从胚胎学角度研究大脑中浅静脉的解剖形态和分类
1
Morphological Pattern and Classification of the Superficial Middle Cerebral Vein by Cadaver Dissections: An Embryological Viewpoint
从胚胎学角度研究大脑中浅静脉的解剖形态和分类
Yasutaka IMADA1，Kaoru KURISU2，Toru TAKUMI3,4，Hirohiko AOYAMA5,6，Takashi SADATOMO7，Keisuke MIGITA8，and Kiyoshi YUKI7
山西白求恩医院神经外科 王永红翻译
Abstract 摘要
In this study, we used 45 adult cadaveric cerebral hemispheres to investigate the anatomical classification of the superficial middle cerebral vein (SMCV) based on the number of stems, course, and anastomosis at the distal portion. We classified the SMCVs into five types based on embryological concept. Type A (18 cases, 40.0%) is that the frontosylvian veins (FSVs) merge with the vein of Trolard (VT) and the vein of Labbé (VL) at the distal portion of the sylvian fissure. Type B (5 cases, 11.1%) is that the temporosylvian veins (TSVs) merge with the VT and the VL at the distal portion. Type C (13 cases, 28.9%) is that no vein merge with the VT and the VL at the distal portion. The VT merges with the SMCV from the FSV and the VL merges with the SMCV from the TSV. They course along the sylvian fissure and merge at the proximal portion. In Type D (eight cases: 17.8%), the VT and the VL merge at the distal portion, and the SMCV from the FSV and the SMCV from the TSV join their confluence without merging. Type E (one case, 2.2%) show an undeveloped SMCV. Formation rate of intravenous anastomoses or bridging veins(BVs) at the distal portion between the frontosylvian trunk (FST) and the temporosylvian trunk (TST), between the FST and the temporal lobe, and between the TST and the frontal lobe was very low, because these formation may be difficult to occur during the embryological process in which the SMCV is formed from the telencephalic vein.
在这项研究中，我们使用了45具成人大脑半球尸体来研究大脑中浅静脉(SMCV)的解剖分类，基于(SMCV)远端部分的静脉主干数目、走行和侧枝吻合。我们根据胚胎学的概念将SMCV分为五种类型。A型(18例，40.0%)是额侧裂静脉在侧裂远端与Trolard (VT)静脉和Labbé (VL)静脉融合。B型(5例，11.1%)是颞侧裂静脉(TSVs)在远端与Trolard (VT)静脉和Labbé (VL)静脉融合。C型(13例，28.9%)是没有静脉在侧裂远端部分与Trolard (VT)静脉和Labbé (VL)静脉融合。VT从FSV与SMCV合并，VL从TSV与SMCV合并。它们沿着外侧裂行进，并在近端部分汇合。在D型(8例：17.8%)中，VT和VL在侧裂远端部分汇合，FSV的SMCV和TSV的SMCV在汇合处汇合而不融合。E型(1例，2.2%)显示未发育SMCV。静脉吻合或桥接静脉(BVs)在额侧裂干(FST)和颞侧裂干(TST)之间的远端部分、FST和颞叶之间以及TST和额叶之间的形成率非常低，这些(吻合或桥接)难以发生是因为在胚胎发育过程中SMCV由端脑静脉形成的。
Key words: superficial middle cerebral vein, frontosylvian vein, temporosylvian vei, trans-sylvian approach
关键词：大脑中浅静脉，额侧裂静脉，颞侧裂静脉，经侧裂入路
Introduction 引言
Neurosurgery with a pterional approach by frontotemporal craniotomy is obstructed by the superficial middle cerebral vein (SMCV), and its structure and the network of venous return should be considered during planning of a surgical approach and strategy. Therefore, it is necessary to understand the structure of the SMCV and the anatomical relationships between the frontal lobe, the temporal lobe, and the sylvian fissure. In the past, identification of the SMCV has focused mainly on the outflow point,[1–7]) however, because the SMCV shows variation in number of stems, course, and anastomoses at the distal portion, it can be difficult to define the SMCV.[5,8–15]) There is a little detailed discussion of methods to dissect the SMCV in the trans-sylvian approach in the clinical literature, and a consensus for a best approach has not been obtained.[8,12,14–16]) In this study, we examined the morphological pattern and characteristics of the SMCV from detailed observations using cadaveric cerebral hemispheres. Our observations of the number of stems, the course of the SMCV, and distal anastomoses from an embryological viewpoint may establish an anatomical classification of the SMCV that is useful in the trans-sylvian approach. In addition, we investigated how to dissect the SMCV according to this classification.
