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Parent artery occlusion therapy has been used as an alternative for directly untreatable basilar head giant aneurysms. However, some aneurysms still require additional technique to further induce intraaneurysmal stagnation and thrombosis. Using a hydraulic model, half-life of the dye in the model aneurysm was measured as an index of the intraaneurysmal stagnation. The ratio of diameters (D1, D2) of the two posterior communicating arteries (PCom) is defined as diameter ratio (DR) (D1/D2, D1 < D2). Occlusion therapy was simulated in 4 different sites. The most distal site was at the distal BA (Type A) and the most proximal site at the bilateral VA (Type D). The additional technique investigated was bypass placement to the P2 segment of the posterior cerebral artery (PCA) on the smaller PCom side. The half-life was 2.5 +/- 0.2 (mean +/- 2SD) sec before occlusion. Occlusion therapy significantly increased the half-life depending on the occlusion site and DR values with the maximum values of infinite in Type A and 25 sec in Type D. Placement of the bypass decreased the tangential flow volume to the aneurysmal neck, and increased the time markedly in Types A and B, considerably in Type C and slightly in Type D. Parent artery occlusion therapy has been considered less beneficial for patients with a diameter ratio of less than 0.70 since aneurysmal stagnation depends on the diameter ratio. Bypass placement additional to the occlusion therapy is very useful in enhancing the aneurysmal stagnation, which would make those patients indicated for the therapy.

We simulated parent artery occlusion therapy for basilar head aneurysms to elucidate the hemodynamic changes induced by different occlusion sites and diameters of the posterior communicating arteries (PCom) as collateral pathways. A vascular model of the vertebrobasilar system with a basilar head aneurysm was constructed. Four types of occlusion were simulated: Basilar artery occlusion distal to (Type A), between (Type B) and proximal to (Type C) the superior cerebellar arteries, and bilateral vertebral artery occlusion (Type D). Glycerol solution was perfused into the model, and the half-life of the dye injected into the aneurysm was calculated and regarded as an index of stagnant flow in the aneurysm. The half-life was increased significantly and nonlinearly after parent artery occlusion, depending on the occlusion site and the ratio of two PCom diameters (diameter ratio). Intra-aneurysmal stagnation developed markedly in Type A and Type B in the diameter ratio higher than 0.70 and considerably in Type C in the ratio higher than 0.80. Additional P1 occlusion of the posterior cerebral artery enhanced the stagnation in Type A and B. Since the results are consistent with the published clinical data, the simulation study will be useful for speculating the efficacy of the therapeutic occlusion.

Purpose: We evaluated the prevalence and features of cerebral aneurysms in the family members of people with asymptomatic aneurysms among 8680 participants undergoing magnetic resonance angiography., Methods: Of the 8680 participants, 380 had family histories of aneurysms and 8300 did not. The prevalence and features of asymptomatic aneurysms were compared in these two subgroups. In addition, the prevalence in all living first- or second-degree relatives was evaluated in 20 families., Results: The prevalence of asymptomatic aneurysms was 7.0% (606 of 8680 participants) overall and 10.5% (40 of 380 participants) and 6.8% (566 of 8300 participants) in the subgroups with and without family histories of aneurysms, respectively. The prevalence in the female participants with family histories of aneurysms (12.3%, 28 of 228 participants) was higher than that in the male participants with family histories of aneurysms (7.9%, 12 of 152 participants) (P < 0.0001). Compared with the entire group, this subgroup more commonly showed aneurysms situated at the junction of the internal carotid and posterior communicating arteries (P < 0.0005) and at the middle cerebral artery (P < 0.0001). The prevalence of aneurysms in 115 members of the 20 families was 33.9%. Although the members of 14 families with aneurysmal subarachnoid hemorrhage showed higher prevalence of ruptured and asymptomatic aneurysms (42.1%) than did the members of 6 families with only asymptomatic aneurysms (17.9%), the former had very low prevalence of asymptomatic aneurysms., Conclusion: The prevalence of aneurysms is significantly elevated in family members of people with asymptomatic aneurysms. It is suggested that familial asymptomatic aneurysms are more likely to rupture in families having members with aneurysmal subarachnoid hemorrhage than in those without.

