Recent Advances for Global Perspectives on Etiology, Pathophysiology, Clinical Presentations, and Management of Moyamoya Disease

Moyamoya disease (MMD) is a condition characterized by the gradual narrowing and blockage of blood vessels in the brain, specifically those in the circle of Willis and the arteries that supply it. This results in reduced blood flow and oxygen to the brain, leading to progressive symptoms and potential complications. The underlying pathophysiological mechanism remains elucidated. However, recent studies have highlighted numerous etiologic factors: abnormal immune complex responses, susceptibility genes, branched-chain amino acids, antibodies, heritable diseases, and acquired diseases, which may be the great potential triggers for the development of moyamoya disease. Its clinical presentation has varying degrees from transient asymptomatic events to significant neurological deficits. Moyamoya disease (MMD) shows different patterns in children and adults. Children with MMD are more susceptible to ischemic events due to decreased blood flow to the brain. Conversely, adults with MMD are more prone to hemorrhagic events involving brain bleeding. Children with MMD may experience a range of symptoms including motor impairments, sensory issues, seizures, headaches, dizziness, cognitive delays, or ongoing neurological problems. Although adults may present with similar clinical symptoms as children, they are more prone to experiencing sudden onset intraventricular, subarachnoid, or intracerebral hemorrhages. One of the challenges in moyamoya disease is the potential for misdiagnosis or delayed diagnosis, particularly when physicians fail to consider MMD as a possible cause in stroke patients. This review aims to provide a comprehensive overview of recent global studies on the pathophysiology of MMD, along with advancements in its management. Additionally, the review will delve into various surgical treatment options for MMD, as well as its rare occurrence alongside atrioventricular malformations. Exciting prospects include the use of autologous bone marrow transplant and the potential role of Connexin 43 protein treatment in the development of moyamoya disease.

Is medical management useful in Moyamoya disease?

Moyamoya disease(MMD),characterized by progressive internal carotid artery stenosis and collateral vessel formation,prompts cerebral perfusion complications and is stratified into idiopathic and Moyamoya syndrome subtypes.A multifa-ceted approach toward MMD management addresses cerebral infarctions through revascularization surgery and adjunctive medical therapy,while also navigating risks such as intracranial hemorrhage and cerebral infarction resulting from arte-rial stenosis and fragile collateral vessels.Addressing antithrombotic management reveals a potential role for treatments like antiplatelet agents and anticoagulants,despite the ambiguous contribution of thrombosis to MMD-related infarctions and the critical balance between preventing ischemic events and averting hemo-rrhagic complications.Transcranial doppler has proven useful in thromboembolic detection,despite persisting challenges concerning the efficacy and safety of an-tithrombotic treatments.Furthermore,antihypertensive interventions aim to ma-nage blood pressure meticulously,especially during intracerebral hemorrhage,with recommendations and protocols varying based on the patient’s hypertension status.Additionally,lipid-lowering therapeutic strategies,particularly employing statins,are appraised for their possible beneficial role in MMD management,even as comprehensive data from disease-specific clinical trials remains elusive.Com-prehensive guidelines and protocols to navigate the multifaceted therapeutic ave-nues for MMD,while maintaining a delicate balance between efficacy and safety,warrant further meticulous research and development.This protocol manuscript seeks to elucidate the various aspects and challenges imbued in managing and navigating through the complex landscape of MMD treatment.

Analysis of the Effect of the Comprehensive Nursing Model on Patients with Moyamoya Disease Undergoing Intracranial and Extracranial Revascularization Surgery

Objective:To explore the effect of a comprehensive nursing model on patients with Moyamoya disease who underwent intracranial and extracranial revascularization surgery.Methods:110 cases were divided into control and observation groups with 55 cases each.The control group received routine perioperative care,and the observation group received perioperative care along with comprehensive nursing care.The two groups’disease cognition levels,anxiety,symptoms,daily living ability scores,and postoperative complication rates were compared.Results:The anxiety score and total postoperative complications of the observation group upon discharge were lower than that of the control group,and the disease cognition level and daily living ability upon discharge were higher than that of the control group(P<0.05).Conclusion:Applying the comprehensive nursing model in conjunction with perioperative care for patients undergoing surgery can effectively improve their anxiety,strengthen activities of daily living,and reduce the risk of postoperative complications.