神经外科额颞开颅翼点入路手术中常受到大脑中浅静脉(SMCV)的阻碍，在规划手术入路和策略时应考虑其结构和静脉回流网络。因此，有必要了解SMCV的结构以及与额叶、颞叶和外侧裂之间的解剖关系。在过去，SMCV的识别主要集中在流出点，然而，由于SMCV在静脉干的数量、走形和远端吻合处显示出差异，因此很难定义SMCV。在临床文献中，对经侧裂入路中解剖SMCV的方法几乎没有详细的讨论，对于最佳的解剖侧裂入路还没有达成共识。在这项研究中，我们通过使用尸体大脑半球的详细观察来研究SMCV的形态和特征。我们从胚胎学的角度对静脉干的数目、SMCV的走形和远端吻合的观察可以建立一个SMCV的解剖学分类，这在经侧裂入路中是非常有用的。此外，我们还研究了如何根据这种分类来解剖SMCV。
Materials and Methods
材料和方法
Superficial middle cerebral veins were examined using 3× magnification in 45 adult cadaveric cerebral hemispheres in which the arteries and veins had not been perfused with colored silicone. These cadaveric brains were separated from the skull and the dura mater was removed for medical student dissection in 2012. For this reason, we were unable to confirm the final outflow point of the SMCVs, but we could observe the SMCVs on the lateral cerebral surface. We peeled the SMCVs from the surface of the distal to the proximal portion of the sylvian fissure using micrscissors and examined the number of stems, course, and anastomoses between adjacent superficial middle cerebral veins, and anastomoses between the SMCV and the frontosylvian veins (FSVs) or temporosylvian veins (TSVs). Although the arteries and veins were not perfused with colored silicone, it was relatively easy to distinguish the arteries and the veins.
在45具未灌注彩色硅胶的成人大脑半球标本上，用3倍放大率观察大脑中浅静脉。2012年，这些尸体大脑从颅骨中分离出来，硬脑膜被移除用于医学学生解剖。由于这个原因，我们无法确定大脑中静脉的最终流出点，但我们可以观察到大脑侧面的大脑中静脉。我们用显微镜从外侧裂的远端到近端部分剥离了大脑中静脉，并检查了相邻大脑中浅静脉之间的静脉干数量、走行和吻合，以及SMCV静脉和额侧裂静脉(FSV)或颞侧裂静脉(TSV)之间的吻合。虽然动脉和静脉没有灌注彩色硅胶，但动脉和静脉的区分相对容易。
Results 结果
The sylvian veins were defined as described in previous studies.[5,17,18]) The SMCV receive FSVs, PSVs, and TSVs, and usually arise at the posterior end of the sylvian fissure and course anteriorly and inferiorly along the edges of the sylvian fissure. The FSVs are a group of 3–6 veins that descend on the frontal operculum and drain the inferior and adjoining part of the middle frontal gyri and the inferior part of the precentral gyrus. The PSVs are 2–4 small trunks that arise on the postcentral gyrus and the inferior parietal lobule and pass anteroinferiorly toward the sylvian fissure where they join the SMCV. The TSVs are a group of smaller veins that arise along the full extent of the superior temporal gyrus from the temporal pole to the posterior end of the sylvian fissure.
侧裂静脉的定义如先前的研究中所述。SMCV接收FSV、PSV和TSV，通常出现在侧裂的后端，沿着侧裂的边缘向前和向下延伸。FSV是一组3-6条静脉，下行于额盖，引流额中回的下部和毗邻部分以及中央前回的下部。PSV是2-4个小干，位于中央后回和顶下小叶上，向前下至外侧裂，在此处与SMCV连接。颞浅静脉是一组较小的静脉，沿颞上回从颞极到侧裂后端的整个范围延伸。
Based on these anatomical characterizations, we tentatively defined the SMCV as follows. The frontosylvian trunk (FST) is the SMCV that receives FSV or PSV . The temporosylvian trunk (TST) is the SMCV that receives TSV . The superficial middle cerebral common trunk (SMCCT) is the SMCV that receives both FSV and PSV , whose main component is the vein of Trolard, and the TSV , whose main component is the vein of Labbé, at the posterior end of the sylvian fissure (Fig. 1a).
