KOR J CEREBROVASCULAR SURGERY June 2OO9 Vol. 11 No 2, page 75-80 전남대학교병원신경외과허혁 주성필 서보라 김태선 김재휴 김수한 Surgical Experience of Distal Middle Cerebral Artery Aneurysm Rupture Hyuk -Hur, MD, Sung-Pil Joo, MD, Bo-Ra Seo, MD, Tae - Sun Kim, MD, Jae -Hyoo Kim, MD, Soo-Han Kim, MD Department of Neurosurgery, Chonnam National University Hospital ABSTRACT Objective : Distal middle cerebral artery (MCA) aneurysms are the least frequent aneurysms of the MCA, and they represent about 1.1 to 5% of all MCA aneurysms. Patients with ruptured distal MCA aneurysms generally have a poor clinical outcome. The purpose of this article is to review the characteristics of distal MCA aneurysms to avoid the complications of microsurgical dissection and clipping of distal MCA aneurysms. Methods : A total of 1187 patients with ruptured aneurysms were treated at our hospital between January 1997 and May 2008. All patients underwent surgical procedures. Computed tomography (CT) revealed rupture of distal MCA aneurysms in 15 (1.26%) patients. The location of the aneurysm were the M2 (insular) segment in seven patients, the M2-3 junction in three and the M3 (opercular) segment in five. Brain CT images revealed the presence of both subarachnoid hemorrhage (SAH) and intracranial hemorrhage (ICH) in 11 of 15 (77.3%) patients, with a mean ICH volume of 14.5 cc (range : 5 to 32 cc). Rebleeding occurred in 7 out of the 15 (46.7%) patients. Results : All the patients underwent early surgical procedures, including clipping in seven, trapping in two, bypass surgery in four, Guglielmi detachable coil embolization in one and exploratory craniotomy in one patient. The aneurysm had a fusiform appearance in 9 out of 15 cases (60%), and the mean size of the aneurysm was 10.4 mm (range : 2 to 35 mm). Three patients died due to severe brain swelling (20%). Conclusion : In this study, distal MCA aneurysms had a relatively fusiform shape as well as high rates of rebleeding and ICH. A good clinical outcome was associated with early surgery for adequately controlling brain swelling and preventing rebleeding. (Kor J Cerebrovascular Surgery 11(2):75-80, 2009) KEY WORDS : Subarachnoid hrmorrhage Intracerebral hemorrhage Distal middle cerebral artery Fusiform aneurysm Rebleeding Early surgery. 