneurysms were diagnosed from a growing aneurysmal bulge revealed at a non-bifurcated site via repeated carotid angiography. Two patients underwent surgical intervention (trapping or clipping), and their outcome was favorable, whereas the third patient died of delayed rebleeding before receiving surgical treatment. Hemorrhagic dissecting aneurysms in the A1 portion cause severe subarachnoid hemorrhage. Surgical treatments that include revascularization are necessary to prevent rebleeding, and direct surgery is recommended, particularly at the A1 portion.     

Aneurysm of peripheral cerebral arteries with developmental anomaly of the anterior cerebral artery

We report a 71-year-old woman who was initially admitted because of a ruptured internal carotid aneurysm, and found to have an aneurysm of the terminal portion (A5 portion) of pericallosal artery. Both of the aneurysms were surgically treated at one stage operation. A saccular aneurysm of the pericallosal artery was verified at operation. Right internal carotid angiography disclosed that medial part of the right anterior cerebral hemisphere was supplied by the right callosomarginal artery, and that unpaired pericallosal artery made a trifurcation at A5 portion, where the saccular aneurysm arose. According to Baptista's classification, anomaly of the anterior cerebral artery (ACA) in this patient was bihemispheric ACA type. Distal ACA aneurysms almost always locate at or near the genu of corpus callosum, either in pericallosal-callosomarginal or in pericallosal-frontopolar junction. In reviewing the literature, we were able to find 14 cases, including ours, of aneurysms located beyond either pericallosal-callosomarginal junction or the genu of corpus callosum. Also the possible role of hemodynamic stress caused by vascular anomaly for aneurysm formation are discussed.     

Surgery for giant intracranial aneurysms using advanced technology

PURPOSE: Outcome of surgery for giant intracranial aneurysms is still unsatisfactory. The reason for complications is occlusion of perforators or parent arteries by the aneurysmal clipping itself or temporary occlusion of the main arteries. We report the surgical outcome of treatment of giant aneurysms using several advanced techniques which we devised to prevent these complications. MATERIALS AND METHODS: The subjects were eight patients with giant intracranial aneurysms who underwent surgery during the recent five years. Six patients had ruptured and two had unruptured aneurysms. Aneurysms were located at the ICA in five and the MCA in three patients. Aneurysmal sizes ranged from 25 to 50 mm. Preoperative 3DCTA was performed to investigate the aneurysm and the surrounding vessels in all cases. Patients with unruptured aneurysms at the ICA underwent balloon occlusion tests to check the potential for safe temporary occlusion of the parent artery, with SEP monitoring and Xe-SPECT. Intraoperative angiography and neuroendoscopes were used to prevent problems and complications which might be caused by aneurysmal clipping. RESULTS: In seven of eight cases, the aneurysmal neck was completely obliterated with clips and in one case the aneurysm was trapped with STA-MCA anastomosis. Glasgow Outcome Scale of the patients showed good recovery in six, moderately disabled (MD) in one and dead in one. The patient demonstrating MD developed hemiparesis due to vasospasm. One patient died from rebleeding of the aneurysm caused by slippage of the aneurysmal clip despite the confirmation of complete obliteration by intraoperative angiography. CONCLUSIONS: A better surgical outcome of treatment for giant aneurysms was obtained by temporary clips whose placement was based on the results of balloon occlusion test, as well as the use of intraoperative angiography and neuroendoscopes.     

Dissecting aneurysms of the anterior cerebral artery and accessory middle cerebral artery. Case report

A 66-year-old woman presented with dissecting aneurysms of the anterior cerebral artery (ACA) and accessory middle cerebral artery (MCA) manifesting as subarachnoid hemorrhage but without radiological evidence of the dissecting aneurysms. Intraoperative observation revealed that the vessel walls were dark purple in color, a typical finding of dissecting aneurysm. The abnormal A1 segment was trapped and the dissecting aneurysm of the accessory MCA was wrapped. In the case of SAH of unknown origin, dissecting aneurysm should always be kept in mind even if the angiogram does not show any abnormal finding. This is the first reported case of dissecting aneurysm of the accessory MCA.     

