经小脑延髓裂入路行第四脑室手术的显微解剖研究

目的 探讨经小脑延髓裂入路到达第四脑室的解剖研究，及在不切开下蚓部的情况下如何分离此裂隙以获得最佳的手术视野。方法 应用显微外科解剖技术，对经甲醛固定、颈内动脉系统彩色乳胶灌注的10具成人尸头标本，在手术显做镜下解剖分离小脑延髓裂，观察第四脑室顶部、底部及外侧隐窝等，切开脉络膜等暴露第四脑室各区域。结果 小脑延髓裂充分暴露后，可以不切开下蚓部，即可获得第四脑室各壁的良好术野。开放小脑延髓裂可依据第四脑室壁的位置及需要暴露的程度分为3种方式：广泛型(导水管型)、外侧壁型及外侧隐窝型。结论 经小脑延髓裂入路可通过正常的解剖间隙到达第四脑室以及脑干，且术野充分，可减少手术的损伤及术后并发症。因广泛型可以最大程度显露第四脑室底部及各区域，因此可以作为该入路的标准方式。     

Anatomical basis for the lateral approach to the fourth ventricle.

This study focused on the posterior inferior cerebellar artery bifurcation and branching patterns in the fissures around the fourth ventricle. The vertebral arteries in 25 unfixed human cerebellum were cannulated and injected with polyester colored resin. The suboccipital surface of the cerebellum was exposed and the cisterna magna main landmarks localized. The average distance was 12.6 mm between the tonsillovermian notches and 21.8 mm between the inferior tips of the tonsils. The mean vertical distance between these horizontal planes was 14.5 mm. The posterior inferior cerebellar artery was found in the cerebellomedullary fissure in 42 of 50 cerebellar hemispheres, in seven cases the artery was absent and in one it was hypoplastic. The mean outer diameter was 1.8 mm and the average length was 27.9 mm. The posterior inferior cerebellar artery presented four bifurcation point patterns: superomedial, superolateral, inferomedial, and inferolateral. These patterns were characterized into subtypes based on the courses of the vermian and tonsillohemispheric branches. The perforating and choroidal branches originating in these segments were also studied. The mean number of perforating branches per hemisphere was 5.1. The range of the length was 2-10 mm and the range of the outer diameter was 0.1-0.3 mm. An average of 4.6 choroidal arteries originated from the tonsillomedullary and telovelotonsillar segments, a mean of 4 arose from both vermian and tonsillohemispheric branches. This information will facilitate surgical planning in approaching the fourth ventricle as well as the interpretation of cerebellar infarcts in the posterior inferior cerebellar artery area.     

小脑延髓裂入路切除第四脑室肿瘤

目的 报道经小脑延髓裂入路(transcerebeliomedullochoroidal fissure,TCMCF)手术切除四脑室肿瘤的临床疗效.方法 采用枕下正中切口、小脑延髓裂入路在手术显微镜下切除四脑室肿瘤.结果 手术治疗19例,其中肿瘤全切除14例,近全切除5例.术后无患者出现小脑性缄默综合征.结论 经小脑延髓裂入路,不需切开小脑蚓部,可避免损伤正常小脑组织,应用显微外科技术有助切除四脑室肿瘤,提高手术疗效.     

Importance of the perforating arteries in the proximal part of the PICA for surgical approaches to the brain stem and fourth ventricle - an anatomical study

Objective

The purpose of this study is to examine the perforating arteries (PAs) in the proximal part of the posterior inferior cerebellar artery (PICA) for surgical approaches to the brain stem and fourth ventricle, and to stress their importance in microsurgical procedures.

Methods

Twenty-six adult cadaver obtained from routine autopsies were used. During the examination, the PAs and the segmental structure of the proximal part of the PICAs and their relation to the neighbouring anatomical structures were demonstrated.