基于这些解剖学特征，我们对SMCV的初步定义如下。额侧裂干(FST)是接收FSV或PSV的SMCV。颞侧裂干(TST)是接收TSV的SMCV。大脑中浅静脉干(SMCCT)是接收FSV，PSV，和TSV的SMCV，FSV和PSV其主要成分是Trolard静脉，TSV其主要成分是在侧裂后端的Labbé静脉(图1a)。
Fig.1 (a) Nomenclature of the superficial middle cerebral veins. Frontosylvian trunk (FST) is the superficial middle cerebral vein (SMCV) that receives the frontosylvian veins (FSV) or the parietosylvian veins (PSV). Temporosylvian trunk (TST) is the SMCV that receives the temporosylvian veins (TSV). Superficial middle cerebral common trunk (SMCCT) is the SMCV that receives both the FSV (or PSV) and the TSV at the posterior end of the sylvian fissure. (b) Classification of the SMCV.
图1.(a)大脑中浅静脉的命名。额侧裂干(FST)是大脑中浅静脉(SMCV)，接收额侧裂静脉(FSV)或顶侧裂静脉(PSV)。颞侧裂干(TST)是接收颞侧裂静脉(TSV)的SMCV。大脑中浅静脉干(SMCCT)是在外侧裂后端接收FSV(或PSV)和TSV的SMCV。(b)SMCV的分类。
We classified the SMCVs into five types as follows (Fig. 1b). Type A SMCVs correspond to the SMCCT and have some anastomoses with the FST or the FSV on the sylvian fissure. This type was observed in 40.0% (n=18) of the 45 cerebral hemispheres and was the most frequent form. Anastomoses between the SMCCT and the TSV were observed in 22.2% (n=4) of these Type A SMCVs. All these anastomoses were small bridging veins between the SMCCT and the temporal lobe, and anastomoses between the SMCCT and the TST was not observed. In one third of Type A cases (n=6), the proximal end of the SMCCT did not empty into any skull base sinus, and became a blind end at the base of the frontal lobe or connected to the deep sylvian veins directly. In two third of Type A cases (n=12), the proximal end of the SMCCT seemed to empty into either skull base sinus according to its course within the observable range, but it was impossible to identify accurately (Table 1).
我们将SMCV分为以下五种类型(图1b)。A型SMCV对应于SMCCT，在侧裂与FST或FSV有一些吻合。这种类型在45个大脑半球中的40.0% (n=18)被观察到，并且是最常见的形式。在22.2%(4例)的A型SMCV中观察到 SMCCT和TSV之间的吻合。所有这些吻合都是 SMCCT和颞叶之间的小桥接静脉，未见 SMCCT和TST之间的吻合。1/3的A型病例(n=6)SMCCT的近端没有回流到任何颅底静脉窦内，在额叶底部成为盲端或直接与深部侧裂静脉相连。在三分之二的A型病例(n=12)中，SMCCT的近端根据其在可观察范围内的行程似乎流入任一颅底静脉窦，但不可能准确识别(表1)。
Type B SMCVs correspond to the SMCCT and have no anastomoses with the FST or the FSV on the sylvian fissure. This type was observed in 11.1% (n=5) of the 45 cerebral hemispheres. Anastomoses between the SMCCT and the TSV were observed in 60% (n=3) of these Type B SMCVs. In all cases, the proximal end of the SMCCT seemed to empty into either skull base sinus according to its course within the observable range, but it was impossible to identify accurately (Table 1). The SMCCT was derived from the FST in 78.3% of cases, while the frequency that the SMCCT was derived from the TST was 21.7%. The frequency of derivation of the SMCCT from the FST was high.
Type C SMCVs show no SMCCT. In other words, the FST and the TST run in parallel along the sylvian fissure and course toward the skull base. This type was observed in 28.9% (n=13) of the 45 cerebral hemispheres. Anastomoses between the FST and the FSV were observed in 84.6% (n=11) of these Type C SMCVs, while anastomoses between the TST and the TSV was seen in 53.8% (n = 7). In nine of the 13 cases (69.2%), merger of the FST and the TST at the proximal portion was confirmed, but, in the other four cases, it was impossible to identify accurately within the observable range. In all cases, BVs between the FST and the TST were not observed (Table 2).