서 론 논문접수일 : 2009 년 05 월 25 일심사완료일 : 2009 년 06 월 20 일교신저자 : Sung-Pil Joo, MD, Department of Neurosurgery, Chonnam National University Hospital, 8 Hak-Dong, Dong-Ku, Gwangju, 501-757, South Korea. 전화 : (062) 220-6608 전송 : (062) 224-9865 E-mail : nsjsp@hanmail.net 원위부중대뇌동맥류는모든중대뇌동맥류의 1.1~5% 를차지하는적은빈도를갖는다. 6)10)18)19)20)24)26) 가장흔한원인은진균성색전에의한감염으로발생하는이차적동맥류형성이며, 동맥박리에의해발생하기도한다. 파열된동맥류에대한미세현미경적수술이발달하였음에도, 원위부중대뇌동맥류파열환자들은동반된뇌내출혈등의원인으로좋지않은예후를갖는다. 2)3)19)24)25) 동맥류결찰이성공적이었다하더라도뇌내출혈은뇌부종이나종괴효과를발 75
생시켜치명적일수있다. 원위부중대뇌동맥류는또한진균에의한염증성이거나박리형일수있다. 22)24) 이논문의목적은원위부중대뇌동맥류의특성과수술합병증을막는방법에대해고찰해보는것이다. 방법 1997년 1월부터 2008년 5월까지 1187명의지주막하출혈환자들이본병원에서치료를받았다. 모든환자들은수술적치료를시행받았다 ( 결찰술 990명, 코일색전술 174명, 랩핑, 트랩핑, 우회술등 23명 ). 이중 15명 (1.26%) 의환자에서원위부중대뇌동맥류를보이고있었다 : M2(insular구간 ), M2-3 분기부, M3(opercular구간 ), M4(cortical 구간 ). 5)6) 이중 10명은남자, 5명은여자였으며, 평균나이는 48.5세였다 (21~73세). 15명환자모두진단받은지3일이내에조기수술을시행하였고, 7명은결찰술, 2명은포착술, 4명은우회술, 1명은코일색전술, 1명은시험적개두술 ( 심한뇌부종으로열었다가닫음 ) 을시행하였다 (Table 1). 수술전검사상뇌내출혈이없었던 4명의환자중 3명은실비안이랑을통한접근법을, 1명은 Guglielmi Detachable Coil(GDC) 색전술을시행하였다. 수술전검사상뇌내출혈을보였던 11명의환자중 6명은실비안이랑을통한접근법, 3명은경피질접근법, 1명은시험적개두술을시행하였다. 수술후환자들은중환자실에서치료하였고. 수술후 1일째, 3일째, 14일째뇌 CT를시행하였으며, 7일째에뇌 CT angiography(cta) 시행하였다. 만약혈관연축이발생하면적극적인수액치료및혈압조절을시행하였다. 우리는 15명의환자들의의무기록과영상의학적소견들을검토하였다. 뇌전산화단층혈관촬영은초기진단도구로삼았다. 글라스고우혼수등급 (GCS), 훈트-헤스등급 (H-H grade) 및피셔등급 (Fischer grade) 으로환자의입원및퇴원당시의신경학적상태를판단하였다. 치료결과는퇴원시와외래추적관찰당시의글라스고우회복등급 (GOS) 을사용하여분류하였다. 좋은예후 (good recovery) 와중등도의장애 (moderate disability) 에포함되는환자를임상적으로좋은치료결과를보인것으로, 심각한장애 (severe disability), 식물상태 (vegetative state), 사망 (death) 에포함되는환자를좋지않은치료결과를보인것으로판단하였다. 결과 15명의환자에서수술후훈트-헤스등급, 피셔등급, 수술전글라스고우혼수등급은 Table 1과같다. 수술전검사에서 뇌내출혈이없었던 4명의환자들의훈트-헤스등급최빈값은 2 였으며, 뇌내출혈이있었던 11명의환자들의훈트-헤스등급최빈값은 3 이었다. 뇌전산화단층촬영상뇌내출혈을보였던환자는뇌부종등에의해수술전의식상태가좋지않은경향이있었다. 평균동맥류크기는 10.4 mm(2~35 mm) 이었고 7 mm이하의동맥류는 5명 (33.3%), 7 mm와 14 mm사이의동맥류는 8명 (53.3%), 15 mm이상의동맥류는 2명 (13.4%) 이었다. 동맥류의위치상 M2 구간 (insular) 7명, M2-3 분기부 3명, M3(opercular) 구간인환자가 5명이었다. 원위부중대뇌동맥류환자중다른동맥류가동반된경우는 2명 (13.3%) 이었다. 이연구에서 5명 (33.3%) 에서낭형동맥류였고, 9명 (60%) 에서방추형동맥류였으며 1명 (6.7%) 에서혈전성동맥류를보였다. 그러나동맥류의모양을분석하기위한조직병리학적인검사를시행하지는못했다. 수술전뇌 CT에서지주막하출혈과뇌내출혈이동반된환자는 11명 (77.3%) 이었고, 뇌내출혈의평균용적은 14.5 cc(5~32 cc) 였다. 방추형동맥류 9 명중 8명 (88.9%) 에서지주막하출혈과뇌내출혈이동반되어있었던반면, 낭형동맥류환자 5명중에서는 2명 (40%) 만이뇌내출혈이동반되어있었다. 