| Chapter 2(Section 1)Comparison of magnetic resonance 4D flow characteristics of cerebrospinal fluid between Chiari Ⅰ malformation with small and large syrinxObjective To identify whether there is difference in cerebrospinal fluid(CSF)dynamical characteristics between Chiari Ⅰ malformation(CMI)patients with small and large syrinx using 4D magnetic resonance phase contrast(4D-PC)flow imaging.Methods 28 CMI patients and 12 age matched healthy pediatric volunteers were enrolled in this study.According to the ratio of the syrinx diameter(S)to the cord diameter(C),patients were divided into the large syrinx(LS)group and small syrinx(SS)group.Morphometric features of the posterior cranial fossa(PCF)and 4D-PC CSF flow data were acquired through MR scanning and compared between these three groups.Additionally,Pearson correlation analysis was performed to identify the strength of relationships between CSF flow parameters and PCF morphometric measurements.Results 16 patients were identified with small syrinx(maximal S/C ratio < 50%),12 with large syrinx(maximal S/C ratio ≥ 50%).At the level of the foramen magnum,the systolic and diastolic maximal CSF flow velocities were significantly decreased in LS group compared to SS group and controls,but it did not differ significantly between the two latter groups.Besides,the clivus gradient(∠α)was found to be significantly decreased in LS group compared to SS group and normal individuals.Correlation analysis noted that there was a statistically significant association between the CSF peak flow velocities and the clivus gradient.Conclusion Our research first proved that the flatter clivus gradient(∠α)in patients with distended syrinx was correlated with the alternation in CSF hydrodynamics.The restriction of the circulation of CSF at the anterior paramedial subarachnoid space caused by the decreased clivus angle may be the initiator of the development and progression of syrinx.Chapter 2(Section 2)Posterior instrumented spinal fusion for left thoracic scoliosis: a matched comparison between Chiari 1 malformation-associated scoliosis and adolescent idiopathic scoliosisObjective Published research comparing the surgical outcomes between Chiari 1 malformation-associated scoliosis(CMS)and adolescent idiopathic scoliosis(AIS)was mainly based on right thoracic curves(RT)or a group of mixed curve patterns.Apart from the difficulty that many corrective maneuvers must be reversed in the surgery of left thoracic curves(LT),previous studies suggested there might be certain substantial differences between LT and the other curve patterns in CMS patients.Accordingly,the current study was designed to compare the radiographic and clinical outcomes of left thoracic scoliosis undergoing posterior spinal fusion between CMS and AIS(LT-CMS vs LT-AIS).Methods 38 patients with a mean age of 15 years were ultimately enrolled including 19 with LT-CMS(10 males and 9 females)and 19 age-and Cobb angle-matched patients diagnosed as LT-AIS(10 males and 9 females).Demographic data and radiographic parameters were compared between the two groups before surgery,immediately after operation and at the latest follow-up(after a minimum of 2 years).Intraoperative records and postoperative complications were also reviewed and evaluated.The Scoliosis Research Society(SRS)-22 Questionnaire completed by patients prior to spinal fusion and at the recent follow-up were used for clinical outcome assessment.Results The gender ratio,Risser grade,age at surgery and duration of follow-up were similar between the two groups.No significant differences were noted between patients with LT-CMS and LT-AIS in terms of the primary curve magnitude(57.7±13.3° vs 57.1±17.7°,P=0.881).Patients with LT-CMS tended to have less major curve flexibility,greater apical vertebral translation(AVT)and greater thoracic kyphosis(TK),but did not reach significant.During the operation,a trend toward more estimated blood loss(EBL)and transfusion was observed in the LT-CMS group.After surgery,the two groups were similar in the overall major curve correction rate(56.0±15.3% LT-CMS group vs 59.6±13.9% LT-AIS group,P=0.393).Moreover,no significant differences of postoperative coronal and sagittal balance were found between the two groups.At the final follow-up,no intergroup differences were noted with respect to the major curve correction loss or preservation of global