Purpose: To evaluate the usefulness of magnetic resonance (MR) angiographic source images for determining the feasibility of M1 segment control via the distal approach in pterional craniotomy for middle cerebral artery (MCA) aneurysms., Methods: MR angiographic source and conventional angiographic source images were obtained in 40 patients with MCA aneurysms. Each aneurysm was treated surgically using a pterional craniotomy. We initially approached the aneurysm distally. When this was judged inappropriate, the approach was altered to proximally. We compared the topography based on these angiograms to that confirmed during surgery., Results: MR angiographic source images visualized the aneurysm, the M1 and M2 segments of the MCA, the insula, and the frontal and temporal opercula in all 40 patients. In 22 (55%) of them, the distal portion of the M1 segment was recognized from the posterolateral perspective between the aneurysmal neck and the insular surface. These aneurysms were successfully clipped via the distal approach after definite proximal control of the MCA was obtained., Conclusions: It was concluded that MR angiographic source images have a distinguishing feature in defining cerebral tissue-vascular relationships and that they are useful in the surgical planning for MCA aneurysms.

Background: This study evaluated the usefulness of magnetic resonance (MR) angiography on preoperative depiction of surgical topography around anterior communicating artery aneurysms., Methods: Twenty cases of anterior communicating artery aneurysms, nine ruptured and 11 unruptured, were included. MR angiographic source images and projection images were obtained by three-dimensional (3D) time-of-flight techniques. Conventional angiography was performed by femoral artery catheterization. By comparing the topography based on these angiograms to that confirmed during surgery, we evaluated the information provided by MR angiography that was beneficial during surgery., Results: MR angiographic source images could visualize cerebral and nerve tissues around the aneurysms in all 20 cases. In five cases, the source images provided additional useful information to that from conventional angiography. It included visualization of aneurysmal domes in the gyrus rectus in two cases and aneurysmal adhesion to the optic nerve or chiasma in three cases. These findings were considered to have contributed to successful aneurysmal surgery. The remaining 15 cases, however, had such typ ical anatomy around the aneurysm that clipping was conventionally performed without additional information from the source images., Conclusions: MR angiographic source images have a distinguishing feature in defining neural tissue-vascular relationships and can significantly improve preoperative depiction of surgical topography. They would be useful only when there are still questions after careful reading of conventional angiography.

This study evaluated the usefulness of axial source images of magnetic resonance angiography (MRA) on preoperative depiction of surgical topography around posterior communicating artery aneurysms. Twenty patients with posterior communicating artery aneurysms, two ruptured and eighteen unruptured, underwent conventional angiography as well as axial source and projection images obtained by three-dimensional time-of-flight MRA techniques. By comparing the topography based on these angiograms to that confirmed during surgery, we evaluated useful information specific to the source images of MRA. Source images of MRA visualized the posterior communicating artery and the anterior choroidal artery in eighteen cases (90%) and five cases (25%), respectively. The posterior communicating artery was recognized at a higher rate by source images of MRA than by conventional angiography (65%), while the anterior choroidal artery was recognized at a lower rate than by combined angiography (75%). We realized some specific information to the source images of MRA including the topographical relations between the aneurysmal neck and the orifice of the posterior communicating artery, the relations between the aneurysmal dome and the oculomotor nerve and the aneurysmal dome buried into the temporal lobe. The information suggested a satisfactory direction of safe aneurysmal clipping so as not to occlude the posterior communicating artery. It was concluded that the source images of MRA provided additional useful information on surgical topography in 60% of the cases involving posterior communicating artery aneurysms. Although not essential in every case, the information would be beneficial in cases with the aneurysmal dome suspected to be in the temporal lobe or when the surrounding topography can not be clearly understood by angiography.

Paraclinoid internal carotid artery aneurysms arising between the roof of the cavernous sinus and the origin of the posterior communicating artery are of considerable interest with regard to their anatomical variations and technical surgical challenges. Twenty-seven patients with 30 paraclinoid aneurysms were treated surgically through pterional intradural approach. Neck clipping was performed in 22 (73%) of the 30 aneurysms, coating in seven, and trapping in one. The surgical outcome was excellent in 24 patients (24/27, 89%), with two patients showing ipsilateral partial visual field defect (2/27, 7%). There was one death (4%) due to infarction after unintended carotid artery trapping. The characteristic topographic anatomical features which we considered to pose technical difficulties and to be responsible for the complications or failure in neck clipping were aneurysmal dome extending into the anterior clinoid process, atheroma at the neck, multiple paraclinoid aneurysms, ophthalmic artery originating at the neck, and marked supero-medial shift of the C2 segment of the carotid artery. pre-operative depiction of the topographical anatomy around the paraclinoid aneurysm is essential but not always possible on the basis of conventional angiography. Magnetic resonance or three-dimensional computerized tomographic angiography, and their axial source imaging, were useful in delineating the topography with unusual aneurysmal growth, overlap of aneurysm with the parent artery, and uncommon variations of the surrounding structures.

