脑疝分类及影像学表现图解

图解脑疝*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；②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 脑疝部位命名 别名 疝入脑组织命名 1．大脑镰下疝 扣带回疝 2．小脑天幕疝前疝后疝 小脑幕切迹疝、小脑幕下降疝脚间池疝环池疝，四叠体疝 颞叶钩回疝海马回疝 3．小脑幕孔中心疝 间脑 4．小脑幕孔上疝 小脑幕上疝 小脑蚓部疝 5．枕骨大孔疝 小脑扁桃体疝示意图解剖关系解剖关系解剖关系Thesuprasellarcistern&thequadrigeminalcistern Theleftandcenterimagesshowthesuprasellarcistern.Itsanteriorbordersareformedbythefrontallobes(F).Itslateralbordersareformedbytheuncus(U)ofthetemporallobes.Theleftimageshowsthe5-pointedstarappearanceofthesuprasellarcisternwheretheposteriorborderisformedbythepons(Po).Theblackarrowpointstothefourthventricle.Thecenterimageshowsahighercutwherethesuprasellarcisternhasa6-pointedstarappearancesincetheposteriorborderisformedbythecerebralpeduncles(P)whichhaveacentralcleft. Therightimageshowsthequadrigeminalcistern(blackarrow).Notethe"baby'sbottom"appearanceofitsanteriorborder.WhenICPisincreased,thequadrigeminalcisternspaceiscompressedorobliterated.Thesuprasellarcistern&thequadrigeminalcistern. ThemidlinesagittalMRIscanshowsthelevelsoftheaxialdiagrams.Thequadrigeminalcisternislocatedabove(anteriorto)the"Q"inthehighestcutshown(number9).Theanteriorborderofthequadrigeminalcisternisformedbythesuperiorcolliculi(c).Image8(lowercut)alsoshowsthequadrigeminalcistern.Inthiscase,itsanteriorborderisformedbytheinferiorcolliculi(c).Thisgivestheanteriorborderofthequadrigeminalcisterntheappearanceofa"baby'sbottom".Thequadrigeminalplateiscomprisedofthesuperiorandinferiorcolliculi.Thequadrigeminalcisternisposteriortothisquadrigeminalplate,thusitsanteriorbordermaybeformedbytheinferiororsuperiorcolliculi.镰下疝 临床现 影像所见 并发症 头痛对侧下肢无力 同侧额角截断大脑镰前份不对称同侧侧脑室腔消失透明隔移位 因大脑前动脉卡压到大脑镰上引起同侧ACA供血区梗塞伴有其他疝Subfalcineherniation(cingulateherniation)Transtentorialherniation Thesuprasellarcistern(leftimage)isobliterated.Thequadrigeminalcisternisverycompressedandpushedposteriorly(centerimage). Asubduralhematomawithamidlineshiftisnoted.Thereiscentraltranstentorialandsubfalcineherniation.ACA供血区梗塞Uncalherniation 临床表现 影像所见 并发症 同侧瞳孔散大、眼动受限（动眼神经受压）对侧偏瘫（同侧大脑脚受压）有时颞叶疝压迹会导致同侧偏瘫（对侧大脑脚受压。假定位体征） 对侧颞角增宽同侧环池增宽同侧桥前池增宽钩回进入鞍上池 大脑后动脉受压导致枕叶梗塞鞍上池缺角冠状位CT与MRI海马旁回褶皱对侧颞角增宽同侧桥前池增宽同侧环池增宽UncalherniationUncalherniation obliterationofthesuprasellarcistern(redarrow)andthequadrigeminalcistern(greenarrow)Uncalherniation Theipsilateralventricle,sulci,fissuresarecompressedandobliterated,isappeared. obliterationofthesuprasellarcistern(s)andquadrigeminalcistern(q)Uncalherniation Acuteinfarction 1stday Acuteinfarction 4thdayUncalherniation Beforesurgery,abigGBMinthelefttemporallobewithuncalherniation. Aftersurgery,theGBMwasremoved,thesuprasellarcisternandquadrigeminalcisternsarenormal.Uncalherniation Acuteinfarctionofrightposteriorartery(PCA),thisisacomplicationofuncal/transtentorialherniation,becausethePCAwascompressedbybrainherniation.双侧大脑后动脉梗塞双侧大脑后动脉梗塞DurettehemorrhageDurettehemorrhageKernohan’snotch颞叶疝压迹Uncalherniation Whenmasseffectswithinoradjacenttothetemporallobeoccur,themedialportionofthetemporallobe(uncus)isforcedmediallyanddownwardoverthetentorium.Thereisipsilateralpupillarydilation.Theuncusispushedmediallyintothesuprasellarcistern.Thereisbilateraluncalherniation.Thesuprasellarcisternisobliterated.earlyuncalherniation Therightuncusispushingintothesuprasellarcistern;earlyrightuncalherniation.中心疝 临床表现 影像所见 并发症 意识改变呼吸模式改变去皮层、去脑小瞳孔 因脉络膜前动脉受压引起苍白球和视束梗塞中心疝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 临床表现 影像所见 并发症 恶心呕吐意识障碍 中脑外观呈陀螺状双侧环池变窄四叠体池充满 因小脑上动脉受压引起梗塞Galen静脉移位脑积水意识障碍迅速出现，并可能死亡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 临床表现 影像所见 并发症 双侧上肢感觉减退意识障碍 轴位像见到小脑扁桃体位于齿状突水平矢状位见到小脑扁桃体低于枕大孔5mm（成人）或7mm（儿童） 小脑扁桃体出血性坏死意识障碍和死亡枕大孔疝Tonsillarherniation Intonsillarherniation(rare),amasseffectintheposteriorfossacausesthecerebellartonsilstoherniateinferiorlythroughtheforamenmagnumcompressingthemedullaanduppercervicalspinalcord.Consciouspatientscomplainofneckpainandvomiting.Theymayhavenystagmus,pupillarydilatation,bradycardia,hypertensionandrespiratorydepression.Earlytonsillarherniationisdifficulttorecognizeinanunconsciouspatient.ItmaynotbeevidentonCTscansinceaxialviewscannotseethepathologywell.ItisbestseenonsagittalMRI.Clinicallychangesinvitalsignsmaybetheonlyclinicalclueinanunconsciouspatient.Tonsillarherniationamalepatientinhis30'swhodiedofbrainstemherniationaftercompletingamarathon. 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.Ascendingtranstentorialherniation.Thesagittalimagingplaneispreferred. 4.Cerebellartonsillarherniation.Sagittalandcoronalimagingplanesarepreferred.小结 占位效应引起的脑组织移位 影像上识别脑疝的关键是看脑池的变化*