The authors report here on a rare case of aneurysm involving the distal lenticulostriate artery (LSA) in a 66-year-old man who presented with intracerebral hemorrhage (ICH) in the right basal ganglia and also intraventricular hemorrhage (IVH). Three-dimensional computed tomography angiography (3D-CTA) and conventional cerebral angiography showed a 4 mm, round-shaped aneurysm in the right distal LSA and this was combined with moyamoya-like disease. We performed proximal clipping of the aneurysm using a microsurgical technique and we evacuated the hematoma. After the operation, there was recurrent bleeding around the operation site and hydrocephalus gradually developed, and we implanted a ventriculo-peritoneal (V-P) shunt. The patient did well after the final shunt surgery and rehabilitation. Presently, he has no motor weakness or significant neurologic deficit, but mild cognitive dysfunction remains. When spontaneous ICH occurs in an unusual site, a thorough investigation is important to rule out a structural vascular abnormality.

The incidence of unilateral blindness and ophthalmoplegia after aneurysm surgery is very rare, especially in an anterior communicating artery (ACoA) aneurysm, but if it occurs, it is mainly caused by intra-operative nerve injury or retinal ischemia. We experienced 2 cases of unilateral blindness immediately after surgery. Both patients were classified into Hunt-Hess grade 1 and Fisher grade 3. Angiographic findings of these patients revealed that the aneurysms were located at the left ACoA. The aneurysms were clipped easily with minimal brain retraction via standard pterional craniotomy. In both cases, injury of the optic nerve during surgery was unlikely. Both patients complained of visual loss with ophthalmoplegia ipsilateral to the site of surgery on the 1st postoperative day and showed evidence of retinal ischemia with central retinal artery occlusion on fundoscopic examination. In our patients, we hypothesize that the complications were most likely related to the intra-orbital ischemia initiated by the collapse of the arterial and venous channels in the orbit and/or to the direct or indirect contusion on the intra-orbital structures. These situations could be produced by inadvertent pressure placed on the eyeball with a bulky retracted frontal skin flap. Visual acuity in both patients ranged from no light perception to finger-counting. Their external ophthalmoplegia had completely disappeared 2 weeks after surgery and visual acuity in one patient began to improve. But in the other patient, the condition was irreversible. The degree of visual recovery seems to be dependent on the duration and severity of retinal ischemia by orbital compression. Unfortunately, there is no satisfactory treatment. We recommend careful surgical manipulation, including the use of an eye shield just before aneurysm surgery to protect the ipsilateral eyeball.

A posttraumatic pseudoaneurysm of the internal carotid artery (ICA) is a rare cause of massive epistaxis, and this can be fatal. Treating a ruptured traumatic pseudoaneurysm of the cavernous ICA is challenging as the treated patient has the same risk profile as an untreated patient if the procedure results in only incomplete occlusion. For this reason, additional procedures need to be performed for these cases. The present report describes two cases of a traumatic ICA pseudoaneurysm that was only partially occluded by endovascular balloon placement because an external carotid-ophthalmic artery anastomosis was not detected. The patients were immediately and successfully treated by performing surgical clipping of the ICA.

We describe a true posterior communicating artery (PCoA) aneurysm, which is an uncommon variant of intracranial aneurysm that was treated by endosaccular embolization. A 64-year-old woman was admitted for management of an unruptured left PCoA aneurysm. She had undergone microsurgical clipping of an ipsilateral internal carotid artery (ICA)-PCoA aneurysm 23 years prior to the current presentation. Angiography showed a saccular aneurysm 3 mm distal to the junction of the ICA and the fetal-type PCoA arising on the opposite side of the vessel to that of the previous clipping. Endovascular embolization was performed to occlude the lumen of the aneurysm while preserving the patency of the PCoA. Based on angiograms, hemodynamic stress seems to be the most feasible explanation for the de novo development of an aneurysm at the first acute bend within the PCoA in our patient. For this anatomical reason, endosaccular coil deployment was possible without the use of a balloon or stent.