Unlabelled: MATERIAL AND RESULT: A large thrombosed aneurysm arising from the distal superior cerebellar artery was successfully resected., Discussion and Conclusion: An aneurysm in this location is very rare. Accumulation of intraoperative hemodynamic data may be useful in evaluating the capacity of collateral circulation.

A number of surgical experiences with paraclinoidal carotid artery aneurysms have been reported recently. However, neuroradiological examinations can not sufficiently visualize the topographic relations around the aneurysms due to variations in the size of the anterior clinoid process (ACP) or course of the carotid artery in individual cases. Although three-dimensional computerized tomography angiography (3-D-CT-A) is known to be useful for the surgical management of cerebral aneurysms in common locations, its usefulness for paraclinoidal carotid artery aneurysms has not been investigated. Ten cases involving a total of 13 aneurysms located in the clinoid portion of the carotid artery were included in this study according to Al-Radham's classification (Table). The CT scan used was an X Force system manufactured by Toshiba Electric Co, Japan. Non-ionic, iodinated contrast solution, a total of 2ml/kg, was intravenously infused at a rate of 2ml/sec. Helical scanning was begun 30 seconds after initiating the infusion, 1mm pitch/1.5 second/rotation. 3-D images and original images of axial slices were compared to conventional angiography, DSA and surgical findings. The 3-D images of 3-D-CT-A was able to demonstrate both aneurysms located in the C2 segment of the carotid artery (groups I and II), and five of nine carotid cave aneurysms (group III). The aneurysms located more proximally (group IV or V) could not be visualized.(ABSTRACT TRUNCATED AT 250 WORDS)

Numerous anatomical observations of the transverse sinus (TS) have been reported and features of this sinus, as assessed by cerebral angiography, are referred to in many monographs. However, there are no studies on the hemodynamics in the TS. We recently investigated the TS, using cerebral angiography with cinematographic films. The subjects were 35 patients who underwent angiography of 3 or 4 vessels at our institute, using Seldinger's method. The contrast material was infused manually. Cinematography permitted observation of the size of the bilateral TS and the direction of blood flow. Depending on the features of the bilateral TS, the patients could be divided into three groups. Type I (cases where the right TS was dominant) accounted for the highest percentage (54.3%, 19/35). In 11 of these 19 cases, the left TS also showed antegrade blood flow. In 6 of the Type I group, the blood flow through the left TS was in two directions (towards the Torcular Herophili and towards the left sigmoid sinus). In the other two cases rated as Type I, the blood flow through the left TS was in the direction from the Torcular Herophili to the right TS. Fourteen cases (40.0%) were rated as Type II (in which both sinuses were similar in size). In 13 of these 14 cases, blood flow through the bilateral TS was almost symmetrical (Type II-A). In one of the 14 cases, the blood flow through the left TS was in two directions (towards the Torcular Herophili and towards the left sigmoid sinus).

A 42-year-old male presented with a giant thrombosed aneurysm of the left vertebral artery. The aneurysm was resected through a combined subtemporal and suboccipital approach after a saphenous vein bypass graft was placed between the right external carotid artery and the posterior cerebral artery. Intraoperative measurements of the blood flow volume and pressure demonstrated good blood flow in the bypass. Postoperatively, uncontrollable hypertension resulted in huge intracerebral hematoma formation and increased intracranial pressure. Control of systemic hypertension is essential in such patients.

