Chiari畸形Ⅰ型合并脊髓空洞症后颅窝减压术后影响脊髓空洞早期转归的影像学因素

Imaging factors affecting early prognosis of syrinx after posterior fossa decompression surgery for Chiari malformation type Ⅰ combined with syringomyelia

中文关键词:  Chiari畸形Ⅰ型  脊髓空洞症  后颅窝减压术  转归  影像学参数

英文关键词:Chiari malformation type Ⅰ  Syringomyelia  Posterior fossa decompression  Prognosis  Imaging parameters

中文摘要:

  【摘要】 目的：探究Chiari畸形Ⅰ型（Chiari malformation type Ⅰ，CMⅠ）合并脊髓空洞症（syringomyelia，SM）患者行后颅窝减压术（posterior fossa decompression，PFD）后影响脊髓空洞早期转归的影像学因素。方法：回顾性分析2013年3月~2022年11月北京大学第三医院神经外科收治的60例CMⅠ合并SM患者的临床资料，男18例，女42例；年龄48.8±9.1岁（27~65岁）。所有患者均行PFD治疗。在术前颈椎MRI及X线片上测量空洞最大前后径、空洞最大横径、脊髓前后径、延髓脑桥沟纵距、第四脑室顶点纵距、小脑扁桃体下端纵距、McRae线长度、斜坡长度、斜坡椎管角、C0-C2 Cobb角、C2-C7 Cobb角及颈椎矢状面轴向距离等参数，并计算空洞/脊髓最大比值及空洞最大截面积，通过术后1个月内颈椎MRI测量空洞最大前后径并计算其变化率，根据空洞最大前后径变化率反映的空洞转归情况进行分组，变化率≥20%者纳入改善组；变化率<20%者纳入未改善组，比较两组间影像学结果。采用多因素Logistic回归分析空洞转归的影响因素。结果：随访12.2±7.1d（5~31d），PFD术后空洞改善24例（改善组），未改善36例（未改善组），两组患者年龄与性别无统计学差异（P＞0.05）。术后出现发热2例，短暂性枕部疼痛2例，脑脊液漏4例，切口愈合不良1例，并发症的发生比例组间无统计学差异（P>0.05）。改善组术前的斜坡椎管角和颈椎矢状面轴向距离（153.47°±9.99°，22.10±11.10mm）均显著大于未改善组（147.98°±9.55°，15.83±9.00mm）（P<0.05），术前空洞最大横径（8.34±3.20mm）显著性小于未改善组（10.36±3.71mm，P<0.05），其余术前影像学参数两组间无显著性差异（P＞0.05）。多因素Logistic回归分析显示，术前空洞最大横径长度是空洞缩小的危险因素（OR=1.281，95%CI 1.042~1.576，P<0.05），术前颈椎矢状面轴向距离长度是空洞缩小的保护因素（OR=0.916，95%CI 0.853~0.984，P<0.05）。结论：对于Chiari畸形Ⅰ型合并脊髓空洞症患者，术前空洞最大横径与颈椎矢状面轴向距离是术后早期空洞转归的独立影响因素。

英文摘要:

  【Abstract】 Objectives: To investigate the imaging factors influencing the early prognosis of syrinx in patients with Chiari malformation type Ⅰ(CMⅠ) and syringomyelia (SM) who underwent posterior fossa decompression (PFD). Methods: Clinical data of 60 patients with CMⅠ and SM treated in the Department of Neurosurgery of Peking University Third Hospital from March 2013 to November 2022 were analyzed retrospectively. There were 18 males and 42 females with an average age of 48.8±9.1(range, 27-65) years old. All the patients underwent PFD. Imaging assessments were performed preoperatively by cervical spine MRI and X-ray, and parameters were collected, including maximum anterior-posterior and transverse diameters of syrinx, spinal cord anterior-posterior diameter, longitudinal distances of bulbo-pontine sulcus, fourth ventricle and cerebellar tonsil, length of McRae line, length of clivus, clivus-canal angle, C0-C2 and C2-C7 Cobb angles as well as cervical sagittal vertical axis. The maximum syrinx/cord ratio and maximum syrinx area were calculated. Within 1 month postoperatively, the maximum anterior-posterior diameter of syrinx was measured again by cervical spine MRI and its change rate was calculated to evaluate the early prognosis of syrinx. The patients were divided into improved(the change rate≥20%) and unimproved(the change rate<20%) groups. The imaging findings were compared between the two groups, and a multi-variate logistic regression analysis was employed to identify significant predictors. Results: All the patients were followed up for 12.2±7.1d(range, 5-31d). After PFD surgery, 24 cases were improved in syrinx(the improved group), while 36 cases were not improved(the unimproved group). Age and gender were not significantly different between the two groups(P>0.05). Postoperatively, there were 2 cases with fever, 2 cases with transient occipital pain, 4 cases with CSF leakage, 1 case with poor incision healing, and there was no significant difference of overall complication ratio between the two groups(P>0.05). The clivus-canal angle and cervical sagittal vertical axis of CMⅠ patients in improved group(153.47°±9.99°, 22.10±11.10mm) were significantly greater than those of unimproved patients(147.98°±9.55°, 15.83±9.00mm)(P<0.05). The maximum transverse diameter of syrinx in improved group(8.34±3.20mm) was significantly smaller than that of unimproved group(10.36±3.71mm, P<0.05). No significant differences were found in other preoperative imaging parameters(P>0.05). The multi-variate logisitic analysis revealed that the maximum transverse diameter of syrinx before operation was a risk factor of syrinx size reduction(OR=1.281, 95%CI 1.042-1.576, P<0.05), while the offset distance of cervical sagittal vertical axis acted as a protective factor of syrinx size reduction(OR=0.916, 95%CI 0.853-0.984, P<0.05). Conclusions: In patients with CMⅠ and SM, preoperative maximum transverse diameter of syrinx and offset distance of cervical sagittal vertical axis are independent influencing factors for early postoperative prognosis of syrinx.