Objective : Since posterior circulation vascular lesions are adjacent to important structures such as the brain stem and lower cranial nerves, the acquisition of anatomical information and the careful selection of approaches are essential for the surgical treatment of these lesions. We examined the characteristics and the indications of the far lateral suboccipital approach which exposes lesions without retraction of the brain stem for the treatment of either a vertebral artery (VA) or posterior inferior cerebellar artery (PICA) aneurysm. We present the best diagnostic tool to determine the approaches. Methods : We have reviewed 11 patients who received surgical treatments between 2005 and 2011 for VA or PICA aneurysms. All of the patients had 3-dimensional computed tomography (3DCT) angiography performed to investigate the relation of the location between the aneurysm and hypoglossal canal. Results : Eight of the 11 patients were treated with the transcondylar fossa approach (TCFA) as their lesions were located proximal to the hypoglossal canal, while three were treated with the transcondylar approach (TCA) as their lesions were located distal to the hypoglossal canal. Of the three patients treated with the TCA, one had temporary palsy of the $11^{th}$ cranial nerve and the others recovered without any neurological defects. 3DCT angiography showed the relation of the location between the aneurysm and hypoglossal canal. Conclusion : The TCFA and TCA are good approaches to expose lesions without retraction of the brain stem. To determine the approaches for the surgery of VA or PICA aneurysms, using 3DCT before surgery is advantageous in understanding the positional relations between the hypoglossal canal and the lesions. During the actual surgery, the posterior condylar canal through which the posterior condylar emissary vein passes can be used as an anatomical landmark for TCFA. With this approach, craniocervical instability can be avoided.

Objective : To analyze the clinical characteristics and outcomes of ruptured distal anterior cerebral artery (DACA) aneurysms and to discuss optimal treatment strategy. Methods : Out of 488 patients with ruptured intracranial aneurysms, 24 were treated for DACA aneurysms between February 2001 and January 2009. The medical records, radiological data and outpatient clinic charts of these patients were retrospectively reviewed. Results : The 24 patients (6 men, 18 women) had a mean age of 52 years (range, 30-70). Among the 24 patients, 6 underwent coiling and 17 underwent clipping. Fifteen patients had a Hunt-Hess grade of II, 5 with III 3 with IV and 1 had a grade of V. Nine patients had a Fisher grade of II, 1 with III and 14 had a grade of IV. Twenty-one (88%) patients had a good clinical course after treatment with endovascular (5 of 6 patients, 83%) or surgical (16 of 18 patients, 89%) treatments. Nineteen of 20 patients (95%) with good preoperative states (Hunt-Hess grade I-III) and 2 of the 4 patients (50%) with poor preoperative states (Hunt-Hess grade IV and V) demonstrated good clinical outcomes with Glasgow Outcome Scale (GOS) scores of 4-5. Two patients (8%) died due to pneumonia or preoperative severe brain damage. Conclusions : Acceptable and favorable outcomes were achieved in patients with good preoperative states who were treated with either clipping or coiling of ruptured DACA aneurysms. Immediate and active treatment should be mandatory for favorable outcomes.

Objective : The endovascular treatment of wide-necked intracranial aneurysms is challenging. The stent-assisted coil embolization has facilitated treatment of such complex aneurysms. However, the single stent-assisted technique has a limitation for the wide-necked intracranial aneurysm at the arterial bifurcation. The Y-stent-assisted technique could be an alternative solution for these aneurysms. We present a case series where stent-assisted coil embolization where the Y-configuration stent was used. Methods : Between January 2007 to December 2010, 8 wide-necked bifurcation aneurysms in 8 patients were treated with the Y-stent technique. Among the eight patients, there were six unruptured aneurysms and the remaining two patients presented with subarachnoid hemorrhage (SAH). Three out of eight aneurysms were located at the anterior communicating artery (ACOM), three at the top of the basilar artery (BA), one at the middle cerebral artery (MCA) bifurcation and one at the pericallosal artery. The size of aneurysm ranged from 3.6 mm to 28.2 mm (mean 8.7 mm, neck size from 3 to 7 mm). Four patients were female and aged ranged from 52 to 73 years. Results : The Y-stent-assisted coil embolization was successfully performed in all 8 cases. The immediate angiographic results were complete occlusion in 7 cases with a remnant neck the remaining case. Angiographic follow-up was done in six patients and stable occlusion was confirmed in all aneurysms. Acute thromboembolism (TE) during the procedure occurred in 4 patients. There were one acute cerebral infarction due to distal coil migration and one delayed cerebral infarction due to in-stent thrombosis after 2 months. Conclusion : Traditionally microsurgery has been the treatment of choice for wide-necked intracranial aneurysms at the arterial bifurcation. However, with the advancement of new techniques and instruments for endovascular treatment, the Y-stent-assisted coil embolization seems to be a feasible treatment option for reconstruction of these complex aneurysms.