이연구에서원위부중대뇌동맥류는낭형보다방추형이더많았고 (Table 1, 3) 방추형동맥류를갖은환자에서뇌내출혈이더많이동반되었다. 재출혈은 15명중 7명 (46.7%) 에서발생하였다 (Table 1, 3). 재출혈한 7명중 4명 (57.1%) 은방추형, 2명 (40%) 은낭형이었다. 이연구에서 10명 (66.7%) 에서좋은치료결과 ( 글라스고우회복등급 4,5) 를보였고 5명 (33.3%) 에서좋지않은치료결과 ( 글라스고우회복등급 1, 2, 3) 를보였다. 수술전검사상뇌내출혈이없었던 4명의환자는모두좋은치료결과 ( 글라스고우회복등급 5 : 3명, 글라스고우회복등급 4 : 1명 ) 를보였다. 그러나수술전검사에서뇌내출혈이있었던 11명의환자에서는 6명 (54.5%) 에서좋은치료결과를보였고, 나머지 5명 (45.5%) 은좋지않은치료결과를보였다. 이 5명중 4명은감압적두개골절제술을시행하였고 1명은심각한뇌부종으로개두후더이상의수술적치료를하지못하였다. 수술전검사에서뇌내출혈이있었던 5명의환자들은수술전뇌 CT에서뇌내출혈의용적이 15.2 cc에달했다. 마니톨, 혼수치료등적극적인치료에도불구하고, 3명의환자는사망하였고 2 명의환자는지속적식물상태로퇴원하였다. 15명중 2명은당뇨, 1명은고혈압을가지고있었으며나머지환자는특별한과거력이없었다. 내원당시문진에서 6명의환자가흡연자였다. 좋지않은치료결과를보였던 5명의환자중 4명 (80%) 은흡연자였고이들은당뇨, 고혈압등또다른내과적문제를가지고있었다. 76 Kor J Cerebrovascular Surgery 11(2):75-80, 2009
허혁 주성필 서보라 김태선 김재휴 김수한 Table 1. Summery of nine patients with ruptured distal MCA aneurysm. Case Age/ H-H Fisher Preop. Size Op. Postop. GOS at GOS Shape Location Rebleeding App. No. Sex Gr. Gr. ICH (cc) (mm) name ICH (cc) discharge after 6months 1 72/F 3 4 5 sac. 8 rt. M2 X Craniotomy transsylvian 5< 5 5 2 54/M 2 3 0 sac. 5 rt. M2-3 X Craniotomy transsylvian 0 5 5 junction 3 41/F 4 4 15 fusi. 10 lt. M3 O Craniectomy transcortical 5< 4 4 4 73/M 4 4 10 fusi. 3 rt. M2 O Craniotomy transsylvian 5< 2 4 5 70/M 3 4 25 fusi. 2 lt. M3 O Craniectomy transsylvian 5< 4 4 6 34/M 3 4 15 fusi. 8 lt. M2-3 X Craniectomy transcortical 5< 1 1 junction 7 22/M 5 4 10 fusi. 35 rt. M2 O Craniectomy transcortical 5< 1 1 & bypass 8 45/M 2 3 0 sac. 4 rt. M2-3 X Craniotomy transsylvian 0 5 5 junction 9 49/F 3 4 16 fusi. 9 lt.m3 X Carniotomy transsylvian 5< 4 5 &excision &bypass 10 61/F 2 3 0 sac. 4 rt. M2 O Craniotomy transsylvian 5< 5 5 11 44/M 5 4 30 sac. 11 rt. M2 O Open & (-) (-) 1 1 & closure 12 73/M 3 3 0 fusi. 12 rt. M3 X Coil (-) (-) 4 5 embolization 13 41/F 2 2 5 sac. 9 rt. M2 O Craniotomy transsylvian 5< 5 5 14 21/M 5 4 25 thr. 25 lt. M3 X Craniectomy transsylvian 5< 2 2 15 27/M 2 4 5 fusi. 11 lt. M2 X Cranioctomy transsylvian 5< 5 5 GOS : Glasgow Outcome Scale, OP : operation, App : approach, ICH : intracerebral hematoma, rt : right, lt : left, sac:saccular, fusi : fusiform, thr. : thrombosed Table 2. Characteristics of ruptured distal MCA aneurysm. No. of total patients 15 Aneurysm size Small(<7mm) 5(33.3%) Medium(7-14mm) 