We investigated haemodynamic effects of therapeutic vertebral artery (VA) occlusion on giant aneurysms at the bifurcation of the VA-posterior inferior cerebellar artery (PICA). An hydraulic model of the human vertebro-basilar artery was manufactured from glass and silicone tubes. Glass-spheres 2.5 cm in diameter were placed at the bifurcation as model aneurysms with respective distances of 8.5, 7.5, 6.5 and 5.5 mm between the VA union and aneurysmal neck. A 40% glycerol solution was perfused in this system and the half-life of the dye injected into aneurysms was regarded as an index of intra-aneurysmal stagnation. Flow conditions in aneurysms depended on the presence or absence of the effect of contralateral VA flow as well as the PICA flow. The half-life increased significantly after VA occlusion proximal to the PICA when the aneurysmal neck was more than 7.5 mm away from the VA union and PICA flow volume was less than 12 ml min-1. The half-life in aneurysms located within 6.5 mm from the union changed little after VA occlusion regardless of the PICA flow volumes. The haemodynamic simulation study would be helpful in speculating on the efficacy of this treatment.

We report an unusual case of exostosis arising from the lateral aspect of the posterior clinoid process. Its presence should be considered in approaching the parasellar regions.

Although therapeutic occlusion of the vertebral artery has been an accepted treatment for an inaccessible VA giant aneurysm, several problems have been reported such as incomplete thrombosis, growth or rupture of the aneurysms, and cerebral embolism originating from the aneurysmal cavity. Hemodynamic changes after occlusion therapy are suspected to be responsible for these phenomena. It is usually difficult to solve these problems or to predict them before operation because multiple factors are related in a complex fashion in a living body. One of the effective means is to simulate these hemodynamic conditions by a hydraulic vascular model. To evaluate hemodynamics after gradual therapeutic occlusion of the vertebral artery, a glass sphere of 2.5 cm in diameter was placed in a hydraulic model and regarded as a VA-PICA aneurysm. 40% glycerol solution at 25 degrees C, having similar viscosity and specific gravity to human whole blood at 37 degrees C, was used as a perfusate in this study. The dye was injected into the aneurysm and intensity change of the transmitted light was measured. Half-life of the dye was calculated from the thus-obtained clearance curve and was regarded as an index of intra-aneurysm stagnation. The flow volumes of each arterial site have been estimated in our previous study: 60 ml/min to the territory of one posterior cerebral artery, and 80 ml/min to the cerebellum and the brain stem. Clearance curves were recorded in the following various conditions. The flow value of the PICA was set to be 5, 10, 15, 20, 25, and 30 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapeutic occlusion of the basilar artery has been one of the alternative treatments for surgically or intravascularly inaccessible basilar bifurcation giant aneurysms. However, several problems have been reported, such as incomplete thrombosis of the aneurysms, their growth or rupture, and cerebral embolism originating from their cavities. Since hemodynamic changes after occlusion therapy are suspected to be responsible for these phenomena, they were investigated by a hydraulic vascular model. A hydraulic vascular model of the vertebrobasilar artery was constructed with silicone and glass tubes. A glass-made sphere of 2.5 cm in diameter was attached to the model and was regarded as a basilar head aneurysm. A 40% glycerol solution at 25 degrees C was found to be of similar viscosity and specific gravity to those of human whole blood at 37 degrees C and was perfused in the model. A device to measure intra-aneurysmal clearance was made from a stable luminous source and a Cds photocell. Good correlation was found between the output and an intra-aneurysmal dye concentration. The dye was injected into the aneurysm and its half-life was calculated from clearance curves. It was then regarded as an index of stagnation in an aneurysmal cavity. The flow volumes were estimated as: 60ml/min to the territory of one posterior cerebral artery (PCA) and 80ml/min to the cerebellum and the brain stem. Half-life was recorded in the following conditions: 120ml/min of flow in the basilar artery (BA) into bilateral PCAs stimulating the condition before BA occlusion, and various flow values (60ml/min to 10ml/min) of P1 segment simulating the conditions after BA occlusion distal to the superior cerebellar artery.(ABSTRACT TRUNCATED AT 250 WORDS)

A patient who had bilateral distal anterior cerebral artery aneurysms and a right middle cerebral artery aneurysm in association with polycystic kidney and liver disease is reported. A 57-year-old woman was referred to our center with headache and disturbance of consciousness. On admission, her level of consciousness as evaluated by the Japan Coma Scale was 10. CT revealed subarachnoid hemorrhage, especially in the interhemispheric fissures. Right carotid angiography demonstrated bilateral distal anterior cerebral artery aneurysms and a right middle cerebral artery aneurysm. All three aneurysms were clipped in a one-stage procedure. The patient was discharged without any neurological deficits two weeks after the operation. Bilateral distal anterior cerebral artery aneurysms are extremely rare. This is the first report of such aneurysms and a right middle cerebral artery aneurysm in association with polycystic kidney and liver disease. The etiology of these aneurysms is discussed.

