脑静脉血栓形成

脑静脉血栓形成 脑静脉血栓形成(CVT):包括皮质静脉、深部静脉、硬脑膜静脉，与动脉卒中不同，是一组由多种病因导致的脑静脉系统血管病，过去多称静脉窦血栓，由于发病部位并不局限于静脉窦，脑皮层静脉、深部静脉均可发病，因此称为脑静脉血栓形成更为合理。CVT可发生于任何年龄、性别，但多见于年轻成年人和儿童，且女性多见于20,40岁者，可能是由于该年龄段女性较多服用避孕药或经历产褥期血液处于高凝状态所致。1825年Ribes首先报道本病，随着影像技术的发展(CT、MRI、DSA)，更多的病例被确诊，早期诊断、及时治疗关系到CVT患者的预后。虽然CVT于矢状窦、侧窦和海绵窦均可出现，但上矢状窦血栓形成最多见，发生在直窦的很少报告，总发病率为0.3%,0.5%，且大范围临床资料显示，女性比例较大，于产后1,3周为发病高峰。 病因分类: CVT是脑血管病中的一种特殊临床类型，可分为原发性和继发性两类，原发性即特发性，病因不明，常见的继发性原因为外伤、外科手术、内分泌失调(如妊娠、产褥期、口服避孕药等)、肿瘤(如脑膜瘤、转移瘤等)、感染(如面部危险三角区感染、牙龈炎、中耳炎、乳突炎、鼻窦炎等)、脱水(如烧伤、医源性过度脱水等)和营养不良(消耗性血栓形成)、血液病(红细胞增多症、镰状细胞贫血、白血病、DIC及其他凝血功能障碍)、白塞病等，以及各种原因造成血管壁损伤(如静脉置管)、血流状态改变(如休克纠正后、心肺复苏后)、凝血机制异常导致血栓形成而发病，另外饮酒、劳累、心功能不全、低血压等亦可为本病诱因。其中因细菌感染引起的，称为化脓性静脉窦炎或血栓形成，以及化脓性血栓性静脉炎。 临床表现:据临床资料显示CVT的表现特异性不强，甚至隐匿，给早期诊断及治疗带来很大困难，多数病例因此而误诊并延误治疗。CVT的主要临床表现有以下特点:?群组症候群—高颅压症状和局灶性神经功能损害症状;?患者多为中青年，20,40岁的女性多见，发病前体质较好，并常有促血液高凝形成的诱因;?多为急性、亚急性起病。 ?影像学检查:目前CT与MRI联合是诊断CVT的首选确诊依据，发病几天后CT扫描作为本病诊断的初步依据。其间接征象为脑实质内缺血性或出血性病灶，静脉炎梗死的典型表现为位于非动脉供血区，皮层下两侧对称的异常信号病灶。通常上矢状窦血栓属大脑上静脉回流受阻，故引起的梗死位于颞、枕、顶叶， CT平扫可显示矢状窦旁出血、脑水肿、脑室变小、小脑幕静脉扩大，CT增强扫描如见 “空三角征”则高度提示上矢状窦血栓形成。横窦血栓引起的梗死位于颞叶，若并发脑干或基底节梗死则提示大脑深静脉血栓形成可能。MRI影像对CVT的敏感性要明显提高，MRI和MRV显示血栓形成初期正常血液流空现象消失，并可见静脉窦内条索状异常信号影，表现为T1WI等信号或高信号，T2WI高信号，随着时间的推移，于发病1,2周后T1WI、T2WI均呈等信号，故利用MRI平扫鉴别急性期脑静脉窦血栓的信号与正常脑静脉窦内血液流空信号仍存在一定困难，但CT和MRI检查正常亦不能排除静脉窦血栓形成。MRV直接征象为受累静脉窦闭塞、不规则狭窄或充盈缺损。脑血管造影检查对诊断最为可靠，血栓形成的静脉窦和引流静脉不显影为血栓形成的直接证据。 À N}à?Ûäñ—www.china-radiology.com@•á-ñÈâ}?? 综上及临床资料表明以下4点有助于静脉窦血栓形成的MRI诊断:?À N}à?Ûäñ—www.china-radiology.com@•á-ñÈâ}?? 轴面、矢状面、冠状面扫描显示正常血液流空信号消失，而呈现T1WI等信号或低信号;?延长TR时间，静脉窦高信号依然存在;?T2WI静脉窦内极低信号，而静脉窦壁高信号;are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo ?同时进行MRI增强和MRV有助于诊断。? 脑静脉血栓形成发生率依次: 1、大的硬脑膜窦:上矢状窦、横窦、乙状窦、直窦。 2、脑皮层静脉:引流颞叶血流的下吻合静脉。上吻合静脉是最大的皮层引流静脉，引流至上矢状窦。 3、深部静脉:大脑内静脉、丘脑纹状体静脉。 4、海绵窦。 脑静脉血栓没有特异性表现，因此发现细微影像学表现尤为重要，间接征象可以提示血栓存在。虽然这些征象存在于初次检查，但是经常是回顾性读片发现问题。脑静脉血栓患者常表现癫痫样发作，这一症状在动脉性脑梗塞中通常不会出现。常规非增强MRI或CT发现以下征象需要考虑到脑静脉血栓的可能性。1、血栓直接征象。2、非动脉区域脑梗塞，特别是双侧性，伴有出血性。3、脑皮层或周边性脑组织。4、皮层水肿。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 血凝块CT平扫直接征象表现为高密度血凝块征。出现这一征象仅占1/3病人。正常静脉密度略高于脑组织，部分病例很难分清静脉密度是正常还是密度增高。这些病例增强扫描必不可少。 脑皮层静脉血栓呈线样高密度，又称“线样”征(箭)。 