8(53.3%) Large(>15mm) 2(13.4%) Aneurysm side Right 9(60%)1. Left 6(40%)1. Aneurysm location M2 7(46.7%) M2-3 junction 3(20%)1. M3 5(33.3%) Associated aneurysms single distal MCA aneurysm only 13(86.7%)1 multiple aneurysms 2(13.3%) Table 3. Shape of aneurysm, ICH and rebleeding. Shape of aneurysm, ICH and rebleeding Total patients 15 Fusiform 9 Saccular 5 Others 1 Patients with ICH 11 Fusiform 8 Saccular 2 Others 1 Patients with Re-bleeding 7 Fusiform 4 Saccular 3 Others 0 Kor J Cerebrovascular Surgery 11(2):75-80, 2009 77
증례 1 49세여자환자로두통과반신마비를동반한기면상태를주소로내원하였다. 특별한과거력은없었다. 뇌 CT에서기저조의지주막하출혈, 대뇌섬과좌측측두엽의뇌내출혈소견을보이고있었다 (Fig. 1A, 1B). 수술전응급뇌혈관조형술을시행하였고, 좌측 M3 부위에 9 mm 크기의방추형의동맥류가발견되었다 (Fig. 1C). 응급수술을시행하였다. M3 부위의동맥류가노출되자동맥류원위부에서두개의동맥이기시하고있었다. 우리는동맥류를최대한절제하고 M3와 M4의분지에대해우회술을시행하였으며다른 M4 분지와측두동맥의분지를문합해주었다 (Fig. 1D, E). 수술후뇌 CTA에서동맥류가전절제되었으며, 중대뇌동맥원위부의혈류는잘유지되고있었다 (Fig. 1F, G). 환자는특별한편마비없이회복되었다. 증례 2 21세남자환자로갑작스런두통과실신을주소로내원하였다. 환자는내원당시혼수상태였으며우측으로등급 1의편마비가있었다. 특별한과거력은없었다. 뇌 CT에서뇌실내출혈을동반한좌측기저핵부위와전측두엽에급성혈종및지주막하출혈양상을보이고있었고 (Fig. 2A), 뇌 CTA에서 뇌동맥류는발견되지않았다 (Fig. 2B). 뇌혈관조형술은시행하지않고응급수술을시행하였다. 수술당시좌측중대뇌동맥의 M3 부위에서혈전성동맥류를찾았다. 조심스럽게동맥류의근위부를절제하고측두동맥의분지와절제된좌측중대뇌동맥의 M3 근위부를직접문합해주었다 (Fig. 2C, D). 술후뇌 CTA에서중대뇌동맥원위부까지혈류가잘유지되고있었으나, 심한뇌부종및좌측전측두엽의경색소견을보이고있었다 (Fig. 2E, F). 비록뇌압조절을위해적극적인치료를하였으나환자는지속적식물상태가되었다. 고찰 Poppen 17) 이 1951년처음으로원위부중대뇌동맥류에대해보고한이후로이병변에대한증례발표가이어졌다. 파열성원위부중대뇌동맥류는모든뇌동맥류의 0.47%, 중대뇌동맥류의 2% 를차지할정도로드물다. 가장흔한원인은진균성혈전에의한감염성심내막염처럼감염에의한이차적동맥류형성이다. 16) 대부분세균성심내막염이원인이되는진균성동맥류는다발성인경우가많고현미경하파열성동맥류절제외에도항생제치료가필요한경우가많다. 또다른보고된원인으로는점액종이나융모막암종등에의한종양성혈전 Fig. 1. (A and B) Axial computed tomography demonstrating a dense subarachnoid hemorrhage at basal cistern and ICH at insular portion and left temporal lobe. (C) Preoperative cerebral angiography showing an aneurysm at left M3 portion of MCA and associated small aneurysm at supraclinoid portion of left internal carotid artery. (D) Exposed aneurysm at the M3 portion with two arteries arose from distal end of the aneurysm. (E) Intraoperative finding; in-situ bypass between M3 and one M4 branch and endto-end anastomoses using branch of superficial temporal artery and the other M4 branch (F and G) Postoperative CT angiography; total obliteration of the aneurysm and good patency of the distal MCA. 78 Kor J Cerebrovascular Surgery 11(2):75-80, 2009