C型SMCVs没有显示SMCCT。换句话说，FST和TST沿着外侧裂平行走向颅底。在45个大脑半球中有28.9% (n=13)观察到这种类型。在84.6%(11例)的C型SMCV中观察到了FST和FSV之间的吻合，而在53.8%(7例)的病例中观察到了TST和TSV之间的吻合。在13例病例中的9例(69.2%)中，近端部分的FST和TST融合得到确认，但在其他4例病例中，在可观察范围内不能准确识别。在所有情况下，都没有观察到FST和TST之间的桥静脉(表2)。
Type D SMCVs are a merging of the vein of Trolard and the vein of Labbé at the posterior end of the sylvian fissure. Type D SMCVs divide into the FST and the TST again toward the proximal portion. This type was observed in 17.8% (n=8) of the 45 cerebral hemispheres. Anastomoses between the FST and the FSV were observed in 87.5% (n=7) of these Type D SMCVs, while anastomoses between the TST and the TSV were observed in 87.5% (n=7). Tiny BVs between the FST and the TST were observed in 28.6% (n=n=2) of these Type D SMCVs. In seven of the eight cases of Type D SMCVs, the proximal end of the FST did not empty into any skull base sinus, and was connected to the veins of the basal surface of the frontal lobe or deep sylvian veins directly. The remaining case seemed to empty into either skull base sinus according to its course within the observable range, but it was impossible to identify accurately. In all cases, the proximal end of the TST seemed to empty into either skull base sinus according to its course within the observable range, but it was impossible to identify accurately(Table 2).
D型SMCV是Trolard静脉和Labbé静脉在外侧裂后端的融合。之后D型SMCV再次向侧裂近端部分分裂成FST和TST。这种类型在45个大脑半球中的17.8% (n=8)被观察到。在这些D型SMCV中，87.5%(7例)的 FST与FSV吻合，87.5%(7例)的吻合是TST和TSV吻合。在28.6% (n=n=2)的这些D型SMCV中观察到FST和TST之间的小的桥静脉。在8例D型SMCV病例中，有7例的FST近端没有汇入任何颅底静脉窦，而是直接与额叶基底面静脉或深部侧裂静脉相连。根据其在可观察范围内的走行，其余病例似乎都汇入了任一颅底静脉窦，但无法准确识别。在所有病例中，根据其在可观察范围内的走行，TST的近端似乎汇入了任一颅底静脉窦，但不可能准确识别(表2)。
Type E SMCVs are underdeveloped on the sylvian fissure. This type was observed in 2.2% (n=1) of the 45 cerebral hemispheres. In this case, the merger of the vein of Trolard and the vein of Labbé at the posterior end of the sylvian fissure was observed, and BVs between the frontal and the temporal lobe were not observed (Table 3). However, the frontobasal BV was excluded from the evaluation as a BV in this study.
E型SMCV在外侧裂发育不全。这种类型在45个大脑半球中的2.2% (n=1)被观察到。在这种情况下，观察到Trolard静脉和Labbé静脉在侧裂后端的融合，并且没有观察到额叶和颞叶之间的BVs(表3)。然而，额底BV作为在这项研究中BV被排除在外。
Discussion 讨论
There have been many morphological classifications of the SMCVs according to draining pattern of veins.[3,6]) However, we classified into five patterns from an embryological viewpoint, because the process of embryological formation of the SMCV would help to estimate the pattern of the venous return for each type.
From morphological viewpoint, Hacker et al.[19]) classified the superficial veins into three groups according to draining pattern from the cortical surface. The first group, superior cerebral veins, drain the superior part of the medial and lateral surface of the hemisphere, and include the vein of Trolard. These veins empty into the superior sagittal sinus. The second group, the SMCV , drain the regions of the frontal, temporal, and parietal lobes adjoining the sylvian fissure and empty into the sphenoparietal or cavernous sinus. The third group, the inferior cerebral veins, drain the lateral surface of the temporal lobe and the basal surface of the temporal and occipital lobes, and include the vein of Labbé. These veins empty into the transverse or tentorial sinuses.