Enhancement Expression of bFGF in Chinese Patients with Moyamoya Disease

Objective To detect the content of the basic fibroblast growth factor in blood samples of patients with Moyamoya disease, and investigate the relationship between Moyamoya disease and the basic fibroblast growth factor. Methods This tissue microarray study included 24 cases of superficial temporal artery samples, 15 cases of Moyamoya disease, and 9 cases of normal arteries as control, and bFGF immunofluorescence assay was applied to test the samples. The number of positive cells and total cells of the muscular layer and the endothelium layer were counted separately in every picture, the positive rates were calculated, and the experimental data were analyzed statistically. Results The bFGF immunofluorescence staining of smooth muscular layer cells, intima cells and endothelial cells from the moyamoya disease group were obviously stronger than that from the control group （P0.01）. Conclusion The enhancement expression of bFGF in the Moyamaya disease group implicates that bFGF plays an important part in the pathogenesis of Moyamoya disease.

Microstructural damage pattern of vascular cognitive impairment: a comparison between moyamoya disease and cerebrovascular atherosclerotic disease

Moyamoya disease and cerebrovascular atherosclerotic disease are both chronic ischemic diseases with similar presentations of vascular cognitive impairment. The aim of the present study was to investigate the patterns of microstructural damage associated with vascular cognitive impairment in the two diseases. The study recruited 34 patients with moyamoya disease(age 43.9 ± 9.2 years; 20 men and 14 women, 27 patients with cerebrovascular atherosclerotic disease(age: 44.6 ± 7.6 years; 17 men and 10 women), and 31 normal controls(age 43.6 ± 7.3 years; 18 men and 13 women) from Huashan Hospital of Fudan University in China. Cognitive function was assessed using the Mini-Mental State Examination, long-term delayed recall of Auditory Verbal Learning Test, Trail Making Test Part B, and the Symbol Digit Modalities Test. Single-photon emission-computed tomography was used to examine cerebral perfusion. Voxel-based morphometry and tract-based spatial statistics were performed to identify regions of gray matter atrophy and white matter deterioration in patients and normal controls. The results demonstrated that the severity of cognitive impairment was similar between the two diseases in all tested domains. Patients with moyamoya disease and those with cerebrovascular atherosclerotic disease suffered from disturbed supratentorial hemodynamics. Gray matter atrophy in bilateral middle cingulate cortex and parts of the frontal gyrus was prominent in both diseases, but in general, was more severe and more diffuse in those with moyamoya disease. White matter deterioration was significant for both diseases in the genu and body of corpus callosum, in the anterior and superior corona radiation, and in the posterior thalamic radiation, but in moyamoya disease, it was more diffuse and more severe. Vascular cognitive impairment was associated with regional microstructural damage, with a potential link between, gray and white matter damage. Overall, these results provide insight into the pathophysiological nature of vascular cognitive impairment. This study was approved by the Institutional Review Board in Huashan Hospital, China(approval No. 2014-278). This study was registered with ClinicalTrials.gov on December 2, 2014 with the identifier NCT02305407.

Recognition of moyamoya disease and its hemorrhagic risk using deep learning algorithms:sourced from retrospective studies

Although intracranial hemorrhage in moyamoya disease can occur repeatedly,predicting the disease is difficult.Deep learning algorithms developed in recent years provide a new angle for identifying hidden risk factors,evaluating the weight of different factors,and quantitatively evaluating the risk of intracranial hemorrhage in moyamoya disease.To investigate whether convolutional neural network algorithms can be used to recognize moyamoya disease and predict hemorrhagic episodes,we retrospectively selected 460 adult unilateral hemispheres with moyamoya vasculopathy as positive samples for diagnosis modeling,including 418 hemispheres with moyamoya disease and 42 hemispheres with moyamoya syndromes.Another 500 hemispheres with normal vessel appearance were selected as negative samples.We used deep residual neural network(ResNet-152)algorithms to extract features from raw data obtained from digital subtraction angiography of the internal carotid artery,then trained and validated the model.The accuracy,sensitivity,and specificity of the model in identifying unilateral moyamoya vasculopathy were 97.64±0.87%,96.55±3.44%,and 98.29±0.98%,respectively.The area under the receiver operating characteristic curve was 0.990.We used a combined multi-view conventional neural network algorithm to integrate age,sex,and hemorrhagic factors with features of the digital subtraction angiography.The accuracy of the model in predicting unilateral hemorrhagic risk was 90.69±1.58%and the sensitivity and specificity were 94.12±2.75%and 89.86±3.64%,respectively.The deep learning algorithms we proposed were valuable and might assist in the automatic diagnosis of moyamoya disease and timely recognition of the risk for re-hemorrhage.This study was approved by the Institutional Review Board of Huashan Hospital,Fudan University,China(approved No.2014-278)on January 12,2015.