허혁 주성필 서보라 김태선 김재휴 김수한 과두부외상, 그리고병리학적인연구에의해증명된혈관박리등이있다. 4)7)16)22)23) Horiuchi 6) 등은파열성원위부중대뇌동맥류 9명의환자중 8명이낭형, 1명이방추형동맥류였다고보고하였다. 뇌내낭형동맥류는선천성중막결손, 또는혈역학적부담이나죽상경화성변성에의해내탄력층의변성에기인한다고생각되어진다. 비죽상경화성동맥류는내탄력층의조직학적양상에의해고전적인박리성동맥류 (classic dissecing aneurysm), 분절확장 (segmental ectasia), dolichodectatic 박리성동맥류 (dissecting aneurysms), 그리고낭형동맥류 (saccular aneurysm) 등네가지종류로분류된다. 반면, 다른연구에서는원위부중대뇌동맥류는넓은동맥류목을가지고있다고보고했다. 3)8)10)13)19) 방추형의원위부중대뇌동맥류의병인에대해서는아직잘알려져있지않다. 우리의연구에서파열성원위부중대뇌동맥류환자 15명중 9명 (60%) 이방추형동맥류였다. 우리의연구에서는그원인은거론되지않았다. 비록낭형또는방추형동맥류를결정하는원인은밝히지못하였으나, 파열되기쉬운원위부중대뇌동맥류의위치는연구가필요한중요한특징이다. 6)11) 원위부중대뇌동맥류는특히또다른동맥류의존재와관련이있다. Reza Dashti 18) 등은 18명의원위부중대뇌동맥류 환자에서 10명 (56%) 에서다른동맥류가동반되었다고보고하였다. 그러나우리의연구에서는 2명 (13.3%) 만이이에해당되었다 (Table 2). 원위분지에위치한동맥류는터지기쉽고, 재출혈도잘한다고알려져있다. 보고된바에의하면동맥류파열시동맥류의크기는모동맥의직경과두께에의해영향을받는다. 12)21) 원위부분지동맥은직경과두께가작기때문에원위부중대뇌동맥류와같은원위분지동맥류는그크기가작더라도쉽게파열되거나재출혈한다. 또한이런현상은작은동맥류일수록더높은동맥압을받는경향이있다는것으로설명할수있다. 만약동맥류의성장속도가혈관벽복원능력을초과한다면혈관벽의취약성이작은동맥류의조기출혈을유발할수있다. 본연구에서재출혈은 15명중 7명 (46.7%) 에서발생하였다 (Table 1, 3). 재출혈한 7명중 4명 (57.1%) 은방추형, 2명 (40%) 은낭형이었다. 이결과는방추형의원위부중대뇌동맥류가낭형동맥류보다재출혈의위험성이더높다는것을시사한다. 지주막하출혈의양에영향을미치는요소에는혈관벽에미치는압력, 혈관벽의강도, 동맥류의목과기저부의비율, 동맥류의모양등이있다. 9) 재출혈은환자에게치명적이므로조기수술이시행되어야한다. 그러나원위부중대뇌동맥류처럼실비안조깊숙히있거나작은동맥류는위치를찾아내기어렵다. Fig. 2. (A) Computed tomography demonstrating a dense hematoma with ventricular hemorrhage with midline shifting to right side. (B) Preoperative Computed tomography angiography showing no aneurysmal sac. (C) Thrombosed aneurysm at M3 portion of left MCA. (D) Intraoperative finding; Direct anastomoses between the branch of superficial temporal artery and proximal end of resected M3 portion of left MCA. (E) Postoperative CT; Brain swelling and cerebral infarction of the left frontal and temporal lobes. (F) Postoperative CT angiography; Good patency of the distal MCA. Kor J Cerebrovascular Surgery 11(2):75-80, 2009 79
중대뇌동맥류파열환자는 44% 에서뇌내출혈을동반한다. 26) Rinne 19) 등은원위부중대뇌동맥류파열시뇌내출혈이쉽게동반된다고보고하였다. 그래서뇌내출혈로인해원위부중대뇌동맥류파열환자는예후가좋지않다. 본연구에서수술전뇌내출혈이있었던 11명의환자중, 5명 (45.5%) 의환자에서좋지않은치료결과를보였는데, 이는수술전뇌내출혈은최초의뇌손상을일으켜치료결과에영향을주는주된요소로생각된다. 1)14)15) 뇌내출혈은치명적인결과를낳을수있으므로조기에동맥류절제및뇌내출혈제거를시행하는것이좋은임상적치료결과를가져올수있는중요한요소다. 뇌혈관외과의는파열성원위부중대뇌동맥류수술을할때근위부에위치할수록측두동맥-중대뇌동맥문합술을준비해야한다. 원위부중대뇌동맥류의원인론이나영상의학적소견, 치료그리고임상적치료결과에대한더많은연구가필요하다. 