Objective : Extracranial carotid artery aneurysm is a rare vascular disease. In this study, we present our experience with extracranial carotid artery aneurysm and we review the related articles with addressing different treatment options and their results. Methods : Between 2003 and 2011, 11 patients (mean age : 52.7 years) were diagnosed to harbor extracranial carotid artery aneurysms. Five patients underwent various surgeries and 2 patients were treated by endovascular methods. Four patients were managed conservatively. Results : There were no perioperative/periprocedural mortality or morbidity related to the treatment of extracranial carotid artery aneurysms. During follow-up (mean follow-up : 39.3 months), 1 patient died of an unrelated cause and 2 other patients underwent stenting and/or angioplasty due to asymptomatic progressive stenosis of the treated site. Conclusion : Aneurysm can be treated with low periprocedural risk by utilizing various therapeutic modalities. Long-term follow-up is mandatory to check for stenosis around the treatment site.

Objective : Delayed cerebral ischemia due to vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a leading cause of morbidity and mortality. Recent reports have confirmed that intra-arterial infusion of calcium-channel blockers, which are widely used to counteract vasospasm, is effective for treating SAH with a low risk of complications. Here we report on our experience with intra-arterial nicardipine angioplasty in a consecutive series of 32 patients with SAH. Methods : This retrospective review evaluated a series of 32 consecutive patients with symptomatic vasospasm that was treated with intra-arterial nicardipine. The patients included in the study were diagnosed with aneurysmal SAH between January 2007 and February 2011. All the patients underwent microsurgical clipping or endovascular coiling. Angioplasty using intra-arterial nicardipine was performed in those patients who were refractory to medical therapy such as triple H therapy. Results : The 32 patients underwent a total of 55 procedures. The total amount of nicardipine used in each angioplasty procedure did not exceed 12 mg, with a maximum dose of 3 mg for each vessel. The Glasgow Coma Scale (GCS) score improved in all patients with an average improvement of 2.4 (range : 1~5). During angioplasty, there were no complications such as thromboembolic events and/or acute transitory spasm. The clinical results were evaluated using the modified Rankin Scale (mRS). Good outcomes (mRS 0~2) were determined in 19 (63.3%) of the 30 patients. The 11 patients (36.7%) with poor outcomes initially had a high Hunt and Hess grade (III or IV) or they had intra- operative complications (mRS: 3~6). Conclusion : Our study results support the effectiveness and safety of low-dose nicardipine when performing intra-arterial angioplasty for the treatment of vasospasm after aneurysmal SAH.