Results

We classified the PICAs into 4 types on the basis of the distance of the middle point of the width of the caudal loop to the midline, and their presence or absence as Group A (symmetrical, anterior medullary type: 26.9%), Group B (lateral medullary type: 15.4%), Group C (asymmetrical type: 38.5%), and Group D (unilateral type: 19.2%). The number of the PAs in the tonsillomedullary segment and the caudal loop was higher than those originating from the other segments.

Conclusions

Approaches to the medial or lateral of the PICA should be made in a way that protects the PAs (avoiding retraction of the PICA). Otherwise the PAs will be damaged and as a result brain stem ischaemia may occur, which can have serious clinical outcomes.     

经脉络膜裂体部到第三脑室的显微解剖简

目的研究经脉络膜裂体部到第三脑室的解剖学特点,为手术治疗第三脑室病变提供解剖学依据。方法选择经10％甲醛固定的完整成人湿性尸头标本10具（20侧）,显微镜下模拟经脉络膜裂体部入路到第三脑室的手术,对相关解剖结构进行测量。结果脉络膜裂体部是侧脑室体部内的一条自然裂隙,经其可以显露全部第三脑室内的结构;经双侧大脑内静脉之间对第三脑室前中部显露更好,并可避免大脑内静脉属支的损伤;而经大脑内静脉外侧则无需进入中间帆即可获得对第三脑室中后部良好的显露。结论经脉络膜裂体部入路到第三脑室手术是治疗第三脑室病变一条良好的路径,尤其适合位于第l=脑室中后部向一侧侵犯明显的病变。     

第四脑室神经鞘瘤的临床特点及手术治疗并文献复习

目的探讨原发性第四脑室神经鞘瘤的临床特征及手术方法。方法分析1例原发性第四脑室神经鞘瘤手术治疗患者的临床资料,并结合文献分析该病的临床特点和手术方法。结果患者为女性,53岁,表现为剧烈头痛、吞咽困难、共济失调、四肢无力等症状,影像学示第四脑室巨大肿瘤,合并脑积水。手术采用经枕下正中小脑延髓裂入路,肿瘤镜下获得全切除,术后病理诊断为神经鞘瘤。术后随访8个月,未见肿瘤复发。结论尽管脑室内神经鞘瘤罕见,且诊断困难,但该类型肿瘤为良性肿瘤,其边界清楚。因此,手术若能获得有效的全切除,远期预后良好。     

远外侧入路的解剖学基础

目的 通过显微外科解剖学方法探讨寰枕区解剖结构的特点,为深入理解和施行远外侧入路手术提供解剖学基础.方法 观察6具(12侧)尸头寰枕区枕动脉走行与位置、椎动脉与枕后肌肉三角的关系,以及小脑后下动脉的起始位置;并于导航系统引导下测量寰枕关节磨除程度与手术视野显露的关系和后组脑神经在切口处的位置.结果 经远外侧入路手术时,倒"U"形切口显露清晰、手术视野优于直线切口.6具(12侧)尸头枕动脉均走行于头夹肌的下方和头最长肌的上方;在枕后肌肉三角内均有椎动脉走行并于硬膜外发出肌支和硬膜支;11侧小脑后下动脉起源于硬膜内椎动脉,1侧起源于硬膜外椎动脉.寰枕关节磨除至根部可清楚地显露硬膜内小脑后下动脉起始部及第Ⅸ(舌咽神经)、X(迷走神经)和Ⅺ对(副神经)脑神经,但距第Ⅻ对脑神经(舌下神经)的距离较远[(7.20±2.33)cm];磨除寰枕关节后1/3,至舌下神经和脑干腹侧的手术距离明显缩短[(6.50±2.31)cm];二者比较差异有统计学意义(t=4.743,P=0.008).结论 经远外侧入路施行延髓腹侧和腹外侧病变手术可清楚地显露下斜坡邻近区、延髓腹侧和小脑后下动脉起始部.手术中应注意保护枕后肌肉三角内的椎动脉或起源于椎动脉硬膜外段的小脑后下动脉.对于舌下神经外侧病变无需磨除寰枕关节,需要时以磨除后1/3为宜,进一步磨除寰枕关节只能减少手术视野的深度而不能扩大显露范围.     