从形态学的观点来看，Hacker等人根据皮层表面的引流模式将浅静脉分为三组。第一组，大脑上静脉，引流半球内侧和外侧表面的上部，包括Trolard静脉。这些静脉流入上矢状窦。第二组，SMCV，引流毗邻侧裂的额叶、颞叶和顶叶，注入蝶顶窦或海绵窦。第三组，即大脑下静脉，引流颞叶外侧表面和颞叶及枕叶基底表面，包括Labbé静脉。这些静脉汇入横窦或小脑幕窦。
These superficial veins are formed from the development of the pial venous network originating from the meninx primitiva.[20–22]) According to Padget, the superficial telencephalic vein drains the lateral surface of the hemisphere and the deep telencephalic vein drains the sylvian fossa in early embryonic stages. The former corresponds to the subsequent SMCV, and the latter corresponds to the subsequent deep middle cerebral vein. These veins converge on the sylvian fossa forward and downward, and empty into the transverse sinus via the primitive tentorial sinus. Subsequent growth of the posterior cerebral hemisphere causes the tentorial sinus to elongate posteriorly, and the anterior portion is shifted medially to anastomose with the sphenoparietal or cavernous sinus. The posterior part of the primitive tentorial sinus regresses gradually and the anastomoses between the sphenoparietal and cavernous sinuses develop.[21,23]) In accordance with the completeness of these two secondary anastomoses, the variation of the outflow of the superficial telencephalic vein occurs.[2,6,21,23])
这些浅静脉是由起源于原脑膜的软脑膜静脉网的发育形成的。根据Padget的说法，在胚胎早期，端脑浅静脉引流半球的侧面，而端脑深静脉引流侧裂窝。前者对应于随后的SMCV，后者对应于随后的大脑中深静脉。这些静脉向前和向下会聚于侧裂窝，通过原始的小脑幕窦汇入横窦。大脑半球的后部后续发育生长导致小脑幕窦向后伸长，且前部向内移位以与蝶顶窦或海绵窦吻合。原始小脑幕静脉窦的后部逐渐退化，蝶顶窦和海绵窦之间的吻合形成。随着这两次吻合的完成，出现了端脑浅静脉流出量的变化。
In the distal part, the SMCV and its tributaries are well developed from the superficial telencephalic vein and the vein around the sylvian fissure at the gestational ages of 3 and 4 months. The SMCV and its tributaries rapidly regress from the 5th to 7th month. The superior and inferior cerebral veins, on the other hand, develop rapidly during this period. The anastomotic veins between the SMCV, the superior cerebral vein and the inferior cerebral vein are also recognizable during this period.[21,23,24]) This process of embryological formation of the SMCV shows individual differences in the degree of degeneration of the SMCV and in the degree of the formation of the anastomoses between the SMCV and the superior or inferior cerebral vein. This variation results in the various patterns of the distal portion of the SMCV (Fig. 2a). For this reason, a classification based on the variation of outflow path of the SMCV has been reported, but there are few studies examining the number of stems, course, and anastomoses of the SMCV at the distal portion.[8,12,14,15]) So we investigated the anatomical classification of the SMCV based on the number of stems, course, and the anastomotic form at the distal portion from an embryological viewpoint.
在远端，SMCV及其分支在妊娠3个月和4个月时从端脑浅静脉和外侧裂周围的静脉发育良好。从第5个月到第7个月，SMCV及其支流迅速退化。另一方面，大脑上静脉和下静脉在此期间发展迅速。在此期间，SMCV、大脑上静脉和大脑下静脉之间的吻合静脉也是可识别的。SMCV的胚胎学形成过程显示了SMCV的退化程度和SMCV与大脑上静脉或大脑下静脉之间的吻合形成程度的个体差异。这种变化导致SMCV远端部分的各种形式(图2a)。由于这个原因，一个基于SMCV流出路径变化的分类已经被报道，但是很少有研究检查侧裂远端部分SMCV的静脉干、走行和吻合的数量。因此，我们从胚胎学的观点研究了基于静脉干、静脉走行的数量和远端部分的吻合形式的SMCV的解剖学分类。
The SMCV is composed of the three components: the FSV , which drains the lower part of the lateral frontal lobe; the PSV , which drains the postcentral gyrus and the inferior parietal lobule; and the TSV ,which drains the superior temporal gyrus from the temporal pole to the posterior end of the sylvian fissure.[5,18]) In embryonic development, the SMCV is formed by joining the telencephalic veins draining each region of the sylvian fissure.