OBJECTIVE : Fusiform and dissecting aneurysms cannot be treated with conventional clipping or coiling surgery. Various methods are used for treating these aneurysms, including proximal occlusion of the parent artery or trapping the aneurysms with or without cerebral revascularization. We report here on our experience with treating unclippable and uncoilable aneurysms and we present the clinical and angiographic outcomes. METHODS : Nine patients with unclippable and uncoilable aneurysms were managed during a 5 year period at our institution. We retrospectively reviewed all the patients with aneurysms and who underwent multimodal techniques. The mean age of the 9 patients was 56.5 years. The mean clinical follow-up period was 28.1 months. Six patients presented with subarachnoid hemorrhage and 2 had diplopia. Of these patients, 3 had aneurysms arising from the posterior inferior cerebellar artery (PICA), 2 had vertebral artery (VA) aneurysms, 2 had internal carotid artery aneurysms and 2 had middle cerebral artery aneurysms. Eight aneurysms were fusiform and 1 was a giant saccular aneurysm. RESULTS : The treatment included surgical trapping with bypass in 4 patients, endovascular trapping with bypass in 4 patients and vein graft bypass in 1 patient. Among the bypass surgeries, high-flow bypass was performed for a giant internal cerebral artery (ICA) aneurysm. Trapping of the aneurysms with coil and occipital artery (OA)-PICA bypass were performed for 2 VA aneurysms of the PICA origin. There was no recurrent bleeding or ischemic symptoms during the follow-up periods. CONCLUSION : The cerebral bypass technique is a useful, safe for the treatment of dissecting and otherwise unclippable/uncoilable aneurysms.

Objective : The objective of this study was to determine whether postoperative conventional angiography conducted during the early stage after aneurysm clipping is useful in patients with ruptured aneurysm. Methods : Between May 2008 and November 2009, 57 patients who presented with ruptured cerebral aneurysms were treated with surgical clipping. Among them, a consecutive series of 45 patients who underwent postoperative angiography was analyzed retrospectively. Parameters of the postoperative angiography were categorized as incomplete clippings, vasospasms, vascular compromises, or other aneurysms. Results : The average age of the patients was 49.2 years and ranged from 18 to 72 years. The average timing of the postoperative angiography after the onset of hemorrhage was 11.1 (${\pm}5.6$) days. Complete aneurysm closure was achieved in 43 (95%) patients. A neck remnant aneurysm was discovered in two patients and a fundus remnant was revealed in one patient. Twelve (27%) patients showed angiographic vasospasms and seven needed angioplasty. Four cases (9%) revealed either parent artery stenosis or branch occlusions, and two of them (4%) were clinically significant. Two cases showed aneurysms at another location, one of which was a ruptured aneurysm. Overall, 21 (47%) patients exhibited significant findings on the postoperative angiography. Conclusions : Our retrospective analysis revealed that postoperative angiography might be valuable in patients with ruptured aneurysms, especially in the acute stage, in order to determine the presence of vasospasms, incomplete clippings, vascular compromises, or other aneurysms that were missed at the initial cerebral angiography.

Objective : This study is aimed to describe our experience with performing hemicraniectomy for treating patients with malignant cerebral infarction. This study also aimed at describing the difference between our experience and that of the published articles. Methods : Ten patients who had anterior circulation territory cerebral infarction underwent decompressive hemicraniectomy for treating their life threatening brain swelling between August 2004 and October 2007. We retrospectively analyzed the patients' medical records and radiological films and we described the patients' clinical and radiological details. The outcomes were measured according to the case fatality rate at 2 weeks and the modified Rankin scale (mRS) at 9 months. We compared our institution's outcomes with the pooled analysis result of three randomized controlled trials (DESTINY, DECIMAL, HAMLET trial). Results : Nine men and one woman were included in this study. Their mean age was $61.5{\pm}11.9$ years, and the mean National Institute of Health Stroke Scale (NIHSS) score on admission was $17.3{\pm}6.0$. Five patients died within 2 weeks after operation. Four patients had a mRS of 5 and one had a mRS of 4 at 9 months. Our series included elder patients (mean difference : 9.9~18.3 years) who had a low NIHSS score on admission (mean difference : -4.8~-6.8) as compared to that of the pooled analysis group. Our series revealed a higher proportion of an unfavorable outcome (mRS ${\geq}4$) compared to that of the pooled analysis results (p=0.01). No patient in our series would have been eligible, according to the inclusion criteria, for inclusion in the pooled analysis studies. Conclusion : We think that the higher proportion of an unfavorable outcome in our series was a consequence of the elder age of our patients.