Etiological differences between the isolated lateral ventricle and the isolated fourth ventricle

Objective To determine if an etiological difference exists between isolation of the lateral ventricle and isolation of the fourth ventricle after ventricular shunting.Methods Cases of symptomatic isolation of the lateral and fourth ventricles were reviewed retrospectively. The ages at presentation of ventricular isolation, the time course to development of isolation, the number of shunt surgeries leading up to symptomatic isolation, the types of shunt valves utilized, and the background of infection were analyzed.Results Twenty-six patients had lateral ventricle isolation and 11 patients had fourth ventricle isolation. Infection, hemorrhage, Chiari malformation/myelomeningocele, and aqueductal stenosis were factors contributing to hydrocephalus requiring treatment in these patients. Compared to 26.9% of patients with lateral ventricle isolation, 90.9% of patients with fourth ventricle isolation had a previous history of infection.Conclusions Prior meningitis and ventriculitis frequently contributed to fourth ventricle isolation. Lateral ventricle isolation seems to arise from functional obstruction of the foramen of Monro related to prior shunting.     

无共济失调小脑梗死12例临床分析

目的:探讨无共济失调小脑梗死的临床特点、梗死区域及早期诊断对疾病预后的意义。方法:回顾性分析12例以眩晕为主要症状但无共济失调表现的小脑梗死的临床资料。结果:患者年龄58～78岁,CT检查未发现梗死灶,MRI阳性率为100%。脑梗死主要危险因素为高血压、糖尿病、高脂血症和心房颤动。11例患者小脑梗死的病灶主要位于单侧小脑半球后下部,属于小脑后下动脉(PICA)供血区域;1例小脑梗死的病灶位于小脑蚓部后部及其附近的两侧小脑半球,属于小脑后下动脉中间支(mPICA)供血区域。结论:无共济失调小脑梗死常见于PICA供血区。对于中老年眩晕患者,无论有无共济失调表现,都应完善MRI检查明确有无小脑梗死。     

小脑后下动脉动脉瘤的治疗进展

小脑后下动脉（PICA）动脉瘤是导致蛛网膜下腔出血及后循环缺血的原因之一,由于解剖结构较复杂,故该动脉瘤治疗难度较大,预后较差。根据动脉瘤位置的不同、性质的不同,可选用的治疗方案也各不相同。该文在复习文献的基础上就累及PICA动脉瘤的最新治疗进展进行综述。     

经胼胝体-脉络膜裂入路的显微解剖学研究

目的 探讨经胼胝体-脉络膜裂入路的显微解剖学特征和临床应用价值.方法 显微镜下对12例成人尸头湿标本进行侧脑室、第三脑室区显微解剖,观察侧脑室、脉络丛、脉络膜裂及第三脑室顶的解剖学特点;在3例成人尸头新鲜标本上模拟经胼胝体-脉络膜裂入路手术,观察与本人路相关的重要解剖结构并测量相关距离.结果 脉络丛位于侧脑室底部内侧,脉络膜裂位于丘脑和穹窿之间,可借助与之相连的脉络丛进行辨认.切开脉络膜裂穹窿带到达第三脑室顶中间帆后,于两侧大脑内静脉间分离打开第三脑室顶即到达第三脑室腔.经测量,大脑内侧缘冠状缝处至胼胝体沟的距离为(39.12±3.94)mm,大脑内侧缘冠状缝处至室间孔的距离为(61.53±4.02)mm,室间孔后缘至穹窿与胼胝体融合处的距离为(28.65±2.23)mm,前后连合的距离为(25.94±2.16)mm,室间孔至乳头体的长度为(19.62±1.79)mm.结论 与其他手术人路相比,经胼胝体-脉络膜裂入路循自然裂隙进入第三脑室,具有路径直接、术野暴露广泛等特点,值得临床推广应用.     

