1、脑疝影像学表现1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。2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
2、。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。3示意图a)subfalcial(cingulate)herniation;镰下疝b)uncal herniation;钩疝c)downward(central,transtentorial)herniation;下行性小脑幕疝d)external herniation;颅外疝e)tonsillar herniation.扁桃体疝f)ascending transtentorial herniation(reversed tentorial)上行性小脑幕疝g)sphenoi
3、d herniation蝶骨嵴疝4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 5示意图6解剖关系7解剖关系FQcMb3vTOSyCClvFPOSpCClvss8解剖关系FTCesPd4th VFTMbCes9The suprasellar cistern&the quadrigeminal cisternThe left and center images show the suprasellar ciste
4、rn.Its anterior borders are formed by the frontal lobes(F).Its lateral borders are formed by the uncus(U)of the temporal lobes.The left image shows the 5-pointed star appearance of the suprasellar cistern where the posterior border is formed by the pons(Po).The black arrow points to the fourth ventr
5、icle.The center image shows a higher cut where the suprasellar cistern has a 6-pointed star appearance since the posterior border is formed by the cerebral peduncles(P)which have a central cleft.The right image shows the quadrigeminal cistern(black arrow).Note the babys bottom appearance of its ante
6、rior border.When ICP is increased,the quadrigeminal cistern space is compressed or obliterated.10The suprasellar cistern&the quadrigeminal cistern.The midline sagittal MRI scan shows the levels of the axial diagrams.The quadrigeminal cistern is located above(anterior to)the Q in the highest cut show
7、n(number 9).The anterior border of the quadrigeminal cistern is formed by the superior colliculi(c).Image 8(lower cut)also shows the quadrigeminal cistern.In this case,its anterior border is formed by the inferior colliculi(c).This gives the anterior border of the quadrigeminal cistern the appearanc
8、e of a babys bottom.The quadrigeminal plate is comprised of the superior and inferior colliculi.The quadrigeminal cistern is posterior to this quadrigeminal plate,thus its anterior border may be formed by the inferior or superior colliculi.11镰下疝临床表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
9、大脑镰上引起同侧ACA供血区梗塞伴有其他疝12Subfalcine herniation(cingulate herniation)Transtentorial herniation The suprasellar cistern(left image)is obliterated.The quadrigeminal cistern is very compressed and pushed posteriorly(center image).A subdural hematoma with a midline shift is noted.There is central transtent
10、orial and subfalcine herniation.13ACA供血区梗塞14Uncal herniation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15鞍上池缺角16冠状位CT与MRI17海马旁回褶皱18对侧颞角增宽19同侧桥前池增宽20同侧环池增宽21Uncal herniation22Uncal herniationobliteration of the suprasellar cistern(re
11、d arrow)and the quadrigeminal cistern(green arrow)23Uncal herniationThe ipsilateral ventricle,sulci,fissures are compressed and obliterated,isappeared.obliteration of the suprasellar cistern(s)and quadrigeminal cistern(q)24Uncal herniationAcute infarction1st dayAcute infarction 4th daysq25Uncal hern
12、iationBefore surgery,a big GBM in the left temporal lobe with uncal herniation.After surgery,the GBM was removed,the suprasellar cistern and quadrigeminal cisterns are normal.26Uncal herniationAcute infarction of right posterior artery(PCA),this is a complication of uncal/transtentorial herniation,b
13、ecause the PCA was compressed by brain herniation.27双侧大脑后动脉梗塞28双侧大脑后动脉梗塞29Durette hemorrhage 30Durette hemorrhage31Kernohans notch颞叶疝压迹32Uncal herniationWhen mass effects within or adjacent to the temporal lobe occur,the medial portion of the temporal lobe(uncus)is forced medially and downward over
14、the tentorium.There is ipsilateral pupillary dilation.The uncus is pushed medially into the suprasellar cistern.There is bilateral uncal herniation.The suprasellar cistern is obliterated.33early uncal herniation The right uncus is pushing into the suprasellar cistern;early right uncal herniation.34中
15、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35中心疝36Superior vermian herniation(ascending transtentorial herniation)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37陀螺状外观38双侧环池变窄39四叠体池充满40不露齿的微笑41皱眉42第一天的四叠体池和环池43第二天，四叠体池和环池消失44脑积水45a
16、scending transtentorial herniation46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47枕大孔疝48Tonsillar herniation In tonsillar herniation(rare),a mass effect in the posterior fossa causes the cerebellar tonsils to herniate inferiorly through the foramen magn
17、um compressing the medulla and upper cervical spinal cord.Conscious patients complain of neck pain and vomiting.They may have nystagmus,pupillary dilatation,bradycardia,hypertension and respiratory depression.Early tonsillar herniation is difficult to recognize in an unconscious patient.It may not b
18、e evident on CT scan since axial views cannot see the pathology well.It is best seen on sagittal MRI.Clinically changes in vital signs may be the only clinical clue in an unconscious patient.49Tonsillar herniation50a male patient in his 30s who died of brain stem herniation after completing a marath
19、on.The CT shows(A)loss of the rostral cerebral sulci suggesting increase in ICP,(B)and(C)a large hydrocephalus with widening of both temporal horns.The grey matter can still be differentiated from the white matter,but all sulci are lost.This suggests that the brain oedema is of relative recent onset
20、 and massive tissue ischaemia has not yet occurred.(D)Compression of the fourth ventricle with dilatation of the third ventricle and the caudal aspect of both temporal horns.This is observed with considerable brain oedema and obstructive hydrocephalus.(E)Herniation of the medulla and pons into the f
21、oramen magnum.(F)The tonsils are located at the level of the dens which is a good indicator for foramen magnum herniation.51(A)The disc shows florid hemorrhages with relatively little swelling,indicating a rapid,dramatic increase in CSF pressure.Progressive changes of optic disc oedema are seen in a
22、 patient with an intracranial tumour who declined treatment(B-D).(B)Early nerve fiber dilatation is seen particularly superiorly,inferiorly and nasally.(C)This increases and venous engorgement develops.(D)Temporal nerve fiber dilatation and swelling of the disc increases and hemorrhages appear.(E)In
23、 gross chronic disc oedema the normal retinal vasculature is masked and dilated superficial capillaries are observed.(F)In atrophic optic disc oedema nerve fibers are eventually destroyed and the optic disc without viable nerve fibers does not swell.This patient had longstanding benign intracranial
24、hypertension.Retinochoroidal venous collaterals are present(black arrowhead).52颅外疝53核磁选择1.Subfalcine herniation.This is best seen on coronal MR images.2.Descending transtentorial herniation(uncal herniation,hippocampal herniation).best seen on coronal images,but the compression of the brainstem is best observed on axial T2-WI.3.Ascending transtentorial herniation.The sagittal imaging plane is preferred.4.Cerebellar tonsillar herniation.Sagittal and coronal imaging planes are preferred.545556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57