SMCV由三个部分组成：FSV，引流外侧额叶的下部；PSV引流中央后回和顶下小叶的肺静脉；和TSV，它从颞极引流颞上回到外侧裂的后端。[5,18]在胚胎发育中，SMCV是通过连接端脑静脉引流外侧裂的各个区域而形成的。
There are four major points along with an embryological viewpoint to describe our classification obtained from detail morphological observation of 45 adult cadaveric cerebral hemispheres.
从胚胎学的观点来描述我们的分类包括四个要点，它是从45具成人尸体大脑半球的详细形态学观察中得来的。
(1) Flow of the SMCV should be consistent with an embryologic development (Fig. 2b).
(1)SMCV的血液流动应该与胚胎发育一致(图2b)。
Fig. 2 (a) Embryologic process of the superficial middle cerebral vein (SMCV). (b) Consideration on the origin of the SMCV from the viewpoint of embryologic development. Purple: vein of Trolard, light blue: frontosylvian trunk or frontosylvian vein, green: vein of Labbé, light green: temporosylvian trunk or temporosylvian vein.
图2.(a)大脑中浅静脉的胚胎发育过程(SMCV)。(b)从胚胎发育的角度研究SMCV的起源。紫色：Trolard，静脉；淡蓝色：额侧裂干或额侧裂静脉；绿色：Labbé静脉；淡绿色：颞侧裂干或颞侧裂静脉。
Type A SMCV can be described as superior cerebral veins, composed mainly of the vein of Trolard, and the inferior cerebral veins, composed mainly of the vein of Labbé, merged with the FST derived from the FSV at the distal portion of the sylvian fissure.
Type B SMCV can be described as superior cerebral veins, composed mainly of the vein of Trolard, and the inferior cerebral veins, composed mainly of the vein of Labbé, that merge with the TST derived from the TSV at the distal portion of the sylvian fissure.
B型SMCV可以描述为大脑上静脉(主要由Trolard静脉组成)，大脑下静脉(主要由Labbé静脉组成)，及与TST(来自在侧裂的远端部分TSV)的融合。
Type C SMCV can be described as superior cerebral veins, composed mainly of the vein of Trolard, and the inferior cerebral veins, composed mainly of the vein of Labbé, that did not merge at the distal portion of the sylvian fissure. The former merged with the FST and the latter with the TST at the distal portion of the sylvian fissure, and they ran in parallel along the sylvian fissure and merge at the proximal portion.
Type D SMCV can be described as superior cerebral veins, composed mainly of the vein of Trolard, and the inferior cerebral veins, composed mainly of the vein of Labbé, that merge at the distal portion of the sylvian fissure. The FST and the TST join to their confluence, and the FST and the TST do not merge at the proximal portion.
D型SMCV可描述为主要由特罗拉德静脉组成的大脑上静脉和主要由Labbé静脉组成的大脑下静脉，它们融合在外侧裂的远端部分。FST和TST在它们的汇合处汇合，而FST和TST在侧裂近端的部分没有融合。
Type E SMCV can be described as an underdeveloped SCMV regardless of whether superior cerebral veins, composed mainly of the vein of Trolard, and the inferior cerebral veins, composed mainly of the vein of Labbé, merge or not.
E型SMCV都可被描述为发育不完全的SCMV。无论大脑上静脉(主要由Trolard静脉组成的)和大脑下静脉(主要由Labbé静脉组成的)是否融合。
(2) Flow of the BVs of the SMCV should be along with an embryological development. Our results demonstrate that the rate of anastomoses or BVs between the FST and the TST at the distal portion of the sylvian fissure was very low, the rate of BVs between the FST and the temporal lobe was very low, and the rate of BVs between the TST and the frontal lobe was also very low. These results indicate that the formation of intravenous anastomoses or BVs between the FST and the TST, the FST and the temporal lobe, and the TST and the frontal lobe at the distal portion of the sylvian fissure may be difficult to occur during the embryological process in which the FST and the TST are formed from the superficial telencephalic vein according to each drainage area.