Objective : Cranial nerve dysfunction is common after endovascular treatment of a cavernous sinus dural arteriovenous fistula and sometimes this symptom persists. We reviewed the treatment outcomes of the patients with cavernous sinus dural arteriovenous fistula and who were treated with endovascular technique, and we analyzed the characteristics of those patients who had cranial nerve palsy after treatment. Methods : Between May 2003 and July 2010, 25 patients were treated by an endovascular technique at our institution. Their medical records were reviewed and we analyzed their data, including the clinical presentation, the neurological deficits, the radiographic features and the treatment outcomes. Results : In our series, a total of 25 patients (28 cases) received endovascular treatment. There were four male patients and twenty one female patients with an age range of 26-78 years (mean age : 57.4 years). Complete occlusion was observed in nineteen cases (67.9%) and 5 cases (17.9%) showed near complete occlusion. Additional procedures were required for four cases with fistulas that were partially occluded by previous treatment. Twenty four patients (96%) showed improved symptoms during the follow up and only one patient suffered from persistent symptoms. Procedure-related complications were observed in 2 cases. New cranial nerve palsy was observed in four patients (16%) and two patients experienced aggravation of their existing cranial nerve palsy. One of them had persistent deficits at the final follow up. Conclusion : Sufficient occlusion and avoidance of over-compaction of coils are important to prevent cranial nerve palsy when performing endovascular treatment of cavernous sinus dural arteriovenous fistulas.

Objectives : In this study, we evaluated early surgical results including 30 days early stroke and death rate and complications in 168 cases carotid endarterectomy (CEA). Methods : A retrospective review of patients who underwent CEA at our institute between September 1999 and August 2010 was done. Preoperative symptoms were stroke in 72 cases, transient ischemic stroke or reversible ischemic neurologic deficit in 56 cases and asymptomatic in 40 cases. Most of the patients had conventional cerebral angiography or neck computed tomography angiography (CTA) for preoperative evaluation. Immediate radiological follow up was performed by neck CTA 1 week postoperatively. Results : The overall postoperative stroke rate including transient ischemic attack within 30 days of the treatment was 1.7%. Major stroke rate with morbidity and death rate within 30 days was 0.6% (1 : major stroke, 1 : death). The cause of death was airway occlusion due to wound hematoma. Cranial nerve palsy developed in two patients (1.1%) and neck hematoma in six patients (3.5%). Neck CTA revealed total occlusion of internal carotid artery in one patient with acute cerebral infarction and then recovered fully. Intracranial hemorrhage relating to the hyperperfusion syndrome developed in one patient. Radiological patency rate was 98.7%. The comparison of 30 days morbidity and mortality rate between CEA and carotid angioplasty and stenting were each 0.6% and 1.5%, but there was no statistical significance. Conclusions : Carotid endarterectomy provides considerable future risk prevention against stroke in patients with symptomatic and asymptomatic carotid stenosis.

Objective : The purpose of this study was to reveal the incidence of subarachnoid hemorrhage (SAH) of initial negative angiography and to find a useful method of follow up angiography through retrospective review. Additional objective was to determine the relationship between the hidden aneurysm and initial Computed Tomography (CT) pattern (i.e. amount and distribution of SAH). Methods : Among 593 cases of spontaneous SAH performed initial cerebral angiography, 83 (12%) patients did not show any identifiable vascular lesions in initial angiographic studies. Repeated angiographic studies were performed in 67 patients by using transfemoral catheter angiography (TFCA) in 26 patients, CT angiography (CTA) in 39 and Magnetic Resornance (MR) angiography in 2. Results : Ten (15%) out of 67 patients who underwent repeated angiography revealed aneurysms. At the comparison of initial CT scan and repeated angiography, 31 patients had thick layer of blood and 25% of these patients revealed aneurysms on repeated angiography (P=0.05). According to the initial CT pattern, 38 patients had diffuse blood distribution and 23% of these patients revealed aneurysms on repeated angiography (P=0.05). The timing of follow up angiography was $8.5{\pm}6.0$ days (mean ${\pm}$ SD) after ictus and CTA was applied in the earlier period than TFCA. Conclusions : If initial CT scans show thick layer of SAH or diffuse type of blood distribution in patients with initial negative angiography, repeated angiographic study should be performed to find hidden vascular lesions. CT angiography might be useful in the detection of hidden aneurysm early in the course.