Significance of Cyclooxygenase-2 Elevation in Middle Cerebral Artery for Patients with Hemorrhagic Moyamoya Disease

The etiology and pathogenesis of moyamoya disease（MMD） remain elusive. Some inflammatory proteins, such as cyclooxygenase（COX）-2, are believed to be implicated in the development of MMD. So far, the relationship between COX-2 and MMD is poorly understood and reports on the intracranial vessels of MMD patients are scanty. In this study, tiny pieces of middle cerebral artery（MCA） and superficial temporal artery（STA） from 13 MMD patients were surgically harvested. The MCA and STA samples from 5 control patients were also collected by using the same technique. The expression of COX-2 was immunohistochemically detected and the average absorbance（A） of positively-stained areas was measured. High-level COX-2 expression was found in all layers of the MCA samples from all 5 hemorrhagic MMD patients, while positive but weak expression of COX-2 was observed only in the endothelial layer of the MCA samples from most ischemic MMD patients（6/8, 75%）. The average A values of COX-2 in the hemorrhagic MMD patients were substantially higher than those in their ischemic counterparts（t=4.632, P=0.001）. There was no significant difference in the COX-2 expression among the ＂gender＂ groups, or ＂radiographic grade＂ groups, or ＂lesion location＂ groups（P0.05 for all）. The COX-2 expression was detected neither in the MCA samples from the controls nor in all STA specimens. Our results suggested that COX-2 was up-regulated in the MCA of MMD patients, especially in hemorrhagic MMD patients. We are led to speculate that COX-2 may be involved in the pathogenesis of MMD and even contribute to the hemorrhagic stroke of MMD patients.

Acute recurrent cerebral infarction caused by moyamoya disease complicated with adenomyosis:A case report

BACKGROUND Moyamoya disease is essentially an ischemic cerebrovascular disease.Here,we describe a case of acute recurrent cerebral infarction caused by moyamoya disease with concurrent adenomyosis which,to our knowledge,is the first in the literature.A literature review is also presented.CASE SUMMARY A 38-year-old female presented to the Research and Treatment Center of Moyamoya Disease in our hospital with"left limb weakness"as the main symptom.She was diagnosed with acute cerebral infarction and moyamoya disease through magnetic resonance imaging and digital subtraction angiography.Prior to this,she had experienced a prolonged menstrual period of one-month duration.This was investigated and adenomyosis was diagnosed.After passing the acute cerebral infarction phase,the patient underwent surgery for adenomyosis followed by combined cerebral revascularization.During the postoperative follow-up,improvements of the perfusion imaging stage and modified Rankin Scale were observed.A review of the literature showed only 16 reported cases of gynecological diseases complicated with stroke.The clinical characteristics,pathogenesis,therapeutic effects,and long-term prognosis of these cases have been studied and discussed.CONCLUSION In patients with moyamoya disease,early management of gynecological-related bleeding disorders is essential to prevent the complications of cerebral events.

Histopathological Features of Middle Cerebral Artery and Superficial Temporal Artery from Patients with Moyamoya Disease and Enlightenments on Clinical Treatment

The histopathological features of the middle cerebral artery（MCA） and superficial temporal artery（STA） from moyamoya disease（MMD） and their relationships with gender,age,angiography stage were explored.The causes and the clinical significance of vasculopathy of STA were also discussed.The clinical data and specimens of MCA and STA from 30 MMD patients were collected.Twelve samples of MCA and STA from non-MMD patients served as control group.Histopathological examination was then performed by measuring the thickness of intima and media,and statistical analysis was conducted.The MCA and STA specimens from MMD group had apparently thicker intima and thinner media than those from the control group.There was no significant pathological difference between the hemorrhage group and non-hemorrhage group,and between the males and females in MMD patients.Neither the age nor the digital subtraction angiography（DSA） stage was correlated with the thickness of intima in MCA and STA.MMD is a systemic vascular disease involving both intracranial and extracranial vessels.Preoperative external carotid arteriography,especially super-selective arteriography of the STA,benefits the selection of donor vessel.