高密度血凝块征(3) 左侧颞叶出血性脑梗塞(红箭)，左侧横窦血栓形成后密度增高(蓝箭) are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 空三角征 CECT显示上矢状窦空三角征，这一征象包括三角形增强区域与中央相对低密度血栓。比较合理的解释是富血供硬脑膜静脉侧枝循环围绕血栓形成的静脉窦，形成这一征象。血栓形成早期可能无“空三角”征，需要依靠增强CT鉴别有无血栓。 空三角征(2) are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 左右横窦、左侧乙状窦血栓形成，血栓周围强化围绕低密度血栓 流空消失 图示T2WI右侧颈静脉、乙状窦正常流空效应，左侧血栓形 成呈高信号(红箭)。 自旋回波序列上，脑静脉通常表现低信号的流空效应，T2WI与FLAIR显示最佳，有时T1WI图像也可以显示，血栓形成通常表现流空消失。虽然这一征象不是完全可靠，但是出现这一征象提示静脉血栓形成的可能，下一步需要增强扫 描。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo T1WI显示自深静脉、直窦至横窦、右侧乙状窦高信号，左 侧横窦显示正常流空效应。发现流空消失对诊断脑静脉血栓 非常有价值，但是也存在一定的缺陷。静脉血流缓慢可以表 现T1WI高信号。 静脉性梗塞 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 静脉性梗塞在诊断脑静脉血栓中起着非常重要的作用。静脉血栓导致静脉压力增高，受累脑白质区形成血管源性水肿。继续发展形成静脉性梗塞、细胞毒性水肿、血管性水肿。这与动脉性梗塞不同，动脉性梗塞仅仅是细胞性水肿，没有血管性水肿。由于静脉压力增高，出血较动脉性梗塞常见。由于不太熟悉静脉性梗塞，我们经常认为这是非典型部位梗塞或非动脉性分布，然而静脉性梗塞有典型分布特征，如图所示。 左图显示大脑内静脉血栓形成、下吻合静脉血栓形成，右图显示上矢状窦血栓形成。上矢状窦、直窦、大脑内静脉属于中线结构，发生静脉梗塞多为双侧性。 上矢状窦血栓形成(静脉性梗塞) 旁矢状窦水肿伴少量出血。 上矢状窦血栓形成是最常发生血栓的脑静脉，75%病例显示梗塞，旁矢状窦异常，常为双侧，60%病例发现出血。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 重建CT矢状位显示上矢状窦血栓形成，旁矢状窦出血，增强CT显示上矢状窦条状血栓形成低密度缺损(红箭)。 下吻合静脉血栓形成致左侧颞叶静脉性梗塞。 由于出血，梗塞区可见线样高密度，左侧横窦轻微高密度(箭)是诊断的关键。这是血栓形成的直接征象，下一步需要CECT进一步明确诊断。 鉴别诊断包括动脉性梗塞、感染、肿瘤等。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo 左侧下吻合静脉血栓形成致颞叶出血性梗塞。出血性梗塞血 肿较大，周围伴有血管性水肿，类似其他原因所致的出血。 此例增强显示左侧乙状窦充盈缺损(蓝箭)。 下吻合静脉血栓形成致颞叶出血性梗塞。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo :Galen静脉与直窦静脉血栓形成。 FLAIR显示左侧丘脑高信号，右侧基底节斑片状高信号，这 种双侧性病变高度怀疑深静脉血栓形成。CT增强矢状位重 建显示Galen静脉、直窦充盈缺损。 年轻患者双侧基底节异常信号，基于该影像表现，鉴别诊断 包括:小血管病变、脱髓鞘病变、中毒性病变、代谢性病变。 are some differences in level of development of the various modes of transport, leading to traffic levels have a greater imbalance. Yibin city, based on the 2008 ~2013 year of external transport of passenger and cargo traffic volume statistics. 2008 ~2013 year, Yibin city, external table 3.1-1 railways roads water transport passenger traffic passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) share (%) Passenger traffic (million) in 2008 ~2013 year, Yibin city, external transport railways roads water transport traffic statistics 3.1-2 time of air cargo