小脑后下动脉(PICA)的显微解剖研究

目的研究小脑后下动脉(PICA)的显微解剖结构。方法对16具(共32侧)完好的人脑标本在显微镜下测量PICA。结果平均管径(1.23±0.48)mm,24侧(75.0%)由同侧椎动脉发出,距椎基汇合点(18.83±4.92)mm,19侧(59.4%)走行于第Ⅸ￣Ⅺ脑神经后方。结论小脑后下动脉是颅后窝椎基动脉系统较重要的分支,变异多;熟悉其解剖结构,在手术中多加保护是非常必要的。     

Bilateral Cerebellar Infarctions Caused by a Stenosis of a Congenitally Unpaired Posterior Inferior Cerebellar Artery

Bilateral symmetrical cerebellar infarcts in the territory supplied by the medial posterior inferior cerebellar artery (PICA) branches are extremely rare. In the few cases published, it has not been possible to clearly pinpoint the cause of this infarct pattern. The authors present the case history of a 58-year-old man who had acute headaches accompanied by pronounced rotatory vertigo with nausea and vomiting. The neurological examination revealed bilateral cerebellar signs. Cranial magnetic resonance imaging showed bilateral, nearly symmetrical infarcts in the territory of the medial branches of both PICAs. These bilateral PICA infarctions were caused by a stenosis of an unpaired PICA originating from the left vertebral artery supplying both cerebellar hemispheres.     

经额中回-侧脑室-脉络裂入路显微手术切除第三脑室前部肿瘤

目的介绍并探讨一种切除第三脑室前部病变的显微手术入路。方法经额中回-侧脑室-脉络裂入路手术切除第三脑室前部肿瘤10例。结果显微镜下全切除8例,近全切除2例;死亡1例。结论该入路利用脑室的自然裂隙到达第三脑室,几乎不损伤正常脑组织和血管结构,具有手术损伤小,术野暴露清楚等优点,是切除第三脑室前部肿瘤的优选入路之一。     

Microsurgical anatomy of the lower basilar artery

Abstract

This study was designed to study the microvascular anatomy of the basilar artery between the superior cerebellar artery and the vertebrobasilar junction (i.e. the lower basilar artery). Twenty unfixed brains were injected with silicone rubber solution and studied with a Zeiss OPMI microscope. The length of this segment of the basilar artery was 28.1 + 1.35 mm and its course was straight in 9 (45%) brains, curved in 7 (35%) and tortuous in 4 (20%). The total number of perforators found in 20 brains was 340 with an average of 17 per brain. Of these, 118 (34.7%) were median and 222 ( 65.2%) were lateral. Median branches had a mean length of 5.8 + 1.25 mm, whereas left and right lateral branches had a mean length of 16 + 1.25 mm and 16 + 1.58 mm respectively.     

经额胼胝体-透明膈入路显微切除第三脑室及侧脑室肿瘤

目的 探讨经额胼胝体-透明膈入路显微切除第三脑室并累及侧脑室肿瘤的临床疗效及优点.方法 选择皖南医学院弋矶山医院神经外科自2005年10月至2009年4月收治的第三脑室并累及侧脑室肿瘤患者12例.采用经额胼胝体-透明膈入路行显微切除手术.结果 肿瘤全切除4例,近全切除3例,大部分切除5例,无手术死亡患者.结论 该手术入路由生理间隙进入,显微镜下直视操作,术野暴露清晰且对周围结构损伤小,切除第三脑室及侧脑室内肿瘤较安全,并发症少.     