Objective : The aim of this study was to compare titanium and cobalt alloy clip induced artifacts in 16- and 64-row multislice computed tomography angiograms. Methods : A total of 40 intracranial aneurysms in 37 patients treated using titanium or cobalt-alloy clips were enrolled in this study. Computed tomography angiography (CTA) was performed using a 16-row (12 aneurysms; cobalt-alloy clips in 8 and titanium clips in 4) or 64-row (28 aneurysms; cobalt-alloy clips in 14 and titanium clips in 14) multislice CT machine after surgical clipping. Clip-induced artifacts were divided into white and black components, and artifact sizes were quantified by measuring the areas of these components. Results : The titanium clips ($634.9{\pm}308.44mm^2$) produced smaller artifacts than cobalt alloy clips ($2,797.4{\pm}3,121.98mm^2$) by CTA (p=0.006), but the mean size of titanium clip induced artifacts was smaller for 64-row ($544.0{\pm}68.77mm^2$) than for 16-row ($953.3{\pm}279.95mm^2$) multislice CTA (p=0.026). On the other hand, cobalt alloy clip related artifacts were similarly sized (64-row, $2,191.5{\pm}2,072.86mm^2$ versus 16-row, $3,857.6{\pm}4,386.56mm^2$, p=0.246). Conclusion : Titanium clips produce smaller artifacts than cobalt-alloy clips and 64-row multislice CTA reduced titanium clip-induced artifacts as compared with 16-row multislice CTA. However, cobalt-alloy clip artifacts were huge and were not reduced by the higher row CTA unit.

Objective : Elevation of serum S100B protein has been reported after cerebral ischemic strokes. Previous studies had revealed the positive correlation between peak concentration of serum S100B protein and extent of ischemic stroke. However its peak level usually reaches at 48~72 hours from stroke onset time. We evaluate the usefulness of serum S100B protein during hyperacute stage in the patients with ischemic stroke as a marker for expecting clinical severity and prognosis. Methods : Total 67 patients who arrived in the Emergency Department within 6 hours from ischemic stroke onset were retrospectively recruited. Subjects were grouped according to the level of serum S100B protein (normal vs elevated group). We analyzed the differences of clinical (National Institute of Health Stroke Scale, NIHSS), laboratory (initial serum glucose, initial systolic blood pressure, lipid profiles, homocysteine) and radiologic (visible lesion in the initial MRI) data between those two groups. Results : Mean serum S100B protein was normal in 27 patients and elevated in 40 patients. Infarction sizes, cortical lesions and level of serum triglyceride (TG) were significantly different between two groups. There were no significant differences in the age, sex, stroke etiology, initial NIHSS, initial serum glucose, blood pressure and other lipid profiles. Conclusion : Elevated serum S100B protein in the hyperacute phase of ischemic stroke was correlated with infarction extent, cortical involvement and lower serum TG level. Serum S100B protein may be used as an easily assessable and inexpensive marker for predicting infarction size and cortical involvement during hyperacute stage in patients with ischemic stroke regardless of other clinical factors.