Different modalities of treatment of intracranial mycotic aneurysms: Report of 4 cases

BACKGROUND: Intracranial mycotic aneurysms, although rare neurovascular pathology, represented a neurosurgical challenge that required careful stepwise decision making. Different approaches for their management were used. We present our experience with 4 patients treated in terms of indications and efficacy of different treatment modalities. METHODS: Four patients with infective endocarditis and 5 intracranial mycotic aneurysms were treated during the last 5 years. All of the patients were men; their ages ranged between 29 and 62 years (mean, 47.3 years). Distal MCA was the commonest site (3 patients) of aneurysm, 1 was located at the distal PCA, whereas the remaining aneurysm was at the distal ACA. Angiographic studies were done in 2 patients because of neurologic signs and for screening in 2 patients with documented endocarditis. RESULTS: One patient was treated conservatively because of his moribund general condition; 1 patient was treated with direct surgical clipping; 1 patient was treated with surgical trapping and resection of the aneurysm without revascularization; and the remaining patient, harboring 2 distal mycotic aneurysms, was treated with selective embolization for his PCA aneurysm and endovascular trapping for the distal ACA aneurysm. Follow-up angiographic results showed stable occlusion of the aneurysms. No periprocedural technical complications were reported, and none of the patients, including the patient with medical treatment only, has ever experienced new neurologic events after definitive treatment. CONCLUSIONS: Prolonged courses of antibiotics are recommended for all patients with mycotic aneurysms. Selective endovascular embolization or trapping with soft and ultrasoft electrolytically detachable coils seems to be an effective technique that should be considered for treatment of dynamic unruptured mycotic aneurysms, with conventional surgical repair restricted for ruptured aneurysms with associated hematoma and high intracranial pressure.     

Unruptured cerebral aneurysms; the features of cases undetected with MR angiography

With the development of MRI and MRA, many unruptured aneurysms have been detected and treated. Nevertheless, not a few false-positive and false-negative cases are found. We investigate aneurysms that were suspected after screening MRA at the neurosurgical outpatient clinic and the features of aneurysms detected not with MRA but with DSA were studied. Seventy-six patients (85 aneurysms) were suspected due to screening MRA and DSA was performed in 64 (71 aneurysms) of them. Correct diagnosis of cerebral aneurysms with MRA was obtained in 44 patients (45 aneurysms, 63.4%), while false-negative cases were found in 17 patients (plus 20 aneurysms) and false-positive cases in 7 patients (10 aneurysms). The accuracy was 97.2% in ACA, 93% in MCA, 94.4% in VA-BA, and 78.9% in IC, while the sensitivity 100%, 88.2%, 81.8%, 64.7% and the specificity 96.5%, 94.4%, 96.7%, 91.9%, respectively. The features of aneurysms correctly diagnosed with MRA were relatively large ACA, including AcoA, MCA and VA-BA aneurysms, whereas the features of aneurysms undetected with MRA were small IC aneurysms (1-3mm in diameter), especially at the C2-3 portion. These aneurysms at the C2-3 portion or at unusual portions tended to be difficult to detect even with 3D-CTA. Though most of the aneurysms detected with DSA but not with MRA tended to be small and not interventionally treated in the present study, we should pay attention to the fact that these aneurysms are overlooked despite the possibility that they may become enlarged or rupture. Though ruptured aneurysms were surgically treated with only MRA or 3D-CTA without conventional angiography in these days, we recommend the examination of the unruptured cases, which are usually asymptomatic and not hasty, with precise inspection by target MIP, high-performance 3D-CTA or DSA.     

Giant fusiform aneurysms in the middle cerebral artery presenting with hemorrhages of different origins. Report of three cases and review of the literature

Three cases of giant fusiform aneurysms in the middle cerebral artery (MCA) presenting with hemorrhages of different origins are reported, and appropriate literature is reviewed to investigate the characteristics of these lesions. Two patients had suffered a subarachnoid hemorrhage and the other had an intramural hemorrhage (dissection). Pathologically, these aneurysms presented with hemorrhages of different origins; classic rupture type (Case 1), dissection type (Case 2), and atherosclerosis-related thrombosis type (Case 3). Based on surgical and pathological investigations in these three cases and a review of the reported literature, the authors propose that giant fusiform aneurysms in the MCA are characterized by weaknesses in the internal elastic lamina with intimal thickening. Therefore, these lesions have the potential to present with hemorrhage in each of the three types. This finding indicates that there is a strong relationship between the pathological features of giant fusiform aneurysms and their clinical course, and that it is necessary to determine appropriate therapy for giant fusiform aneurysms in the MCA by evaluating cerebral blood flow, even if the lesions are found incidentally.