Forty three expired cases due to ruptured cerebral aneurysm were studied in electrocardiographic alterations with special reference to other complications of the autonomic nervous system. The cases with past history of ischemic cardiovascular disease had been excluded. The age of the patients ranged between 23 to 79 years old (average 50.1 years old). The clinical condition of the patients according to Hunt & Kosnik classification I in 1 case, II in 11 cases, III in 14 cases, and IV & V in 17 cases. The duration between the aneurysm rupture and admission was within 24 hours in 16 cases, 2 to 3 days in 13 cases, 4 to 7 days in 9 cases, and 2 to 3 weeks in 5 cases. The site of ruptured aneurysms was anterior communicating artery in 12 cases, internal carotid artery in 24 cases, and others in 7 cases. The direct surgeries to the aneurysms were performed in 22 cases, and not done in 21 cases. The electrocardiographic alterations were found as follows: flat or inverted T in 19 cases, prolonged QTc in 33 cases, manifest U in 14 cases, ST elevation or depression in 10 cases, Ta (atrial T) in 10 cases, left ventricular hypertrophy in 8 cases, sinus tachycardia in 7 cases, sinus bradycardia in 12 cases, and arrhythmias with SVPC or VPC (supraventricular or ventricular premature contraction), or sinus arrhythmia in 12 cases. Prolonged QTc, and flat or inverted T were most often found in the cases with ruptured aneurysm of the anterior communicating artery, and next in those with the internal carotid artery, and least often in those with others.(ABSTRACT TRUNCATED AT 250 WORDS)

Although carotid ligation or balloon occlusion has been an accepted method for the inaccessible ICA aneurysm, there have been several reports of growth or rupture of the aneurysm, and cerebral embolism originating from the site of arterial occlusion or from the aneurysm. The hemodynamic changes after operation are suspected to play some role in these events. It is, therefore, very important to predict what will happen after operation in individual patients. However, it is usually difficult because multiple factors are related in a complex fashion in a living body. One of the effective means is to simulate these hemodynamic conditions by a hydraulic vascular model. We have already reported the hemodynamic changes resulting from EC-IC bypass for MCA stenosis. In this research, a glass-model aneurysm of 2.5 cm in diameter is placed at the ICA bifurcation of the model to evaluate hemodynamics after therapeutic carotid occlusion with or without EC-IC bypass. Dye was injected into the aneurysm and intensity change of the light transmitted there was measured by a photocell. Half-life of the dye was calculated from thus obtained clearance curve and was regarded as an index of intraaneurysmal stagnation, while embolus formation in an aneurysm is considered to be due to the stagnation there. The results obtained are: 1. Half-life of the dye increases significantly after carotid ligation even if collateral flow through the anterior communicating artery (A-com) or EC-IC bypass equals the ICA flow before ligation. 2. The higher collateral flow through A-com results in the more normograde flow in M1 portion, which shortens the half-life.(ABSTRACT TRUNCATED AT 250 WORDS)