결 이연구에서원위부중대뇌동맥류는방추형인경우가많았다. 방추형원위부중대뇌동맥류는뇌내출혈동반되는경우가많았고, 재출혈의위험성도높았다. 조기수술을통해뇌내출혈제거및동맥류결찰또는포착을시행하여재출혈을방지하고, 뇌부종을조절하는것이좋은임상적치료결과와관련되어있다. 중심단어 : 뇌지주막하출혈, 뇌실질내출혈, 원위부중내동맥, 방추형동맥류, 재출혈, 조기수술. REFERENCES 11) Başkaya MK, Menendez JA, Yüceer N, Polin RS, Nanda A. Results of surgical treatment of intrasylvian hematomas due to ruptured intracranial aneurysms. Clin Neurol Neurosurg 103:23-8, 2001 12) Brandt L, Sonesson B, Ljunggren B, Saveland H. Ruptured middle cerebral artery aneurysm with intracerebral hemorrhage in younger patients appearing moribund: emergency operation. Neurosurgery 20:925-9, 1987 13) Chyatte D, Porterfield R. Nuances of middle cerebral artery aneurysm microsurgery. Neurosurgery 48:339-46, 2001 14) Damasio H, Seabra-Gomes R, da Silva JP, Damasio AR, Antunes JL. Multiple cerebral aneurysms and cardiac myxoma. Arch Neurol 32:269-70, 1975 15) Gibo H, Carver CC, Rhoton AL Jr. Lenkey C, Mitchell RJ: Microsurgical anatomy of the middle cerebral artery. J Neurosurg 54:151-69, 1981 16) Horiuchi T, Tanaka Y, Takasawa H, Murata T, Yako T, Hongo K. Ruptured distal middle cerebral artery aneurysm. J Neurosurg 100:384-8, 2004 17) Johnson HR, South JR. Traumatic dissecting aneurysm of the middle cerebral artery. Surg Neurol 14:224-6, 1980 18) Kim MS, Hur JW, Lee JW, Lee HK. Middle cerebral artery 론 anomalies detected by conventional angiography and magentic resonance angiography. J Korean Neurosurg Soc 37:263-7, 2005 19) Kyriacou SK, Humphrey JD. Influence of size, shape and properties on the mechanics of axisymmetric saccular aneurysms. J Biomech 29:1015-22, 1996 10) Lee JH, Ko JK, Lee SW, Choi CH. Occlusion of the middle cerebral artery branch mimicking aneurysm. J Korean Neurosurg Soc 42:413-5, 2007 11) Marchel A. Results of the surgical treatment of patients with single aneurysms of the middle cerebral artery. Neurol Neurochir Pol 21:534-40, 1987 12) Ohashi Y, Horikoshi T, Sugita M, Yaqishita T, Nukui H. Size of cerebral aneurysms and related factors in patientswith subarachnoid hemorrhage. Surg Neurol 61:239-45, 2004 13) Osawa M, Hongo K, Tanaka Y, Nakamura Y, Kitazawa K, Kobayashi S. Results of direct surgery for aneurysmal subarachnoid haemorrhage: outcome of 2055 patients who underwent direct aneurysm surgery and profile of ruptured intracranial