（2）SMCV的桥静脉(BV) 的血液流动应该伴随着胚胎学的发展。我们的结果表明，在外侧裂的远端，FST和TST之间的吻合或桥静脉出现率很低，FST和颞叶之间的桥静脉出现率很低，TST和额叶之间的桥静脉出现率也很低。这些结果表明，在胚胎发生过程中，在外侧裂远端的FST和TST、FST和颞叶、TST和额叶之间的静脉吻合或桥静脉(BV)的形成可能是困难的，因为在胚胎发生过程中FST和TST是根据每个静脉的引流区域从端脑浅静脉形成的。
（3）SMCV的静脉回流应该从进化发展的角度研究。虽然我们无法在本研究中准确评估SMCV的流出点，但一些来自FSV的FST或SMCCT并未回流至颅底静脉窦，而所有来自TSV的TST和SMCCT均引流至颅底静脉窦。因此，颅底静脉窦由Hacker定义的蝶骨基底型和蝶骨岩型，或由Suzuki定义的导血管型、岩上型和基底型可能倾向于由TST或由TSV衍生的SMCCT形成。并且，在SMCCT或FST在额叶底部变成盲端的情况下，静脉回流可从近端部分流向远端部分。这些观点需要进一步研究来澄清。
(4) Intraoperative dissection of the SMCV in a trans-sylvian approach should be performed based on these anatomical features. Although many neurosurgeons start to dissect between the SMCV and the frontal lobe in a trans-sylvian approach, it is often necessary to cut off the BVs with the frontal lobe in order to expand the operative field widely, which may cause vein infarction. On the other hand, some reports recommend dissection between multiple superficial middle cerebral veins or between the SMCV and the temporal lobe based on the number of stems, course and anastomotic form,[12,14]) but there is no consensus yet.
（4）在经侧裂入路的术中应根据这些解剖特征解剖SMCV。虽然许多神经外科医生在经侧裂入路中开始在SMCV和额叶之间进行解剖，但为了广泛扩大手术范围，通常需要切断与额叶的BVs，这可能导致静脉性梗死。另一方面，一些研究报告建议在多个大脑中浅静脉之间或在SMCV和颞叶之间根据静脉干的数量、走行和吻合形式进行解剖，但是还没有达成共识。
For cerebrovascular surgery, we strongly suggest dissection of the SMCV based on our classification to preserve the venous structure (Fig. 3). In Type A SMCV , it is recommended to start to dissect the SMCV on the temporal side of the SMCCT and then dissect between the SMCCT or the FST and the frontal lobe on the base side as much as needed. These procedures will make it possible to increase the mobility of the temporal lobe and get wide operative field while preserving veins. Of course, it is necessary to dissect the frontobasal BV from the frontal lobe as much as possible to increase the more mobility of the frontal lobe.On the other hand, it may be enough to dissect only the temporal side of the SMCCT for some cases of an aneurysm of middle cerebral artery’s bifurcation in distal trans-sylvian approach.
对于脑血管病手术，我们强烈建议根据我们的分类解剖SMCV，以保留静脉结构(图3)。在A型SMCV中，建议开始在SMCCT颞侧开始解剖SMCV，然后根据需要在SMCCT或FST与额叶底面之间解剖。这些手术将有可能增加颞叶的活动度，并在保留静脉的同时获得更宽的手术视野。当然要尽量多的解剖来自额叶的额底桥静脉(BV)，增加额叶更多的活动度。另一方面，对于大脑中动脉分叉部动脉瘤的一些病例，在经侧裂入路中只解剖SMCCT 的颞侧可能就足够了。
Fig. 3 Dissection of the superficial middle cerebral vein (SMCV) based on our classification to preserve the venous structure. Red arrows show the dissection line of the SMCV to preserve the veins as much as possible. FST: frontosylvian trunk, SMCV: superficial middle cerebral vein, TST: temporosylvian trunk, SMCCT: superficial middle cerebral common trunk.