There have been known two routes in pterional approach to the distal basilar artery aneurysms: one is via the space between the optic nerve and internal carotid artery (optic-carotid triangle: OCT) and the other is lateral to the ICA (retrocarotid approach: RCA). Although the approach via OCT has several advantages of its own, it had been considered to be used in very limited cases. Since we successfully clipped the aneurysms via OCT in 4 cases out of 12 (33%), neuroradiological findings observed in these 4 cases are analyzed and reported. Measurements were made in the following items on the carotid angiogram of the cases operated via OCT (OCT group) and RCA (RCA group): the distance of ICA bifurcation from midline (D), height of ICA bifurcation from the base line between anterior and posterior clinoid processes (H). Although these two values seemed higher in OCT group than those in RCA group, no significant difference was found. The product of D and H (D X H) was observed to be significantly higher in OCT group than in RCA group. The value of D X H is considered one of the indicators of the size of OCT and is proved to be useful to judge whether approach via OCT is applicable or not. Values of D X H obtained from cases with aneurysm increase with age. Regression line calculated between age and D X H value suggests that more than half of the patients over 45 years of age should have space in OCT wide enough to apply clips to the aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-two patients with posterior inferior cerebellar artery (PICA) aneurysms were treated in our department from 1965 to 1982. Except for six cases with peripheral PICA aneurysms, all aneurysm were located on the vertebral artery at the origin of PICA (VA-PICA aneurysm). Direct approach to the aneurysm was carried out in 11 cases out of 16 with VA-PICA aneurysm. We encountered difficulties in access to the aneurysm in 5 cases (case 2,4,6,13,15) and in clipping procedures in 4 cases (cases 6, 7, 10, 15). Surgical procedures through either bilateral (case 2,4) or unilateral suboccipital craniotomy included exploration in 1 case; wrapping in 1, proximal vertebral artery clipping in 3 and neck clipping in 6. These difficulties encountered during operation were evaluated in relation to angiographical findings. The aneurysms located between 0 to 5 mm from the midline or more than 21 mm from the lateral point of the foramen magnum could be reached with difficulty through unilateral suboccipital craniotomy (Figure 3,4). The aneurysms with the dome directed posteriorly had to be treated carefully because of their possible adhesion to or invagination into the medullar oblongata. The aneurysms with the dome directed medially were difficult to be clipped because they existed on the opposite side of the vertebral artery. Although all aneurysms overlying the lower third of the clivus, even on the midline, can be exposed through unilateral suboccipital craniotomy, great care should be taken especially to the aneurysms located in high position, with the dome directed medially or posteriorly, and with the distal vertebral artery running medially.(ABSTRACT TRUNCATED AT 250 WORDS)

Sixty cases with ruptured intracranial aneurysms over 65 years of age were classified as aged group and were compared with 81 cases (control group) between 50 and 59 years of age. The results obtained are as followed: 1. Aneurysms in aged group occur frequently in female (83%) and in internal carotid artery (42%). 2. Cases with "Excellent" operative result in aged group was found significantly lower in ratio (34%) than in control group (59%), which seems attributable to high incidence of their poor results in the cases with serious conditions (Hunt and Kosnik Grade III & VI) and in those operated early after episode of hemorrhage. 3. Symptomatic vasospasm and primary brain damage due to subarachnoid hemorrhage occurred frequently in aged group (22% and 8%, respectively), and are proved to be two major causes of their unfortunate outcome. 4. In aged group difficulty in full enforcement due to cardiovascular complications was considered to make hypervolemia-hypertension therapy less effective to prevent and improve ischemia symptoms due to vasospasm. Accordingly, one has to choose such other means as meticulous and almost complete removal of subarachnoid hematoma in early operation or by some drainage systems. 5. Although the primary brain damage occurred in similar frequency in both aged and control groups, its recovery was significantly lower in aged group than in the control. Under the sustaining conditions of the primary brain damage, one should take care of latently progressing intracranial pathology such as vasospasm.

In spite of a recent remarkable progress in operative results of ruptured middle cerebral artery aneurysms, a mortality rate of 2-8% appears to be unavoidable. In the present study, 53 ruptured MCA aneurysms were retrospectively analyzed to determine causative factors of unfortunate outcome (fair, poor and dead). Surgical results of 53 ruptured MCA aneurysms are shown in Table 1, where the outcome was unfortunate in 7 cases (17%). Intracerebral hematoma was responsible for 4 cases, two of which were fatal and postoperative vasospasm for 3 cases. There were 13 cases with intracerebral hematomas (25%) ranging from 21 mm to 68 mm in diameter. Although hematomas less than 40 mm in diameter localized in temporal or frontal subcortical areas and yielded no neurological deficits, those more than 60mm extended to the caudate nucleus or thalamus through the internal capsule and led to deep coma (Table 2, Fig. 1). Intracerebral hematoma with the diameter between 50 to 60 mm seems to be critical in regard to postoperative outcome. Repeated rupture caused intracerebral hematoma (50%) more frequently than single rupture (21%) and aneurysm with intracerebral hematoma was liable to bleed (27%), resulting in acute deterioration of neurological conditions by marked enlargement of the hematoma (Fig. 2). Accordingly it is essential for the cases with intracerebral hematoma to prevent rerupture. Subarachnoid hemorrhage and symptomatic vasospasm were observed less frequently in hematoma group than in non-hematoma group. However, prophylactic treatment of vasospasm is important even in the cases with intracerebral hematoma since more than half of them suffer from relatively thicker subarachnoid clot.