aneurysms. Acta Neurochir (Wien) 143:655-63, 2001 14) Papo I, Bodoski M, Doczi T. Intracerebral haematomas from aneurysm rupture: their clinical significance. Acta Neurochir (Wien) 89:100-5, 1987 15) Pasqualin E, Bazzan A, Cavazzani P, Scienza R, Licata C, Da pian R. Intracranial hematomas following aneurysmal rupture: experience with 309 cases. Surg Neurol 25:6-17, 1986 16) Piepgras DG, McGrail KM, Tazelaar HD. Intracranial dissection of the distal middle cerebral artery as an uncommon cause of distal cerebral artery aneurysm. Case report. J Neurosurg 80:909-13, 1994 17) Poppen JL. Specific treatment of intracranial aneurysms; experiences with 143 surgically treated patients. J Neurosurg 8:75-102, 1951 18) Reza Dashti, Juha Hernesniemi, Mika Niemela, Jaakko Rinne, Martin Lehecka, Hu Shen, et al. Microsurgical management of distal middle cerebral artery aneurysms. Surg Neurology 67:553-63, 2007 19) Rinne J, Hernesniemi J, Niskanen M, Vapalahti M. Analysis of 561 patients with 690 middle cerebral artery aneurysms: anatomic and clinical features as correlated to management outcome. Neurosurgery 38:2-11, 1996 20) Rosner SS, Rhoton AJ Jr, Ono M, Barry M. Microsurgical anatomy of the anterior perforating arteries. J Neurosurg 61: 468-85, 1984 21) Russell SM, Lin K, Hahn SA, Jafar JJ. Smaller cerebral aneurysms producing more extensive subarachnoid hemorrhage following rupture: a radiological investigation and discussion of theoretical determinants. J Neurosurg 99:248-53, 2003 22) Sakamoto S, Ikawa F, Kawamoto H, Ohabayashi N, Inaqawa T. Acute Surgery for ruptured dissecting aneurysm of the M3 portion of the middle cerebral artery. Neurol Med chir (Tokyo) 43:188-91, 2003 23) Sato O, Bascom JF, Logothetis J. Intracranial dissecting aneurysm. Case report. J Neurosurg 35:483-7, 1971 24) Stoodley MA, Macdonald RL, Weir BK. Surgical treatment of middle cerebral artery aneurysms. Neurosurg Clin N Am 9:823-34, 1998 25) Suzuki J, Yoshimoto T, Kayama T. Surgical treatment of middle cerebral artery aneurysms. No Shinkei Geka 12:289-96, 1984 26) Yasargil MG. Clinical considerations, surgery of the intracranial aneurysms and results. Stuttgart New york, Georg Thieme Verlag, Microneurosurgery II: 1984, pp.124-64 80 Kor J Cerebrovascular Surgery 11(2):75-80, 2009