Clinical manifestations and cerebral angiographic findings of moyamoya disease

Objective To study the clinical features and angiographic findings of moyamoya disease (MMD) as well as their relationship. Methods A total of 22 MMD patients received routine digital substraction angiography (DSA). The clinical manifestations and angiographic findings were analyzed. Results Clinical manifestations varied and each patient often had multiple symptoms,including cerebral infarction in 9 patients with an average age of 23.6 (13-39 years) and cerebral hemorrhage in 7 patients with an average age of 31.2 (28-46 years). Angiographic examination found that all the diseased sides showed MMD blood vessels. The patients who received encephalo-myo-arterio-synangiosis (EMAS) had better prognosis than those without receiving the treatment. Conclusion Cerebral infarction is frequent in children and adolescents with MMD,whereas cerebral hemorrhage is common in adults. DSA is a golden criterion for diagnosing MMD. Surgical treatment,EMAS blood supply reconstruction in particular,should be prescribed.

On-pump coronary artery bypass in moyamoya disease: A case report

A 54-year-old female with pre-existing idiopathic moyamoya disease developed chest pain with acute myocardial infarction. Coronary angiography detected occluded and stenotic lesions in the coronary arteries. Right coronary artery stenosis was treated by balloon angioplasty and stenting. Because of the restenosis, on-pump cardiopulmonary bypass was performed. The operation was uneventful and no perioperative cerebral ischemic episode occurred. The conclusion is that on-pump cardiopulmonary bypass preserving intraoperative hemodynamic parameters at an optimal level is a safe procedure in a patient with moyamoya disease.

Involuntary Movements Induced and Remitted by Indirect Bypass Surgery in a Patient with Moyamoya Disease

Involuntary movement is an uncommon manifestation of moyamoya disease. We describe a 12-year-old boy who suffered from involuntary movement after the first surgery but it improved dramatically after the second surgery. Initially, the patient underwent an encephalo-duro-arterio-myosynangiosis on the right side and encephalo-duro-periostealsynangiosis on the bifrontal side, which ameliorated his motor weakness in his left upper extremity. However, involuntary movement appeared in his right upper extremity. Secondly, the patient underwent encephalo-duro-arterio-myo-periostealsynangiosis on the left side. Thereafter, the patient’s involuntary movement completely resolved. The involuntary movement might occur due to the unequal distribution of the blood flow in the basal ganglia.

Anesthetic and Obstetric Considerations of Moyamoya Disease in Pregnancy after Intracranial Bypass Grafting: A Case Report and Literature Review

Moyamoya disease (MD) is a chronic idiopathic vasculopathy characterized by bilateral stenosis of the distal internal carotid arteries (ICA’s) with subsequent formation of abnormal collateral vessels. The underlying etiology is unknown [1]. Patients with MD are predisposed to intracranial hemorrhage or cerebral ischemia given the fragile nature of the collateral circulation. Although there is no curative treatment for MD, there are surgical palliative procedures that can augment cerebral blood flow to areas of impaired perfusion and circumvent the abnormal collateral circulation. Medical management exists for patients who are not surgical candidates. Because the incidence of MD peaks during the second and third decades of life, it can potentially affect women of childbearing age [2]. However, the optimal anesthetic and obstetric management of the parturient with MD remains controversial. We present a case of a primigravida with a history of MD who underwent intracranial bypass grafting prior to conception and subsequently had a successful cesarean delivery that was complicated by transient ischemic attacks (TIA) in the postpartum period.

Moyamoya病侧支途径的DSA评价及其与临床的关系

目的 应用 DSA分析 Moyamoya病的侧支途径 ,探讨侧支循环建立情况与临床、CT表现之间的关系。材料与方法 回顾分析 30例经脑血管造影确诊的 Moyamoya病患者的血管造影表现、CT结果及临床资料。结果 所有病例均出现颈内动脉或其分支不同程度狭窄或闭塞和颅底异常血管网 (MMD血管 ) ;7例可见后组 MMD血管 ;2 0例由 Willis环提供侧支血流 ;14例眼动脉增粗 ;17例软脑膜吻合支明显增粗 ;1例脉络膜前动脉增粗。 30例中头颅 CT显示有脑梗塞灶 4例 ,正常表现 3例 ,脑出血 2 3例。结论 DSA是诊断 Moyamoya病的金标准 ,对其侧支途径的研究提供了可靠方法。 Moyamoya病的侧支循环建立情况与临床密切相关。明确 Moyamoya病的侧支循环情况 ,可为临床治疗和预后判断提供可靠依据。

