脑疝分类及影像学表现图解

.,图解脑疝,北京天坛医院神经内科杜万良（reflexhammer）,.,脑疝,是指在颅内压增高的情况下，脑组织通过某些脑池向压力相对较低的部位移位的结果，即脑组织由其原来正常的位置而进入了一个异常的位置。,.,脑疝的类型：,a.大脑镰疝：一侧大脑半球占位病变可使同侧扣带回经大脑镰下缘疝入对侧，胼胝体受压下移。小脑幕切迹疝b.前疝：也称颞叶沟回疝，是颞叶沟回疝于脚间池及环池的前部；后疝：颞叶内侧部疝于四叠体池及环池的后部；f.小脑幕切迹上疝：后颅凹占位病变时，小脑上蚓部可向上疝入小脑幕切迹的四叠体池。c.中心疝：幕上压力增高，致使大脑深部结构及脑干纵轴牵张移位。d.颅外疝：脑组织通过颅外缺损疝出。e.枕骨大孔疝：后颅凹占位病变时，可致小脑扁桃体疝入枕骨大孔。g.蝶骨嵴疝：颅前凹和颅中凹的占位病变，由于病变部压力相对高一些，则额眶回可越过蝶骨嵴进入颅中凹，可颞叶前部挤向颅前凹。,.,示意图,a)subfalcial(cingulate)herniation;镰下疝b)uncalherniation;钩疝c)downward(central,transtentorial)herniation;下行性小脑幕疝d)externalherniation;颅外疝e)tonsillarherniation.扁桃体疝f)ascendingtranstentorialherniation(reversedtentorial)上行性小脑幕疝g)sphenoidherniation蝶骨嵴疝,.,类型,.,示意图,.,解剖关系,.,解剖关系,.,解剖关系,.,Thesuprasellarcisternearlyrightuncalherniation.,.,中心疝,.,中心疝,.,Superiorvermianherniation(ascendingtranstentorialherniation),由于后颅凹的占位效应，小脑蚓和小脑半球通过小脑幕切迹向上移动,.,陀螺状外观,.,双侧环池变窄,.,四叠体池充满,.,不露齿的微笑,.,皱眉,.,第一天的四叠体池和环池,.,第二天，四叠体池和环池消失,.,脑积水,.,ascendingtranstentorialherniation,.,枕大孔疝,.,枕大孔疝,.,Tonsillarherniation,Intonsillarherniation(rare),amasseffectintheposteriorfossacausesthecerebellartonsilstoherniateinferiorlythroughtheforamenmagnumcompressingthemedullaanduppercervicalspinalcord.Consciouspatientscomplainofneckpainandvomiting.Theymayhavenystagmus,pupillarydilatation,bradycardia,hypertensionandrespiratorydepression.Earlytonsillarherniationisdifficulttorecognizeinanunconsciouspatient.ItmaynotbeevidentonCTscansinceaxialviewscannotseethepathologywell.ItisbestseenonsagittalMRI.Clinicallychangesinvitalsignsmaybetheonlyclinicalclueinanunconsciouspatient.,.,Tonsillarherniation,.,amalepatientinhis30swhodiedofbrainstemherniationaftercompletingamarathon.,TheCTshows(A)lossoftherostralcerebralsulcisuggestingincreaseinICP,(B)and(C)alargehydrocephaluswithwideningofbothtemporalhorns.Thegreymattercanstillbedifferentiatedfromthewhitematter,butallsulciarelost.Thissuggeststhatthebrainoedemaisofrelativerecentonsetandmassivetissueischaemiahasnotyetoccurred.(D)Compressionofthefourthventriclewithdilatationofthethirdventricleandthecaudalaspectofbothtemporalhorns.Thisisobservedwithconsiderablebrainoedemaandobstructivehydrocephalus.(E)Herniationofthemedullaandponsintotheforamenmagnum.(F)Thetonsilsarelocatedatthelevelofthedenswhichisagoodindicatorforforamenmagnumherniation.,.,(A)Thediscshowsfloridhemorrhageswithrelativelylittleswelling,indicatingarapid,dramaticincreaseinCSFpressure.Progressivechangesofopticdiscoedemaareseeninapatientwithanintracranialtumourwhodeclinedtreatment(B-D).(B)Earlynervefiberdilatationisseenparticularlysuperiorly,inferiorlyandnasally.(C)Thisincreasesandvenousengorgementdevelops.(D)Temporalnervefiberdilatationandswellingofthediscincreasesandhemorrhagesappear.(E)Ingrosschronicdiscoedemathenormalretinalvasculatureismaskedanddilatedsuperficialcapillariesareobserved.(F)Inatrophicopticdiscoedemanervefibersareeventuallydestroyedandtheopticdiscwithoutviablenervefibersdoesnotswell.Thispatienthadlongstandingbenignintracranialhypertension.Retinochoroidalvenouscollateralsarepresent(blackarrowhead).,.,颅外疝,.,核磁选择,1.Subfalcineherniation.ThisisbestseenoncoronalMRimages.2.Descendingtranstentorialherniation(uncalherniation,hippocampalherniation).bestseenoncoronalimages,butthecompressionofthebrainstemisbestobservedonaxialT2-WI.3.Ascendingtranst