Dissecting aneurysms of the posterior inferior cerebellar artery: report of four cases and review of the literature

Dissecting aneurysms frequently involve the vertebral arteries and their branches, but those exclusively on the posterior inferior cerebellar artery (PICA) represent only 24 cases in the literature, including the four cases discussed in this article. The clinical diagnosis lacks pathognomonic signs or symptoms, with presentations such as subarachnoid haemorrhage or ischaemia of the brain stem or the cerebellum, and the management is controversial. Wrapping, clipping and embolisation of the aneurysms were tried in this series with different outcomes. Exclusion of the pathological segment should be performed, as shown by rebleeding from our case which was wrapped or by progression of the vascular disease in cases where treatment was delayed. Surgical or endovascular occlusion are well tolerated in our cases and in those reported from the literature, which implies the absence of normal perforating branches to the brain stem arising from the proximal dissected segment of the PICA and a good collateral circulation. A revascularisation procedure using the occipital artery can be performed in order to prevent infarction if an endovascular test occlusion is not tolerated.     

The benefit of image guidance for the contralateral interhemispheric approach to the lateral ventricle

OBJECTIVES: Recently, neurosurgeons have increasingly faced small intracerebral lesions in asymptomatic or minimally symptomatic patients. Here, we evaluated a series of four patients with nearly asymptomatic intraventricular tumors close to the corpus callosum that had been treated with the aid of an image-guided transcallosal approach. PATIENTS AND METHODS: Four consecutive patients suffering from left intra- and paraventricular tumors were operated on via a contralateral interhemispheric transcallosal approach with the aid of neuronavigation. Our image-guided system directed: (1) the skin incision, (2) the interhemispheric dissection, and (3) the incision of the corpus callosum. RESULTS: Using the image-guided contralateral interhemispheric transcallosal approach to the left ventricle all lesions have been completely resected without the risk of damage to the dominant hemisphere. The callosal incision was kept as limited as possible (1.2-2.1cm) depending on the size of the tumor. No postoperative neurological or neuropsychological deficit was observed in our series. CONCLUSION: Neuronavigation facilitates a safe and targeted contralateral interhemispheric transcallosal approach to the dominant hemisphere's lateral ventricle. Our technique minimizes the risk of damage to the dominant hemisphere and requires only a limited opening of the corpus callosum, which might decrease the risk of neuropsychological morbidity.     

Telovelar approach: technical issues for large fourth ventricle tumors

Objects Fourth ventricle is conventionally accessed via resection of the part of the vermis for total excision of the tumors at the expense of significant morbidity. Numerous avenues have been identified to minimize the morbidity; some of which include transforaminal, subtonsillar, telovelar approaches, etc. These approaches are devised on the basis that accurate dissection along the natural avascular planes will avoid injury to the important structures in this area minimizing morbidity. We attempt to emphasize the technique of telovelar approach and the problems encountered while employing this technique for excision of large fourth ventricle tumors. Materials and methods Fifteen patients with fourth ventricle tumors were operated during January to September 2005 at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fourteen of these cases were medulloblastomas, and one was ependymoma. All the patients were operated in prone oblique position via telovelar approach. Conclusion Clear understanding of the normal anatomy will help in meticulous dissection and will result in reduced morbidity. Significant incidence of postoperative ataxia and mutism is seen with this approach in large tumors, and this can be avoided by staged dissection of the uvulotonsillar cleft.     

Aneurysms of Distal Posterior Inferior Cerebellar Artery

Objective

Aneurysms are very rarely encountered in the distal posterior inferior cerebellar artery (PICA). The authors experienced 5 cases with a distal PICA aneurysm among 368 cases of intracranial aneurysms during the period from January 2003 to January 2008. Here, the authors describe their clinical and surgical experiences and include a review of the relevant literature.

Methods

Using radiologic findings and charts, we retrospectively reviewed the surgical results of 5 cases with a distal PICA aneurysm treated from January 2003 to January 2008.

Results

The current five cases were composed of four cases of ''Good'' and one case of ''Fair''. No postoperative complications occurred other than a ventriculo-peritoneal shunt due to hydrocephalus in Case 2. In all five cases, treatment was successful without neurological deficit.

Conclusion

Surgical outcome of PICA aneurysms have been reported to be excellent because the amount of intraparenchymal injury is limited. More clinical experience, microsurgical technique developments, and endovascular surgery advancements are certain to improve treatment outcomes.