A Clinical Study Of Establishing Craniocervical Junction Compression Index For Evaluating Chiari Malformation Type ? Preoperatively

Objective Using the radiologic parameters of craniocervical junction to eestablishing the craniocervical junction compression severity index(CVJCSI)for Preoperation evaluate of Chiari malformation Type I(CMI)patient compression condition,meanwhile,the relationship between CVJCSI and CMI patient 's fossa imaging parameters,efficacy,choice of operation methods was discussed.Methods Retrospective review of posterior decompression— Posterior fossa decompression(PFD),Posterior fossa decompression with duraplasty(PFDD),Resection of tonsils(RT)— in the Department of Neurosurgery,Sichuan Provincial People's Hospital from 2008 to 2018.The Chicago Chiari Efficacy Scale(CCOS)was used to evaluate postoperative outcome.CVJCSI was establishied by the tonsils herniation degree,whether combined with ventral compression,whether emerged brain stems herniation and with/without syrinx.Using the Spearman's correlation and multivariate logistic regression model to analyze the relationship between CVJCSI and patient's demographics,posterior cranial fossa(PCF)imaging parameters.Pearson's correlation analysis,Multiple linear regression model,Multivariate variance analysis was done to identify the CVJCSI and other preoperative variables that correlated with the CCOS sore,additionally,the choice of surgical methods were explored.Result A total of 169 women and 90 male patients were included in the study.The CVJCSI consists of six grades,I.no obvious compression type(49 cases),II.dorsal compression by tonsil herniation alone(76 cases),III.dorsal compression by tonsil and brainstem herniation both(34 cases),IV.ventral compression alone(10 cases),V.dorsal and ventral simultaneous compression(59 cases),VI group.Ventral and dorsal simultaneous compression combine with brainstem herniation(31 cases).The Spearman's correlation analysis and multivariate ordered logistic regression model about the relationship of CVJCSI and other preoperative parameters showed that Clivus Angle(B=-0.26,P<0.001),Cranial Base Angle(B=0.11,P<0.001),M-line-FVV distance(B=-0.22,P<0.001)were independently associated with CVJCSI.The overall CCOS score=12.29±0.16,and the improvement rate was 67.33%.Pearson's correlation analysis and multiple linear regression models(surgical methods as dummy variables)about CVJCSI,PCF parameters with CCOS scores showed that CVJCSI(P<0.001,B=-0.47,VIF=2.00),Syrinx segment(B=-0.07,P<0.001,VIF=1.23)were independently and negatively correlated with CCOS score.Further multivariate variance analysis showed statistically significant differences in CCOS scores between different CVJCSI(P < 0.001)and surgical methods(P = 0.02).After controlling CVJCSI,it showed: CVJCSI = I: The highest PFD score(14.21 ± 1.12,P = 0.04);II: The highest PFDD(14.08 ± 1.29,P = 0.002);III:The highest RT(14.250 ± 1.34,P <0.1);IV: RT is highest and only reaches 13 points(13.00 ± 1.00,P> 0.1);V: RT is highest and only reaches 12 points(12.77 ± 1.51,P =0.024);VI: the scores of the three operation methods were all low(11.50 ± 1.07,11.57± 1.62,12.07 ± 2.02,P > 0.1).Conclusion The CVJCSI established in this study is divided into I-VI grades,which can be used as an ideal tool to quantify the preoperative degree of CVJ compression in CMI patients and to guide the surgical plan.As the CVJCSI level become severe,the Syrinx size gradually increases,but when CVJCSI ? IV,the Syrinx gradually shrinks or even disappears.Moreover,with the increase of CVJCSI,the cranial base gradually flattened,the slope of the clivus decreased,and the M-line-FVV distance was shorter,indicating that the posterior cranial fossa malformation and crowding were more serious.CVJCSI was independently and negatively correlated with CCOS scores in three different posterior decompression procedures.PFD should be the first choice in patients with CVJCSI=I and PFDD in patients with II.When CVJCSI=III,RT is the preferred surgical procedure;When CVJCSI=IV-V,RT is the only effective treatment,and very few patients continue to deteriorate after surgery,but in VI,patients with CVJ compression are heavier,the posterior decompression effect is poor,and the possibility of combined anterior decompression is large.