出血型Moyamoya病临床分析

目的 回顾性分析首都医科大学附属北京天坛医院神经外科15年来收治的82例出血型烟雾病(Moyamoya)患者的临床资料,以提高对出血型Moyamoya病的进一步认识.方法 全部患者均经脑血管造影检查确诊为Moyamoya病.根据CT检查及脑血管造影将其分为3组.A组:10例(12%),脑血管造影显示合并有动脉瘤.B组:38例(46%),CT显示为脑内出血(ICH),脑血管造影无动脉瘤.C组:34例(42%),CT显示为脑室出血(IVH),无动脉瘤或ICH.手术治疗49例患者,保守治疗33例.回顾性分析患者的临床及影像学资料并对其恢复情况做随访调查.结果 共随访64例患者,其中手术治疗者42例,保守治疗者22例.疗效优良者46例,良好者9例,1例恢复差,8例死亡.有10例患者在随访期间在初次出血后0.3～8年间发生再出血,再出血率为12%,82例患者中有2例死于初次出血,死亡率为2.4%,6例患者死于再出血,死亡率为60%.结论 出血是Moyamoya患者的重要死亡原因,再出血是出血型Moyamoya病的主要死亡原因. 其预后主要取决于颅内出血部位、出血量和有无再次出血及治疗时机等.

Moyamoya病的MRI和MRA诊断(附15例报告)

目的：探讨ＭＲＩ和ＭＲＡ对Ｍｏｙａｍｏｙａ病的诊断价值。材料与方法：１５例Ｍｏｙａｍｏｙａ病患者中男６例，女９例。年龄４～４９岁，２０岁以下者１１例。应用Ｓｉｅｍｅｎｓ１．０Ｔ超导型ＭＲ系统（Ｉｍｐａｃｔ）行ＳＥ序列ＭＲＩ和三维时间飞跃法（３ＤＴＯＦ）ＭＲＡ。均有ＳＥ序列Ｔ１ＷＩ和Ｔ２ＷＩ，１４例有３ＤＴＯＦＭＲＡ，１例有ＤＳＡ，６例有平扫ＣＴ。选择２０例ＭＲＩ和ＭＲＡ正常者作为对照组。结果：ＭＲＩ均见丘脑基底节区（单侧３例，双侧１２例）有扩张的流空血管（Ｍｏｙａｍｏｙａ血管），其中１０例Ｔ２ＷＩ鞍上池有明确的异常血管网。１４例ＭＲＡ和１例ＤＳＡ均见颈内动脉（ＩＣＡ）上段或大脑中动脉（ＭＣＡ）、大脑前动脉（ＡＣＡ）近端闭塞以及丘脑基底节区的Ｍｏｙａｍｏｙａ血管，这些病理血管分布与ＳＥ序列ＭＲＩ所见一致。对照组ＭＲＩ和ＭＲＡ均见不到丘脑基底节区正常细小的穿支血管。６例有ＣＴ者仅２例可疑有Ｍｏｙａｍｏｙａ血管。结论：ＭＲＩ和ＭＲＡ是诊断Ｍｏｙａｍｏｙａ病的有效非创伤性方法。ＭＲＡ尚适用于随诊Ｍｏｙａｍｏｙａ病的演变、血管旁路术后血管再通情况以及高危人群普查。ＭＲＩ诊断Ｍｏｙａｍｏｙａ病优于平扫ＣＴ。