图3.基于保留静脉结构的大脑中浅静脉(SMCV)的解剖分类。红色箭头表示SMCV的解剖线，以尽可能保留静脉。FST：额侧裂干；SMCV：大脑中浅静脉；TST：颞侧裂干；SMCCT：大脑中浅静脉干。
In Type B SMCV , it is recommended to dissect the SMCV on the frontal side of the SMCCT. In Type C SMCV , it is recommended to start to dissect between the FST and the TST until their proximal junction and then dissect between the FST and the frontal lobe on the base side as much as needed. These procedures will make it possible to increase the mobility of the temporal lobe and get wide operative field while preserving veins. It may be enough to dissect only between the FST and the TST until their proximal junction for some cases of an aneurysm of middle cerebral artery’s bifurcation in distal trans-sylvian approach.
在B型SMCV，建议在SMCCT的额侧解剖SMCV。在C型SMCV中，建议开始在FST和TST之间解剖，直到它们的近端连接处，然后根据需要在FST和额叶基底面之间解剖。这些手术将有可能增加颞叶的活动度，并在保留静脉的同时获得更宽的手术视野。对于一些大脑中动脉分叉处动脉瘤的病例，在经侧裂入路中，仅在FST和TST之间解剖直到它们的近侧连接处可能就足够了。
In Type D SMCV , it is recommended to start to dissect between the FST and the TST, and it is unnecessary to dissect between the FST and the frontal lobe, if the proximal end of the FST is connected to the veins of the basal surface of the frontal lobe or deep sylvian veins directly. In Type E SMCV , there is no choice but to dissect between the frontal and the temporal lobe. And, in the case which the SMCCT or the FST becomes blind end at the base of the frontal lobe in Type A or D SMCV , the sacrifice of the SMCCT or the FST may cause the venous infarction of the frontal lobe with a high probability.Because the SMCCT or the FST may drain the lower part of the lateral frontal lobe mainly from the proximal portion to the distal portion. Although it is necessary to investigate in more detail by clinical cases, this classification of the SMCVs with the above characteristics can be helpful in discussing how to dissect the SMCV in a trans-sylvian approach.
在D型SMCV中，建议开始在FST和TST之间解剖，如果FST的近端直接连接到额叶基底面的静脉或侧裂深静脉，则不必在FST和额叶之间解剖。在E型SMCV中，除了在额叶和颞叶之间解剖，别无选择。并且，在A型或D型SMCV中，在额叶基底处，SMCCT或FST成为盲端的情况下，损伤SMCCT或FST可能引起额叶静脉性梗塞的概率较高。因为SMCCT或FST可能主要由近向远引流额叶外侧的下部。虽然有必要通过临床病例进行更详细的研究，但这种具有上述特征的大脑中浅静脉( SMCVs)的分类有助于讨论如何在经外侧裂入路中解剖SMCV。
Conclusion 结论
The SMCVs show various courses and anastomoses. We classified them into five types from an embryological viewpoint. To preserve these veins during surgery, it is useful to dissect the SMCV according to these classifications in trans-sylvian approach.
SMCVs显示各种走形和吻合。我们从胚胎学的角度将它们分为五种类型。为了在手术中保留这些静脉，在经侧裂入路中根据这些分类解剖SMCV是非常有用的。
References
专家简介
王永红，主任医师，教授，医学博士，硕士研究生导师。山西白求恩医院、山西医学科学院神经外科副主任，神经创伤病区主任。留美国、欧洲访问学者。中国研究型医院学会神经外科学专业委员会神经重症学组委员会委员，欧美同学会（中国留学人员联谊会）医师协会脑血管病分会常务委员，中国医师协会脑胶质瘤专业委员会 MDT学组委员，首届中国研究型医院学会神经外科学专业委员会青年委员。山西省医学会神经外科学专业委员会神经内镜学组委员，山西省医师协会癫痫和神经电生理医师分会常务委员，熟练掌握神经外科常见病多发病的诊治。擅长于垂体瘤的内镜微创手术治疗，脑外伤，脑出血，神经系统肿瘤，术中神经电生理检测及神经重症监测。近年发表论文国家级三篇，SCI两篇，参与翻译论著一本，主持省级科研项目四项。
声明：脑医汇旗下神外资讯、神介资讯、脑医咨询所发表内容之知识产权为脑医汇及主办方、原作者等相关权利人所有。未经许可，禁止进行转载、摘编、复制、裁切、录制等。经许可授权使用，亦须注明来源。欢迎转发、分享。