balance.Complications occurred in 2 cases,including one case of rod fracture at 2.5 years operation in the LT-CMS group and one case of superficial wound infection in the LT-AIS group.All patients completed the SRS-22 questionnaire at the recent follow-up.Patients of the two groups scored similarly in all the five domains.Conclusion Chiari malformation patients with left thoracic scoliosis undergoing posterior spinal fusion could obtain comparable radiographic and clinical outcomes to AIS.Although surgeons have to reverse many corrective maneuvers and there is a tendency to have a greater intraoperative blood loss in the surgery of LT-CMS,no special risk of postoperative complications was found in those patients.Chapter 2(Section 3)Posterior correction does not aggravate the tonsillar herniation in patients with Chiari Ⅰ malformation associated scoliosisObjective Posterior scoliosis correction without prior posterior fossa decompression was advocated for neurologically asymptomatic patients with Chiari Ⅰ malformation associated scoliosis(CMS).However,the influence of correction surgery on the tonsillar herniation in CMS patients was still unclear.This study was designed to investigate the change of tonsillar herniation in CMS patients undergoing one-stage posterior correction surgery.Methods A total of 27 CMS patients without syringomyelia(22F,5M,average age 15.1±2.4 years)undergoing one-stage posterior correction surgery during January 2010 to January 2017 were enrolled in this study.The extent of tonsillar herniation,the distance from Mc Rae’s Line to the bulbopontine sulcus(line a)and the fourth ventricle vertex(line b)were measured at presentation and 3 weeks after surgery.A difference of 2 mm or more between pre-and post-operation was considered a change.Results There was no significant difference between pre-and post-operation in the tonsillar herniation,line a and line b(P>0.05).Two patients had downward changes in cerebellar tonsil,four in bulbopontine sulcus and two in fourth ventricle vertex,respectively.According to the grade of tonsillar ectopia,no patients had an aggravated grade after correction surgery.No neurologic complication was observed in all patients.Conclusion Posterior scoliosis correction surgery does not significantly aggravate the tonsillar herniation in CMS patients.One-stage posterior scoliosis correction in CMS patients with no or minor neurological deficit is safe and the prophylactic posterior fossa decompression is unnecessary in these patients.Chapter 3 Correction of scoliosis with large thoracic curves in Marfan syndrome: does the high-density pedicle screw construct contribute to better surgical outcomes?Objective To determine whether higher density screw constructs resulted in better surgical outcomes in patients with scoliosis secondary to Marfan syndrome(MF-S)with large thoracic curves(>70°).Methods 34 MF-S patients met the inclusion criteria and were evaluated radiographically before surgery,2 weeks after operation and at the final follow-up.Take the mean screw density as the boundary,patients were categorized as either high density(HD)group or low density(HD)group.Parameters measured included coronal Cobb angle,T5-T12 kyphosis(TK)and T12-S1 lordosis(LL).Additionally,the operation duration,estimated blood loss,screw accuracy,complication rate and clinical outcomes were also compared between the two groups.Results The mean screw density of all patients was 1.40±0.15(range 1.13 to 1.67).Correction rate of the thoracic curve was closely related to the screw density at the concave side(r=0.783,P=0.007).Intergroup comparison showed a significantly higher correction rate of the thoracic coronal curve in HD group(56.59%±4.80% vs 44.54%±9.61%,P=0.036).At last follow-up,coronal correction loss of >5° occurred in 8 cases(47.1%)in the LD group and 3 cases(17.6%)in the HD group.Both groups demonstrated improvement in each domain of the SRS-22 questionnaires after surgery and no significant intergroup difference was found.Conclusion The high-density pedicle screw construct contributed to the significantly improved correction rate of thoracic curves in MF-S patients with large thoracic curves(≥70°).Additionally,increasing of pedicle screw number could help to enhance the structural stability and reduce the correction loss during the follow-up period. |
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