Moyamoya病CT、MRI和DSA的诊断价值比较

目的:比较CT、磁共振成像(MRI)和数字减影血管造影(DSA)对Moyamoya病的诊断价值。方法:对经临床和影像学证实的153例Moyamoya患者的CT、MRI及DSA进行回顾性分析。153例患者中,83例有CT平扫,30例有CT增强,25例有CT血管造影(CTA);135例有MRISE序列平扫,3D TOFMR血管成像(MRA)130例;113例有DSA。结果:83例CT平扫发现脑梗死38例,脑出血33例,仅3例隐约可见丘脑、基底节区和鞍上池的略高密度烟雾血管影;135例MRI平扫患者中发现脑梗死108例,脑出血38例。CT平扫、CTA、CT增强诊断阳性率分别为3.6%(3/83)、92%(23/25)和93.3%(28/30)。MRI平扫和3D TOFMRA的诊断阳性率分别为95.6%(129/135)和100%(135/135)。DSA诊断阳性率100%(113/113)。CTA、MRA和DSA显示颈外动脉侧支循环的阳性率分别为24%(6/25)、27.7%(36/130)和35.4%(40/113)。与DSA比较,CTA和MRA显示烟雾血管少,常高估脑动脉狭窄。结论:DSA是诊断烟雾病的最佳影像学手段,但具有创伤性。CT增强、CTA、MRI平扫和MRA均是诊断烟雾病的重要方法,CT平扫难以诊断烟雾病。

Moyamoya病发生、发展及转归实验研究

目的研究Ｍｏｙａｍｏｙａ病的发生、发展及转归过程。方法建立Ｍｏｙａｍｏｙａ病的实验动物模型。结果颈动脉逐渐狭窄或闭塞的过程是内弹力纤维变性、断裂后，中膜平滑肌细胞沿断裂处向内膜游走、深入增生的过程。早期，因侧支循环血管建立不完善，脑组织缺血、缺氧出现多灶性脑软化坏死。随时间延长，脑内大量小动脉及毛细血管代偿性增生，其血管壁腔大壁薄,形成异网。同时５个粟粒状或囊状动脉瘤．蛛网膜下腔、脑室内及脑实质内有小的出血灶。结论Ｍｏｙａｍｏｙａ病临床表现早期以缺血性脑血管病为主，后期以出血性脑血管病为主，是由Ｍｏｙａｍｏｙａ病理的演变过程所决定的，是疾病的发展规律。

Moyamoya病的病理、CT与临床研究(附70例报告)

目的研究ｍｏｙａｍｏｙａ病的临床及病理特点。方法分析经脑血管造影（５５例）及剖检（１５例）证实的ｍｏｙａｍｏｙａ病的临床、ＣＴ及病理资料。结果７０例平均年龄２９．２５岁。出血组５５例，平均年龄３３．１３岁，以原发性脑室出血（２１例）、脑叶出血（１３例）及ＳＡＨ（９例）为多，出血原因为异网血管、动脉瘤破裂及梗塞性出血；缺血组１５例，平均年龄１８．４岁，８０％病灶多发，８６．７％为２次以上发病，８０％有两侧症状及体征。结论儿童及青壮年发生脑血管病，血压不高，反复出现脑梗塞或出现脑室出血。

Moyamoya病脑出血与侧支循环的关系研究

目的 探讨Moyamoya病脑出血与侧支循环的关系。资料与方法 分析 37例脑出血型Moyamoya病患者的临床资料及DSA、MRA、MRI和CT结果。结果 全部病例在DSA和MRA像上均显示颈内动脉分叉以上狭窄或闭塞 ,其中双侧病变 2 5例 ,单侧 12例。在 6 2个病变侧中 ,5 3侧基底节区可见异常血管网形成 ,其中丰富者 43侧 ,较少者 10侧 ,极少或没有者 9侧。 32个病变侧显示扩张的软脑膜吻合支 ,后交通动脉增粗 2 3支 ,眼动脉增粗 2 6支 ,通过前交通动脉供血 5侧。所有造影像上均未见血管造影可显示的动脉瘤。在MRI和CT像上显示基底节脑出血 12例 ,脑叶内出血 7例 ,丘脑出血 2例 ,蛛网膜下腔出血 6例 ,脑室内出血 10例。脑出血以突发头痛、神志不清、失语、偏瘫为主要症状。结论 Moyamoya病临床表现与其侧支循环有密切关系。丰富的侧支循环对脑循环起重要代偿作用 ,可以保护缺血的脑组织 ;另一方面 ,如果异常扩张的侧支血管破裂 ,可引起脑出血。笔者认为Moyamoya病脑出血与其丰富的侧支循环关系密切 ,基底节、丘脑及脑室出血与脑底异常血管网有关 ,脑叶内出血可能与扩张的软脑膜吻合支破裂有关。而这两种侧支血管破裂均可引起蛛网膜下腔出血。