Chiari畸形后颅凹形态学的临床研究

目的　探讨Chiari畸形的发病机理及外科手术方法的选择。方法　测量Chiari畸形病人及正常人枕骨基底部、枕骨鳞部、枕骨外侧部、斜坡长度、脑干长度、小脑最大距离 ,小脑幕与TewinsLine的夹角并计算枕骨斜坡部 斜坡比率 ,结果采用两样本均值的t检验 ,数据以Stata软件处理 ,P <0 0 5为差异显著性标准。结果　结果显示Chiari畸形病人枕骨基底部、枕骨鳞部、枕骨外侧部、斜坡长度 ,小脑幕与TewinsLine的夹角与正常人群相差显著 ,而脑干长度、小脑最大距离与正常人群无显著性差异。结论　Chiari畸形是一种原发性中胚层发育障碍致枕骨发育不良 ,后颅凹狭小 ,致小脑扁桃体下疝并形成脊髓空洞。手术主要是后颅凹减压、硬脑膜扩大修补、后颅凹、枕大池重建 ,必要时切除下疝的小脑扁桃体 ,不主张行脊髓空洞分流术

The clinical study on the morphology of posterior cranial fossa in Chiari malformation

ObjectiveTo demonstrate the pathogenesis of Chiari malformat ion with small post erior cranial fossa and herniation of the cerebellar tonsils due to underdevelo ped occipital bone.To explore the cause of syringomyelia and seek for the more effective surgical treatment.MethodsWe examined the MRI of 22 Chiari malformat ion patients and normal people,measured accurately the three occipital enchondra l parts(the supraocciput,exocciput and basiocciput)and the axial length of the c livus(the basiocciput and basisphenoid),brainstem,cerebellar hemisphere,the an gle of cerebellar tentorium and the ratio of basiocciput to clivus.Resul tsThe a verage lengths between clivus exocciput,supraocciput and basiocciput in Chiari m alformation and control people,and the angles of cerebellar tentorium between Ch i ari malformation and control people were significantly different(P<0.05),t he average length of brainstem and cerebellar hemisphere had no significant differ ence.ConclusionThese results suggest that in Chiari malformati on an underdevelo ped occipital bone are possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm,then induce overcrowding and tighting in the posterior cranial fossa,which contains the normal developed hindbrain and ce rebellum,exacerbate the circulatory disturbances of cerebrospinal fluid,formate the syringomyelia.The purpose of operation is to decompress and reconstruct pos t erior fossa,reconstruct cisterna and duraplasty.It is important to resect the c erebellar tonsils for resuming the normal circulation of cerebrospinal fluid.We are not in favour of syringosubarachnoid shunting in most cases,when a syringomy elia is present.