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1、图解脑疝,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
2、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。,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 herniat
3、ion (reversed tentorial)上行性小脑幕疝 g) sphenoid herniation蝶骨嵴疝,4,类型,5,示意图,6,解剖关系,7,解剖关系,8,解剖关系,9,The suprasellar cistern early right uncal herniation.,34,中心疝,35,中心疝,36,Superior vermian herniation ( ascending transtentorial herniation ),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
4、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,45,ascending transtentorial herniation,46,枕大孔疝,47,枕大孔疝,48,Tonsillar herniation,In tonsillar herniation (rare), a mass effect in the posterior fossa causes the cerebellar tonsils to herniate inferiorly through the foramen magnum compressing the medulla a
5、nd 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 be evident on CT scan
6、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.,49,Tonsillar herniation,50,a male patient in his 30s who died of brain stem herniation after completing a marathon.,The CT show
7、s (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 and
8、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
9、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 s
10、een in a 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 hemorrha
11、ges appear. (E) In 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
12、 benign intracranial 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.,54,55,56,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,
