Supplementary Material for: Intracranial Cerebral Artery Dissection of Anterior Circulation as a Cause of Convexity Subarachnoid Hemorrhage

<b><i>Background:</i></b> Convexity subarachnoid hemorrhage (cSAH), defined as intrasulcal bleeding restricted to hemispheric convexities, has several etiologies: reversible cerebral vasoconstriction syndrome, cerebral amyloid angiopathy, and internal carotid artery (ICA) stenosis or occlusion. However, it remains unknown whether cerebral artery dissection causes cSAH. <b><i>Methods:</i></b> We retrospectively investigated patients admitted to our hospital between 2005 and 2013 with ischemic stroke or transient ischemic attack caused by cerebral artery dissection. Cerebral artery dissection was diagnosed by cervical or cerebral magnetic resonance imaging (MRI) or computed tomography (CT) showing a wall hematoma. CT angiography, ultrasonography, or intra-arterial digital-subtraction angiography detected cerebral artery dissection if a double lumen, string sign, intimal flap, or dissecting aneurysm was observed at a nonbifurcation site. We used CT or MRI to detect cSAH, which was defined as blood collection restricted to one or few cerebral sulci without extending to the basal cisterns, ventricles, or Sylvian and interhemispheric fissures. Demographic, neuroimaging, treatment, and prognostic data were collected. <b><i>Results:</i></b> In total, 82 patients were diagnosed with ischemic stroke caused by cerebral artery dissection. The following arteries were affected: the ICA (9 patients), anterior cerebral artery (ACA; 12 patients), middle cerebral artery (MCA; 12 patients), vertebral artery (37 patients), basilar artery (5 patients), posterior cerebral artery (2 patients), and posterior inferior cerebellar artery (4 patients). In addition, 1 patient presented with simultaneous dissection in both the vertebral and internal carotid arteries, and 6 patients (7%) presented with cSAH (3 men and 3 women, age 39-67 years). The MCA was dissected in four cases and the ACA in two cases, with cSAH frequencies of 33 (4 of 12) and 17% (2 of 12), respectively, in those vessels. Artery dissection in the vertebrobasilar artery system was not responsible for cSAH (0 of 48). In all the MCA dissection cases, cSAH occurred in the arterial border zone between the ACA and MCA territories. Although 2 patients showed early reperfusion with temporary cSAH enlargement, cSAH was self-limiting. Antithrombotic treatment did not complicate the clinical course when used in 4 patients during acute or subacute phases. All patients achieved a 3-month poststroke modified Rankin Scale of 0-2. <b><i>Conclusion:</i></b> Our data suggest that cSAH caused by intracranial cerebral artery dissection is not rare. Further investigations are needed to elucidate the precise mechanism underlying cSAH in cerebral artery dissection.

<b><i>背景：</i></b> 凸面蛛网膜下腔出血（convexity subarachnoid hemorrhage, cSAH）指局限于大脑半球凸面脑沟内的出血，其病因包括可逆性脑血管收缩综合征、脑淀粉样血管病，以及颈内动脉（internal carotid artery, ICA）狭窄或闭塞。但目前尚不清楚脑动脉夹层是否会引发cSAH。<b><i>方法：</i></b> 本研究回顾性分析了2005年至2013年间在本院就诊的、由脑动脉夹层导致的缺血性脑卒中或短暂性脑缺血发作（transient ischemic attack, TIA）患者。脑动脉夹层的诊断依据为：颈部或颅脑磁共振成像（magnetic resonance imaging, MRI）或计算机断层扫描（computed tomography, CT）显示存在壁血肿；若在非分叉部位观察到双腔征、线样征、内膜瓣或夹层动脉瘤，则可通过CT血管造影、超声检查或动脉内数字减影血管造影确诊脑动脉夹层。本研究采用CT或MRI检测cSAH，cSAH的定义为：血液积聚局限于一处或少数几处脑沟内，未延伸至基底池、脑室、外侧裂及大脑半球间裂。研究收集了患者的人口统计学资料、神经影像学资料、治疗情况及预后数据。<b><i>结果：</i></b> 共计82例患者被确诊为脑动脉夹层所致缺血性脑卒中。受累动脉包括：颈内动脉（9例）、大脑前动脉（anterior cerebral artery, ACA；12例）、大脑中动脉（middle cerebral artery, MCA；12例）、椎动脉（37例）、基底动脉（5例）、大脑后动脉（2例）及小脑后下动脉（4例）。此外，1例患者同时存在椎动脉与颈内动脉夹层，6例（7%）患者合并cSAH（其中男性3例、女性3例，年龄39~67岁）。4例患者的夹层累及大脑中动脉，2例累及大脑前动脉，对应的cSAH发生率分别为33%（4/12）与17%（2/12）。椎-基底动脉系统的动脉夹层未引发cSAH（0/48）。在所有大脑中动脉夹层病例中，cSAH均发生于大脑前动脉与大脑中动脉供血区之间的动脉交界区。尽管有2例患者出现早期再灌注，伴cSAH暂时性扩大，但cSAH呈自限性。4例患者在急性期或亚急性期接受了抗血栓治疗，未导致临床病程复杂化。所有患者在卒中后3个月的改良Rankin量表（modified Rankin Scale, mRS）评分均为0~2分。<b><i>结论：</i></b> 本研究数据表明，颅内脑动脉夹层所致的cSAH并非罕见。未来需开展进一步研究以阐明脑动脉夹层引发cSAH的确切机制。