Objectives : In vascular neurosurgery, the pterional approach has primarily been used in the treatment of a wide variety of diseases. However, there has been an increasing interest in minimally invasive procedures or keyhole approaches for treating cerebral aneurysms. We report our experience with a neuronavigation-guided keyhole approach in the treatments of various intracranial aneurysms. Methods : Between December 2008 and December 2010, 32 patients with unruptured intracranial aneurysms were treated by direct surgical neck clipping through the neuronavigation-guided keyhole approach. A 4 to 5 cm-sized skin incision and a small $2.5{\times}4cm$ craniotomy was performed around the sylvian fissure. The remainder of the aneurysm surgery was performed using conventional microsurgical techniques. Results : The enrolled patients comprised 15 men and 17 women, with a mean age of 63.06 years (range, 47 to 79 years). Of these, 21 aneurysms were in the middle cerebral artery (MCA) bifurcation; 3, in the M1; 5, in the posterior communicating artery segment; 2, in the anterior communicating artery; and 1, in the anterior choroidal artery segment. The size of the aneurysms ranged from 3.5 to 4.8 mm. Mean operation time was 2.19 hours (range, 100 to 150 minutes). All patients were clipped successfully. There were no procedure related complications. Conclusion : We suggest that the navigation-guided keyhole approach is useful for the treatment of anterior circulation aneurysms in selected cases. It has the advantages of less operative time, fewer days of hospitalization, and cosmetic results.

Objective : It has been known that the prognosis of aneurysm rupture is depend on the preoperative clinical state, presence of rebleeding, vasospasm, hydrocephalus, but the direction of aneurysm might be one of the important prognostic factors in the anterior communicating artery (ACOM) aneurysm. Methods : One hundred forty three cases of ACOM aneurysms, operated from 1996 to 2005, were analysed retrospectively according to the surgical outcomes and directions of aneurysms. Result : The results of analysis were summarized as follows 1) The direction of ACOM aneurysms were as follows; anterior-superior direction in 33.6%, anterior-inferior 30.1%, posterior-superior 10.5%, anterior 7.7%, superior 7.0%, inferior 7.0% and posterior-inferior in 4.2%. 2) There was no significant relationship between the direction of aneurysm and the preopertive clinical state, but the incidence of Hunt-Hess grade IV and V was high in the posterior-superior and anterior-superior direction groups. 3) Intraventricular hemorrhage (IVH) or intracerebral hemorrhage (ICH) was accompanied in 28.7%. In posterior-superior and anterior-superior direction group, there is statistically significance between direction and IVH or ICH (p < 0.05). 4) Vasospasm was observed in 23.8% and cerebral infarction in 17.5%. The incidence was increased in the posterior-superior group. 5) Superior and posterior-superior direction group showed high mortality rate (20.0%). Conclusion : Although there was no statistic significance, we found that the direction of aneurysm might affect the clinical characteristics and prognosis in the patients underwent clipping surgery of ACOM aneurysm. Especially, posterior-superior and anterior-superior direction groups revealed the high incidence of ICH, IVH, vasospasm and cerebral infarction. Therefore, we should pay more careful attention to the patients with the superiorly directed ACOM aneurysms.

Background : External ventricular drainage (EVD) is one of the most frequently performed operative procedures in neurosurgery. A retrospective analysis was conducted for patients who underwent EVD to determine the incidence rate of post-procedural intracranial hemorrhage and to identify underlying risk factors. Methods : Patients who underwent EVD between January 2003 and January 2011 were selected. Catheter-induced hemorrhage (CIH) was defined as any evidence of new hemorrhage on the post-procedural computerized tomography (CT) scan obtained within 24 hours of catheter insertion. The rate of hemorrhage was calculated, and the possible risk factors were statistically analyzed. Results : The data of 229 patients were analyzed. Twenty-one patients developed CIH, for an incidence rate of 9.17%. The factors that increased the rate of CIH were age ${\geq}60$ years, bilateral catheter insertion, and pre-existing heart disease. The patients ${\geq}60$ years of age had a 2.8-fold increased risk of CIH. A history of heart disease contributed to a 20-fold increased risk of CIH (p < 0.001). Those three parameters were evaluated by multiple logistic regression analysis and patients who had all three risk factors were 18 times more likely to have CIH than patients with no factors. Conclusion : CIH is a frequent complication that cannot be over looked in patients who undergo EVD insertions. Age ${\geq}60$ years, bilateral catheter insertion, and a history of heart disease are the three most significant risk factors for CIH. Since these risk factors are not modifiable, all possible contributors should be considered to minimize the risk such as skilled maneuvers and techniques or high blood pressure.